// Copyright 2015 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 "chrome/browser/chromeos/file_system_provider/throttled_file_system.h"

#include <limits>
#include <vector>

#include "base/files/file.h"
#include "chrome/browser/chromeos/file_system_provider/queue.h"

namespace chromeos {
namespace file_system_provider {

ThrottledFileSystem::ThrottledFileSystem(
    scoped_ptr<ProvidedFileSystemInterface> file_system)
    : file_system_(file_system.Pass()), weak_ptr_factory_(this) {
  const int opened_files_limit =
      file_system_->GetFileSystemInfo().opened_files_limit();
  open_queue_.reset(opened_files_limit
                        ? new Queue(static_cast<size_t>(opened_files_limit))
                        : new Queue(std::numeric_limits<size_t>::max()));
}

ThrottledFileSystem::~ThrottledFileSystem() {
}

AbortCallback ThrottledFileSystem::RequestUnmount(
    const storage::AsyncFileUtil::StatusCallback& callback) {
  return file_system_->RequestUnmount(callback);
}

AbortCallback ThrottledFileSystem::GetMetadata(
    const base::FilePath& entry_path,
    MetadataFieldMask fields,
    const GetMetadataCallback& callback) {
  return file_system_->GetMetadata(entry_path, fields, callback);
}

AbortCallback ThrottledFileSystem::ReadDirectory(
    const base::FilePath& directory_path,
    const storage::AsyncFileUtil::ReadDirectoryCallback& callback) {
  return file_system_->ReadDirectory(directory_path, callback);
}

AbortCallback ThrottledFileSystem::ReadFile(
    int file_handle,
    net::IOBuffer* buffer,
    int64 offset,
    int length,
    const ReadChunkReceivedCallback& callback) {
  return file_system_->ReadFile(file_handle, buffer, offset, length, callback);
}

AbortCallback ThrottledFileSystem::OpenFile(const base::FilePath& file_path,
                                            OpenFileMode mode,
                                            const OpenFileCallback& callback) {
  const size_t task_token = open_queue_->NewToken();
  return open_queue_->Enqueue(
      task_token,
      base::Bind(
          &ProvidedFileSystemInterface::OpenFile,
          base::Unretained(file_system_.get()),  // Outlives the queue.
          file_path, mode,
          base::Bind(&ThrottledFileSystem::OnOpenFileCompleted,
                     weak_ptr_factory_.GetWeakPtr(), task_token, callback)));
}

AbortCallback ThrottledFileSystem::CloseFile(
    int file_handle,
    const storage::AsyncFileUtil::StatusCallback& callback) {
  return file_system_->CloseFile(
      file_handle,
      base::Bind(&ThrottledFileSystem::OnCloseFileCompleted,
                 weak_ptr_factory_.GetWeakPtr(), file_handle, callback));
}

AbortCallback ThrottledFileSystem::CreateDirectory(
    const base::FilePath& directory_path,
    bool recursive,
    const storage::AsyncFileUtil::StatusCallback& callback) {
  return file_system_->CreateDirectory(directory_path, recursive, callback);
}

AbortCallback ThrottledFileSystem::DeleteEntry(
    const base::FilePath& entry_path,
    bool recursive,
    const storage::AsyncFileUtil::StatusCallback& callback) {
  return file_system_->DeleteEntry(entry_path, recursive, callback);
}

AbortCallback ThrottledFileSystem::CreateFile(
    const base::FilePath& file_path,
    const storage::AsyncFileUtil::StatusCallback& callback) {
  return file_system_->CreateFile(file_path, callback);
}

AbortCallback ThrottledFileSystem::CopyEntry(
    const base::FilePath& source_path,
    const base::FilePath& target_path,
    const storage::AsyncFileUtil::StatusCallback& callback) {
  return file_system_->CopyEntry(source_path, target_path, callback);
}

