// Copyright (c) 2010 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 "chrome/browser/chromeos/wm_overview_controller.h"

#include <algorithm>
#include <vector>

#include "base/linked_ptr.h"
#include "chrome/browser/browser.h"
#include "chrome/browser/browser_process.h"
#include "chrome/browser/chromeos/wm_ipc.h"
#include "chrome/browser/chromeos/wm_overview_snapshot.h"
#include "chrome/browser/renderer_host/render_view_host.h"
#include "chrome/browser/tab_contents/tab_contents.h"
#include "chrome/browser/tab_contents/tab_contents_view.h"
#include "chrome/browser/tab_contents/thumbnail_generator.h"
#include "chrome/browser/views/frame/browser_extender.h"
#include "chrome/browser/views/frame/browser_view.h"
#include "chrome/common/notification_service.h"
#include "views/widget/root_view.h"
#include "views/widget/widget_gtk.h"
#include "views/window/window.h"

using std::vector;

#if !defined(OS_CHROMEOS)
#error This file is only meant to be compiled for ChromeOS
#endif

namespace chromeos {

class BrowserListener : public TabStripModelObserver {
 public:
  BrowserListener(Browser* browser, WmOverviewController* parent);
  ~BrowserListener();

  // Begin TabStripModelObserver methods
  virtual void TabInsertedAt(TabContents* contents,
                             int index,
                             bool foreground);
  virtual void TabClosingAt(TabContents* contents, int index) {}
  virtual void TabDetachedAt(TabContents* contents, int index);
  virtual void TabMoved(TabContents* contents,
                        int from_index,
                        int to_index);
  virtual void TabChangedAt(TabContents* contents, int index,
                            TabStripModelObserver::TabChangeType change_type);
  virtual void TabStripEmpty();
  virtual void TabDeselectedAt(TabContents* contents, int index) {}
  virtual void TabSelectedAt(TabContents* old_contents,
                             TabContents* new_contents,
                             int index,
                             bool user_gesture);
  // End TabStripModelObserver methods

  // Returns the number of tabs in this child.
  int count() const { return browser_->tabstrip_model()->count(); }

  // Returns the browser that this child gets its data from.
  Browser* browser() const { return browser_; }

  // Removes all the snapshots and re-populates them from the browser.
  void RecreateSnapshots();

  // Updates the selected index and tab count on the toplevel window.
  void UpdateSelectedIndex(int index);

  // Finds the first cell with no snapshot and invokes ConfigureCell
  // for it.  Returns false if there are no more cells to configure on
  // this listener.
  bool ConfigureNextUnconfiguredSnapshot();

  // Saves the currently selected tab.
  void SaveCurrentTab() { original_selected_tab_ = browser_->selected_index(); }

  // Reverts the selected browser tab to the tab that was selected
  // when This BrowserListener was created, or the last time
  // SaveCurrentTab was called.
  void RestoreOriginalSelectedTab();

  // Selects the tab at the given index.
  void SelectTab(int index);

  // Shows any snapshots that are not visible, and updates their
  // bitmaps.
  void ShowSnapshots();

 private:
  // Returns the tab contents from the tab model for this child at index.
  TabContents* GetTabContentsAt(int index) const  {
    return browser_->tabstrip_model()->GetTabContentsAt(index);
  }

  // Configures a cell from the tab contents.
  void ConfigureCell(WmOverviewSnapshot* cell, TabContents* contents);

  // Configures a cell from the model.
  void ConfigureCell(WmOverviewSnapshot* cell, int index) {
    ConfigureCell(cell, GetTabContentsAt(index));
  }

  // Inserts a new snapshot, initialized from the model, at the given
  // index, and renumbers any following snapshots.
  void InsertSnapshot(int index);

  // Removes the snapshot at index.
  void ClearSnapshot(int index);

  // Renumbers the index atom in the snapshots starting at the given
  // index.
  void RenumberSnapshots(int start_index);

  Browser* browser_;  // Not owned
  WmOverviewController* controller_;  // Not owned

  // Widgets containing snapshot images for this browser.
  typedef std::vector<WmOverviewSnapshot* > SnapshotVector;
  SnapshotVector snapshots_;

  // True if the snapshots are showing.
  bool snapshots_showing_;

  // The tab selected the last time SaveCurrentTab is called.
  int original_selected_tab_;

  DISALLOW_COPY_AND_ASSIGN(BrowserListener);
};

