// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_BROWSER_FILE_SYSTEM_ACCESS_FILE_SYSTEM_ACCESS_OBSERVER_OBSERVATION_H_
#define CONTENT_BROWSER_FILE_SYSTEM_ACCESS_FILE_SYSTEM_ACCESS_OBSERVER_OBSERVATION_H_

#include <memory>
#include <variant>

#include "base/sequence_checker.h"
#include "base/thread_annotations.h"
#include "content/browser/file_system_access/file_system_access_observation_group.h"
#include "content/browser/file_system_access/file_system_access_watcher_manager.h"
#include "content/public/browser/web_contents_observer.h"
#include "mojo/public/cpp/bindings/pending_remote.h"
#include "mojo/public/cpp/bindings/remote.h"
#include "storage/browser/file_system/file_system_url.h"
#include "third_party/blink/public/mojom/file_system_access/file_system_access_observer.mojom.h"

namespace content {
class FileSystemAccessDirectoryHandleImpl;
class FileSystemAccessFileHandleImpl;
class FileSystemAccessObserverHost;

// Browser-side representation of a successful `FileSystemObserver.observe()`
// call from JavaScript. Forwards changes to the observed file or directory
// to a mojo pipe whose receiver is owned by the renderer.
//
// TODO(crbug.com/341213353): Consider removing this class in favor of
// giving the ObserverHost a FileSystemAccessObserver mojo::RemoteSet. See
// https://chromium-review.googlesource.com/c/chromium/src/+/4809069/comment/8d90508d_74ae7891/.
class FileSystemAccessObserverObservation
    : public WebContentsObserver,
      public FileSystemAccessPermissionGrant::Observer {
 public:
  FileSystemAccessObserverObservation(
      FileSystemAccessObserverHost* host,
      std::unique_ptr<FileSystemAccessObservationGroup::Observer> observation,
      mojo::PendingRemote<blink::mojom::FileSystemAccessObserver> remote,
      std::variant<std::unique_ptr<FileSystemAccessDirectoryHandleImpl>,
                   std::unique_ptr<FileSystemAccessFileHandleImpl>> handle);
  ~FileSystemAccessObserverObservation() override;

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

  const storage::FileSystemURL& handle_url() const;

  // WebContentsObserver override.
  void RenderFrameHostStateChanged(
      RenderFrameHost* render_frame_host,
      RenderFrameHost::LifecycleState old_state,
      RenderFrameHost::LifecycleState new_state) override;

  // FileSystemAccessPermissionGrant::Observer override.
  void OnPermissionStatusChanged() override;

 private:
  void OnReceiverDisconnect();

  // Called repeatedly by `observation_` whenever there are file changes. It
  // processes the received change data and sends a file change event via mojo
  // pipe.
  void OnChanges(
      const std::optional<std::list<FileSystemAccessObservationGroup::Change>>&
          changes_or_error);

  // Invoked if an error occurred while watching file changes. It sends a file
  // change event with `kErrored` type and destroys this observation so that
  // it is no longer observing. Currently, an error indicates that this
  // observation is in a non-recoverable state.
  void HandleError();

  void RecordCallbackCountUMA();

  SEQUENCE_CHECKER(sequence_checker_);

  int callback_count_ = 0;

  bool received_changes_while_in_bf_cache_ = false;
  bool received_error_while_in_bf_cache_ = false;

  // The host which owns this instance.
  const raw_ptr<FileSystemAccessObserverHost> host_ = nullptr;

  // The `FileSystemHandle` being observed.
  const std::variant<std::unique_ptr<FileSystemAccessDirectoryHandleImpl>,
                     std::unique_ptr<FileSystemAccessFileHandleImpl>>
      handle_;

  std::unique_ptr<FileSystemAccessObservationGroup::Observer> observation_
      GUARDED_BY_CONTEXT(sequence_checker_);

  // Mojo pipes that send file change notifications back to the renderer.
  // Each connection corresponds to a file system watch set up with
  // `Observe()`.
  mojo::Remote<blink::mojom::FileSystemAccessObserver> remote_
      GUARDED_BY_CONTEXT(sequence_checker_);

  base::WeakPtrFactory<FileSystemAccessObserverObservation> weak_factory_
      GUARDED_BY_CONTEXT(sequence_checker_){this};
};

}  // namespace content

#endif  // CONTENT_BROWSER_FILE_SYSTEM_ACCESS_FILE_SYSTEM_ACCESS_OBSERVER_OBSERVATION_H_