// Copyright 2012 Google Inc. All Rights Reserved.

//

// Use of this source code is governed by a BSD-style license

// that can be found in the COPYING file in the root of the source

// tree. An additional intellectual property rights grant can be found

// in the file PATENTS. All contributing project authors may

// be found in the AUTHORS file in the root of the source tree.

// -----------------------------------------------------------------------------

//

// PNG decode.

#include "./pngdec.h"

#ifdef HAVE_CONFIG_H

#include "webp/config.h"

#endif

#include <stdio.h>

#ifdef WEBP_HAVE_PNG

#include <png.h>

#include <setjmp.h>   // note: this must be included *after* png.h

#include <stdlib.h>

#include <string.h>

#include "webp/encode.h"

#include "./imageio_util.h"

#include "./metadata.h"

static void PNGAPI error_function(png_structp png, png_const_charp error) {

  if (error != NULL) fprintf(stderr, "libpng error: %s\n", error);

  longjmp(png_jmpbuf(png), 1);

}

// Converts the NULL terminated 'hexstring' which contains 2-byte character

// representations of hex values to raw data.

// 'hexstring' may contain values consisting of [A-F][a-f][0-9] in pairs,

// e.g., 7af2..., separated by any number of newlines.

// 'expected_length' is the anticipated processed size.

// On success the raw buffer is returned with its length equivalent to

// 'expected_length'. NULL is returned if the processed length is less than

// 'expected_length' or any character aside from those above is encountered.

// The returned buffer must be freed by the caller.

static uint8_t* HexStringToBytes(const char* hexstring,

                                 size_t expected_length) {

  const char* src = hexstring;

  size_t actual_length = 0;

  uint8_t* const raw_data = (uint8_t*)malloc(expected_length);

  uint8_t* dst;

  if (raw_data == NULL) return NULL;

  for (dst = raw_data; actual_length < expected_length && *src != '\0'; ++src) {

    char* end;

    char val[3];

    if (*src == '\n') continue;

    val[0] = *src++;

    val[1] = *src;

    val[2] = '\0';

    *dst++ = (uint8_t)strtol(val, &end, 16);

    if (end != val + 2) break;

    ++actual_length;

  }

  if (actual_length != expected_length) {

    free(raw_data);

    return NULL;

  }

  return raw_data;

}

static int ProcessRawProfile(const char* profile, size_t profile_len,

                             MetadataPayload* const payload) {

  const char* src = profile;

  char* end;

  int expected_length;

  if (profile == NULL || profile_len == 0) return 0;

  // ImageMagick formats 'raw profiles' as

  // '\n<name>\n<length>(%8lu)\n<hex payload>\n'.

  if (*src != '\n') {

    fprintf(stderr, "Malformed raw profile, expected '\\n' got '\\x%.2X'\n",

            *src);

    return 0;

  }

  ++src;

  // skip the profile name and extract the length.

  while (*src != '\0' && *src++ != '\n') {}

  expected_length = (int)strtol(src, &end, 10);

  if (*end != '\n') {

    fprintf(stderr, "Malformed raw profile, expected '\\n' got '\\x%.2X'\n",

            *end);

    return 0;

  }

  ++end;

  // 'end' now points to the profile payload.

  payload->bytes = HexStringToBytes(end, expected_length);

  if (payload->bytes == NULL) return 0;

  payload->size = expected_length;

  return 1;

}

static const struct {

  const char* name;

  int (*process)(const char* profile, size_t profile_len,

                 MetadataPayload* const payload);

  size_t storage_offset;

} kPNGMetadataMap[] = {

  // http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/PNG.html#TextualData

  // See also: ExifTool on CPAN.

  { "Raw profile type exif", ProcessRawProfile, METADATA_OFFSET(exif) },

  { "Raw profile type xmp",  ProcessRawProfile, METADATA_OFFSET(xmp) },

  // Exiftool puts exif data in APP1 chunk, too.

