// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "media/base/media.h"

#include <windows.h>

#include "base/file_path.h"
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "base/native_library.h"
#include "base/path_service.h"

namespace media {

enum FFmpegDLLKeys {
  FILE_LIBAVCODEC,   // full path to libavcodec media decoding library.
  FILE_LIBAVFORMAT,  // full path to libavformat media parsing library.
  FILE_LIBAVUTIL,    // full path to libavutil media utility library.
};

// Retrieves the DLLName for the given key.
static FilePath::CharType* GetDLLName(FFmpegDLLKeys dll_key) {
  // TODO(ajwong): Do we want to lock to a specific ffmpeg version?
  switch (dll_key) {
    case FILE_LIBAVCODEC:
      return FILE_PATH_LITERAL("avcodec-53.dll");
    case FILE_LIBAVFORMAT:
      return FILE_PATH_LITERAL("avformat-53.dll");
    case FILE_LIBAVUTIL:
      return FILE_PATH_LITERAL("avutil-51.dll");
    default:
      LOG(DFATAL) << "Invalid DLL key requested: " << dll_key;
      return FILE_PATH_LITERAL("");
  }
}

static bool g_media_library_is_initialized = false;

// Attempts to initialize the media library (loading DLLs, DSOs, etc.).
// Returns true if everything was successfully initialized, false otherwise.
bool InitializeMediaLibrary(const FilePath& base_path) {
  if (g_media_library_is_initialized)
    return true;

  FFmpegDLLKeys path_keys[] = {
    media::FILE_LIBAVCODEC,
    media::FILE_LIBAVFORMAT,
    media::FILE_LIBAVUTIL
  };
  HMODULE libs[arraysize(path_keys)] = {NULL};

  for (size_t i = 0; i < arraysize(path_keys); ++i) {
    FilePath path = base_path.Append(GetDLLName(path_keys[i]));

    // Use alternate DLL search path so we don't load dependencies from the
    // system path.  Refer to http://crbug.com/35857
    const wchar_t* cpath = path.value().c_str();
    libs[i] = LoadLibraryEx(cpath, NULL, LOAD_WITH_ALTERED_SEARCH_PATH);
    if (!libs[i])
      break;
  }

  // Check that we loaded all libraries successfully.  We only need to check the
  // last array element because the loop above will break without initializing
  // it on any prior error.
  g_media_library_is_initialized = (libs[arraysize(libs) - 1] != NULL);

  if (!g_media_library_is_initialized) {
    // Free any loaded libraries if we weren't successful.
    for (size_t i = 0; i < arraysize(libs) && libs[i] != NULL; ++i) {
      FreeLibrary(libs[i]);
      libs[i] = NULL;  // Just to be safe.
    }
  }

  return g_media_library_is_initialized;
}

bool IsMediaLibraryInitialized() {
  return g_media_library_is_initialized;
}

bool InitializeOpenMaxLibrary(const FilePath& module_dir) {
  NOTIMPLEMENTED() << "OpenMAX is not used in Windows.";
  return false;
}

}  // namespace media