AbortCallback ThrottledFileSystem::WriteFile(
    int file_handle,
    net::IOBuffer* buffer,
    int64 offset,
    int length,
    const storage::AsyncFileUtil::StatusCallback& callback) {
  return file_system_->WriteFile(file_handle, buffer, offset, length, callback);
}

AbortCallback ThrottledFileSystem::MoveEntry(
    const base::FilePath& source_path,
    const base::FilePath& target_path,
    const storage::AsyncFileUtil::StatusCallback& callback) {
  return file_system_->MoveEntry(source_path, target_path, callback);
}

AbortCallback ThrottledFileSystem::Truncate(
    const base::FilePath& file_path,
    int64 length,
    const storage::AsyncFileUtil::StatusCallback& callback) {
  return file_system_->Truncate(file_path, length, callback);
}

AbortCallback ThrottledFileSystem::AddWatcher(
    const GURL& origin,
    const base::FilePath& entry_path,
    bool recursive,
    bool persistent,
    const storage::AsyncFileUtil::StatusCallback& callback,
    const storage::WatcherManager::NotificationCallback&
        notification_callback) {
  return file_system_->AddWatcher(origin, entry_path, recursive, persistent,
                                  callback, notification_callback);
}

void ThrottledFileSystem::RemoveWatcher(
    const GURL& origin,
    const base::FilePath& entry_path,
    bool recursive,
    const storage::AsyncFileUtil::StatusCallback& callback) {
  file_system_->RemoveWatcher(origin, entry_path, recursive, callback);
}

const ProvidedFileSystemInfo& ThrottledFileSystem::GetFileSystemInfo() const {
  return file_system_->GetFileSystemInfo();
}

RequestManager* ThrottledFileSystem::GetRequestManager() {
  return file_system_->GetRequestManager();
}

Watchers* ThrottledFileSystem::GetWatchers() {
  return file_system_->GetWatchers();
}

void ThrottledFileSystem::AddObserver(ProvidedFileSystemObserver* observer) {
  file_system_->AddObserver(observer);
}

void ThrottledFileSystem::RemoveObserver(ProvidedFileSystemObserver* observer) {
  file_system_->RemoveObserver(observer);
}

void ThrottledFileSystem::Notify(
    const base::FilePath& entry_path,
    bool recursive,
    storage::WatcherManager::ChangeType change_type,
    scoped_ptr<ProvidedFileSystemObserver::Changes> changes,
    const std::string& tag,
    const storage::AsyncFileUtil::StatusCallback& callback) {
  return file_system_->Notify(entry_path, recursive, change_type,
                              changes.Pass(), tag, callback);
}

base::WeakPtr<ProvidedFileSystemInterface> ThrottledFileSystem::GetWeakPtr() {
  return weak_ptr_factory_.GetWeakPtr();
}

void ThrottledFileSystem::OnOpenFileCompleted(int queue_token,
                                              const OpenFileCallback& callback,
                                              int file_handle,
                                              base::File::Error result) {
  if (result != base::File::FILE_ERROR_ABORT)
    open_queue_->Complete(queue_token);

  // If the file is opened successfully then hold the queue token until the file
  // is closed.
  if (result == base::File::FILE_OK)
    opened_files_[file_handle] = queue_token;
  else
    open_queue_->Remove(queue_token);

  callback.Run(file_handle, result);
}

void ThrottledFileSystem::OnCloseFileCompleted(
    int file_handle,
    const storage::AsyncFileUtil::StatusCallback& callback,
    base::File::Error result) {
  // Closing is always final. Even if an error happened, the file is considered
  // closed on the C++ side. Release the task from the queue, so other files
  // which are enqueued can be opened.
  const auto it = opened_files_.find(file_handle);
  DCHECK(it != opened_files_.end());

  const int queue_token = it->second;
  open_queue_->Remove(queue_token);
  opened_files_.erase(file_handle);

  callback.Run(result);
}

}  // namespace file_system_provider
}  // namespace chromeos