/*
    * #%L
    * nom.tam FITS library
    * %%
    * Copyright (C) 2004 - 2024 nom-tam-fits
    * %%
    * This is free and unencumbered software released into the public domain.
    *
    * Anyone is free to copy, modify, publish, use, compile, sell, or
   * distribute this software, either in source code form or as a compiled
   * binary, for any purpose, commercial or non-commercial, and by any
   * means.
   *
   * In jurisdictions that recognize copyright laws, the author or authors
   * of this software dedicate any and all copyright interest in the
   * software to the public domain. We make this dedication for the benefit
   * of the public at large and to the detriment of our heirs and
   * successors. We intend this dedication to be an overt act of
   * relinquishment in perpetuity of all present and future rights to this
   * software under copyright law.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
   * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
   * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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   */
  
  package nom.tam.fits;
  
  import java.math.BigDecimal;
  import java.math.BigInteger;
  import java.util.Locale;
  import java.util.StringTokenizer;
  import java.util.logging.Level;
  import java.util.logging.Logger;
  import java.util.regex.Pattern;
  
  import nom.tam.fits.header.Standard;
  import nom.tam.util.ComplexValue;
  import nom.tam.util.FlexFormat;
  
  import static nom.tam.fits.header.NonStandard.HIERARCH;
  import static nom.tam.fits.header.Standard.CONTINUE;
  
  /**
   * <p>
   * Converts a single 80-character wide FITS header record into a header card. See {@link HeaderCard#create(String)} for
   * a description of the rules that guide parsing.
   * </p>
   * <p>
   * When parsing header records that violate FITS standards, the violations can be logged or will throw appropriate
   * excpetions (depending on the severity of the standard violation and whether
   * {@link FitsFactory#setAllowHeaderRepairs(boolean)} is enabled or not. The logging of violations is disabled by
   * default, but may be controlled via {@link Header#setParserWarningsEnabled(boolean)}.
   * </p>
   *
   * @author Attila Kovacs
   *
   * @see    FitsFactory#setAllowHeaderRepairs(boolean)
   * @see    Header#setParserWarningsEnabled(boolean)
   */
  class HeaderCardParser {
  
      private static final Logger LOG = Logger.getLogger(HeaderCardParser.class.getName());
  
      static {
          // Do not log warnings by default.
          LOG.setLevel(Level.SEVERE);
      }
  
      /** regexp for IEEE floats */
      private static final Pattern DECIMAL_REGEX = Pattern.compile("[+-]?\\d+(\\.\\d*)?([dDeE][+-]?\\d+)?");
  
      /** regexp for complex numbers */
      private static final Pattern COMPLEX_REGEX = Pattern
              .compile("\\(\\s*" + DECIMAL_REGEX + "\\s*,\\s*" + DECIMAL_REGEX + "\\s*\\)");
  
      /** regexp for decimal integers. */
      private static final Pattern INT_REGEX = Pattern.compile("[+-]?\\d+");
  
      /** The header line (usually 80-character width), which to parse. */
      private String line;
  
      /**
       * the value of the card. (trimmed and standardized with . in HIERARCH)
       */
      private String key = null;
  
      /**
       * the value of the card. (trimmed)
       */
      private String value = null;
  
      /**
       * the comment specified with the value.
      */
     private String comment = null;
 
     /**
      * was the value quoted?
      */
     private Class<?> type = null;
 
     /**
      * The position in the string that right after the last character processed by this parser
      */
     private int parsePos = 0;
 
     /**
      * Instantiates a new parser for a FITS header line.
      *
      * @param  line                     a line in the FITS header, normally exactly 80-characters wide (but need not
      *                                      be).
      *
      * @see                             #getKey()
      * @see                             #getValue()
      * @see                             #getComment()
      * @see                             #isString()
      *
      * @throws UnclosedQuoteException   if there is a missing end-quote and header repairs aren't allowed.
      * @throws IllegalArgumentException if the record contained neither a key or a value.
      *
      * @see                             FitsFactory#setAllowHeaderRepairs(boolean)
      */
     HeaderCardParser(String line) throws UnclosedQuoteException, IllegalArgumentException {
         this.line = line;
         // TODO HeaderCard never calls this with a null argument, so the check below is dead code here...
         // if (line == null) {
         // throw new IllegalArgumentException("Cannot parse null string");
         // }
         parseKey();
         parseValue();
         parseComment();
     }
 