BrowserListener::BrowserListener(Browser* browser,
                                 WmOverviewController* controller)
    : browser_(browser),
      controller_(controller),
      snapshots_showing_(false),
      original_selected_tab_(-1) {
  CHECK(browser_);
  CHECK(controller_);
  browser_->tabstrip_model()->AddObserver(this);
}

BrowserListener::~BrowserListener() {
  browser_->tabstrip_model()->RemoveObserver(this);
}

void BrowserListener::TabInsertedAt(TabContents* contents,
                                    int index,
                                    bool foreground) {
  InsertSnapshot(index);
  RenumberSnapshots(index);
  UpdateSelectedIndex(browser_->selected_index());
}

void BrowserListener::TabDetachedAt(TabContents* contents, int index) {
  ClearSnapshot(index);
  UpdateSelectedIndex(browser_->selected_index());
  RenumberSnapshots(index);
}

void BrowserListener::TabMoved(TabContents* contents,
                               int from_index,
                               int to_index) {
  // Need to reorder tab in the snapshots list, and reset the window
  // type atom on the affected snapshots (the one moved, and all the
  // ones after it), so that their indices are correct.
  WmOverviewSnapshot* snapshot = snapshots_[from_index];
  snapshots_.erase(snapshots_.begin() + from_index);
  snapshots_.insert(snapshots_.begin() + to_index, snapshot);

  RenumberSnapshots(std::min(to_index, from_index));
}

void BrowserListener::TabChangedAt(
    TabContents* contents,
    int index,
    TabStripModelObserver::TabChangeType change_type) {
  snapshots_[index]->reload_snapshot();
  controller_->StartDelayTimer();
}

void BrowserListener::TabStripEmpty() {
  snapshots_.clear();
}

void BrowserListener::TabSelectedAt(TabContents* old_contents,
                                    TabContents* new_contents,
                                    int index,
                                    bool user_gesture) {
  UpdateSelectedIndex(index);
}

void BrowserListener::RecreateSnapshots() {
  snapshots_.clear();

  for (int i = 0; i < count(); ++i) {
    InsertSnapshot(i);
  }

  RenumberSnapshots(0);
}

void BrowserListener::UpdateSelectedIndex(int index) {
  WmIpcWindowType type = WmIpc::instance()->GetWindowType(
      GTK_WIDGET(browser_->window()->GetNativeHandle()), NULL);
  // Make sure we only operate on toplevel windows.
  if (type == WM_IPC_WINDOW_CHROME_TOPLEVEL) {
    std::vector<int> params;
    params.push_back(browser_->tab_count());
    params.push_back(index);
    WmIpc::instance()->SetWindowType(
        GTK_WIDGET(browser_->window()->GetNativeHandle()),
        WM_IPC_WINDOW_CHROME_TOPLEVEL,
        &params);
  }
}

bool BrowserListener::ConfigureNextUnconfiguredSnapshot() {
  for (SnapshotVector::size_type i = 0; i < snapshots_.size(); ++i) {
    WmOverviewSnapshot* cell = snapshots_[i];
    if (!cell->configured_snapshot()) {
      ConfigureCell(cell, GetTabContentsAt(i));
      return true;
    }
  }
  return false;
}

void BrowserListener::RestoreOriginalSelectedTab() {
  if (original_selected_tab_ >= 0) {
    browser_->SelectTabContentsAt(original_selected_tab_, false);
  }
}

void BrowserListener::ShowSnapshots() {
  for (SnapshotVector::size_type i = 0; i < snapshots_.size(); ++i) {
    WmOverviewSnapshot* snapshot = snapshots_[i];
    snapshot->reload_snapshot();
    if (!snapshot->IsVisible()) {
      snapshot->Show();
    }
  }
}

void BrowserListener::SelectTab(int index) {
  browser_->SelectTabContentsAt(index, true);
}

void BrowserListener::ConfigureCell(WmOverviewSnapshot* cell,
                                    TabContents* contents) {
  if (contents) {
    if (controller_->allow_show_snapshots()) {
      ThumbnailGenerator* generator =
          g_browser_process->GetThumbnailGenerator();
      // TODO: Make sure that if the cell gets deleted before the
      // callback is called that it sticks around until it gets
      // called.  (some kind of "in flight" list that uses linked_ptr
      // to make sure they don't actually get deleted?)  Also, make
      // sure that any request for a thumbnail eventually returns
      // (even if it has bogus data), so we don't leak orphaned cells.
      ThumbnailGenerator::ThumbnailReadyCallback* callback =
          NewCallback(cell, &WmOverviewSnapshot::SetImage);
      generator->AskForThumbnail(contents->render_view_host(),
                                 callback, cell->size());
    }
  } else {
    // This happens because the contents haven't been loaded yet.

