// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CHROME_BROWSER_ASH_FILEAPI_DIVERSION_BACKEND_DELEGATE_H_
#define CHROME_BROWSER_ASH_FILEAPI_DIVERSION_BACKEND_DELEGATE_H_

#include <memory>

#include "base/memory/weak_ptr.h"
#include "chrome/browser/ash/fileapi/diversion_file_manager.h"
#include "chrome/browser/ash/fileapi/file_system_backend_delegate.h"
#include "storage/browser/file_system/async_file_util.h"

namespace ash {

// A FileSystemBackendDelegate decorator (and, transitively, an AsyncFileUtil
// decorator) that combines its wrappees with a DiversionFileManager. It
// interposes a backed-by-local-disk cache (which also enables efficient
// incremental-append writes) for potentially-remote file systems.
//
// A DiversionBackendDelegate's methods should only be called from the
// content::BrowserThread::IO thread. Callbacks run on the same thread.
class DiversionBackendDelegate : public FileSystemBackendDelegate,
                                 public storage::AsyncFileUtil {
 public:
  explicit DiversionBackendDelegate(
      std::unique_ptr<FileSystemBackendDelegate> wrappee);
  ~DiversionBackendDelegate() override;

  DiversionBackendDelegate(const DiversionBackendDelegate&) = delete;
  DiversionBackendDelegate& operator=(const DiversionBackendDelegate&) = delete;

  // FileSystemBackendDelegate overrides.
  storage::AsyncFileUtil* GetAsyncFileUtil(
      storage::FileSystemType type) override;
  std::unique_ptr<storage::FileStreamReader> CreateFileStreamReader(
      const storage::FileSystemURL& url,
      int64_t offset,
      int64_t max_bytes_to_read,
      const base::Time& expected_modification_time,
      storage::FileSystemContext* context) override;
  std::unique_ptr<storage::FileStreamWriter> CreateFileStreamWriter(
      const storage::FileSystemURL& url,
      int64_t offset,
      storage::FileSystemContext* context) override;
  storage::WatcherManager* GetWatcherManager(
      storage::FileSystemType type) override;
  void GetRedirectURLForContents(const storage::FileSystemURL& url,
                                 storage::URLCallback callback) override;

  // storage::AsyncFileUtil overrides.
  void CreateOrOpen(
      std::unique_ptr<storage::FileSystemOperationContext> context,
      const storage::FileSystemURL& url,
      uint32_t file_flags,
      CreateOrOpenCallback callback) override;
  void EnsureFileExists(
      std::unique_ptr<storage::FileSystemOperationContext> context,
      const storage::FileSystemURL& url,
      EnsureFileExistsCallback callback) override;
  void CreateDirectory(
      std::unique_ptr<storage::FileSystemOperationContext> context,
      const storage::FileSystemURL& url,
      bool exclusive,
      bool recursive,
      StatusCallback callback) override;
  void GetFileInfo(std::unique_ptr<storage::FileSystemOperationContext> context,
                   const storage::FileSystemURL& url,
                   GetMetadataFieldSet fields,
                   GetFileInfoCallback callback) override;
  void ReadDirectory(
      std::unique_ptr<storage::FileSystemOperationContext> context,
      const storage::FileSystemURL& url,
      ReadDirectoryCallback callback) override;
  void Touch(std::unique_ptr<storage::FileSystemOperationContext> context,
             const storage::FileSystemURL& url,
             const base::Time& last_access_time,
             const base::Time& last_modified_time,
             StatusCallback callback) override;
  void Truncate(std::unique_ptr<storage::FileSystemOperationContext> context,
                const storage::FileSystemURL& url,
                int64_t length,
                StatusCallback callback) override;
  void CopyFileLocal(
      std::unique_ptr<storage::FileSystemOperationContext> context,
      const storage::FileSystemURL& src_url,
      const storage::FileSystemURL& dest_url,
      CopyOrMoveOptionSet options,
      CopyFileProgressCallback progress_callback,
      StatusCallback callback) override;
  void MoveFileLocal(
      std::unique_ptr<storage::FileSystemOperationContext> context,
      const storage::FileSystemURL& src_url,
      const storage::FileSystemURL& dest_url,
      CopyOrMoveOptionSet options,
      StatusCallback callback) override;
  void CopyInForeignFile(
      std::unique_ptr<storage::FileSystemOperationContext> context,
      const base::FilePath& src_file_path,
      const storage::FileSystemURL& dest_url,
      StatusCallback callback) override;
  void DeleteFile(std::unique_ptr<storage::FileSystemOperationContext> context,
                  const storage::FileSystemURL& url,
                  StatusCallback callback) override;
  void DeleteDirectory(
      std::unique_ptr<storage::FileSystemOperationContext> context,
      const storage::FileSystemURL& url,
      StatusCallback callback) override;
  void DeleteRecursively(
      std::unique_ptr<storage::FileSystemOperationContext> context,
      const storage::FileSystemURL& url,
      StatusCallback callback) override;
  void CreateSnapshotFile(
      std::unique_ptr<storage::FileSystemOperationContext> context,
      const storage::FileSystemURL& url,
      CreateSnapshotFileCallback callback) override;

  void OverrideTmpfileDirForTesting(const base::FilePath& tmpfile_dir);
  static bool ShouldDivertForTesting(const storage::FileSystemURL& url);
  static base::TimeDelta IdleTimeoutForTesting();

 private:
  enum class OnDiversionFinishedCallSite {
    kEnsureFileExists,
    kCopyFileLocal,
    kMoveFileLocal,
  };

  static void OnDiversionFinished(
      base::WeakPtr<DiversionBackendDelegate> weak_ptr,
      OnDiversionFinishedCallSite call_site,
      std::unique_ptr<storage::FileSystemOperationContext> context,
      const storage::FileSystemURL& dest_url,
      storage::AsyncFileUtil::StatusCallback callback,
      DiversionFileManager::StoppedReason stopped_reason,
      const storage::FileSystemURL& src_url,
      base::ScopedFD scoped_fd,
      int64_t file_size,
      base::File::Error error);

  std::unique_ptr<FileSystemBackendDelegate> wrappee_;
  scoped_refptr<DiversionFileManager> diversion_file_manager_;

  base::WeakPtrFactory<DiversionBackendDelegate> weak_ptr_factory_{this};
};

}  // namespace ash

#endif  // CHROME_BROWSER_ASH_FILEAPI_DIVERSION_BACKEND_DELEGATE_H_