     /**
      * Returns the keyword component of the parsed header line. If the processing of HIERARCH keywords is enabled, it
      * may be a `HIERARCH` style long key with the components separated by dots (e.g.
      * `HIERARCH.ORG.SYSTEM.SUBSYS.ELEMENT`). Otherwise, it will be a standard 0--8 character standard uppercase FITS
      * keyword (including simply `HIERARCH` if {@link FitsFactory#setUseHierarch(boolean)} was set <code>false</code>).
      *
      * @return the FITS header keyword for the line.
      *
      * @see    FitsFactory#setUseHierarch(boolean)
      */
     String getKey() {
         return key;
     }
 
     /**
      * Returns the value component of the parsed header line.
      *
      * @return the value part of the line or <code>null</code> if the line contained no value.
      *
      * @see    FitsFactory#setUseHierarch(boolean)
      */
     String getValue() {
         return value;
     }
 
     /**
      * Returns the comment component of the parsed header line, with all leading and trailing spaces preserved.
      *
      * @return the comment part of the line or <code>null</code> if the line contained no comment.
      *
      * @see    #getTrimmedComment()
      */
     String getUntrimmedComment() {
         return comment;
     }
 
     /**
      * Returns the comment component of the parsed header line, with both leading and trailing spaces removed
      *
      * @return the comment part of the line or <code>null</code> if the line contained no comment.
      *
      * @see    #getUntrimmedComment()
      */
     String getTrimmedComment() {
         return comment == null ? null : comment.trim();
     }
 
     /**
      * Returns whether the line contained a quoted string value. By default, strings with missing end quotes are no
      * considered string values, but rather as comments. To allow processing lines with missing quotes as string values,
      * you must set {@link FitsFactory#setAllowHeaderRepairs(boolean)} to <code>true</code> prior to parsing a header
      * line with the missing end quote.
      *
      * @return true if the value was quoted.
      *
      * @see    FitsFactory#setAllowHeaderRepairs(boolean)
      */
     boolean isString() {
         if (type == null) {
             return false;
         }
         return String.class.isAssignableFrom(type);
     }
 
     /**
      * <p>
      * Returns the inferred Java class for the value stored in the header record, such as a {@link String} class, a
      * {@link Boolean} class, an integer type ({@link Integer}, {@link Long}, or {@link BigInteger}) class, a decimal
      * type ({@link Float}, {@link Double}, or {@link BigDecimal}) class, a {@link ComplexValue} class, or
      * <code>null</code>. For number types, it returns the 'smallest' type that can be used to represent the string
      * value.
      * </p>
      * <p>
      * Its an inferred type as the true underlying type that was used to create the value is lost. For example, the
      * value <code>42</code> may have been written from any integer type, including <code>byte</code> or
      * <code>short<code>, but this routine will guess it to be an <code>int</code> ({@link Integer} type. As such, it
      * may not be equal to {@link HeaderCard#valueType()} from which the record was created, and hence should not be
      * used for round-trip testing of type equality.
      * </p>
      *
      * @return the inferred type of the stored serialized (string) value, or <code>null</code> if the value does not
      *             seem to match any of the supported value types.
      *
      * @see    HeaderCard#valueType()
      */
     Class<?> getInferredType() {
         return type;
     }
 
     /**
      * Parses a fits keyword from a card and standardizes it (trim, uppercase, and hierarch with dots).
      */
     private void parseKey() {
         /*
          * AK: The parsing of headers should never be stricter that the writing, such that any header written by this
          * library can be parsed back without errors. (And, if anything, the parsing should be more permissive to allow
          * reading FITS produced by other libraries, which may be less stringent in their rules). The original
          * implementation strongly enforced the ESO HIERARCH convention when reading, but not at all for writing. Here
          * is a tolerant hierarch parser that will read back any hierarch key that was written by this library. The
          * input FITS can use any space or even '.' to separate the hierarchies, and the hierarchical elements may
          * contain any ASCII characters other than those used for separating. It is more in line with what we do with
          * standard keys too.
          */
 
         // Find the '=' in the line, if any...
         int iEq = line.indexOf('=');
 
