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1   /*
2    * #%L
3    * nom.tam FITS library
4    * %%
5    * Copyright (C) 2004 - 2024 nom-tam-fits
6    * %%
7    * This is free and unencumbered software released into the public domain.
8    *
9    * Anyone is free to copy, modify, publish, use, compile, sell, or
10   * distribute this software, either in source code form or as a compiled
11   * binary, for any purpose, commercial or non-commercial, and by any
12   * means.
13   *
14   * In jurisdictions that recognize copyright laws, the author or authors
15   * of this software dedicate any and all copyright interest in the
16   * software to the public domain. We make this dedication for the benefit
17   * of the public at large and to the detriment of our heirs and
18   * successors. We intend this dedication to be an overt act of
19   * relinquishment in perpetuity of all present and future rights to this
20   * software under copyright law.
21   *
22   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
23   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
24   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
25   * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
26   * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
27   * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
28   * OTHER DEALINGS IN THE SOFTWARE.
29   * #L%
30   */
31  
32  package nom.tam.fits;
33  
34  import java.io.ByteArrayInputStream;
35  import java.io.EOFException;
36  import java.io.IOException;
37  import java.math.BigDecimal;
38  import java.math.BigInteger;
39  import java.util.Arrays;
40  import java.util.logging.Logger;
41  
42  import nom.tam.fits.FitsFactory.FitsSettings;
43  import nom.tam.fits.header.IFitsHeader;
44  import nom.tam.fits.header.NonStandard;
45  import nom.tam.fits.header.Standard;
46  import nom.tam.fits.header.hierarch.IHierarchKeyFormatter;
47  import nom.tam.util.ArrayDataInput;
48  import nom.tam.util.AsciiFuncs;
49  import nom.tam.util.ComplexValue;
50  import nom.tam.util.CursorValue;
51  import nom.tam.util.FitsInputStream;
52  import nom.tam.util.FlexFormat;
53  import nom.tam.util.InputReader;
54  
55  import static nom.tam.fits.header.Standard.BLANKS;
56  import static nom.tam.fits.header.Standard.COMMENT;
57  import static nom.tam.fits.header.Standard.CONTINUE;
58  import static nom.tam.fits.header.Standard.HISTORY;
59  
60  /**
61   * An individual entry in the FITS header, such as a key/value pair with an optional comment field, or a comment-style
62   * entry without a value field.
63   */
64  public class HeaderCard implements CursorValue<String>, Cloneable {
65  
66      private static final Logger LOG = Logger.getLogger(HeaderCard.class.getName());
67  
68      /** The number of characters per header card (line). */
69      public static final int FITS_HEADER_CARD_SIZE = 80;
70  
71      /** Maximum length of a FITS keyword field */
72      public static final int MAX_KEYWORD_LENGTH = 8;
73  
74      /** The length of two single quotes that must surround string values. */
75      public static final int STRING_QUOTES_LENGTH = 2;
76  
77      /** Maximum length of a FITS value field. */
78      public static final int MAX_VALUE_LENGTH = 70;
79  
80      /** Maximum length of a comment-style card comment field. */
81      public static final int MAX_COMMENT_CARD_COMMENT_LENGTH = MAX_VALUE_LENGTH + 1;
82  
83      /** Maximum length of a FITS string value field. */
84      public static final int MAX_STRING_VALUE_LENGTH = MAX_VALUE_LENGTH - 2;
85  
86      /** Maximum length of a FITS long string value field. the &amp; for the continuation needs one char. */
87      public static final int MAX_LONG_STRING_VALUE_LENGTH = MAX_STRING_VALUE_LENGTH - 1;
88  
89      /** if a commend needs the be specified 2 extra chars are needed to start the comment */
90      public static final int MAX_LONG_STRING_VALUE_WITH_COMMENT_LENGTH = MAX_LONG_STRING_VALUE_LENGTH - 2;
91  
92      /** Maximum HIERARCH keyword length (80 chars must fit [&lt;keyword&gt;=T] at minimum... */
93      public static final int MAX_HIERARCH_KEYWORD_LENGTH = FITS_HEADER_CARD_SIZE - 2;
94  
95      /** The start and end quotes of the string and the ampasant to continue the string. */
96      public static final int MAX_LONG_STRING_CONTINUE_OVERHEAD = 3;
97  
98      /** The first ASCII character that may be used in header records */
99      public static final char MIN_VALID_CHAR = 0x20;
100 
101     /** The last ASCII character that may be used in header records */
102     public static final char MAX_VALID_CHAR = 0x7e;
103 
104     /** The default keyword to use instead of null or any number of blanks. */
105     public static final String EMPTY_KEY = "";
106 
107     /** The string "HIERARCH." */
108     private static final String HIERARCH_WITH_DOT = NonStandard.HIERARCH.key() + ".";
109 
110     /** The keyword part of the card (set to null if there's no keyword) */
111     private String key;
112 
113     /** The keyword part of the card (set to null if there's no value / empty string) */
114     private String value;
115 
116     /** The comment part of the card (set to null if there's no comment) */
117     private String comment;
118 
119     private IFitsHeader standardKey;
120 
121     /**
122      * The Java class associated to the value
123      *
124      * @since 1.16
125      */
126     private Class<?> type;
127 
128     /** For thread synchronization */
129     private Object lock = new Object();
130 
131     /**
132      * Value type checking policies for when setting values for standardized keywords.
133      * 
134      * @author Attila Kovacs
135      * 
136      * @since  1.19
137      */
138     public enum ValueCheck {
139         /** No value type checking will be performed */
140         NONE,
141         /** Attempting to set values of the wrong type for standardized keywords will log warnings */
142         LOGGING,
143         /** Throw exception when setting a value of the wrong type for a standardized keyword */
144         EXCEPTION
145     }
146 
147     /**
148      * Default value type checking policy for cards with standardized {@link IFitsHeader} keywords.
149      * 
150      * @since 1.19
151      */
152     public static final ValueCheck DEFAULT_VALUE_CHECK_POLICY = ValueCheck.EXCEPTION;
153 
154     private static ValueCheck valueCheck = DEFAULT_VALUE_CHECK_POLICY;
155 
156     /** Private constructor for an empty card, used by other constructors. */
157     private HeaderCard() {
158     }
159 
160     /**
161      * Creates a new header card, but reading from the specified data input stream. The card is expected to be describes
162      * by one or more 80-character wide header 'lines'. If long string support is not enabled, then a new card is
163      * created from the next 80-characters. When long string support is enabled, cunsecutive lines starting with
164      * [<code>CONTINUE </code>] after the first line will be aggregated into a single new card.
165      *
166      * @param  dis                    the data input stream
167      *
168      * @throws UnclosedQuoteException if the line contained an unclosed single quote.
169      * @throws TruncatedFileException if we reached the end of file unexpectedly before fully parsing an 80-character
170      *                                    line.
171      * @throws IOException            if there was some IO issue.
172      *
173      * @see                           FitsFactory#setLongStringsEnabled(boolean)
174      */
175     @SuppressWarnings("deprecation")
176     public HeaderCard(ArrayDataInput dis) throws UnclosedQuoteException, TruncatedFileException, IOException {
177         this(new HeaderCardCountingArrayDataInput(dis));
178     }
179 
180     /**
181      * Creates a new header card, but reading from the specified data input. The card is expected to be describes by one
182      * or more 80-character wide header 'lines'. If long string support is not enabled, then a new card is created from
183      * the next 80-characters. When long string support is enabled, cunsecutive lines starting with
184      * [<code>CONTINUE </code>] after the first line will be aggregated into a single new card.
185      * 
186      * @deprecated                        (<i>for internal use</i>) Its visibility may be reduced or may be removed
187      *                                        entirely in the future. Card counting should be internal to
188      *                                        {@link HeaderCard}.
189      *
190      * @param      dis                    the data input
191      *
192      * @throws     UnclosedQuoteException if the line contained an unclosed single quote.
193      * @throws     TruncatedFileException if we reached the end of file unexpectedly before fully parsing an
194      *                                        80-character line.
195      * @throws     IOException            if there was some IO issue.
196      *
197      * @see                               #HeaderCard(ArrayDataInput)
198      * @see                               FitsFactory#setLongStringsEnabled(boolean)
199      */
200     @Deprecated
201     public HeaderCard(HeaderCardCountingArrayDataInput dis)
202             throws UnclosedQuoteException, TruncatedFileException, IOException {
203         this();
204         key = null;
205         value = null;
206         comment = null;
207         type = null;
208 
209         String card = readOneHeaderLine(dis);
210         HeaderCardParser parsed = new HeaderCardParser(card);
211 
212         // extract the key
213         key = parsed.getKey();
214         type = parsed.getInferredType();
215 
216         if (FitsFactory.isLongStringsEnabled() && parsed.isString() && parsed.getValue().endsWith("&")) {
217             // Potentially a multi-record long string card...
218             parseLongStringCard(dis, parsed);
219         } else {
220             value = parsed.getValue();
221             type = parsed.getInferredType();
222             comment = parsed.getTrimmedComment();
223         }
224 
225     }
226 
227     /**
228      * Creates a new card with a number value. The card will be created either in the integer, fixed-decimal, or format,
229      * with the native precision. If the native precision cannot be fitted in the available card space, the value will
230      * be represented with reduced precision with at least {@link FlexFormat#DOUBLE_DECIMALS}. Trailing zeroes will be
231      * omitted.
232      *
233      * @param  key                 keyword
234      * @param  value               value (can be <code>null</code>, in which case the card type defaults to
235      *                                 <code>Integer.class</code>)
236      *
237      * @throws HeaderCardException for any invalid keyword or value.
238      *
239      * @since                      1.16
240      *
241      * @see                        #HeaderCard(String, Number, String)
242      * @see                        #HeaderCard(String, Number, int, String)
243      * @see                        #create(IFitsHeader, Number)
244      * @see                        FitsFactory#setUseExponentD(boolean)
245      */
246     public HeaderCard(String key, Number value) throws HeaderCardException {
247         this(key, value, FlexFormat.AUTO_PRECISION, null);
248     }
249 
250     /**
251      * Creates a new card with a number value and a comment. The card will be created either in the integer,
252      * fixed-decimal, or format. If the native precision cannot be fitted in the available card space, the value will be
253      * represented with reduced precision with at least {@link FlexFormat#DOUBLE_DECIMALS}. Trailing zeroes will be
254      * omitted.
