// Copyright 2021 Benjamin Barenblat
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.

#include "src/webp.h"

#include <stddef.h>
#include <stdint.h>
#include <webp/decode.h>

#include <new>
#include <stdexcept>
#include <vector>

#include "third_party/abseil/absl/strings/str_cat.h"
#include "third_party/abseil/absl/strings/string_view.h"
#include "third_party/abseil/absl/types/span.h"

namespace glplanet {

std::vector<uint8_t> DecodeWebp(absl::Span<const uint8_t> webp, int x, int y,
                                int width, int height) {
  size_t bytes = 3 * width * height;
  std::vector<uint8_t> decoded(bytes, '\0');

  WebPDecoderConfig config;
  if (!WebPInitDecoderConfig(&config)) {
    throw std::runtime_error("failed to initialize WebP decoder");
  }

  config.options.use_cropping = 1;
  config.options.crop_left = x;
  config.options.crop_top = y;
  config.options.crop_width = width;
  config.options.crop_height = height;

  config.output.colorspace = MODE_RGB;
  config.output.is_external_memory = 1;
  config.output.u.RGBA.rgba = decoded.data();
  config.output.u.RGBA.stride = 3 * width;
  config.output.u.RGBA.size = bytes;

  int error = WebPDecode(webp.data(), webp.size(), &config);
  if (error != VP8_STATUS_OK) {
    static constexpr absl::string_view error_prefix = "failed to decode WebP: ";
    switch (error) {
      case VP8_STATUS_OUT_OF_MEMORY:
        throw std::bad_alloc();
      case VP8_STATUS_INVALID_PARAM:
        throw std::invalid_argument(
            absl::StrCat(error_prefix, "invalid parameter"));
      case VP8_STATUS_BITSTREAM_ERROR:
        throw std::runtime_error(absl::StrCat(error_prefix, "bitstream error"));
      case VP8_STATUS_UNSUPPORTED_FEATURE:
        throw std::runtime_error(
            absl::StrCat(error_prefix, "unsupported feature"));
      case VP8_STATUS_SUSPENDED:
        throw std::runtime_error(absl::StrCat(error_prefix, "suspended"));
      case VP8_STATUS_USER_ABORT:
        throw std::runtime_error(absl::StrCat(error_prefix, "aborted"));
      case VP8_STATUS_NOT_ENOUGH_DATA:
        throw std::runtime_error(absl::StrCat(error_prefix, "not enough data"));
      default:
        throw std::runtime_error(absl::StrCat(error_prefix, "unknown error"));
    }
  }
  return decoded;
}

}  // namespace glplanet