  { "Raw profile type APP1", ProcessRawProfile, METADATA_OFFSET(exif) },

  // XMP Specification Part 3, Section 3 #PNG

  { "XML:com.adobe.xmp",     MetadataCopy,      METADATA_OFFSET(xmp) },

  { NULL, NULL, 0 },

};

// Looks for metadata at both the beginning and end of the PNG file, giving

// preference to the head.

// Returns true on success. The caller must use MetadataFree() on 'metadata' in

// all cases.

static int ExtractMetadataFromPNG(png_structp png,

                                  png_infop const head_info,

                                  png_infop const end_info,

                                  Metadata* const metadata) {

  int p;

  for (p = 0; p < 2; ++p)  {

    png_infop const info = (p == 0) ? head_info : end_info;

    png_textp text = NULL;

    const png_uint_32 num = png_get_text(png, info, &text, NULL);

    png_uint_32 i;

    // Look for EXIF / XMP metadata.

    for (i = 0; i < num; ++i, ++text) {

      int j;

      for (j = 0; kPNGMetadataMap[j].name != NULL; ++j) {

        if (!strcmp(text->key, kPNGMetadataMap[j].name)) {

          MetadataPayload* const payload =

              (MetadataPayload*)((uint8_t*)metadata +

                                 kPNGMetadataMap[j].storage_offset);

          png_size_t text_length;

          switch (text->compression) {

#ifdef PNG_iTXt_SUPPORTED

            case PNG_ITXT_COMPRESSION_NONE:

            case PNG_ITXT_COMPRESSION_zTXt:

              text_length = text->itxt_length;

              break;

#endif

            case PNG_TEXT_COMPRESSION_NONE:

            case PNG_TEXT_COMPRESSION_zTXt:

            default:

              text_length = text->text_length;

              break;

          }

          if (payload->bytes != NULL) {

            fprintf(stderr, "Ignoring additional '%s'\n", text->key);

          } else if (!kPNGMetadataMap[j].process(text->text, text_length,

                                                 payload)) {

            fprintf(stderr, "Failed to process: '%s'\n", text->key);

            return 0;

          }

          break;

        }

      }

    }

    // Look for an ICC profile.

    {

      png_charp name;

      int comp_type;

#if ((PNG_LIBPNG_VER_MAJOR << 8) | PNG_LIBPNG_VER_MINOR << 0) < \

    ((1 << 8) | (5 << 0))

      png_charp profile;

#else  // >= libpng 1.5.0

      png_bytep profile;

#endif

      png_uint_32 len;

      if (png_get_iCCP(png, info,

                       &name, &comp_type, &profile, &len) == PNG_INFO_iCCP) {

        if (!MetadataCopy((const char*)profile, len, &metadata->iccp)) return 0;

      }

    }

  }

  return 1;

}

typedef struct {

  const uint8_t* data;

  size_t data_size;

  png_size_t offset;

} PNGReadContext;

static void ReadFunc(png_structp png_ptr, png_bytep data, png_size_t length) {

  PNGReadContext* const ctx = (PNGReadContext*)png_get_io_ptr(png_ptr);

  if (ctx->data_size - ctx->offset < length) {

    png_error(png_ptr, "ReadFunc: invalid read length (overflow)!");

  }

  memcpy(data, ctx->data + ctx->offset, length);

  ctx->offset += length;

}

int ReadPNG(const uint8_t* const data, size_t data_size,

            struct WebPPicture* const pic,

            int keep_alpha, struct Metadata* const metadata) {

  volatile png_structp png = NULL;

  volatile png_infop info = NULL;

  volatile png_infop end_info = NULL;