255      *
256      * @param  key                 keyword
257      * @param  value               value (can be <code>null</code>, in which case the card type defaults to
258      *                                 <code>Integer.class</code>)
259      * @param  comment             optional comment, or <code>null</code>
260      *
261      * @throws HeaderCardException for any invalid keyword or value
262      *
263      * @see                        #HeaderCard(String, Number)
264      * @see                        #HeaderCard(String, Number, int, String)
265      * @see                        #create(IFitsHeader, Number)
266      * @see                        FitsFactory#setUseExponentD(boolean)
267      */
268     public HeaderCard(String key, Number value, String comment) throws HeaderCardException {
269         this(key, value, FlexFormat.AUTO_PRECISION, comment);
270     }
271 
272     /**
273      * Creates a new card with a number value, using scientific notation, with up to the specified decimal places
274      * showing between the decimal place and the exponent. For example, if <code>decimals</code> is set to 2, then
275      * {@link Math#PI} gets formatted as <code>3.14E0</code> (or <code>3.14D0</code> if
276      * {@link FitsFactory#setUseExponentD(boolean)} is enabled).
277      *
278      * @param  key                 keyword
279      * @param  value               value (can be <code>null</code>, in which case the card type defaults to
280      *                                 <code>Integer.class</code>)
281      * @param  decimals            the number of decimal places to show in the scientific notation.
282      * @param  comment             optional comment, or <code>null</code>
283      *
284      * @throws HeaderCardException for any invalid keyword or value
285      *
286      * @see                        #HeaderCard(String, Number)
287      * @see                        #HeaderCard(String, Number, String)
288      * @see                        #create(IFitsHeader, Number)
289      * @see                        FitsFactory#setUseExponentD(boolean)
290      */
291     public HeaderCard(String key, Number value, int decimals, String comment) throws HeaderCardException {
292         if (value == null) {
293             set(key, null, comment, Integer.class);
294             return;
295         }
296 
297         try {
298             checkNumber(value);
299         } catch (NumberFormatException e) {
300             throw new HeaderCardException("FITS headers may not contain NaN or Infinite values", e);
301         }
302         set(key, new FlexFormat().setWidth(spaceForValue(key)).setPrecision(decimals).format(value), comment,
303                 value.getClass());
304     }
305 
306     /**
307      * Creates a new card with a boolean value (and no comment).
308      *
309      * @param  key                 keyword
310      * @param  value               value (can be <code>null</code>)
311      *
312      * @throws HeaderCardException for any invalid keyword
313      *
314      * @see                        #HeaderCard(String, Boolean, String)
315      * @see                        #create(IFitsHeader, Boolean)
316      */
317     public HeaderCard(String key, Boolean value) throws HeaderCardException {
318         this(key, value, null);
319     }
320 
321     /**
322      * Creates a new card with a boolean value, and a comment.
323      *
324      * @param  key                 keyword
325      * @param  value               value (can be <code>null</code>)
326      * @param  comment             optional comment, or <code>null</code>
327      *
328      * @throws HeaderCardException for any invalid keyword or value
329      *
330      * @see                        #HeaderCard(String, Boolean)
331      * @see                        #create(IFitsHeader, Boolean)
332      */
333     public HeaderCard(String key, Boolean value, String comment) throws HeaderCardException {
334         this(key, value == null ? null : (value ? "T" : "F"), comment, Boolean.class);
335     }
336 
337     /**
338      * Creates a new card with a complex value. The real and imaginary parts will be shown either in the fixed decimal
339      * format or in the exponential notation, whichever preserves more digits, or else whichever is the more compact
340      * notation. Trailing zeroes will be omitted.
341      *
342      * @param  key                 keyword
343      * @param  value               value (can be <code>null</code>)
344      *
345      * @throws HeaderCardException for any invalid keyword or value.
346      *
347      * @see                        #HeaderCard(String, ComplexValue, String)
348      * @see                        #HeaderCard(String, ComplexValue, int, String)
349      */
350     public HeaderCard(String key, ComplexValue value) throws HeaderCardException {
351         this(key, value, null);
352     }
353 
354     /**
355      * Creates a new card with a complex value and a comment. The real and imaginary parts will be shown either in the
356      * fixed decimal format or in the exponential notation, whichever preserves more digits, or else whichever is the
357      * more compact notation. Trailing zeroes will be omitted.
358      *
359      * @param  key                 keyword
360      * @param  value               value (can be <code>null</code>)
361      * @param  comment             optional comment, or <code>null</code>
362      *
363      * @throws HeaderCardException for any invalid keyword or value.
364      *
365      * @see                        #HeaderCard(String, ComplexValue)
366      * @see                        #HeaderCard(String, ComplexValue, int, String)
367      */
368     public HeaderCard(String key, ComplexValue value, String comment) throws HeaderCardException {
369         this();
370 
371         if (value == null) {
372             set(key, null, comment, ComplexValue.class);
373             return;
374         }
375 
376         if (!value.isFinite()) {
377             throw new HeaderCardException("Cannot represent " + value + " in FITS headers.");
378         }
379         set(key, value.toBoundedString(spaceForValue(key)), comment, ComplexValue.class);
380     }
381 
382     /**
383      * Creates a new card with a complex number value, using scientific (exponential) notation, with up to the specified
384      * number of decimal places showing between the decimal point and the exponent. Trailing zeroes will be omitted. For
385      * example, if <code>decimals</code> is set to 2, then (&pi;, 12) gets formatted as <code>(3.14E0,1.2E1)</code>.
386      *
387      * @param  key                 keyword
388      * @param  value               value (can be <code>null</code>)
389      * @param  decimals            the number of decimal places to show.
390      * @param  comment             optional comment, or <code>null</code>
391      *
392      * @throws HeaderCardException for any invalid keyword or value.
393      *
394      * @see                        #HeaderCard(String, ComplexValue)
395      * @see                        #HeaderCard(String, ComplexValue, String)
396      */
397     public HeaderCard(String key, ComplexValue value, int decimals, String comment) throws HeaderCardException {
398         this();
399 
400         if (value == null) {
401             set(key, null, comment, ComplexValue.class);
402             return;
403         }
404 
405         if (!value.isFinite()) {
406             throw new HeaderCardException("Cannot represent " + value + " in FITS headers.");
407         }
408         set(key, value.toString(decimals), comment, ComplexValue.class);
409     }
410 
411     /**
412      * <p>
413      * This constructor is now <b>DEPRECATED</b>. You should use {@link #HeaderCard(String, String, String)} to create
414      * cards with <code>null</code> strings, or else {@link #createCommentStyleCard(String, String)} to create any
415      * comment-style card, or {@link #createCommentCard(String)} or {@link #createHistoryCard(String)} to create COMMENT
416      * or HISTORY cards.
417      * </p>
418      * <p>
419      * Creates a card with a string value or comment.
420      * </p>
421      *
422      * @param      key                 The key for the comment or nullable field.
423      * @param      comment             The comment
424      * @param      withNullValue       If <code>true</code> the new card will be a value stle card with a null string
425      *                                     value. Otherwise it's a comment-style card.
426      *
427      * @throws     HeaderCardException for any invalid keyword or value
428      *
429      * @see                            #HeaderCard(String, String, String)
430      * @see                            #createCommentStyleCard(String, String)
431      * @see                            #createCommentCard(String)
432      * @see                            #createHistoryCard(String)
433      *
434      * @deprecated                     Use {@link #HeaderCard(String, String, String)}, or
435      *                                     {@link #createCommentStyleCard(String, String)} instead.
436      */
437     @Deprecated
438     public HeaderCard(String key, String comment, boolean withNullValue) throws HeaderCardException {
439         this(key, null, comment, withNullValue);
440     }
441 
442     /**
443      * <p>
444      * This constructor is now <b>DEPRECATED</b>. It has always been a poor construct. You should use
445      * {@link #HeaderCard(String, String, String)} to create cards with <code>null</code> strings, or else
446      * {@link #createCommentStyleCard(String, String)} to create any comment-style card, or
447      * {@link #createCommentCard(String)} or {@link #createHistoryCard(String)} to create COMMENT or HISTORY cards.
448      * </p>
449      * Creates a comment style card. This may be a comment style card in which case the nullable field should be false,
450      * or a value field which has a null value, in which case the nullable field should be true.
451      *
452      * @param      key                 The key for the comment or nullable field.
453      * @param      value               The value (can be <code>null</code>)
454      * @param      comment             The comment
455      * @param      nullable            If <code>true</code> a null value is a valid value. Otherwise, a
456      *                                     <code>null</code> value turns this into a comment-style card.
457      *
458      * @throws     HeaderCardException for any invalid keyword or value
459      *
460      * @see                            #HeaderCard(String, String, String)
461      * @see                            #createCommentStyleCard(String, String)
462      * @see                            #createCommentCard(String)
463      * @see                            #createHistoryCard(String)
464      *
465      * @deprecated                     Use {@link #HeaderCard(String, String, String)}, or
466      *                                     {@link #createCommentStyleCard(String, String)} instead.
467      */
468     @Deprecated
469     public HeaderCard(String key, String value, String comment, boolean nullable) throws HeaderCardException {
470         this(key, value, comment, (nullable || value != null) ? String.class : null);
471     }
472 
473     /**
474      * Creates a new card with a string value (and no comment).
475      *
476      * @param  key                 keyword
477      * @param  value               value
478      *
479      * @throws HeaderCardException for any invalid keyword or value
480      *
481      * @see                        #HeaderCard(String, String, String)
482      * @see                        #create(IFitsHeader, String)
483      */
484     public HeaderCard(String key, String value) throws HeaderCardException {
485         this(key, value, null, String.class);
486     }
487 
488     /**
489      * Creates a new card with a string value, and a comment
490      *
491      * @param  key                 keyword
492      * @param  value               value
493      * @param  comment             optional comment, or <code>null</code>
494      *
495      * @throws HeaderCardException for any invalid keyword or value
496      *
497      * @see                        #HeaderCard(String, String)
498      * @see                        #create(IFitsHeader, String)
499      */
500     public HeaderCard(String key, String value, String comment) throws HeaderCardException {
501         this(key, value, comment, String.class);
502     }
503 
504     /**
505      * Creates a new card from its component parts. Use locally only...
506      *
507      * @param  key                 Case-sensitive keyword (can be null for COMMENT)
508      * @param  value               the serialized value (tailing spaces will be removed)
509      * @param  comment             an optional comment or null.
510      * @param  type                The Java class from which the value field was derived, or null if it's a
511      *                                 comment-style card with a null value.
