// Copyright (c) 2012 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.

#import <Cocoa/Cocoa.h>

#include <memory>

#include "base/strings/string16.h"
#include "content/browser/loader/global_routing_id.h"
#include "content/common/content_export.h"
#include "content/public/common/drop_data.h"
#include "ui/gfx/geometry/point.h"

namespace content {
class RenderViewHost;
class RenderWidgetHostImpl;
class WebContentsImpl;
class WebDragDestDelegate;
}

// A typedef for a RenderViewHost used for comparison purposes only.
typedef content::RenderViewHost* RenderViewHostIdentifier;

// A class that handles tracking and event processing for a drag and drop
// over the content area. Assumes something else initiates the drag, this is
// only for processing during a drag.
CONTENT_EXPORT
@interface WebDragDest : NSObject {
 @private
  // Our associated WebContentsImpl. Weak reference.
  content::WebContentsImpl* webContents_;

  // Delegate; weak.
  content::WebDragDestDelegate* delegate_;

  // Updated asynchronously during a drag to tell us whether or not we should
  // allow the drop.
  NSDragOperation currentOperation_;

  // Tracks the current RenderWidgetHost we're dragging over.
  base::WeakPtr<content::RenderWidgetHostImpl> currentRWHForDrag_;

  // Keep track of the render view host we're dragging over.  If it changes
  // during a drag, we need to re-send the DragEnter message.
  RenderViewHostIdentifier currentRVH_;

  // Tracks the IDs of the source RenderProcessHost and RenderViewHost from
  // which the current drag originated. These are set in
  // -setDragStartTrackersForProcess:, and are used to ensure that drag events
  // do not fire over a cross-site frame (with respect to the source frame) in
  // the same page (see crbug.com/666858). See
  // WebContentsViewAura::drag_start_process_id_ for additional information.
  int dragStartProcessID_;
  content::GlobalRoutingID dragStartViewID_;

  // The data for the current drag, or NULL if none is in progress.
  std::unique_ptr<content::DropData> dropData_;

  // True if the drag has been canceled.
  bool canceled_;
}

// |contents| is the WebContentsImpl representing this tab, used to communicate
// drag&drop messages to WebCore and handle navigation on a successful drop
// (if necessary).
- (id)initWithWebContentsImpl:(content::WebContentsImpl*)contents;

- (content::DropData*)currentDropData;

- (void)setDragDelegate:(content::WebDragDestDelegate*)delegate;

// Sets the current operation negotiated by the source and destination,
// which determines whether or not we should allow the drop. Takes effect the
// next time |-draggingUpdated:| is called.
- (void)setCurrentOperation:(NSDragOperation)operation;

// Messages to send during the tracking of a drag, ususally upon receiving
// calls from the view system. Communicates the drag messages to WebCore.
- (NSDragOperation)draggingEntered:(id<NSDraggingInfo>)info
                              view:(NSView*)view;
- (void)draggingExited:(id<NSDraggingInfo>)info;
- (NSDragOperation)draggingUpdated:(id<NSDraggingInfo>)info
                              view:(NSView*)view;
- (BOOL)performDragOperation:(id<NSDraggingInfo>)info view:(NSView*)view;

// Helper to call WebWidgetHostInputEventRouter::GetRenderWidgetHostAtPoint().
- (content::RenderWidgetHostImpl*)
GetRenderWidgetHostAtPoint:(const NSPoint&)viewPoint
             transformedPt:(gfx::Point*)transformedPt;

// Sets |dragStartProcessID_| and |dragStartViewID_|.
- (void)setDragStartTrackersForProcess:(int)processID;

// Returns whether |targetRWH| is a valid RenderWidgetHost to be dragging
// over. This enforces that same-page, cross-site drags are not allowed. See
// crbug.com/666858.
- (bool)isValidDragTarget:(content::RenderWidgetHostImpl*)targetRWH;

@end

// Public use only for unit tests.
@interface WebDragDest(Testing)
// Given |data|, which should not be nil, fill it in using the contents of the
// given pasteboard.
- (void)populateDropData:(content::DropData*)data
             fromPasteboard:(NSPasteboard*)pboard;
// Given a point in window coordinates and a view in that window, return a
// flipped point in the coordinate system of |view|.
- (NSPoint)flipWindowPointToView:(const NSPoint&)windowPoint
                            view:(NSView*)view;
// Given a point in window coordinates and a view in that window, return a
// flipped point in screen coordinates.
- (NSPoint)flipWindowPointToScreen:(const NSPoint&)windowPoint
                              view:(NSView*)view;
@end
