/*
 * iccprofile.c
 *
 * This file provides code to read and write International Color Consortium
 * (ICC) device profiles embedded in JFIF JPEG image files.  The ICC has
 * defined a standard format for including such data in JPEG "APP2" markers.
 * The code given here does not know anything about the internal structure
 * of the ICC profile data; it just knows how to put the profile data into
 * a JPEG file being written, or get it back out when reading.
 *
 * This code depends on new features added to the IJG JPEG library as of
 * IJG release 6b; it will not compile or work with older IJG versions.
 *
 * NOTE: this code would need surgery to work on 16-bit-int machines
 * with ICC profiles exceeding 64K bytes in size.  If you need to do that,
 * change all the "unsigned int" variables to "INT32".  You'll also need
 * to find a malloc() replacement that can allocate more than 64K.
 */

#include "iccjpeg.h"
#include <cstdlib>          /* define malloc() */


/*
 * Since an ICC profile can be larger than the maximum size of a JPEG marker
 * (64K), we need provisions to split it into multiple markers.  The format
 * defined by the ICC specifies one or more APP2 markers containing the
 * following data:
 *  Identifying string  ASCII "ICC_PROFILE\0"  (12 bytes)
 *  Marker sequence number  1 for first APP2, 2 for next, etc (1 byte)
 *  Number of markers   Total number of APP2's used (1 byte)
 *      Profile data        (remainder of APP2 data)
 * Decoders should use the marker sequence numbers to reassemble the profile,
 * rather than assuming that the APP2 markers appear in the correct sequence.
 */

#define ICC_MARKER  (JPEG_APP0 + 2) /* JPEG marker code for ICC */
#define ICC_OVERHEAD_LEN  14        /* size of non-profile data in APP2 */
#define MAX_BYTES_IN_MARKER  65533  /* maximum data len of a JPEG marker */
#define MAX_DATA_BYTES_IN_MARKER  (MAX_BYTES_IN_MARKER - ICC_OVERHEAD_LEN)


/*
 * This routine writes the given ICC profile data into a JPEG file.
 * It *must* be called AFTER calling jpeg_start_compress() and BEFORE
 * the first call to jpeg_write_scanlines().
 * (This ordering ensures that the APP2 marker(s) will appear after the
 * SOI and JFIF or Adobe markers, but before all else.)
 */

void
write_icc_profile (j_compress_ptr cinfo,
                   const JOCTET *icc_data_ptr,
                   unsigned int icc_data_len)
{
    unsigned int num_markers; /* total number of markers we'll write */
    int cur_marker = 1;       /* per spec, counting starts at 1 */

    /* Calculate the number of markers we'll need, rounding up of course */
    num_markers = icc_data_len / MAX_DATA_BYTES_IN_MARKER;

    if (num_markers * MAX_DATA_BYTES_IN_MARKER != icc_data_len) {
        num_markers++;
    }

    while (icc_data_len > 0) {
        /* length of profile to put in this marker */
        unsigned int length = icc_data_len; /* number of bytes to write in this marker */

        if (length > MAX_DATA_BYTES_IN_MARKER) {
            length = MAX_DATA_BYTES_IN_MARKER;
        }

        icc_data_len -= length;

        /* Write the JPEG marker header (APP2 code and marker length) */
        jpeg_write_m_header(cinfo, ICC_MARKER, (unsigned int) (length + ICC_OVERHEAD_LEN));

        /* Write the marker identifying string "ICC_PROFILE" (null-terminated).
         * We code it in this less-than-transparent way so that the code works
         * even if the local character set is not ASCII.
         */
        jpeg_write_m_byte(cinfo, 0x49);
        jpeg_write_m_byte(cinfo, 0x43);
        jpeg_write_m_byte(cinfo, 0x43);
        jpeg_write_m_byte(cinfo, 0x5F);
        jpeg_write_m_byte(cinfo, 0x50);
        jpeg_write_m_byte(cinfo, 0x52);
        jpeg_write_m_byte(cinfo, 0x4F);
        jpeg_write_m_byte(cinfo, 0x46);
        jpeg_write_m_byte(cinfo, 0x49);
        jpeg_write_m_byte(cinfo, 0x4C);
        jpeg_write_m_byte(cinfo, 0x45);
        jpeg_write_m_byte(cinfo, 0x0);

        /* Add the sequencing info */
        jpeg_write_m_byte(cinfo, cur_marker);
        jpeg_write_m_byte(cinfo, (int) num_markers);

        /* Add the profile data */
        while (length--) {
            jpeg_write_m_byte(cinfo, *icc_data_ptr);
            icc_data_ptr++;
        }

        cur_marker++;
    }
}


/*
 * Prepare for reading an ICC profile
 */

void
setup_read_icc_profile (j_decompress_ptr cinfo)
{
    /* Tell the library to keep any APP2 data it may find */
    jpeg_save_markers(cinfo, ICC_MARKER, 0xFFFF);
}