512      *
513      * @throws HeaderCardException for any invalid keyword or value
514      *
515      * @see                        #set(String, String, String, Class)
516      */
517     private HeaderCard(String key, String value, String comment, Class<?> type) throws HeaderCardException {
518         if (key != null) {
519             key = trimEnd(key);
520         }
521 
522         if (key == null || key.isEmpty() || key.equals(Standard.COMMENT.key()) || key.equals(Standard.HISTORY.key())) {
523             if (value != null) {
524                 throw new HeaderCardException("Standard commentary keywords may not have an assigned value.");
525             }
526 
527             // Force comment
528             type = null;
529         }
530 
531         set(key, value, comment, type);
532         this.type = type;
533     }
534 
535     /**
536      * Sets all components of the card to the specified values. For internal use only.
537      *
538      * @param  aKey                Case-sensitive keyword (can be <code>null</code> for an unkeyed comment)
539      * @param  aValue              the serialized value (tailing spaces will be removed), or <code>null</code>
540      * @param  aComment            an optional comment or <code>null</code>.
541      * @param  aType               The Java class from which the value field was derived, or null if it's a
542      *                                 comment-style card.
543      *
544      * @throws HeaderCardException for any invalid keyword or value
545      */
546     private void set(String aKey, String aValue, String aComment, Class<?> aType) throws HeaderCardException {
547         // TODO we never call with null type and non-null value internally, so this is dead code here...
548         // if (aType == null && aValue != null) {
549         // throw new HeaderCardException("Null type for value: [" + sanitize(aValue) + "]");
550         // }
551 
552         synchronized (lock) {
553             type = aType;
554 
555             // Remove trailing spaces
556             if (aKey != null) {
557                 aKey = trimEnd(aKey);
558             }
559 
560             // AK: Map null and blank keys to BLANKS.key()
561             // This simplifies things as we won't have to check for null keys separately!
562             if ((aKey == null) || aKey.isEmpty()) {
563                 aKey = EMPTY_KEY;
564             }
565 
566             try {
567                 validateKey(aKey);
568             } catch (RuntimeException e) {
569                 throw new HeaderCardException("Invalid FITS keyword: [" + sanitize(aKey) + "]", e);
570             }
571 
572             key = aKey;
573 
574             try {
575                 validateChars(aComment);
576             } catch (IllegalArgumentException e) {
577                 throw new HeaderCardException("Invalid FITS comment: [" + sanitize(aComment) + "]", e);
578             }
579 
580             comment = aComment;
581 
582             try {
583                 validateChars(aValue);
584             } catch (IllegalArgumentException e) {
585                 throw new HeaderCardException("Invalid FITS value: [" + sanitize(aValue) + "]", e);
586             }
587 
588             if (aValue == null) {
589                 value = null;
590                 return;
591             }
592             if (isStringValue()) {
593                 try {
594                     setValue(aValue);
595                 } catch (Exception e) {
596                     throw new HeaderCardException("Value too long: [" + sanitize(aValue) + "]", e);
597                 }
598             } else {
599                 aValue = aValue.trim();
600 
601                 // Check that the value fits in the space available for it.
602                 if (aValue.length() > spaceForValue()) {
603                     throw new HeaderCardException("Value too long: [" + sanitize(aValue) + "]",
604                             new LongValueException(key, spaceForValue()));
605                 }
606 
607                 value = aValue;
608             }
609         }
610     }
611 
612     @Override
613     protected HeaderCard clone() {
614         try {
615             return (HeaderCard) super.clone();
616         } catch (CloneNotSupportedException e) {
617             return null;
618         }
619     }
620 
621     /**
622      * Returns the number of 80-character header lines needed to store the data from this card.
623      *
624      * @return the size of the card in blocks of 80 bytes. So normally every card will return 1. only long stings can
625      *             return more than one, provided support for long string is enabled.
626      */
627     public int cardSize() {
628         synchronized (lock) {
629             if (FitsFactory.isLongStringsEnabled() && isStringValue() && value != null) {
630                 // this is very bad for performance but it is to difficult to
631                 // keep the cardSize and the toString compatible at all times
632                 return toString().length() / FITS_HEADER_CARD_SIZE;
633             }
634             return 1;
635         }
636     }
637 
638     /**
639      * Returns an independent copy of this card. Both this card and the returned value will have identical content, but
640      * modifying one is guaranteed to not affect the other.
641      *
642      * @return a copy of this carf.
643      */
644     public HeaderCard copy() {
645         HeaderCard copy = clone();
646         return copy;
647     }
648 
649     /**
650      * Returns the keyword component of this card, which may be empty but never <code>null</code>, but it may be an
651      * empty string.
652      *
653      * @return the keyword from this card, guaranteed to be not <code>null</code>).
654      *
655      * @see    #getValue()
656      * @see    #getComment()
657      */
658     @Override
659     public final String getKey() {
660         synchronized (lock) {
661             return key;
662         }
663     }
664 
665     /**
666      * Returns the serialized value component of this card, which may be null.
667      *
668      * @return the value from this card
669      *
670      * @see    #getValue(Class, Object)
671      * @see    #getKey()
672      * @see    #getComment()
673      */
674     public final String getValue() {
675         synchronized (lock) {
676             return value;
677         }
678     }
679 
680     /**
681      * Returns the comment component of this card, which may be null.
682      *
683      * @return the comment from this card
684      *
685      * @see    #getKey()
686      * @see    #getValue()
687      */
688     public final String getComment() {
689         synchronized (lock) {
690             return comment;
691         }
692     }
693 
694     /**
695      * @deprecated                       Not supported by the FITS standard, so do not use. It was included due to a
696      *                                       misreading of the standard itself.
697      *
698      * @return                           the value from this card
699      *
700      * @throws     NumberFormatException if the card's value is null or cannot be parsed as a hexadecimal value.
701      *
702      * @see                              #getValue()
703      */
704     @Deprecated
705     public final long getHexValue() throws NumberFormatException {
706         synchronized (lock) {
707             if (value == null) {
708                 throw new NumberFormatException("Card has a null value");
709             }
710             return Long.decode("0x" + value);
711         }
712     }
713 
714     /**
715      * <p>
716      * Returns the value cast to the specified type, if possible, or the specified default value if the value is
717      * <code>null</code> or if the value is incompatible with the requested type.
718      * </p>
719      * <p>
720      * For number types and values, if the requested type has lesser range or precision than the number stored in the
721      * FITS header, the value is automatically downcast (i.e. possible rounded and/or truncated) -- the same as if an
722      * explicit cast were used in Java. As long as the header value is a proper decimal value, it will be returned as
723      * any requested number type.
724      * </p>
725      *
726      * @param  asType                   the requested class of the value
727      * @param  defaultValue             the value to use if the card has a null value, or a value that cannot be cast to
728      *                                      the specified type.
729      * @param  <T>                      the generic type of the requested class
730      *
731      * @return                          the value from this card as a specific type, or the specified default value
732      *
733      * @throws IllegalArgumentException if the specified Java type of not one that is supported for use in FITS headers.
734      */
735     public <T> T getValue(Class<T> asType, T defaultValue) throws IllegalArgumentException {
736         synchronized (lock) {
737             if (value == null) {
738                 return defaultValue;
739             }
740             if (String.class.isAssignableFrom(asType)) {
741                 return asType.cast(value);
742             }
743             if (value.isEmpty()) {
744                 return defaultValue;
745             }
746             if (Boolean.class.isAssignableFrom(asType)) {
747                 return asType.cast(getBooleanValue((Boolean) defaultValue));
748             }
749             if (ComplexValue.class.isAssignableFrom(asType)) {
750                 return asType.cast(new ComplexValue(value));
751             }
752             if (Number.class.isAssignableFrom(asType)) {
753                 try {
754                     BigDecimal big = new BigDecimal(value.toUpperCase().replace('D', 'E'));
755 
756                     if (Byte.class.isAssignableFrom(asType)) {
757                         return asType.cast(big.byteValue());
758                     }
759                     if (Short.class.isAssignableFrom(asType)) {
760                         return asType.cast(big.shortValue());
761                     }
762                     if (Integer.class.isAssignableFrom(asType)) {
763                         return asType.cast(big.intValue());
764                     }
765                     if (Long.class.isAssignableFrom(asType)) {
766                         return asType.cast(big.longValue());
767                     }
768                     if (Float.class.isAssignableFrom(asType)) {
769                         return asType.cast(big.floatValue());
770                     }
771                     if (Double.class.isAssignableFrom(asType)) {
772                         return asType.cast(big.doubleValue());
773                     }
774                     if (BigInteger.class.isAssignableFrom(asType)) {
775                         return asType.cast(big.toBigInteger());
776                     }
777                     // All possibilities have been exhausted, it must be a BigDecimal...
778                     return asType.cast(big);
779                 } catch (NumberFormatException e) {
780                     // The value is not a decimal number, so return the default value by contract.
781                     return defaultValue;
782                 }
783             }
784         }
785 
786         throw new IllegalArgumentException("unsupported class " + asType);
787     }
788 
789     /**
790      * Checks if this card has both a valid keyword and a (non-null) value.
791      *
792      * @return Is this a key/value card?
793      *
794      * @see    #isCommentStyleCard()
795      */
796     public boolean isKeyValuePair() {
797         synchronized (lock) {
798             return !isCommentStyleCard() && value != null;
799         }
800     }
801 
802     /**
803      * Checks if this card has a string value (which may be <code>null</code>).
804      *
805      * @return <code>true</code> if this card has a string value, otherwise <code>false</code>.
806      *
807      * @see    #isDecimalType()
808      * @see    #isIntegerType()
809      * @see    #valueType()
810      */
811     public boolean isStringValue() {
812         synchronized (lock) {
813             if (type == null) {
814                 return false;
815             }
816             return String.class.isAssignableFrom(type);
817         }
818     }
819 
820     /**
821      * Checks if this card has a decimal (floating-point) type value (which may be <code>null</code>).
822      *
823      * @return <code>true</code> if this card has a decimal (not integer) type number value, otherwise
824      *             <code>false</code>.
825      *
826      * @see    #isIntegerType()
827      * @see    #isStringValue()
828      * @see    #valueType()
829      *
830      * @since  1.16
831      */
832     public boolean isDecimalType() {
833         synchronized (lock) {
834             if (type == null) {
835                 return false;
836             }
837             return Float.class.isAssignableFrom(type) || Double.class.isAssignableFrom(type)
838                     || BigDecimal.class.isAssignableFrom(type);
839         }
840     }
841 
842     /**
843      * Checks if this card has an integer type value (which may be <code>null</code>).
844      *
845      * @return <code>true</code> if this card has an integer type value, otherwise <code>false</code>.