         // The stem is in the first 8 characters or what precedes an '=' character
         // before that.
         int endStem = (iEq >= 0 && iEq <= HeaderCard.MAX_KEYWORD_LENGTH) ? iEq : HeaderCard.MAX_KEYWORD_LENGTH;
         endStem = Math.min(line.length(), endStem);
 
         String rawStem = line.substring(0, endStem).trim();
 
         // Check for space at the start of the keyword...
         if (endStem > 0 && !rawStem.isEmpty()) {
             if (Character.isSpaceChar(line.charAt(0))) {
                 LOG.warning("[" + sanitize(rawStem) + "] Non-standard starting with a space (trimming).");
             }
         }
 
         String stem = rawStem.toUpperCase();
 
         if (!stem.equals(rawStem)) {
             LOG.warning("[" + sanitize(rawStem) + "] Non-standard lower-case letter(s) in base keyword.");
         }
 
         key = stem;
         parsePos = endStem;
 
         // If not using HIERARCH, then be very resilient, and return whatever key the first 8 chars make...
 
         // If the line does not have an '=', can only be a simple key
         // If it's not a HIERARCH keyword, then return the simple key.
         if (!FitsFactory.getUseHierarch() || (iEq < 0) || !stem.equals(HIERARCH.key())) {
             return;
         }
 
         // Compose the hierarchical key...
         StringTokenizer tokens = new StringTokenizer(line.substring(stem.length(), iEq), " \t\r\n.");
         StringBuilder builder = new StringBuilder(stem);
 
         while (tokens.hasMoreTokens()) {
             String token = tokens.nextToken();
 
             parsePos = line.indexOf(token, parsePos) + token.length();
 
             // Add a . to separate hierarchies
             builder.append('.');
             builder.append(token);
         }
 
         key = builder.toString();
 
         if (HIERARCH.key().equals(key)) {
             // The key is only HIERARCH, without a hierarchical keyword after it...
             LOG.warning("HIERARCH base keyword without HIERARCH-style long key after it.");
             return;
         }
 
         if (!FitsFactory.getHierarchFormater().isCaseSensitive()) {
             key = key.toUpperCase(Locale.US);
         }
 
         try {
             HeaderCard.validateKey(key);
         } catch (IllegalArgumentException e) {
             LOG.warning(e.getMessage());
         }
     }
 
     /**
      * Advances the parse position to skip any spaces at the current parse position, and returns whether there is
      * anything left in the line after the spaces...
      *
      * @return <code>true</code> if there is more non-space characters in the string, otherwise <code>false</code>
      */
     private boolean skipSpaces() {
         for (; parsePos < line.length(); parsePos++) {
             if (!Character.isSpaceChar(line.charAt(parsePos))) {
                 // Line has non-space characters left to parse...
                 return true;
             }
         }
         // nothing left to parse.
         return false;
     }
 
     /**
      * Parses the comment components starting from the current parse position. After this call the parse position is set
      * to the end of the string. The leading '/' (if found) is not included in the comment.
      */
     private void parseComment() {
         if (!skipSpaces()) {
             // nothing left to parse.
             return;
         }
 
         // if no value, then everything is comment from here on...
         if (value != null) {
             if (line.charAt(parsePos) == '/') {
                 // Skip the '/' itself, the comment is whatever is after it.
                 parsePos++;
             } else {
                 // Junk after a string value -- interpret it as the start of the comment...
                 LOG.warning("[" + sanitize(getKey()) + "] Junk after value (included in the comment).");
             }
         }
 
         comment = line.substring(parsePos);
         parsePos = line.length();
 
         try {
             HeaderCard.validateChars(comment);
         } catch (IllegalArgumentException e) {
             LOG.warning("[" + sanitize(getKey()) + "]: " + e.getMessage());
         }
     }
 
     /**
      * Parses the value component from the current parse position. The parse position is advanced to the first character
      * after the value specification in the line. If the header line does not contain a value component, then the value
      * field of this object is set to <code>null</code>.
      *
      * @throws UnclosedQuoteException if there is a missing end-quote and header repairs aren't allowed.
      *
      * @see                           FitsFactory#setAllowHeaderRepairs(boolean)
      */
     private void parseValue() throws UnclosedQuoteException {
         if (key.isEmpty() || key.equals(Standard.COMMENT.key()) || key.equals(Standard.HISTORY.key())) {
             return;
         }
 