/*
 * Handy subroutine to test whether a saved marker is an ICC profile marker.
 */
static boolean
marker_is_icc (jpeg_saved_marker_ptr marker)
{
    return
        marker->marker == ICC_MARKER &&
        marker->data_length >= ICC_OVERHEAD_LEN &&
        /* verify the identifying string */
        GETJOCTET(marker->data[0]) == 0x49 &&
        GETJOCTET(marker->data[1]) == 0x43 &&
        GETJOCTET(marker->data[2]) == 0x43 &&
        GETJOCTET(marker->data[3]) == 0x5F &&
        GETJOCTET(marker->data[4]) == 0x50 &&
        GETJOCTET(marker->data[5]) == 0x52 &&
        GETJOCTET(marker->data[6]) == 0x4F &&
        GETJOCTET(marker->data[7]) == 0x46 &&
        GETJOCTET(marker->data[8]) == 0x49 &&
        GETJOCTET(marker->data[9]) == 0x4C &&
        GETJOCTET(marker->data[10]) == 0x45 &&
        GETJOCTET(marker->data[11]) == 0x0
            ? TRUE
            : FALSE;
}


/*
 * See if there was an ICC profile in the JPEG file being read;
 * if so, reassemble and return the profile data.
 *
 * TRUE is returned if an ICC profile was found, FALSE if not.
 * If TRUE is returned, *icc_data_ptr is set to point to the
 * returned data, and *icc_data_len is set to its length.
 *
 * IMPORTANT: the data at **icc_data_ptr has been allocated with malloc()
 * and must be freed by the caller with free() when the caller no longer
 * needs it.  (Alternatively, we could write this routine to use the
 * IJG library's memory allocator, so that the data would be freed implicitly
 * at jpeg_finish_decompress() time.  But it seems likely that many apps
 * will prefer to have the data stick around after decompression finishes.)
 *
 * NOTE: if the file contains invalid ICC APP2 markers, we just silently
 * return FALSE.  You might want to issue an error message instead.
 */

boolean
read_icc_profile (j_decompress_ptr cinfo,
                  JOCTET **icc_data_ptr,
                  unsigned int *icc_data_len)
{
    jpeg_saved_marker_ptr marker;
    int num_markers = 0;
    int seq_no;
    JOCTET *icc_data;
    unsigned int total_length;
#define MAX_SEQ_NO  255     /* sufficient since marker numbers are bytes */
    char marker_present[MAX_SEQ_NO + 1];    /* 1 if marker found */
    unsigned int data_length[MAX_SEQ_NO + 1]; /* size of profile data in marker */
    unsigned int data_offset[MAX_SEQ_NO + 1]; /* offset for data in marker */

    *icc_data_ptr = nullptr;     /* avoid confusion if FALSE return */
    *icc_data_len = 0;

    /* This first pass over the saved markers discovers whether there are
     * any ICC markers and verifies the consistency of the marker numbering.
     */

    for (seq_no = 1; seq_no <= MAX_SEQ_NO; seq_no++) {
        marker_present[seq_no] = 0;
    }

    for (marker = cinfo->marker_list; marker != nullptr; marker = marker->next) {
        if (marker_is_icc(marker)) {
            if (num_markers == 0) {
                num_markers = GETJOCTET(marker->data[13]);
            } else if (num_markers != GETJOCTET(marker->data[13])) {
                return FALSE;    /* inconsistent num_markers fields */
            }

            seq_no = GETJOCTET(marker->data[12]);

            if (seq_no <= 0 || seq_no > num_markers) {
                return FALSE;    /* bogus sequence number */
            }

            if (marker_present[seq_no]) {
                return FALSE;    /* duplicate sequence numbers */
            }

            marker_present[seq_no] = 1;
            data_length[seq_no] = marker->data_length - ICC_OVERHEAD_LEN;
        }
    }

    if (num_markers == 0) {
        return FALSE;
    }

    /* Check for missing markers, count total space needed,
     * compute offset of each marker's part of the data.
     */

    total_length = 0;

    for (seq_no = 1; seq_no <= num_markers; seq_no++) {
        if (marker_present[seq_no] == 0) {
            return FALSE;    /* missing sequence number */
        }

        data_offset[seq_no] = total_length;
        total_length += data_length[seq_no];
    }

    /* Allocate space for assembled data */
    icc_data = (JOCTET *) malloc(total_length * sizeof(JOCTET));

    if (icc_data == nullptr) {
        return FALSE;    /* oops, out of memory */
    }

    /* and fill it in */
    for (marker = cinfo->marker_list; marker != nullptr; marker = marker->next) {
        if (marker_is_icc(marker)) {
            JOCTET FAR *src_ptr;
            JOCTET *dst_ptr;
            unsigned int length;
            seq_no = GETJOCTET(marker->data[12]);
            dst_ptr = icc_data + data_offset[seq_no];
            src_ptr = marker->data + ICC_OVERHEAD_LEN;
            length = data_length[seq_no];

            while (length--) {
                *dst_ptr++ = *src_ptr++;
            }
        }
    }

    *icc_data_ptr = icc_data;
    *icc_data_len = total_length;

    return TRUE;
}