846      *
847      * @see    #isDecimalType()
848      * @see    #isStringValue()
849      * @see    #valueType()
850      *
851      * @since  1.16
852      */
853     public boolean isIntegerType() {
854         synchronized (lock) {
855             if (type == null) {
856                 return false;
857             }
858             return Number.class.isAssignableFrom(type) && !isDecimalType();
859         }
860     }
861 
862     /**
863      * Checks if this card is a comment-style card with no associated value field.
864      *
865      * @return <code>true</code> if this card is a comment-style card, otherwise <code>false</code>.
866      *
867      * @see    #isKeyValuePair()
868      * @see    #isStringValue()
869      * @see    #valueType()
870      *
871      * @since  1.16
872      */
873     public final boolean isCommentStyleCard() {
874         synchronized (lock) {
875             return (type == null);
876         }
877     }
878 
879     /**
880      * Checks if this card cas a hierarch style long keyword.
881      *
882      * @return <code>true</code> if the card has a non-standard HIERARCH style long keyword, with dot-separated
883      *             components. Otherwise <code>false</code>.
884      *
885      * @since  1.16
886      */
887     public final boolean hasHierarchKey() {
888         synchronized (lock) {
889             return isHierarchKey(key);
890         }
891     }
892 
893     /**
894      * Sets a new comment component for this card. The specified comment string will be sanitized to ensure it onlly
895      * contains characters suitable for FITS headers. Invalid characters will be replaced with '?'.
896      *
897      * @param comment the new comment text.
898      */
899     public void setComment(String comment) {
900         synchronized (lock) {
901             this.comment = sanitize(comment);
902         }
903     }
904 
905     /**
906      * Sets a new number value for this card. The new value will be shown in the integer, fixed-decimal, or format,
907      * whichever preserves more digits, or else whichever is the more compact notation. Trailing zeroes will be omitted.
908      *
909      * @param  update                the new value to set (can be <code>null</code>, in which case the card type
910      *                                   defaults to <code>Integer.class</code>)
911      *
912      * @return                       the card itself
913      *
914      * @throws NumberFormatException if the input value is NaN or Infinity.
915      * @throws LongValueException    if the decimal value cannot be represented in the alotted space
916      *
917      * @see                          #setValue(Number, int)
918      */
919     public final HeaderCard setValue(Number update) throws NumberFormatException, LongValueException {
920         return setValue(update, FlexFormat.AUTO_PRECISION);
921     }
922 
923     /**
924      * Sets a new number value for this card, using scientific (exponential) notation, with up to the specified decimal
925      * places showing between the decimal point and the exponent. For example, if <code>decimals</code> is set to 2,
926      * then &pi; gets formatted as <code>3.14E0</code>.
927      *
928      * @param  update                the new value to set (can be <code>null</code>, in which case the card type
929      *                                   defaults to <code>Integer.class</code>)
930      * @param  decimals              the number of decimal places to show in the scientific notation.
931      *
932      * @return                       the card itself
933      *
934      * @throws NumberFormatException if the input value is NaN or Infinity.
935      * @throws LongValueException    if the decimal value cannot be represented in the alotted space
936      *
937      * @see                          #setValue(Number)
938      */
939     public HeaderCard setValue(Number update, int decimals) throws NumberFormatException, LongValueException {
940         synchronized (lock) {
941             if (update instanceof Float || update instanceof Double || update instanceof BigDecimal
942                     || update instanceof BigInteger) {
943                 checkValueType(IFitsHeader.VALUE.REAL);
944             } else {
945                 checkValueType(IFitsHeader.VALUE.INTEGER);
946             }
947 
948             if (update == null) {
949                 value = null;
950                 type = Integer.class;
951             } else {
952                 type = update.getClass();
953                 checkNumber(update);
954                 setUnquotedValue(new FlexFormat().forCard(this).setPrecision(decimals).format(update));
955             }
956         }
957         return this;
958     }
959 
960     private static void checkKeyword(IFitsHeader keyword) throws IllegalArgumentException {
961         if (keyword.key().contains("n")) {
962             throw new IllegalArgumentException("Keyword " + keyword.key() + " has unfilled index(es)");
963         }
964     }
965 
966     private void checkValueType(IFitsHeader.VALUE valueType) throws ValueTypeException {
967         if (standardKey != null) {
968             checkValueType(key, standardKey.valueType(), valueType);
969         }
970     }
971 
972     private static void checkValueType(String key, IFitsHeader.VALUE expect, IFitsHeader.VALUE valueType)
973             throws ValueTypeException {
974         if (expect == IFitsHeader.VALUE.ANY || valueCheck == ValueCheck.NONE) {
975             return;
976         }
977 
978         if (valueType != expect) {
979             if (expect == IFitsHeader.VALUE.REAL && valueType == IFitsHeader.VALUE.INTEGER) {
980                 return;
981             }
982 
983             ValueTypeException e = new ValueTypeException(key, valueType.name());
984 
985             if (valueCheck == ValueCheck.LOGGING) {
986                 LOG.warning(e.getMessage());
987             } else {
988                 throw e;
989             }
990         }
991     }
992 
993     /**
994      * Sets a new boolean value for this cardvalueType
995      *
996      * @param  update             the new value to se (can be <code>null</code>).
997      *
998      * @throws LongValueException if the card has no room even for the single-character 'T' or 'F'. This can never
999      *                                happen with cards created programmatically as they will not allow setting
1000      *                                HIERARCH-style keywords long enough to ever trigger this condition. But, it is
1001      *                                possible to read cards from a non-standard header, which breaches this limit, by
1002      *                                ommitting some required spaces (esp. after the '='), and have a null value. When
1003      *                                that happens, we can be left without room for even a single character.
1004      * @throws ValueTypeException if the card's standard keyword does not support boolean values.
1005      *
1006      * @return                    the card itself
1007      */
1008     public HeaderCard setValue(Boolean update) throws LongValueException, ValueTypeException {
1009         synchronized (lock) {
1010             checkValueType(IFitsHeader.VALUE.LOGICAL);
1011 
1012             if (update == null) {
1013                 value = null;
1014             } else if (spaceForValue() < 1) {
1015                 throw new LongValueException(key, spaceForValue());
1016             } else {
1017                 // There is always room for a boolean value. :-)
1018                 value = update ? "T" : "F";
1019             }
1020 
1021             type = Boolean.class;
1022         }
1023         return this;
1024     }
1025 
1026     /**
1027      * Sets a new complex number value for this card. The real and imaginary part will be shown in the integer,
1028      * fixed-decimal, or format, whichever preserves more digits, or else whichever is the more compact notation.
1029      * Trailing zeroes will be omitted.
1030      *
1031      * @param  update                the new value to set (can be <code>null</code>)
1032      *
1033      * @return                       the card itself
1034      *
1035      * @throws NumberFormatException if the input value is NaN or Infinity.
1036      * @throws LongValueException    if the decimal value cannot be represented in the alotted space
1037      *
1038      * @see                          #setValue(ComplexValue, int)
1039      *
1040      * @since                        1.16
1041      */
1042     public final HeaderCard setValue(ComplexValue update) throws NumberFormatException, LongValueException {
1043         return setValue(update, FlexFormat.AUTO_PRECISION);
1044     }
1045 
1046     /**
1047      * Sets a new complex number value for this card, using scientific (exponential) notation, with up to the specified
1048      * number of decimal places showing between the decimal point and the exponent. Trailing zeroes will be omitted. For
1049      * example, if <code>decimals</code> is set to 2, then (&pi;, 12) gets formatted as <code>(3.14E0,1.2E1)</code>.
1050      *
1051      * @param  update                the new value to set (can be <code>null</code>)
1052      * @param  decimals              the number of decimal places to show in the scientific notation.
1053      *
1054      * @return                       the HeaderCard itself
1055      *
1056      * @throws NumberFormatException if the input value is NaN or Infinity.
1057      * @throws LongValueException    if the decimal value cannot be represented in the alotted space
1058      *
1059      * @see                          #setValue(ComplexValue)
1060      *
1061      * @since                        1.16
1062      */
1063     public HeaderCard setValue(ComplexValue update, int decimals) throws LongValueException {
1064         synchronized (lock) {
1065             checkValueType(IFitsHeader.VALUE.COMPLEX);
1066 
1067             if (update == null) {
1068                 value = null;
1069             } else {
1070                 if (!update.isFinite()) {
1071                     throw new NumberFormatException("Cannot represent " + update + " in FITS headers.");
1072                 }
1073                 setUnquotedValue(update.toString(decimals));
1074             }
1075 
1076             type = ComplexValue.class;
1077         }
1078         return this;
1079     }
1080 
1081     /**
1082      * Sets a new unquoted value for this card, checking to make sure it fits in the available header space. If the
1083      * value is too long to fit, an IllegalArgumentException will be thrown.
1084      *
1085      * @param  update             the new unquoted header value for this card, as a string.
1086      *
1087      * @throws LongValueException if the value is too long to fit in the available space.
1088      */
1089     private void setUnquotedValue(String update) throws LongValueException {
1090         synchronized (lock) {
1091             if (update.length() > spaceForValue()) {
1092                 throw new LongValueException(spaceForValue(), key, value);
1093             }
1094             value = update;
1095         }
1096     }
1097 
1098     /**
1099      * @deprecated                    Not supported by the FITS standard, so do not use. It was included due to a
1100      *                                    misreading of the standard itself.
1101      *
1102      * @param      update             the new value to set
1103      *
1104      * @return                        the HeaderCard itself
1105      *
1106      * @throws     LongValueException if the value is too long to fit in the available space.
1107      *
1108      * @since                         1.16
1109      */
1110     @Deprecated
1111     public HeaderCard setHexValue(long update) throws LongValueException {
1112         synchronized (lock) {
1113             setUnquotedValue(Long.toHexString(update));
1114             type = (update == (int) update) ? Integer.class : Long.class;
1115             return this;
1116         }
1117     }
1118 
1119     /**
1120      * Sets a new string value for this card.
1121      *
1122      * @param  update                         the new value to set
1123      *
1124      * @return                                the HeaderCard itself
1125      *
1126      * @throws ValueTypeException             if the card's keyword does not support string values.
1127      * @throws IllegalStateException          if the card has a HIERARCH keyword that is too long to fit any string
1128      *                                            value.
1129      * @throws IllegalArgumentException       if the new value contains characters that cannot be added to the the FITS
1130      *                                            header.
1131      * @throws LongStringsNotEnabledException if the card contains a long string but support for long strings is
1132      *                                            currently disabled.
