// Copyright (c) 2009 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/path_service.h"

// Enable timing code by turning on TESTING macro.
//#define TESTING 1

#ifdef TESTING
#include "base/string_util.h"
#include "base/time.h"

namespace {
// Fetch current time as milliseconds.
// Return as double for high duration and precision.
// TODO(fbarchard): integrate into base/time.h
static inline double GetTime() {
  return base::TimeTicks::HighResNow().ToInternalValue() * (1.0 / 1000.0);
}
}
#endif

namespace media {

namespace {

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.
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-52.dll");
    case FILE_LIBAVFORMAT:
      return FILE_PATH_LITERAL("avformat-52.dll");
    case FILE_LIBAVUTIL:
      return FILE_PATH_LITERAL("avutil-50.dll");
    default:
      LOG(DFATAL) << "Invalid DLL key requested: " << dll_key;
      return FILE_PATH_LITERAL("");
  }
}

}  // namespace

// 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) {
  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]));
#ifdef TESTING
    double dll_loadtime_start = GetTime();
#endif
    const wchar_t* cpath = path.value().c_str();
    libs[i] = LoadLibrary(cpath);
    if (!libs[i])
      break;
#ifdef TESTING
    double dll_loadtime_end = GetTime();
    std::wstring outputbuf = StringPrintf(L"DLL loadtime %5.2f ms, %ls\n",
        dll_loadtime_end - dll_loadtime_start,
        cpath);
    OutputDebugStringW(outputbuf.c_str());
#endif
  }

  // 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.
  if (libs[arraysize(libs)-1])
    return true;

  // 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 false;
}

}  // namespace media