/*
    * #%L
    * nom.tam FITS library
    * %%
    * Copyright (C) 1996 - 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,
   * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
   * OTHER DEALINGS IN THE SOFTWARE.
   * #L%
   */
  
  package nom.tam.util;
  
  // What do we use in here?
  import java.io.DataInput;
  import java.io.DataInputStream;
  import java.io.EOFException;
  import java.io.IOException;
  import java.io.InputStream;
  import java.nio.ByteBuffer;
  
  import nom.tam.fits.FitsFactory;
  import nom.tam.fits.utilities.FitsCheckSum;
  
  /**
   * For reading FITS files through an {@link InputStream}.
   * <p>
   * Testing and timing routines are provided in the nom.tam.util.test.BufferedFileTester class.
   * <p>
   * Prior versions under the old <code>BufferedDataInputStream</code>:
   * <ul>
   * <li>Version 1.1 -- October 12, 2000: Fixed handling of EOF to return partially read arrays when EOF is detected</li>
   * <li>Version 1.2 -- July 20, 2009: Added handling of very large Object arrays. Additional work is required to handle
   * very large arrays generally.</li>
   * </ul>
   * <p>
   * Version 2.0 -- October 30, 2021: Completely overhauled, with new name and hierarchy. Performance is 2-4 times better
   * than before (Attila Kovacs)
   *
   * @see FitsInputStream
   * @see FitsFile
   */
  @SuppressWarnings("deprecation")
  public class FitsInputStream extends ArrayInputStream implements ArrayDataInput {
  
      /** buffer for checksum calculation */
      private ByteBuffer check;
  
      /** aggregated checksum */
      private long sum;
  
      /** the input, as accessible via the <code>DataInput</code> interface */
      private DataInput data;
  
      /**
       * Create a BufferedInputStream based on a input stream with a specified buffer size.
       *
       * @param i         the input stream to use for reading.
       * @param bufLength the buffer length to use.
       */
      public FitsInputStream(InputStream i, int bufLength) {
          super(i, bufLength);
          data = new DataInputStream(this);
          check = ByteBuffer.allocate(FitsFactory.FITS_BLOCK_SIZE);
          check.limit(check.capacity());
          setDecoder(new FitsDecoder(this));
      }
  
      /**
       * Create a BufferedInputStream based on an input stream.
       *
       * @param i the input stream to use for reading.
       */
      public FitsInputStream(InputStream i) {
          this(i, FitsIO.DEFAULT_BUFFER_SIZE);
      }
  
      @Override
      protected FitsDecoder getDecoder() {
         return (FitsDecoder) super.getDecoder();
     }
 
     @Override
     public int read() throws IOException {
         int i = super.read();
         if (i >= 0) {
             check.put((byte) i);
             if (check.remaining() <= 0) {
                 aggregate();
             }
         }
         return i;
     }
 
     @Override
     public int read(byte[] b, int from, int len) throws IOException {
         int n = super.read(b, from, len);
         for (int i = 0; i < n;) {
             int l = Math.min(n - i, check.remaining());
             check.put(b, from + i, l);
             if (check.remaining() <= 0) {
                 aggregate();
             }
             i += l;
         }
         return n;
     }
 
     private void aggregate() {
         sum = FitsCheckSum.sumOf(sum, FitsCheckSum.checksum(check));
         check.position(0);
     }
 
     /**
      * (<i>for internal use</i>) Returns the aggregated checksum for this stream since the last call to this method, or
      * else since instantiation. Checksums for a block of data thus may be obtained by calling this method both before
      * and after reading the data block -- the first call resets the checksum and the block checksum is returned on the
      * second call. The checksummed block must be a multiple of 2880 bytes (the FITS block size) for the result to be
      * valid.
      * 
      * @return the aggregated checksum since the last call to this method, or else since instantiation, on an integer
      *             number of FITS blocks read in the meantime.
      * 
      * @since  1.18.1
      */
     public final long nextChecksum() {
         long ret = sum;
         sum = 0;
         return ret;
     }
 
     @Override
     public void readFully(byte[] b) throws IOException {
         readFully(b, 0, b.length);
     }
 