1133      *
1134      * @see                                   FitsFactory#setLongStringsEnabled(boolean)
1135      * @see                                   #validateChars(String)
1136      */
1137     public HeaderCard setValue(String update)
1138             throws ValueTypeException, IllegalStateException, IllegalArgumentException, LongStringsNotEnabledException {
1139         synchronized (lock) {
1140             checkValueType(IFitsHeader.VALUE.STRING);
1141 
1142             int space = spaceForValue(key);
1143             if (space < STRING_QUOTES_LENGTH) {
1144                 throw new IllegalStateException("No space for string value for [" + key + "]");
1145             }
1146 
1147             if (update == null) {
1148                 // There is always room for a null string...
1149                 value = null;
1150             } else {
1151                 validateChars(update);
1152                 update = trimEnd(update);
1153                 int l = getHeaderValueSize(update);
1154 
1155                 if (space < l) {
1156                     if (FitsFactory.isLongStringsEnabled()) {
1157                         throw new IllegalStateException("No space for long string value for [" + key + "]");
1158                     }
1159 
1160                     throw new LongStringsNotEnabledException("New string value for [" + key + "] is too long."
1161                             + "\n\n --> You can enable long string support by FitsFactory.setLongStringEnabled(true).\n");
1162                 }
1163                 value = update;
1164             }
1165 
1166             type = String.class;
1167         }
1168         return this;
1169     }
1170 
1171     /**
1172      * Returns the modulo 80 character card image, the toString tries to preserve as much as possible of the comment
1173      * value by reducing the alignment of the Strings if the comment is longer and if longString is enabled the string
1174      * can be split into one more card to have more space for the comment.
1175      *
1176      * @return                                the FITS card as one or more 80-character string blocks.
1177      *
1178      * @throws LongValueException             if the card has a long string value that is too long to contain in the
1179      *                                            space available after the keyword.
1180      * @throws LongStringsNotEnabledException if the card contains a long string but support for long strings is
1181      *                                            currently disabled.
1182      * @throws HierarchNotEnabledException    if the card contains a HIERARCH-style long keyword but support for these
1183      *                                            is currently disabled.
1184      *
1185      * @see                                   FitsFactory#setLongStringsEnabled(boolean)
1186      */
1187     @Override
1188     public String toString() throws LongValueException, LongStringsNotEnabledException, HierarchNotEnabledException {
1189         return toString(FitsFactory.current());
1190     }
1191 
1192     /**
1193      * Same as {@link #toString()} just with a prefetched settings object
1194      *
1195      * @param  settings                       the settings to use for writing the header card
1196      *
1197      * @return                                the string representing the card.
1198      *
1199      * @throws LongValueException             if the card has a long string value that is too long to contain in the
1200      *                                            space available after the keyword.
1201      * @throws LongStringsNotEnabledException if the card contains a long string but support for long strings is
1202      *                                            disabled in the settings.
1203      * @throws HierarchNotEnabledException    if the card contains a HIERARCH-style long keyword but support for these
1204      *                                            is disabled in the settings.
1205      *
1206      * @see                                   FitsFactory#setLongStringsEnabled(boolean)
1207      */
1208     protected String toString(final FitsSettings settings)
1209             throws LongValueException, LongStringsNotEnabledException, HierarchNotEnabledException {
1210         synchronized (lock) {
1211             return new HeaderCardFormatter(settings).toString(this);
1212         }
1213     }
1214 
1215     /**
1216      * Returns the class of the associated value, or null if it's a comment-style card.
1217      *
1218      * @return the type of the value.
1219      *
1220      * @see    #isCommentStyleCard()
1221      * @see    #isKeyValuePair()
1222      * @see    #isIntegerType()
1223      * @see    #isDecimalType()
1224      */
1225     public Class<?> valueType() {
1226         synchronized (lock) {
1227             return type;
1228         }
1229     }
1230 
1231     /**
1232      * Returns the value as a boolean, or the default value if the card has no associated value or it is not a boolean.
1233      *
1234      * @param  defaultValue the default value to return if the card has no associated value or is not a boolean.
1235      *
1236      * @return              the boolean value of this card, or else the default value.
1237      */
1238     private Boolean getBooleanValue(Boolean defaultValue) {
1239         if ("T".equals(value)) {
1240             return true;
1241         }
1242         if ("F".equals(value)) {
1243             return false;
1244         }
1245         return defaultValue;
1246     }
1247 
1248     /**
1249      * Parses a continued long string value and comment for this card, which may occupy one or more consecutive
1250      * 80-character header records.
1251      *
1252      * @param  dis                    the input stream from which to parse the value and comment fields of this card.
1253      * @param  next                   the parser to use for each 80-character record.
1254      *
1255      * @throws IOException            if there was an IO error reading the stream.
1256      * @throws TruncatedFileException if the stream endedc ubnexpectedly in the middle of an 80-character record.
1257      */
1258     @SuppressWarnings("deprecation")
1259     private void parseLongStringCard(HeaderCardCountingArrayDataInput dis, HeaderCardParser next)
1260             throws IOException, TruncatedFileException {
1261 
1262         StringBuilder longValue = new StringBuilder();
1263         StringBuilder longComment = null;
1264 
1265         while (next != null) {
1266             if (!next.isString()) {
1267                 break;
1268             }
1269             String valuePart = next.getValue();
1270             String untrimmedComment = next.getUntrimmedComment();
1271 
1272             if (valuePart == null) {
1273                 // The card cannot have a null value. If it does it wasn't a string card...
1274                 break;
1275             }
1276 
1277             // The end point of the value
1278             int valueEnd = valuePart.length();
1279 
1280             // Check if there card continues into the next record. The value
1281             // must end with '&' and the next card must be a CONTINUE card.
1282             // If so, remove the '&' from the value part, and parse in the next
1283             // card for the next iteration...
1284             if (!dis.markSupported()) {
1285                 throw new IOException("InputStream does not support mark/reset");
1286             }
1287 
1288             // Peek at the next card.
1289             dis.mark();
1290 
1291             try {
1292                 // Check if we should continue parsing this card...
1293                 next = new HeaderCardParser(readOneHeaderLine(dis));
1294                 if (valuePart.endsWith("&") && CONTINUE.key().equals(next.getKey())) {
1295                     // Remove '& from the value part...
1296                     valueEnd--;
1297                 } else {
1298                     // ok move the input stream one card back.
1299                     dis.reset();
1300                     // Clear the parser also.
1301                     next = null;
1302                 }
1303             } catch (EOFException e) {
1304                 // Nothing left to parse after the current one...
1305                 next = null;
1306             }
1307 
1308             // Append the value part from the record last parsed.
1309             longValue.append(valuePart, 0, valueEnd);
1310 
1311             // Append any comment from the card last parsed.
1312             if (untrimmedComment != null) {
1313                 if (longComment == null) {
1314                     longComment = new StringBuilder(untrimmedComment);
1315                 } else {
1316                     longComment.append(untrimmedComment);
1317                 }
1318             }
1319         }
1320 
1321         synchronized (lock) {
1322             comment = longComment == null ? null : longComment.toString().trim();
1323             value = trimEnd(longValue.toString());
1324             type = String.class;
1325         }
1326     }
1327 
1328     /**
1329      * Removes the trailing spaces (if any) from a string. According to the FITS standard, trailing spaces in string are
1330      * not significant (but leading spaces are). As such we should remove trailing spaces when parsing header string
1331      * values.
1332      * 
1333      * @param  s the string as it appears in the FITS header
1334      * 
1335      * @return   the input string if it has no trailing spaces, or else a new string with the trailing spaces removed.
1336      */
1337     private String trimEnd(String s) {
1338         int end = s.length();
1339         for (; end > 0; end--) {
1340             if (!Character.isSpaceChar(s.charAt(end - 1))) {
1341                 break;
1342             }
1343         }
1344         return end == s.length() ? s : s.substring(0, end);
1345     }
1346 
1347     /**
1348      * Returns the minimum number of characters the value field will occupy in the header record, including quotes
1349      * around string values, and quoted quotes inside. The actual header may add padding (e.g. to ensure the end quote
1350      * does not come before byte 20).
1351      *
1352      * @return the minimum number of bytes needed to represent this value in a header record.
1353      *
1354      * @since  1.16
1355      *
1356      * @see    #getHeaderValueSize(String)
1357      * @see    #spaceForValue()
1358      */
1359     int getHeaderValueSize() {
1360         synchronized (lock) {
1361             return getHeaderValueSize(value);
1362         }
1363     }
1364 
1365     /**
1366      * Returns the minimum number of characters the value field will occupy in the header record, including quotes
1367      * around string values, and quoted quotes inside. The actual header may add padding (e.g. to ensure the end quote
1368      * does not come before byte 20). If the long string convention is enabled, this method returns the minimum number
1369      * of characters needed in the leading 80-character record only. The call assumes that the value has been
1370      * appropriately trimmed of trailing and leading spaces as appropriate.
1371      * 
1372      * @param  aValue The proposed value for this card
1373      * 
1374      * @return        the minimum number of bytes needed to represent this value in a header record.
1375      *
1376      * @since         1.16
1377      *
1378      * @see           #spaceForValue()
1379      * @see           #trimEnd(String)
1380      */
1381     private int getHeaderValueSize(String aValue) {
1382         if (aValue == null) {
1383             return 0;
1384         }
1385 
1386         synchronized (lock) {
1387             if (!isStringValue()) {
1388                 return aValue.length();
1389             }
1390 
1391             int n = STRING_QUOTES_LENGTH;
1392 
1393             if (FitsFactory.isLongStringsEnabled()) {
1394                 // If not empty string we need to write at least &...
1395                 return aValue.isEmpty() ? n : n + 1;
1396             }
1397 
1398             n += aValue.length();
1399             for (int i = aValue.length(); --i >= 0;) {
1400                 if (aValue.charAt(i) == '\'') {
1401                     // Add the number of quotes that need escaping.
1402                     n++;
1403                 }
1404             }
1405             return n;
1406         }
1407     }
1408 
1409     /**
1410      * Returns the space available for value and/or comment in a single record the keyword.
1411      *
1412      * @return the number of characters available in a single 80-character header record for a standard (non long
1413      *             string) value and/or comment.
1414      *
1415      * @since  1.16
1416      */
1417     public final int spaceForValue() {
1418         synchronized (lock) {
1419             return spaceForValue(key);
1420         }
1421     }
1422 
1423     /**
1424      * Updates the keyword for this card.
1425      *
1426      * @param  newKey                         the new FITS header keyword to use for this card.