  PNGReadContext context = { NULL, 0, 0 };

  int color_type, bit_depth, interlaced;

  int has_alpha;

  int num_passes;

  int p;

  volatile int ok = 0;

  png_uint_32 width, height, y;

  int64_t stride;

  uint8_t* volatile rgb = NULL;

  if (data == NULL || data_size == 0 || pic == NULL) return 0;

  context.data = data;

  context.data_size = data_size;

  png = png_create_read_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0);

  if (png == NULL) goto End;

  png_set_error_fn(png, 0, error_function, NULL);

  if (setjmp(png_jmpbuf(png))) {

 Error:

    MetadataFree(metadata);

    goto End;

  }

  info = png_create_info_struct(png);

  if (info == NULL) goto Error;

  end_info = png_create_info_struct(png);

  if (end_info == NULL) goto Error;

  png_set_read_fn(png, &context, ReadFunc);

  png_read_info(png, info);

  if (!png_get_IHDR(png, info,

                    &width, &height, &bit_depth, &color_type, &interlaced,

                    NULL, NULL)) goto Error;

  png_set_strip_16(png);

  png_set_packing(png);

  if (color_type == PNG_COLOR_TYPE_PALETTE) {

    png_set_palette_to_rgb(png);

  }

  if (color_type == PNG_COLOR_TYPE_GRAY ||

      color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {

    if (bit_depth < 8) {

      png_set_expand_gray_1_2_4_to_8(png);

    }

    png_set_gray_to_rgb(png);

  }

  if (png_get_valid(png, info, PNG_INFO_tRNS)) {

    png_set_tRNS_to_alpha(png);

    has_alpha = 1;

  } else {

    has_alpha = !!(color_type & PNG_COLOR_MASK_ALPHA);

  }

  // Apply gamma correction if needed.

  {

    double image_gamma = 1 / 2.2, screen_gamma = 2.2;

    int srgb_intent;

    if (png_get_sRGB(png, info, &srgb_intent) ||

        png_get_gAMA(png, info, &image_gamma)) {

      png_set_gamma(png, screen_gamma, image_gamma);

    }

  }

  if (!keep_alpha) {

    png_set_strip_alpha(png);

    has_alpha = 0;

  }

  num_passes = png_set_interlace_handling(png);

  png_read_update_info(png, info);

  stride = (int64_t)(has_alpha ? 4 : 3) * width * sizeof(*rgb);

  if (stride != (int)stride ||

      !ImgIoUtilCheckSizeArgumentsOverflow(stride, height)) {

    goto Error;

  }

  rgb = (uint8_t*)malloc((size_t)stride * height);

  if (rgb == NULL) goto Error;

  for (p = 0; p < num_passes; ++p) {

    png_bytep row = rgb;

    for (y = 0; y < height; ++y) {

      png_read_rows(png, &row, NULL, 1);

      row += stride;

    }

  }

  png_read_end(png, end_info);

  if (metadata != NULL &&

      !ExtractMetadataFromPNG(png, info, end_info, metadata)) {

    fprintf(stderr, "Error extracting PNG metadata!\n");

    goto Error;

  }

  pic->width = (int)width;

  pic->height = (int)height;

  ok = has_alpha ? WebPPictureImportRGBA(pic, rgb, (int)stride)

                 : WebPPictureImportRGB(pic, rgb, (int)stride);

  if (!ok) {

    goto Error;

  }

 End:

  if (png != NULL) {

    png_destroy_read_struct((png_structpp)&png,

                            (png_infopp)&info, (png_infopp)&end_info);

  }

  free(rgb);

  return ok;

}

#else  // !WEBP_HAVE_PNG

int ReadPNG(const uint8_t* const data, size_t data_size,

            struct WebPPicture* const pic,

            int keep_alpha, struct Metadata* const metadata) {

  (void)data;

  (void)data_size;

  (void)pic;

  (void)keep_alpha;

  (void)metadata;

  fprintf(stderr, "PNG support not compiled. Please install the libpng "

          "development package before building.\n");

  return 0;

}

#endif  // WEBP_HAVE_PNG

// -----------------------------------------------------------------------------