// 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.

#include "content/browser/web_contents/web_drag_dest_win.h"

#include <windows.h>
#include <shlobj.h>

#include "base/win/win_util.h"
#include "content/browser/renderer_host/render_view_host_impl.h"
#include "content/browser/web_contents/web_drag_utils_win.h"
#include "content/public/browser/web_contents.h"
#include "content/public/browser/web_contents_delegate.h"
#include "content/public/browser/web_drag_dest_delegate.h"
#include "content/public/common/drop_data.h"
#include "net/base/net_util.h"
#include "third_party/WebKit/public/web/WebInputEvent.h"
#include "ui/base/clipboard/clipboard_util_win.h"
#include "ui/base/dragdrop/os_exchange_data.h"
#include "ui/base/dragdrop/os_exchange_data_provider_win.h"
#include "ui/base/window_open_disposition.h"
#include "ui/gfx/point.h"
#include "url/gurl.h"

using WebKit::WebDragOperationNone;
using WebKit::WebDragOperationCopy;
using WebKit::WebDragOperationLink;
using WebKit::WebDragOperationMove;
using WebKit::WebDragOperationGeneric;

namespace content {
namespace {

const unsigned short kHighBitMaskShort = 0x8000;

// A helper method for getting the preferred drop effect.
DWORD GetPreferredDropEffect(DWORD effect) {
  if (effect & DROPEFFECT_COPY)
    return DROPEFFECT_COPY;
  if (effect & DROPEFFECT_LINK)
    return DROPEFFECT_LINK;
  if (effect & DROPEFFECT_MOVE)
    return DROPEFFECT_MOVE;
  return DROPEFFECT_NONE;
}

int GetModifierFlags() {
  int modifier_state = 0;
  if (base::win::IsShiftPressed())
    modifier_state |= WebKit::WebInputEvent::ShiftKey;
  if (base::win::IsCtrlPressed())
    modifier_state |= WebKit::WebInputEvent::ControlKey;
  if (base::win::IsAltPressed())
    modifier_state |= WebKit::WebInputEvent::AltKey;
  if (::GetKeyState(VK_LWIN) & kHighBitMaskShort)
    modifier_state |= WebKit::WebInputEvent::MetaKey;
  if (::GetKeyState(VK_RWIN) & kHighBitMaskShort)
    modifier_state |= WebKit::WebInputEvent::MetaKey;
  return modifier_state;
}

// Helper method for converting Window's specific IDataObject to a DropData
// object.
void PopulateDropData(IDataObject* data_object, DropData* drop_data) {
  base::string16 url_str;
  if (ui::ClipboardUtil::GetUrl(
          data_object, &url_str, &drop_data->url_title, false)) {
    GURL test_url(url_str);
    if (test_url.is_valid())
      drop_data->url = test_url;
  }
  std::vector<base::string16> filenames;
  ui::ClipboardUtil::GetFilenames(data_object, &filenames);
  for (size_t i = 0; i < filenames.size(); ++i)
    drop_data->filenames.push_back(
        DropData::FileInfo(filenames[i], base::string16()));
  base::string16 text;
  ui::ClipboardUtil::GetPlainText(data_object, &text);
  if (!text.empty()) {
    drop_data->text = base::NullableString16(text, false);
  }
  base::string16 html;
  std::string html_base_url;
  ui::ClipboardUtil::GetHtml(data_object, &html, &html_base_url);
  if (!html.empty()) {
    drop_data->html = base::NullableString16(html, false);
  }
  if (!html_base_url.empty()) {
    drop_data->html_base_url = GURL(html_base_url);
  }
  ui::ClipboardUtil::GetWebCustomData(data_object, &drop_data->custom_data);
}

}  // namespace

// InterstitialDropTarget is like a ui::DropTargetWin implementation that
// WebDragDest passes through to if an interstitial is showing.  Rather than
// passing messages on to the renderer, we just check to see if there's a link
// in the drop data and handle links as navigations.
class InterstitialDropTarget {
 public:
  explicit InterstitialDropTarget(WebContents* web_contents)
      : web_contents_(web_contents) {}

  DWORD OnDragEnter(IDataObject* data_object, DWORD effect) {
    return ui::ClipboardUtil::HasUrl(data_object) ?
        GetPreferredDropEffect(effect) : DROPEFFECT_NONE;
  }

  DWORD OnDragOver(IDataObject* data_object, DWORD effect) {
    return ui::ClipboardUtil::HasUrl(data_object) ?
        GetPreferredDropEffect(effect) : DROPEFFECT_NONE;
  }

  void OnDragLeave(IDataObject* data_object) {
  }

  DWORD OnDrop(IDataObject* data_object, DWORD effect) {
    if (!ui::ClipboardUtil::HasUrl(data_object))
      return DROPEFFECT_NONE;

    std::wstring url;
    std::wstring title;
    ui::ClipboardUtil::GetUrl(data_object, &url, &title, true);
    OpenURLParams params(GURL(url), Referrer(), CURRENT_TAB,
                         PAGE_TRANSITION_AUTO_BOOKMARK, false);
    web_contents_->OpenURL(params);
    return GetPreferredDropEffect(effect);
  }

 private:
  WebContents* web_contents_;

  DISALLOW_COPY_AND_ASSIGN(InterstitialDropTarget);
};

