// 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.

#ifndef EXTENSIONS_BROWSER_EXTENSION_API_FRAME_ID_MAP_H_
#define EXTENSIONS_BROWSER_EXTENSION_API_FRAME_ID_MAP_H_

#include <map>
#include <memory>
#include <set>

#include "base/lazy_instance.h"
#include "base/macros.h"

namespace content {
class NavigationHandle;
class RenderFrameHost;
class WebContents;
}  // namespace content

namespace extensions {

// Extension frame IDs are exposed through the chrome.* APIs and have the
// following characteristics:
// - The top-level frame has ID 0.
// - Any child frame has a positive ID.
// - A non-existant frame has ID -1.
// - They are only guaranteed to be unique within a tab.
// - The ID does not change during the frame's lifetime and is not re-used after
//   the frame is removed. The frame may change its current RenderFrameHost over
//   time, so multiple RenderFrameHosts may map to the same extension frame ID.
//
// This class provides a mapping from a (render_process_id, frame_routing_id)
// pair to a FrameData struct, which includes the extension's frame id (as
// described above), the parent frame id, and the tab id (the latter can be
// invalid if it's not in a tab).
//
// Unless stated otherwise, the methods can only be called on the UI thread.
//
// The non-static methods of this class use an internal cache.
class ExtensionApiFrameIdMap {
 public:
  // The data for a RenderFrame. Every RenderFrameIdKey maps to a FrameData.
  struct FrameData {
    FrameData();
    FrameData(int frame_id, int parent_frame_id, int tab_id, int window_id);
    ~FrameData();

    FrameData(const FrameData&);
    FrameData& operator=(const FrameData&);

    // The extension API frame ID of the frame.
    int frame_id;

    // The extension API frame ID of the parent of the frame.
    int parent_frame_id;

    // The id of the tab that the frame is in, or -1 if the frame isn't in a
    // tab.
    int tab_id;

    // The id of the window that the frame is in, or -1 if the frame isn't in a
    // window.
    int window_id;
  };

  // An invalid extension API frame ID.
  static const int kInvalidFrameId;

  // Extension API frame ID of the top-level frame.
  static const int kTopFrameId;

  static ExtensionApiFrameIdMap* Get();

  // Get the extension API frame ID for |rfh|.
  static int GetFrameId(content::RenderFrameHost* rfh);

  // Get the extension API frame ID for |navigation_handle|.
  static int GetFrameId(content::NavigationHandle* navigation_handle);

  // Get the extension API frame ID for the parent of |rfh|.
  static int GetParentFrameId(content::RenderFrameHost* rfh);

  // Get the extension API frame ID for the parent of |navigation_handle|.
  static int GetParentFrameId(content::NavigationHandle* navigation_handle);

  // Find the current RenderFrameHost for a given WebContents and extension
  // frame ID.
  // Returns nullptr if not found.
  static content::RenderFrameHost* GetRenderFrameHostById(
      content::WebContents* web_contents,
      int frame_id);

  // Retrieves the FrameData for a given |render_process_id| and
  // |render_frame_id|.
  FrameData GetFrameData(int render_process_id,
                         int render_frame_id) WARN_UNUSED_RESULT;

  // Called when a render frame is deleted. Stores the FrameData for |rfh| in
  // the deleted frames map so it can still be accessed for beacon requests. The
  // FrameData will be removed later in a task.
  void OnRenderFrameDeleted(content::RenderFrameHost* rfh);

 protected:
  friend struct base::LazyInstanceTraitsBase<ExtensionApiFrameIdMap>;

  // A set of identifiers that uniquely identifies a RenderFrame.
  struct RenderFrameIdKey {
    RenderFrameIdKey();
    RenderFrameIdKey(int render_process_id, int frame_routing_id);

    // The process ID of the renderer that contains the RenderFrame.
    int render_process_id;

    // The routing ID of the RenderFrame.
    int frame_routing_id;

    bool operator<(const RenderFrameIdKey& other) const;
    bool operator==(const RenderFrameIdKey& other) const;
  };

  using FrameDataMap = std::map<RenderFrameIdKey, FrameData>;

  ExtensionApiFrameIdMap();
  ~ExtensionApiFrameIdMap();

  // Determines the value to be stored in |frame_data_map_| for a given key.
  // If |require_live_frame| is true, FrameData will only
  // Returns empty FrameData when the corresponding RenderFrameHost is not
  // alive and |require_live_frame| is true.
  FrameData KeyToValue(const RenderFrameIdKey& key,
                       bool require_live_frame) const;

  // Holds mappings of render frame key to FrameData from frames that have been
  // recently deleted. These are kept for a short time so beacon requests that
  // continue after a frame is unloaded can access the FrameData.
  FrameDataMap deleted_frame_data_map_;

  DISALLOW_COPY_AND_ASSIGN(ExtensionApiFrameIdMap);
};

}  // namespace extensions

#endif  // EXTENSIONS_BROWSER_EXTENSION_API_FRAME_ID_MAP_H_