1427      *
1428      * @throws HierarchNotEnabledException    if the new key is a HIERARCH-style long key but support for these is not
1429      *                                            currently enabled.
1430      * @throws IllegalArgumentException       if the keyword contains invalid characters
1431      * @throws LongValueException             if the new keyword does not leave sufficient room for the current
1432      *                                            non-string value.
1433      * @throws LongStringsNotEnabledException if the new keyword does not leave sufficient rooom for the current string
1434      *                                            value without enabling long string support.
1435      *
1436      * @see                                   FitsFactory#setLongStringsEnabled(boolean)
1437      * @see                                   #spaceForValue()
1438      * @see                                   #getValue()
1439      */
1440     public void changeKey(String newKey) throws HierarchNotEnabledException, LongValueException,
1441             LongStringsNotEnabledException, IllegalArgumentException {
1442 
1443         validateKey(newKey);
1444 
1445         synchronized (lock) {
1446             int l = getHeaderValueSize();
1447             int space = spaceForValue(newKey);
1448 
1449             if (l > space) {
1450                 if (isStringValue() && !FitsFactory.isLongStringsEnabled() && space > STRING_QUOTES_LENGTH) {
1451                     throw new LongStringsNotEnabledException(newKey);
1452                 }
1453                 throw new LongValueException(spaceForValue(newKey), newKey + "= " + value);
1454             }
1455             key = newKey;
1456             standardKey = null;
1457         }
1458     }
1459 
1460     /**
1461      * Checks if the card is blank, that is if it contains only empty spaces.
1462      *
1463      * @return <code>true</code> if the card contains nothing but blank spaces.
1464      */
1465     public boolean isBlank() {
1466         synchronized (lock) {
1467             if (!isCommentStyleCard() || !key.isEmpty()) {
1468                 return false;
1469             }
1470             if (comment == null) {
1471                 return true;
1472             }
1473             return comment.isEmpty();
1474         }
1475     }
1476 
1477     /**
1478      * Returns the current policy for checking if set values are of the allowed type for cards with standardized
1479      * {@link IFitsHeader} keywords.
1480      * 
1481      * @return the current value type checking policy
1482      * 
1483      * @since  1.19
1484      * 
1485      * @see    #setValueCheckingPolicy(ValueCheck)
1486      */
1487     public static ValueCheck getValueCheckingPolicy() {
1488         return valueCheck;
1489     }
1490 
1491     /**
1492      * Sets the policy to used for checking if set values conform to the expected types for cards that use standardized
1493      * FITS keywords via the {@link IFitsHeader} interface.
1494      * 
1495      * @param policy the new polict to use for checking value types.
1496      * 
1497      * @see          #getValueCheckingPolicy()
1498      * @see          Header#setKeywordChecking(nom.tam.fits.Header.KeywordCheck)
1499      * 
1500      * @since        1.19
1501      */
1502     public static void setValueCheckingPolicy(ValueCheck policy) {
1503         valueCheck = policy;
1504     }
1505 
1506     /**
1507      * <p>
1508      * Creates a new FITS header card from a FITS stream representation of it, which is how the key/value and comment
1509      * are represented inside the FITS file, normally as an 80-character wide entry. The parsing of header 'lines'
1510      * conforms to all FITS standards, and some optional conventions, such as HIERARCH keywords (if
1511      * {@link FitsFactory#setUseHierarch(boolean)} is enabled), COMMENT and HISTORY entries, and OGIP 1.0 long CONTINUE
1512      * lines (if {@link FitsFactory#setLongStringsEnabled(boolean)} is enabled).
1513      * </p>
1514      * <p>
1515      * However, the parsing here is permissive beyond the standards and conventions, and will do its best to support a
1516      * wide range of FITS files, which may deviate from the standard in subtle (or no so subtle) ways.
1517      * </p>
1518      * <p>
1519      * Here is a brief summary of the rules that guide the parsing of keywords, values, and comment 'fields' from the
1520      * single header line:
1521      * </p>
1522      * <p>
1523      * <b>A. Keywords</b>
1524      * </p>
1525      * <ul>
1526      * <li>The standard FITS keyword is the first 8 characters of the line, or up to an equal [=] character, whichever
1527      * comes first, with trailing spaces removed, and always converted to upper-case.</li>
1528      * <li>If {@link FitsFactory#setUseHierarch(boolean)} is enabled, structured longer keywords can be composed after a
1529      * <code>HIERARCH</code> base key, followed by space (and/or dot ].]) separated parts, up to an equal sign [=]. The
1530      * library will represent the same components (including <code>HIERARCH</code>) but separated by single dots [.].
1531      * For example, the header line starting with [<code>HIERARCH SMA OBS TARGET =</code>], will be referred as
1532      * [<code>HIERARCH.SMA.OBS.TARGET</code>] withing this library. The keyword parts can be composed of any ASCII
1533      * characters except dot [.], white spaces, or equal [=].</li>
1534      * <li>By default, all parts of the key are converted to upper-case. Case sensitive HIERARCH keywords can be
1535      * retained after enabling
1536      * {@link nom.tam.fits.header.hierarch.IHierarchKeyFormatter#setCaseSensitive(boolean)}.</li>
1537      * </ul>
1538      * <p>
1539      * <b>B. Values</b>
1540      * </p>
1541      * <p>
1542      * Values are the part of the header line, that is between the keyword and an optional ending comment. Legal header
1543      * values follow the following parse patterns:
1544      * <ul>
1545      * <li>Begin with an equal sign [=], or else come after a CONTINUE keyword.</li>
1546      * <li>Next can be a quoted value such as <code>'hello'</code>, placed inside two single quotes. Or an unquoted
1547      * value, such as <code>123</code>.</li>
1548      * <li>Quoted values must begin with a single quote ['] and and with the next single quote. If there is no end-quote
1549      * in the line, it is not considered a string value but rather a comment, unless
1550      * {@link FitsFactory#setAllowHeaderRepairs(boolean)} is enabled, in which case the entire remaining line after the
1551      * opening quote is assumed to be a malformed value.</li>
1552      * <li>Unquoted values end at the fist [/] character, or else go until the line end.</li>
1553      * <li>Quoted values have trailing spaces removed, s.t. [<code>'  value   '</code>] becomes
1554      * [<code>  value</code>].</li>
1555      * <li>Unquoted values are trimmed, with both leading and trailing spaces removed, e.g. [<code>  123  </code>]
1556      * becomes [<code>123</code>].</li>
1557      * </ul>
1558      * <p>
1559      * <b>C. Comments</b>
1560      * </p>
1561      * <p>
1562      * The following rules guide the parsing of the values component:
1563      * <ul>
1564      * <li>If a value is present (see above), the comment is what comes after it. That is, for quoted values, everything
1565      * that follows the closing quote. For unquoted values, it's what comes after the first [/], with the [/] itself
1566      * removed.</li>
1567      * <li>If a value is not present, then everything following the keyword is considered the comment.</li>
1568      * <li>Comments are trimmed, with both leading and trailing spaces removed.</li>
1569      * </ul>
1570      *
1571      * @return                          a newly created HeaderCard from a FITS card string.
1572      *
1573      * @param  line                     the card image (typically 80 characters if in a FITS file).
1574      *
1575      * @throws IllegalArgumentException if the card was malformed, truncated, or if there was an IO error.
1576      *
1577      * @see                             FitsFactory#setUseHierarch(boolean)
1578      * @see                             nom.tam.fits.header.hierarch.IHierarchKeyFormatter#setCaseSensitive(boolean)
1579      */
1580     public static HeaderCard create(String line) throws IllegalArgumentException {
1581         try (ArrayDataInput in = stringToArrayInputStream(line)) {
1582             return new HeaderCard(in);
1583         } catch (Exception e) {
1584             throw new IllegalArgumentException("card not legal", e);
1585         }
1586     }
1587 
1588     final IFitsHeader getStandardKey() {
1589         return standardKey;
1590     }
1591 
1592     /**
1593      * Creates a new card with a standard or conventional keyword and a boolean value, with the default comment
1594      * associated with the keyword. Unlike {@link #HeaderCard(String, Boolean)}, this call does not throw an exception,
1595      * since the keyword and comment should be valid by design.
1596      *
1597      * @param  key                      The standard or conventional keyword with its associated default comment.
1598      * @param  value                    the boolean value associated to the keyword
1599      *
1600      * @return                          A new header card with the speficied standard-style key and comment and the
1601      *                                      specified value, or <code>null</code> if the standard key itself is
1602      *                                      malformed or illegal.
1603      *
1604      * @throws IllegalArgumentException if the standard key was ill-defined.
1605      *
1606      * @since                           1.16
1607      */
1608     public static HeaderCard create(IFitsHeader key, Boolean value) throws IllegalArgumentException {
1609         checkKeyword(key);
1610 
1611         try {
1612             HeaderCard hc = new HeaderCard(key.key(), (Boolean) null, key.comment());
1613             hc.standardKey = key;
1614             hc.setValue(value);
1615             return hc;
1616         } catch (HeaderCardException e) {
1617             throw new IllegalArgumentException(e.getMessage(), e);
1618         }
1619     }
1620 
1621     /**
1622      * <p>
1623      * Creates a new card with a standard or conventional keyword and a number value, with the default comment
1624      * associated with the keyword. Unlike {@link #HeaderCard(String, Number)}, this call does not throw a hard
1625      * {@link HeaderCardException} exception, since the keyword and comment should be valid by design. (A runtime
1626      * {@link IllegalArgumentException} may still be thrown in the event that the supplied conventional keywords itself
1627      * is ill-defined -- but this should not happen unless something was poorly coded in this library, on in an
1628      * extension of it).
1629      * </p>
1630      * <p>
1631      * If the value is not compatible with the convention of the keyword, a warning message is logged but no exception
1632      * is thrown (at this point).
1633      * </p>
1634      *
1635      * @param  key                      The standard or conventional keyword with its associated default comment.
1636      * @param  value                    the integer value associated to the keyword.
1637      *
1638      * @return                          A new header card with the speficied standard-style key and comment and the
1639      *                                      specified value.
1640      *
1641      * @throws IllegalArgumentException if the standard key itself was ill-defined.