WebDragDest::WebDragDest(HWND source_hwnd, WebContents* web_contents)
    : ui::DropTargetWin(source_hwnd),
      web_contents_(web_contents),
      current_rvh_(NULL),
      drag_cursor_(WebDragOperationNone),
      interstitial_drop_target_(new InterstitialDropTarget(web_contents)),
      delegate_(NULL),
      canceled_(false) {
}

WebDragDest::~WebDragDest() {
}

DWORD WebDragDest::OnDragEnter(IDataObject* data_object,
                               DWORD key_state,
                               POINT cursor_position,
                               DWORD effects) {
  current_rvh_ = web_contents_->GetRenderViewHost();

  // TODO(tc): PopulateDropData can be slow depending on what is in the
  // IDataObject.  Maybe we can do this in a background thread.
  scoped_ptr<DropData> drop_data;
  drop_data.reset(new DropData());
  PopulateDropData(data_object, drop_data.get());

  if (drop_data->url.is_empty())
    ui::OSExchangeDataProviderWin::GetPlainTextURL(data_object,
                                                   &drop_data->url);

  // Give the delegate an opportunity to cancel the drag.
  canceled_ = !web_contents_->GetDelegate()->CanDragEnter(
      web_contents_,
      *drop_data,
      WinDragOpMaskToWebDragOpMask(effects));
  if (canceled_)
    return DROPEFFECT_NONE;

  if (delegate_)
    delegate_->DragInitialize(web_contents_);

  // Don't pass messages to the renderer if an interstitial page is showing
  // because we don't want the interstitial page to navigate.  Instead,
  // pass the messages on to a separate interstitial DropTarget handler.
  if (web_contents_->ShowingInterstitialPage())
    return interstitial_drop_target_->OnDragEnter(data_object, effects);

  drop_data_.swap(drop_data);
  drag_cursor_ = WebDragOperationNone;

  POINT client_pt = cursor_position;
  ScreenToClient(GetHWND(), &client_pt);
  web_contents_->GetRenderViewHost()->DragTargetDragEnter(*drop_data_,
      gfx::Point(client_pt.x, client_pt.y),
      gfx::Point(cursor_position.x, cursor_position.y),
      WinDragOpMaskToWebDragOpMask(effects),
      GetModifierFlags());

  if (delegate_)
      delegate_->OnDragEnter(data_object);

  // We lie here and always return a DROPEFFECT because we don't want to
  // wait for the IPC call to return.
  return WebDragOpToWinDragOp(drag_cursor_);
}

DWORD WebDragDest::OnDragOver(IDataObject* data_object,
                              DWORD key_state,
                              POINT cursor_position,
                              DWORD effects) {
  DCHECK(current_rvh_);
  if (current_rvh_ != web_contents_->GetRenderViewHost())
    OnDragEnter(data_object, key_state, cursor_position, effects);

  if (canceled_)
    return DROPEFFECT_NONE;

  if (web_contents_->ShowingInterstitialPage())
    return interstitial_drop_target_->OnDragOver(data_object, effects);

  POINT client_pt = cursor_position;
  ScreenToClient(GetHWND(), &client_pt);
  web_contents_->GetRenderViewHost()->DragTargetDragOver(
      gfx::Point(client_pt.x, client_pt.y),
      gfx::Point(cursor_position.x, cursor_position.y),
      WinDragOpMaskToWebDragOpMask(effects),
      GetModifierFlags());

  if (delegate_)
    delegate_->OnDragOver(data_object);

  return WebDragOpToWinDragOp(drag_cursor_);
}

void WebDragDest::OnDragLeave(IDataObject* data_object) {
  DCHECK(current_rvh_);
  if (current_rvh_ != web_contents_->GetRenderViewHost())
    return;

  if (canceled_)
    return;

  if (web_contents_->ShowingInterstitialPage()) {
    interstitial_drop_target_->OnDragLeave(data_object);
  } else {
    web_contents_->GetRenderViewHost()->DragTargetDragLeave();
  }

  if (delegate_)
    delegate_->OnDragLeave(data_object);

  drop_data_.reset();
}

DWORD WebDragDest::OnDrop(IDataObject* data_object,
                          DWORD key_state,
                          POINT cursor_position,
                          DWORD effect) {
  DCHECK(current_rvh_);
  if (current_rvh_ != web_contents_->GetRenderViewHost())
    OnDragEnter(data_object, key_state, cursor_position, effect);

  if (web_contents_->ShowingInterstitialPage())
    interstitial_drop_target_->OnDragOver(data_object, effect);

  if (web_contents_->ShowingInterstitialPage())
    return interstitial_drop_target_->OnDrop(data_object, effect);

  POINT client_pt = cursor_position;
  ScreenToClient(GetHWND(), &client_pt);
  web_contents_->GetRenderViewHost()->DragTargetDrop(
      gfx::Point(client_pt.x, client_pt.y),
      gfx::Point(cursor_position.x, cursor_position.y),
      GetModifierFlags());

  if (delegate_)
    delegate_->OnDrop(data_object);

  current_rvh_ = NULL;

  // This isn't always correct, but at least it's a close approximation.
  // For now, we always map a move to a copy to prevent potential data loss.
  DWORD drop_effect = WebDragOpToWinDragOp(drag_cursor_);
  DWORD result = drop_effect != DROPEFFECT_MOVE ? drop_effect : DROPEFFECT_COPY;

  drop_data_.reset();
  return result;
}

}  // namespace content