#pragma region CPL License
/*
Nuclex Native Framework
Copyright (C) 2002-2021 Nuclex Development Labs

This library is free software; you can redistribute it and/or
modify it under the terms of the IBM Common Public License as
published by the IBM Corporation; either version 1.0 of the
License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
IBM Common Public License for more details.

You should have received a copy of the IBM Common Public
License along with this library
*/
#pragma endregion // CPL License

// If the library is compiled as a DLL, this ensures symbols are exported
#define NUCLEX_PIXELS_SOURCE 1

#include "LibWebPHelpers.h"

#if defined(NUCLEX_PIXELS_HAVE_LIBWEBP)

#include "Nuclex/Pixels/Errors/FileFormatError.h"

#include <cassert> // for assert()
#include <algorithm> // for std::min()

namespace {

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

} // anonymous namespace

namespace Nuclex { namespace Pixels { namespace Storage { namespace WebP {

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

  bool Helpers::IsValidWebPHeader(const std::uint8_t *fileHeader) {

    // The RIFF format is a chunk-based one and theoretically, it would allow
    // chunks in any order. However, the WebP specification states that a VP8
    // chunk (either vanilla, lossless or extended) should be the first chunk.
    // At least that's my interpretation...
    //
    // https://docs.fileformat.com/image/webp/
    // https://developers.google.com/speed/webp/docs/riff_container
    //
    return (
      (fileHeader[0] == 0x52) &&    //  1 RIFF header (magic number #1)
      (fileHeader[1] == 0x49) &&    //  1 
      (fileHeader[2] == 0x46) &&    //  1
      (fileHeader[3] == 0x46) &&    //  1
      (
        (fileHeader[4] >= 18) ||    //  2 Chunk size
        (fileHeader[5] >= 1) ||     //  2 (header length at least 12 bytes)
        (fileHeader[6] >= 1) ||     //  2
        (fileHeader[7] >= 1)        //  2
      ) &&
      (fileHeader[8] == 0x57) &&    //  3 WebP marker (magic number #2)
      (fileHeader[9] == 0x45) &&    //  3
      (fileHeader[10] == 0x42) &&   //  3
      (fileHeader[11] == 0x50) &&   //  3
      (fileHeader[12] == 0x56) &&   //  4 VP8 marker (magic number #3)
      (fileHeader[13] == 0x50) &&   //  4
      (fileHeader[14] == 0x38) &&   //  4
      (
        (fileHeader[15] == 0x20) || //  4 VP8 marker, vanilla VP8 keyframe
        (fileHeader[15] == 0x4C) || //  4 VP8 marker, lossless VP8 keyframe
        (fileHeader[15] == 0x58)    //  4 VP8 marker, extended VP8 keyframe
      )
    );

  }

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

  std::string Helpers::GetErrorMessage(::VP8StatusCode statusCode) {
    switch(statusCode) {
      case VP8_STATUS_OK: {
        return u8"No error";
      }
      case VP8_STATUS_OUT_OF_MEMORY: {
        return u8"Out of memory - image too big or appearing too big due to corrupted data";
      }
      case VP8_STATUS_INVALID_PARAM: {
        return u8"Invalid parameters - invalid parameters were passed to a WebP function";
      }
      case VP8_STATUS_BITSTREAM_ERROR: {
        return u8"Bitstream error - input data was corrupted";
      }
      case VP8_STATUS_UNSUPPORTED_FEATURE: {
        return u8"Unsupported feature - input data likely conforms to a newer WebP version";
      }
      case VP8_STATUS_SUSPENDED: {
        return u8"Suspended - processing was suspended";
      }
      case VP8_STATUS_USER_ABORT: {
        return u8"User abort - processing was aborted";
      }
      case VP8_STATUS_NOT_ENOUGH_DATA: {
        return u8"Not enough data - input data is truncated or corrupted";
      }
      default: {
        return u8"Unknown error - the error code returned by a WebP function is undocumented";
      }
    }
  }

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

}}}} // namespace Nuclex::Pixels::Storage::WebP

#endif // defined(NUCLEX_PIXELS_HAVE_LIBWEBP)