1642      *
1643      * @since                           1.16
1644      */
1645     public static HeaderCard create(IFitsHeader key, Number value) throws IllegalArgumentException {
1646         checkKeyword(key);
1647 
1648         try {
1649             HeaderCard hc = new HeaderCard(key.key(), (Number) null, key.comment());
1650             hc.standardKey = key;
1651             hc.setValue(value);
1652             return hc;
1653         } catch (HeaderCardException e) {
1654             throw new IllegalArgumentException(e.getMessage(), e);
1655         }
1656     }
1657 
1658     /**
1659      * Creates a new card with a standard or conventional keyword and a number value, with the default comment
1660      * associated with the keyword. Unlike {@link #HeaderCard(String, Number)}, this call does not throw an exception,
1661      * since the keyword and comment should be valid by design.
1662      *
1663      * @param  key                      The standard or conventional keyword with its associated default comment.
1664      * @param  value                    the integer value associated to the keyword.
1665      *
1666      * @return                          A new header card with the speficied standard-style key and comment and the
1667      *                                      specified value.
1668      *
1669      * @throws IllegalArgumentException if the standard key was ill-defined.
1670      *
1671      * @since                           1.16
1672      */
1673     public static HeaderCard create(IFitsHeader key, ComplexValue value) throws IllegalArgumentException {
1674         checkKeyword(key);
1675 
1676         try {
1677             HeaderCard hc = new HeaderCard(key.key(), (ComplexValue) null, key.comment());
1678             hc.standardKey = key;
1679             hc.setValue(value);
1680             return hc;
1681         } catch (HeaderCardException e) {
1682             throw new IllegalArgumentException(e.getMessage(), e);
1683         }
1684     }
1685 
1686     /**
1687      * Creates a new card with a standard or conventional keyword and an integer value, with the default comment
1688      * associated with the keyword. Unlike {@link #HeaderCard(String, Number)}, this call does not throw a hard
1689      * exception, since the keyword and comment sohould be valid by design. The string value however will be checked,
1690      * and an appropriate runtime exception is thrown if it cannot be included in a FITS header.
1691      *
1692      * @param  key                      The standard or conventional keyword with its associated default comment.
1693      * @param  value                    the string associated to the keyword.
1694      *
1695      * @return                          A new header card with the speficied standard-style key and comment and the
1696      *                                      specified value.
1697      *
1698      * @throws IllegalArgumentException if the string value contains characters that are not allowed in FITS headers,
1699      *                                      that is characters outside of the 0x20 thru 0x7E range, or if the standard
1700      *                                      key was ill-defined.
1701      */
1702     public static HeaderCard create(IFitsHeader key, String value) throws IllegalArgumentException {
1703         checkKeyword(key);
1704         validateChars(value);
1705 
1706         try {
1707             HeaderCard hc = new HeaderCard(key.key(), (String) null, key.comment());
1708             hc.standardKey = key;
1709             hc.setValue(value);
1710             return hc;
1711         } catch (HeaderCardException e) {
1712             throw new IllegalArgumentException(e.getMessage(), e);
1713         }
1714     }
1715 
1716     /**
1717      * Creates a comment-style card with no associated value field.
1718      *
1719      * @param  key                 The keyword, or <code>null</code> blank/empty string for an unkeyed comment.
1720      * @param  comment             The comment text.
1721      *
1722      * @return                     a new comment-style header card with the specified key and comment text.
1723      *
1724      * @throws HeaderCardException if the key or value were invalid.
1725      * @throws LongValueException  if the comment text is longer than the space available in comment-style cards (71
1726      *                                 characters max)
1727      *
1728      * @see                        #createUnkeyedCommentCard(String)
1729      * @see                        #createCommentCard(String)
1730      * @see                        #createHistoryCard(String)
1731      * @see                        Header#insertCommentStyle(String, String)
1732      * @see                        Header#insertCommentStyleMultiline(String, String)
1733      */
1734     public static HeaderCard createCommentStyleCard(String key, String comment)
1735             throws HeaderCardException, LongValueException {
1736         if (comment == null) {
1737             comment = "";
1738         } else if (comment.length() > MAX_COMMENT_CARD_COMMENT_LENGTH) {
1739             throw new LongValueException(MAX_COMMENT_CARD_COMMENT_LENGTH, key, comment);
1740         }
1741         HeaderCard card = new HeaderCard();
1742         card.set(key, null, comment, null);
1743         return card;
1744     }
1745 
1746     /**
1747      * Creates a new unkeyed comment card for th FITS header. These are comment-style cards with no associated value
1748      * field, and with a blank keyword. They are commonly used to add explanatory notes in the FITS header. Keyed
1749      * comments are another alternative...
1750      *
1751      * @param  text                a concise descriptive entry (max 71 characters).
1752      *
1753      * @return                     a new COMMENT card with the specified key and comment text.
1754      *
1755      * @throws HeaderCardException if the text contains invalid charaters.
1756      * @throws LongValueException  if the comment text is longer than the space available in comment-style cards (71
1757      *                                 characters max)
1758      *
1759      * @see                        #createCommentCard(String)
1760      * @see                        #createCommentStyleCard(String, String)
1761      * @see                        Header#insertUnkeyedComment(String)
1762      */
1763     public static HeaderCard createUnkeyedCommentCard(String text) throws HeaderCardException, LongValueException {
1764         return createCommentStyleCard(BLANKS.key(), text);
1765     }
1766 
1767     /**
1768      * Creates a new keyed comment card for th FITS header. These are comment-style cards with no associated value
1769      * field, and with COMMENT as the keyword. They are commonly used to add explanatory notes in the FITS header.
1770      * Unkeyed comments are another alternative...
1771      *
1772      * @param  text                a concise descriptive entry (max 71 characters).
1773      *
1774      * @return                     a new COMMENT card with the specified key and comment text.
1775      *
1776      * @throws HeaderCardException if the text contains invalid charaters.
1777      * @throws LongValueException  if the comment text is longer than the space available in comment-style cards (71
1778      *                                 characters max)
1779      *
1780      * @see                        #createUnkeyedCommentCard(String)
1781      * @see                        #createCommentStyleCard(String, String)
1782      * @see                        Header#insertComment(String)
1783      */
1784     public static HeaderCard createCommentCard(String text) throws HeaderCardException, LongValueException {
1785         return createCommentStyleCard(COMMENT.key(), text);
1786     }
1787 
1788     /**
1789      * Creates a new history record for the FITS header. These are comment-style cards with no associated value field,
1790      * and with HISTORY as the keyword. They are commonly used to document the sequence operations that were performed
1791      * on the data before it arrived to the state represented by the FITS file. The text field for history entries is
1792      * limited to 70 characters max per card. However there is no limit to how many such entries are in a FITS header.
1793      *
1794      * @param  text                a concise descriptive entry (max 71 characters).
1795      *
1796      * @return                     a new HISTORY card with the specified key and comment text.
1797      *
1798      * @throws HeaderCardException if the text contains invalid charaters.
1799      * @throws LongValueException  if the comment text is longer than the space available in comment-style cards (71
1800      *                                 characters max)
1801      *
1802      * @see                        #createCommentStyleCard(String, String)
1803      * @see                        Header#insertHistory(String)
1804      */
1805     public static HeaderCard createHistoryCard(String text) throws HeaderCardException, LongValueException {
1806         return createCommentStyleCard(HISTORY.key(), text);
1807     }
1808 
1809     /**
1810      * @deprecated                     Not supported by the FITS standard, so do not use. It was included due to a
1811      *                                     misreading of the standard itself.
1812      *
1813      * @param      key                 the keyword
1814      * @param      value               the integer value
1815      *
1816      * @return                         A new header card, with the specified integer in hexadecomal representation.
1817      *
1818      * @throws     HeaderCardException if the card is invalid (for example the keyword is not valid).
1819      *
1820      * @see                            #createHexValueCard(String, long, String)
1821      * @see                            #getHexValue()
1822      * @see                            Header#getHexValue(String)
1823      */
1824     @Deprecated
1825     public static HeaderCard createHexValueCard(String key, long value) throws HeaderCardException {
1826         return createHexValueCard(key, value, null);
1827     }
1828 
1829     /**
1830      * @deprecated                     Not supported by the FITS standard, so do not use. It was included due to a
1831      *                                     misreading of the standard itself.
1832      *
1833      * @param      key                 the keyword
1834      * @param      value               the integer value
1835      * @param      comment             optional comment, or <code>null</code>.
1836      *
1837      * @return                         A new header card, with the specified integer in hexadecomal representation.
1838      *
1839      * @throws     HeaderCardException if the card is invalid (for example the keyword is not valid).
1840      *
1841      * @see                            #createHexValueCard(String, long)
1842      * @see                            #getHexValue()
1843      * @see                            Header#getHexValue(String)
1844      */
1845     @Deprecated
1846     public static HeaderCard createHexValueCard(String key, long value, String comment) throws HeaderCardException {
1847         return new HeaderCard(key, Long.toHexString(value), comment, Long.class);
1848     }
1849 
1850     /**
1851      * Reads an 80-byte card record from an input.
1852      *
1853      * @param  in                     The input to read from
1854      *
1855      * @return                        The raw, undigested header record as a string.
1856      *
1857      * @throws IOException            if already at the end of file.
1858      * @throws TruncatedFileException if there was not a complete record available in the input.
1859      */
1860     private static String readRecord(InputReader in) throws IOException, TruncatedFileException {
1861         byte[] buffer = new byte[FITS_HEADER_CARD_SIZE];
1862 
1863         int got = 0;
1864 
1865         try {
1866             // Read as long as there is more available, even if it comes in a trickle...
1867             while (got < buffer.length) {
1868                 int n = in.read(buffer, got, buffer.length - got);
1869                 if (n < 0) {
1870                     break;
1871                 }
1872                 got += n;
1873             }
1874         } catch (EOFException e) {
1875             // Just in case read throws EOFException instead of returning -1 by contract.
1876         }
1877 
1878         if (got == 0) {
1879             // Nothing left to read.
1880             throw new EOFException();
1881         }
1882 
1883         if (got < buffer.length) {
1884             // Got an incomplete header card...
1885             throw new TruncatedFileException(
1886                     "Got only " + got + " of " + buffer.length + " bytes expected for a header card");
1887         }
1888 
1889         return AsciiFuncs.asciiString(buffer);
1890     }
1891 
1892     /**
1893      * Read exactly one complete fits header line from the input.
1894      *
1895      * @param  dis                    the data input stream to read the line
1896      *
1897      * @return                        a string of exactly 80 characters
1898      *
1899      * @throwa                        EOFException if already at the end of file.
1900      *
1901      * @throws TruncatedFileException if there was not a complete line available in the input.