     @Override
     public void readFully(byte[] b, int off, int len) throws IOException {
         getDecoder().readFully(b, off, len);
     }
 
     @Override
     public int read(boolean[] b, int start, int length) throws IOException {
         return getDecoder().read(b, start, length);
     }
 
     @Override
     public int read(Boolean[] b, int start, int length) throws IOException {
         return getDecoder().read(b, start, length);
     }
 
     @Override
     public int read(char[] c, int start, int length) throws IOException {
         return getDecoder().read(c, start, length);
     }
 
     @Override
     public int read(short[] s, int start, int length) throws IOException {
         return getDecoder().read(s, start, length);
     }
 
     @Override
     public int read(int[] i, int start, int length) throws IOException {
         return getDecoder().read(i, start, length);
     }
 
     @Override
     public int read(long[] l, int start, int length) throws IOException {
         return getDecoder().read(l, start, length);
     }
 
     @Override
     public int read(float[] f, int start, int length) throws IOException {
         return getDecoder().read(f, start, length);
     }
 
     @Override
     public int read(double[] d, int start, int length) throws IOException {
         return getDecoder().read(d, start, length);
     }
 
     /**
      * This routine provides efficient reading of arrays of any primitive type. It is an error to invoke this method
      * with an object that is not an array of some primitive type. Note that there is no corresponding capability to
      * writePrimitiveArray in BufferedDataOutputStream to read in an array of Strings.
      *
      * @return                 number of bytes read.
      *
      * @param      o           The object to be read. It must be an array of a primitive type, or an array of Object's.
      *
      * @throws     IOException if the underlying read operation fails
      *
      * @deprecated             use {@link #readLArray(Object)} instead
      */
     @Deprecated
     public final int readPrimitiveArray(Object o) throws IOException {
         return (int) readLArray(o);
     }
 
     @Override
     public long skip(long n) throws IOException {
         byte[] b = new byte[FitsFactory.FITS_BLOCK_SIZE];
 
         // Always read so we can checksum.
         long skipped = 0;
         while (skipped < n) {
             int got = read(b, 0, (int) Math.min(n - skipped, b.length));
             if (got < 0) {
                 break;
             }
             skipped += got;
         }
         return skipped;
     }
 
     @Override
     public int skipBytes(int n) throws IOException {
         return (int) super.skip(n);
     }
 
     @Override
     public void skipAllBytes(long toSkip) throws EOFException, IOException {
         long got = 0;
 
         while (got < toSkip) {
             long n = skip(toSkip - got);
             if (n <= 0) {
                 break;
             }
             got += n;
         }
 
         if (got != toSkip) {
             throw new EOFException("Reached end-of-stream after skipping " + got + " of " + toSkip);
         }
     }
 
     @Override
     public boolean readBoolean() throws IOException {
         return getDecoder().readBoolean();
     }
 
     @Override
     public int readUnsignedByte() throws IOException {
         return getDecoder().readUnsignedByte();
     }
 
     @Override
     public byte readByte() throws IOException {
         return getDecoder().readByte();
     }
 
     @Override
     public char readChar() throws IOException {
         return getDecoder().readChar();
     }
 
     @Override
     public int readUnsignedShort() throws IOException {
         return getDecoder().readUnsignedShort();
     }
 
     @Override
     public short readShort() throws IOException {
         return getDecoder().readShort();
     }
 
     @Override
     public int readInt() throws IOException {
         return getDecoder().readInt();
     }
 
     @Override
     public long readLong() throws IOException {
         return getDecoder().readLong();
     }
 
     @Override
     public float readFloat() throws IOException {
         return getDecoder().readFloat();
     }
 
     @Override
     public double readDouble() throws IOException {
         return getDecoder().readDouble();
     }
 
     @Override
     public String readUTF() throws IOException {
         return data.readUTF();
     }
 
     @Override
     public final String readLine() throws IOException {
         return getDecoder().readAsciiLine();
     }
 
     @Override
     public String toString() {
         return super.toString() + "[count=" + count + ",pos=" + pos + "]";
     }
 
 }