         if (!skipSpaces()) {
             return; // nothing left to parse.
         }
 
         if (CONTINUE.key().equals(key)) {
             parseValueBody();
         } else if (line.charAt(parsePos) == '=') {
 
             if (parsePos < HeaderCard.MAX_KEYWORD_LENGTH) {
                 LOG.warning("[" + sanitize(key) + "] assigmment before byte " + (HeaderCard.MAX_KEYWORD_LENGTH + 1)
                         + " for key '" + sanitize(key) + "'.");
             }
             if (parsePos + 1 >= line.length()) {
                 LOG.warning("[" + sanitize(key) + "] Record ends with '='.");
             } else if (line.charAt(parsePos + 1) != ' ') {
                 LOG.warning("[" + sanitize(key) + "] Missing required standard space after '='.");
             }
 
             if (parsePos > HeaderCard.MAX_KEYWORD_LENGTH) {
                 // equal sign = after the 9th char -- only supported with hierarch keys...
                 if (!key.startsWith(HIERARCH.key() + ".")) {
                     LOG.warning("[" + sanitize(key) + "] Possibly misplaced '=' (after byte 9).");
                     // It's not a HIERARCH key
                     return;
                 }
             }
 
             parsePos++;
             parseValueBody();
         }
 
         try {
             HeaderCard.validateChars(value);
         } catch (IllegalArgumentException e) {
             LOG.warning("[" + sanitize(getKey()) + "] " + e.getMessage());
         }
     }
 
     /**
      * Parses the value body from the current parse position. The parse position is advanced to the first character
      * after the value specification in the line. If the header line does not contain a value component, then the value
      * field of this object is set to <code>null</code>.
      *
      * @throws UnclosedQuoteException if there is a missing end-quote and header repairs aren't allowed.
      *
      * @see                           FitsFactory#setAllowHeaderRepairs(boolean)
      */
     private void parseValueBody() throws UnclosedQuoteException {
         if (!skipSpaces()) {
             // nothing left to parse.
             return;
         }
 
         if (isNextQuote()) {
             // Parse as a string value, or else throw an exception.
             parseStringValue();
         } else {
             int end = line.indexOf('/', parsePos);
             if (end < 0) {
                 end = line.length();
             }
             value = line.substring(parsePos, end).trim();
             parsePos = end;
             type = getInferredValueType(key, value);
         }
 
     }
 
     /**
      * Checks if the next character, at the current parse position, is a single quote.
      *
      * @return <code>true</code> if the next character on the line exists and is a single quote, otherwise
      *             <code>false</code>.
      */
     private boolean isNextQuote() {
         if (parsePos >= line.length()) {
             // nothing left to parse.
             return false;
         }
         return line.charAt(parsePos) == '\'';
     }
 
     /**
      * Returns the string fom a parsed string value component, with trailing spaces removed. It preserves leading
      * spaces.
      *
      * @param  buf the parsed string value.
      *
      * @return     the string value with trailing spaces removed.
      */
     private static String getNoTrailingSpaceString(StringBuilder buf) {
         int to = buf.length();
 
         // Remove trailing spaces only!
         while (--to >= 0) {
             if (!Character.isSpaceChar(buf.charAt(to))) {
                 break;
             }
         }
 
         return to < 0 ? "" : buf.substring(0, to + 1);
     }
 
     /**
      * Parses a quoted string value starting at the current parse position. If successful, the parse position is updated
      * to after the string. Otherwise, the parse position is advanced only to skip leading spaces starting from the
      * input position.
      *
      * @throws UnclosedQuoteException if there is a missing end-quote and header repairs aren't allowed.
      *
      * @see                           FitsFactory#setAllowHeaderRepairs(boolean)
      */
     private void parseStringValue() throws UnclosedQuoteException {
         type = String.class;
         StringBuilder buf = new StringBuilder(HeaderCard.MAX_VALUE_LENGTH);
 
         // Build the string value, up to the end quote and paying attention to double
         // quotes inside the string, which are translated to single quotes within
         // the string value itself.
         for (++parsePos; parsePos < line.length(); parsePos++) {
             if (isNextQuote()) {
                 parsePos++;
 
                 if (!isNextQuote()) {
                     // Closing single quote;
                     value = getNoTrailingSpaceString(buf);
                     return;
                 }
             }
             buf.append(line.charAt(parsePos));
         }
 
