// Copyright 2016 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 "services/file/file_service.h"

#include <utility>

#include "base/bind.h"
#include "base/memory/weak_ptr.h"
#include "base/task/post_task.h"
#include "components/services/filesystem/lock_table.h"
#include "components/services/leveldb/leveldb_service_impl.h"
#include "mojo/public/cpp/bindings/receiver_set.h"
#include "mojo/public/cpp/bindings/unique_receiver_set.h"
#include "services/file/file_system.h"
#include "services/file/user_id_map.h"

namespace file {

class FileService::FileSystemObjects
    : public base::SupportsWeakPtr<FileSystemObjects> {
 public:
  // Created on the main thread.
  FileSystemObjects(base::FilePath user_dir) : user_dir_(user_dir) {}

  // Destroyed on the |file_service_runner_|.
  ~FileSystemObjects() = default;

  // Called on the |file_service_runner_|.
  void BindFileSystemReceiver(
      const service_manager::Identity& remote_identity,
      mojo::PendingReceiver<mojom::FileSystem> receiver) {
    if (!lock_table_)
      lock_table_ = new filesystem::LockTable;
    file_system_receivers_.Add(
        std::make_unique<FileSystem>(user_dir_, lock_table_),
        std::move(receiver));
  }

 private:
  scoped_refptr<filesystem::LockTable> lock_table_;
  base::FilePath user_dir_;
  mojo::UniqueReceiverSet<mojom::FileSystem> file_system_receivers_;

  DISALLOW_COPY_AND_ASSIGN(FileSystemObjects);
};

class FileService::LevelDBServiceObjects
    : public base::SupportsWeakPtr<LevelDBServiceObjects> {
 public:
  // Created on the main thread.
  LevelDBServiceObjects(
      scoped_refptr<base::SequencedTaskRunner> file_task_runner)
      : file_task_runner_(std::move(file_task_runner)) {}

  // Destroyed on the |leveldb_service_runner_|.
  ~LevelDBServiceObjects() = default;

  // Called on the |leveldb_service_runner_|.
  void BindLevelDBServiceReceiver(
      const service_manager::Identity& remote_identity,
      mojo::PendingReceiver<leveldb::mojom::LevelDBService> receiver) {
    if (!leveldb_service_) {
      leveldb_service_ =
          std::make_unique<leveldb::LevelDBServiceImpl>(file_task_runner_);
    }
    leveldb_receivers_.Add(leveldb_service_.get(), std::move(receiver));
  }

 private:
  scoped_refptr<base::SequencedTaskRunner> file_task_runner_;

  // Variables that are only accessible on the |leveldb_service_runner_| thread.
  std::unique_ptr<leveldb::mojom::LevelDBService> leveldb_service_;
  mojo::ReceiverSet<leveldb::mojom::LevelDBService> leveldb_receivers_;

  DISALLOW_COPY_AND_ASSIGN(LevelDBServiceObjects);
};

FileService::FileService(
    mojo::PendingReceiver<service_manager::mojom::Service> receiver)
    : service_binding_(this, std::move(receiver)),
      file_service_runner_(base::CreateSequencedTaskRunnerWithTraits(
          {base::MayBlock(), base::TaskShutdownBehavior::BLOCK_SHUTDOWN})),
      leveldb_service_runner_(base::CreateSequencedTaskRunnerWithTraits(
          {base::MayBlock(), base::TaskShutdownBehavior::BLOCK_SHUTDOWN})) {
  binders_.Add<leveldb::mojom::LevelDBService>(base::BindRepeating(
      &FileService::BindLevelDBServiceReceiver, base::Unretained(this)));
  binders_.Add<mojom::FileSystem>(base::BindRepeating(
      &FileService::BindFileSystemReceiver, base::Unretained(this)));
}

FileService::~FileService() {
  file_service_runner_->DeleteSoon(FROM_HERE, file_system_objects_.release());
  leveldb_service_runner_->DeleteSoon(FROM_HERE, leveldb_objects_.release());
}

void FileService::OnStart() {
  file_system_objects_ = std::make_unique<FileService::FileSystemObjects>(
      GetUserDirForInstanceGroup(service_binding_.identity().instance_group()));
  leveldb_objects_ = std::make_unique<FileService::LevelDBServiceObjects>(
      file_service_runner_);
}

void FileService::OnConnect(const service_manager::ConnectSourceInfo& source,
                            const std::string& interface_name,
                            mojo::ScopedMessagePipeHandle receiver_pipe) {
  binders_.TryBind(source.identity, interface_name, &receiver_pipe);
}

void FileService::BindFileSystemReceiver(
    const service_manager::Identity& remote_identity,
    mojo::PendingReceiver<mojom::FileSystem> receiver) {
  file_service_runner_->PostTask(
      FROM_HERE,
      base::BindOnce(&FileService::FileSystemObjects::BindFileSystemReceiver,
                     file_system_objects_->AsWeakPtr(), remote_identity,
                     std::move(receiver)));
}

void FileService::BindLevelDBServiceReceiver(
    const service_manager::Identity& remote_identity,
    mojo::PendingReceiver<leveldb::mojom::LevelDBService> receiver) {
  leveldb_service_runner_->PostTask(
      FROM_HERE,
      base::BindOnce(
          &FileService::LevelDBServiceObjects::BindLevelDBServiceReceiver,
          leveldb_objects_->AsWeakPtr(), remote_identity, std::move(receiver)));
}

}  // namespace user_service