// Copyright 2016 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.

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

//

// Generic image-type guessing.

#include "./image_dec.h"

#include <stddef.h>

#include "./metadata.h"

#include "webp/encode.h"

#include "webp/types.h"

const char* WebPGetEnabledInputFileFormats(void) {

  return "WebP"

#ifdef WEBP_HAVE_JPEG

         ", JPEG"

#endif

#ifdef WEBP_HAVE_PNG

         ", PNG"

#endif

         ", PNM (PGM, PPM, PAM)"

#ifdef WEBP_HAVE_TIFF

         ", TIFF"

#endif

#ifdef HAVE_WINCODEC_H

         ", Windows Imaging Component (WIC)"

#endif

         "";

}

static WEBP_INLINE uint32_t GetBE32(const uint8_t buf[]) {

  return ((uint32_t)buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | buf[3];

}

WebPInputFileFormat WebPGuessImageType(const uint8_t* const data,

                                       size_t data_size) {

  WebPInputFileFormat format = WEBP_UNSUPPORTED_FORMAT;

  if (data != NULL && data_size >= 12) {

    const uint32_t magic1 = GetBE32(data + 0);

    const uint32_t magic2 = GetBE32(data + 8);

    if (magic1 == 0x89504E47U) {

      format = WEBP_PNG_FORMAT;

    } else if (magic1 >= 0xFFD8FF00U && magic1 <= 0xFFD8FFFFU) {

      format = WEBP_JPEG_FORMAT;

    } else if (magic1 == 0x49492A00 || magic1 == 0x4D4D002A) {

      format = WEBP_TIFF_FORMAT;

    } else if (magic1 == 0x52494646 && magic2 == 0x57454250) {

      format = WEBP_WEBP_FORMAT;

    } else if (((magic1 >> 24) & 0xff) == 'P') {

      const int type = (magic1 >> 16) & 0xff;

      // we only support 'P5 -> P7' for now.

      if (type >= '5' && type <= '7') format = WEBP_PNM_FORMAT;

    }

  }

  return format;

}

static int FailReader(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;

  return 0;

}

WebPImageReader WebPGetImageReader(WebPInputFileFormat format) {

  switch (format) {

    case WEBP_PNG_FORMAT:

      return ReadPNG;

    case WEBP_JPEG_FORMAT:

      return ReadJPEG;

    case WEBP_TIFF_FORMAT:

      return ReadTIFF;

    case WEBP_WEBP_FORMAT:

      return ReadWebP;

    case WEBP_PNM_FORMAT:

      return ReadPNM;

    default:

      return FailReader;

  }

}

WebPImageReader WebPGuessImageReader(const uint8_t* const data,

                                     size_t data_size) {

  return WebPGetImageReader(WebPGuessImageType(data, data_size));

}