         // String with missing end quote
         if (!FitsFactory.isAllowHeaderRepairs()) {
             throw new UnclosedQuoteException(line);
         }
         LOG.warning("[" + sanitize(key) + "] Ignored missing end quote (value parsed to end of record).");
         value = getNoTrailingSpaceString(buf);
     }
 
     /**
      * Returns the inferred Java class for the specified value. See {@link #getInferredType()} for a more detailed
      * description.
      *
      * @param  value the serialized (string) representation of a FITS header value.
      *
      * @return       the inferred type of the specified serialized (string) value, or <code>null</code> if the value
      *                   does not seem to match any of the supported value types. <code>null</code> values default to
      *                   <code>Boolean.class</code>.
      */
     private static Class<?> getInferredValueType(String key, String value) {
         // TODO We never call this with null locally, so the following check is dead code here...
         // if (value == null) {
         // return Boolean.class;
         // }
         if (value.isEmpty()) {
             LOG.warning("[" + sanitize(key) + "] Null non-string value (defaulted to Boolean.class).");
             return Boolean.class;
         }
 
         String trimmedValue = value.trim().toUpperCase();
 
         if ("T".equals(trimmedValue) || "F".equals(trimmedValue)) {
             return Boolean.class;
         }
         if (INT_REGEX.matcher(trimmedValue).matches()) {
             return getIntegerType(trimmedValue);
         }
         if (DECIMAL_REGEX.matcher(trimmedValue).matches()) {
             return getDecimalType(trimmedValue);
         }
         if (COMPLEX_REGEX.matcher(trimmedValue).matches()) {
             return ComplexValue.class;
         }
 
         LOG.warning("[" + sanitize(key) + "] Unrecognised non-string value type '" + sanitize(trimmedValue) + "'.");
 
         return null;
     }
 
     /**
      * Returns the guessed decimal type of a string representation of a decimal value.
      *
      * @param  value the string representation of a decimal value.
      *
      * @return       the The Java class ({@link Float}, {@link Double}, or {@link BigDecimal}) that can be used to
      *                   represent the value with the precision provided.
      *
      * @see          #getInferredValueType()
      * @see          #getIntegerType(String)
      */
     private static Class<? extends Number> getDecimalType(String value) {
         value = value.toUpperCase(Locale.US);
         boolean hasD = (value.indexOf('D') >= 0);
 
         if (hasD) {
             // Convert the Double Scientific Notation specified by FITS to pure IEEE.
             value = value.replace('D', 'E');
         }
 
         BigDecimal big = new BigDecimal(value);
 
         // Check for zero, and deal with it separately...
         if (big.stripTrailingZeros().equals(BigDecimal.ZERO)) {
             int decimals = big.scale();
             if (decimals <= FlexFormat.FLOAT_DECIMALS) {
                 return hasD ? Double.class : Float.class;
             }
             if (decimals <= FlexFormat.DOUBLE_DECIMALS) {
                 return Double.class;
             }
             return BigDecimal.class;
         }
 
         // Now non-zero values...
         int decimals = big.precision() - 1;
         float f = big.floatValue();
         if (decimals <= FlexFormat.FLOAT_DECIMALS && (f != 0.0F) && Float.isFinite(f)) {
             return hasD ? Double.class : Float.class;
         }
 
         double d = big.doubleValue();
         if (decimals <= FlexFormat.DOUBLE_DECIMALS && (d != 0.0) && Double.isFinite(d)) {
             return Double.class;
         }
         return BigDecimal.class;
     }
 
     /**
      * Returns the guessed integer type of a string representation of a integer value.
      *
      * @param  value the string representation of an integer value.
      *
      * @return       the The Java class ({@link Integer}, {@link Long}, or {@link BigInteger}) that can be used to
      *                   represent the value with the number of digits provided.
      *
      * @see          #getInferredValueType()
      * @see          #getDecimalType(String)
      */
     private static Class<? extends Number> getIntegerType(String value) {
         int bits = new BigInteger(value).bitLength();
         if (bits < Integer.SIZE) {
             return Integer.class;
         }
         if (bits < Long.SIZE) {
             return Long.class;
         }
         return BigInteger.class;
     }
 
     private static String sanitize(String text) {
         return HeaderCard.sanitize(text);
     }
 
     static Logger getLogger() {
         return LOG;
     }
 
 }