1902      * @throws IOException            if the input stream could not be read
1903      */
1904     @SuppressWarnings({"resource", "deprecation"})
1905     private static String readOneHeaderLine(HeaderCardCountingArrayDataInput dis)
1906             throws IOException, TruncatedFileException {
1907         String s = readRecord(dis.in());
1908         dis.cardRead();
1909         return s;
1910     }
1911 
1912     /**
1913      * Returns the maximum number of characters that can be used for a value field in a single FITS header record (80
1914      * characters wide), after the specified keyword.
1915      *
1916      * @param  key the header keyword, which may be a HIERARCH-style key...
1917      *
1918      * @return     the space available for the value field in a single record, after the keyword, and the assigmnent
1919      *                 sequence (or equivalent blank space).
1920      */
1921     private static int spaceForValue(String key) {
1922         if (key.length() > MAX_KEYWORD_LENGTH) {
1923             IHierarchKeyFormatter fmt = FitsFactory.getHierarchFormater();
1924             int keyLen = Math.max(key.length(), MAX_KEYWORD_LENGTH) + fmt.getExtraSpaceRequired(key);
1925             return FITS_HEADER_CARD_SIZE - keyLen - fmt.getMinAssignLength();
1926         }
1927         return FITS_HEADER_CARD_SIZE - (Math.max(key.length(), MAX_KEYWORD_LENGTH) + HeaderCardFormatter.getAssignLength());
1928     }
1929 
1930     private static ArrayDataInput stringToArrayInputStream(String card) {
1931         byte[] bytes = AsciiFuncs.getBytes(card);
1932         if (bytes.length % FITS_HEADER_CARD_SIZE != 0) {
1933             byte[] newBytes = new byte[bytes.length + FITS_HEADER_CARD_SIZE - bytes.length % FITS_HEADER_CARD_SIZE];
1934             System.arraycopy(bytes, 0, newBytes, 0, bytes.length);
1935             Arrays.fill(newBytes, bytes.length, newBytes.length, (byte) ' ');
1936             bytes = newBytes;
1937         }
1938         return new FitsInputStream(new ByteArrayInputStream(bytes));
1939     }
1940 
1941     /**
1942      * This method was designed for use internally. It is 'safe' (not save!) in the sense that the runtime exception it
1943      * may throw does not need to be caught.
1944      *
1945      * @param      key                 keyword
1946      * @param      comment             optional comment, or <code>null</code>
1947      * @param      hasValue            does this card have a (<code>null</code>) value field? If <code>true</code> a
1948      *                                     null value of type <code>String.class</code> is assumed (for backward
1949      *                                     compatibility).
1950      *
1951      * @return                         the new HeaderCard
1952      *
1953      * @throws     HeaderCardException if the card could not be created for some reason (noted as the cause).
1954      *
1955      * @deprecated                     This was to be used internally only, without public visibility. It will become
1956      *                                     unexposed to users in a future release...
1957      */
1958     @Deprecated
1959     public static HeaderCard saveNewHeaderCard(String key, String comment, boolean hasValue) throws HeaderCardException {
1960         return new HeaderCard(key, null, comment, hasValue ? String.class : null);
1961     }
1962 
1963     /**
1964      * Checks if the specified keyword is a HIERARCH-style long keyword.
1965      *
1966      * @param  key The keyword to check.
1967      *
1968      * @return     <code>true</code> if the specified key may be a HIERARC-style key, otehrwise <code>false</code>.
1969      */
1970     private static boolean isHierarchKey(String key) {
1971         return key.toUpperCase().startsWith(HIERARCH_WITH_DOT);
1972     }
1973 
1974     /**
1975      * Replaces illegal characters in the string ith '?' to be suitable for FITS header records. According to the FITS
1976      * standard, headers may only contain ASCII characters in the range 0x20 and 0x7E (inclusive).
1977      *
1978      * @param  str the input string.
1979      *
1980      * @return     the sanitized string for use in a FITS header, with illegal characters replaced by '?'.
1981      *
1982      * @see        #isValidChar(char)
1983      * @see        #validateChars(String)
1984      */
1985     public static String sanitize(String str) {
1986         int nc = str.length();
1987         char[] cbuf = new char[nc];
1988         for (int ic = 0; ic < nc; ic++) {
1989             char c = str.charAt(ic);
1990             cbuf[ic] = isValidChar(c) ? c : '?';
1991         }
1992         return new String(cbuf);
1993     }
1994 
1995     /**
1996      * Checks if a character is valid for inclusion in a FITS header record. The FITS standard specifies that only ASCII
1997      * characters between 0x20 thru 0x7E may be used in FITS headers.
1998      *
1999      * @param  c the character to check
2000      *
2001      * @return   <code>true</code> if the character is allowed in the FITS header, otherwise <code>false</code>.
2002      *
2003      * @see      #validateChars(String)
2004      * @see      #sanitize(String)
2005      */
2006     public static boolean isValidChar(char c) {
2007         return (c >= MIN_VALID_CHAR && c <= MAX_VALID_CHAR);
2008     }
2009 
2010     /**
2011      * Checks the specified string for characters that are not allowed in FITS headers, and throws an exception if any
2012      * are found. According to the FITS standard, headers may only contain ASCII characters in the range 0x20 and 0x7E
2013      * (inclusive).
2014      *
2015      * @param  text                     the input string
2016      *
2017      * @throws IllegalArgumentException if the unput string contains any characters that cannot be in a FITS header,
2018      *                                      that is characters outside of the 0x20 to 0x7E range.
2019      *
2020      * @since                           1.16
2021      *
2022      * @see                             #isValidChar(char)
2023      * @see                             #sanitize(String)
2024      * @see                             #validateKey(String)
2025      */
2026     public static void validateChars(String text) throws IllegalArgumentException {
2027         if (text == null) {
2028             return;
2029         }
2030 
2031         for (int i = text.length(); --i >= 0;) {
2032             char c = text.charAt(i);
2033             if (c < MIN_VALID_CHAR) {
2034                 throw new IllegalArgumentException(
2035                         "Non-printable character(s), e.g. 0x" + (int) c + ", in [" + sanitize(text) + "].");
2036             }
2037             if (c > MAX_VALID_CHAR) {
2038                 throw new IllegalArgumentException(
2039                         "Extendeed ASCII character(s) in [" + sanitize(text) + "]. Only 0x20 through 0x7E are allowed.");
2040             }
2041         }
2042     }
2043 
2044     /**
2045      * Checks if the specified string may be used as a FITS header keyword according to the FITS standard and currently
2046      * settings for supporting extensions to the standard, such as HIERARCH-style keywords.
2047      *
2048      * @param  key                      the proposed keyword string
2049      *
2050      * @throws IllegalArgumentException if the string cannot be used as a FITS keyword with the current settings. The
2051      *                                      exception will contain an informative message describing the issue.
2052      *
2053      * @since                           1.16
2054      *
2055      * @see                             #validateChars(String)
2056      * @see                             FitsFactory#setUseHierarch(boolean)
2057      */
2058     public static void validateKey(String key) throws IllegalArgumentException {
2059         int maxLength = MAX_KEYWORD_LENGTH;
2060         if (isHierarchKey(key)) {
2061             if (!FitsFactory.getUseHierarch()) {
2062                 throw new HierarchNotEnabledException(key);
2063             }
2064             maxLength = MAX_HIERARCH_KEYWORD_LENGTH;
2065             validateHierarchComponents(key);
2066         }
2067 
2068         if (key.length() > maxLength) {
2069             throw new IllegalArgumentException("Keyword is too long: [" + sanitize(key) + "]");
2070         }
2071 
2072         // Check the whole key for non-printable, non-standard ASCII
2073         for (int i = key.length(); --i >= 0;) {
2074             char c = key.charAt(i);
2075             if (c < MIN_VALID_CHAR) {
2076                 throw new IllegalArgumentException(
2077                         "Keyword contains non-printable character 0x" + (int) c + ": [" + sanitize(key) + "].");
2078             }
2079             if (c > MAX_VALID_CHAR) {
2080                 throw new IllegalArgumentException("Keyword contains extendeed ASCII characters: [" + sanitize(key)
2081                         + "]. Only 0x20 through 0x7E are allowed.");
2082             }
2083         }
2084 
2085         // Check if the first 8 characters conform to strict FITS specification...
2086         for (int i = Math.min(MAX_KEYWORD_LENGTH, key.length()); --i >= 0;) {
2087             char c = key.charAt(i);
2088             if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')) {
2089                 continue;
2090             }
2091             if ((c >= '0' && c <= '9') || (c == '-') || (c == '_')) {
2092                 continue;
2093             }
2094             throw new IllegalArgumentException(
2095                     "Keyword [" + sanitize(key) + "] contains invalid characters. Only [A-Z][a-z][0-9][-][_] are allowed.");
2096         }
2097     }
2098 
2099     /**
2100      * Additional checks the extended components of the HIEARCH key (in bytes 9-77), to make sure they conform to our
2101      * own standards of storing hierarch keys as a dot-separated list of components. That is, the keyword must not have
2102      * any spaces...
2103      *
2104      * @param  key                      the HIERARCH keyword to check.
2105      *
2106      * @throws IllegalArgumentException if the keyword is not a proper dot-separated set of non-empty hierarchical
2107      *                                      components
2108      */
2109     private static void validateHierarchComponents(String key) throws IllegalArgumentException {
2110         for (int i = key.length(); --i >= 0;) {
2111             if (Character.isSpaceChar(key.charAt(i))) {
2112                 throw new IllegalArgumentException(
2113                         "No spaces allowed in HIERARCH keywords used internally: [" + sanitize(key) + "].");
2114             }
2115         }
2116 
2117         if (key.indexOf("..") >= 0) {
2118             throw new IllegalArgumentException("HIERARCH keywords with empty component: [" + sanitize(key) + "].");
2119         }
2120     }
2121 
2122     /**
2123      * Checks that a number value is not NaN or Infinite, since FITS does not have a standard for describing those
2124      * values in the header. If the value is not suitable for the FITS header, an exception is thrown.
2125      *
2126      * @param  value                 The number to check
2127      *
2128      * @throws NumberFormatException if the input value is NaN or infinite.
2129      */
2130     private static void checkNumber(Number value) throws NumberFormatException {
2131         if (value instanceof Double) {
2132             if (!Double.isFinite(value.doubleValue())) {
2133                 throw new NumberFormatException("Cannot represent " + value + " in FITS headers.");
2134             }
2135         } else if (value instanceof Float) {
2136             if (!Float.isFinite(value.floatValue())) {
2137                 throw new NumberFormatException("Cannot represent " + value + " in FITS headers.");
2138             }
2139         }
2140     }
2141 
2142 }