    // Make sure we set the snapshot image to something, otherwise
    // configured_snapshot remains false and ConfigureNextUnconfiguredSnapshot
    // would get stuck.
    if (controller_->allow_show_snapshots()) {
      cell->SetImage(SkBitmap());
    }
  }
}

void BrowserListener::InsertSnapshot(int index) {
  WmOverviewSnapshot* snapshot = new WmOverviewSnapshot;
  gfx::Rect bounds =
      static_cast<BrowserView*>(browser_->window())->GetClientAreaBounds();
  gfx::Size size(bounds.width()/2, bounds.height()/2);
  snapshot->Init(size, browser_, index);
  snapshots_.insert(snapshots_.begin() + index, snapshot);
  snapshot->reload_snapshot();
  controller_->StartDelayTimer();
}

// Removes the snapshot at index.
void BrowserListener::ClearSnapshot(int index) {
  snapshots_[index]->CloseNow();
  snapshots_.erase(snapshots_.begin() + index);
}

void BrowserListener::RenumberSnapshots(int start_index) {
  int changes = 0;
  for (SnapshotVector::size_type i = start_index; i < snapshots_.size(); ++i) {
    if (snapshots_[i]->index() != static_cast<int>(i)) {
      snapshots_[i]->UpdateIndex(browser_, i);
      changes++;
    }
  }
}

///////////////////////////////////
// WmOverviewController methods

// static
WmOverviewController* WmOverviewController::instance() {
  static WmOverviewController* instance = NULL;
  if (!instance) {
    instance = Singleton<WmOverviewController>::get();
  }
  return instance;
}

WmOverviewController::WmOverviewController()
    : allow_show_snapshots_(false) {
  AddAllBrowsers();
  BrowserList::AddObserver(this);
  WmMessageListener::instance()->AddObserver(this);
}

WmOverviewController::~WmOverviewController() {
  WmMessageListener::instance()->RemoveObserver(this);
  BrowserList::RemoveObserver(this);
  listeners_.clear();
}

void WmOverviewController::Observe(NotificationType type,
                                   const NotificationSource& source,
                                   const NotificationDetails& details) {
  // Now that the browser window is ready, we create the snapshots.
  if (type == NotificationType::BROWSER_WINDOW_READY) {
    // This makes sure that the new listener is in the right order (to
    // match the order in the browser list).
    AddAllBrowsers();
  }
}

// Called immediately before a browser is removed from the list.
void WmOverviewController::OnBrowserRemoving(const Browser* browser) {
  for (BrowserListenerVector::iterator i = listeners_.begin();
       i != listeners_.end(); ++i) {
    if ((*i)->browser() == browser) {
      listeners_.erase(i);
      return;
    }
  }
}

BrowserView* GetBrowserViewForGdkWindow(GdkWindow* gdk_window) {
  gpointer data = NULL;
  gdk_window_get_user_data(gdk_window, &data);
  GtkWidget* widget = reinterpret_cast<GtkWidget*>(data);
  if (widget) {
    GtkWindow* gtk_window = GTK_WINDOW(widget);
    return BrowserView::GetBrowserViewForNativeWindow(gtk_window);
  } else {
    return NULL;
  }
}

void WmOverviewController::ProcessWmMessage(const WmIpc::Message& message,
                                            GdkWindow* window) {
  switch (message.type()) {
    case WM_IPC_MESSAGE_CHROME_NOTIFY_LAYOUT_MODE: {
      if (message.param(0) == 0 || BrowserList::size() == 0) {
        Hide(message.param(1) != 0);
      } else {
        Show();
      }
      break;
    }
    case WM_IPC_MESSAGE_CHROME_NOTIFY_TAB_SELECT: {
      BrowserView* browser_window = GetBrowserViewForGdkWindow(window);
      // Find out which listener this goes to, and send it there.
      for (BrowserListenerVector::iterator i = listeners_.begin();
           i != listeners_.end(); ++i) {
        if ((*i)->browser()->window() == browser_window) {
          (*i)->SelectTab(message.param(0));
          break;
        }
      }
      break;
    }
    default:
      break;
  }
}

void WmOverviewController::StartDelayTimer() {
  // We leave the delay timer running if it already is -- this means
  // we're rate limiting the number of times we can reconfigure the
  // snapshots (at most once every 350ms).  If we were to restart the
  // delay timer, it could result in a very long delay until they get
  // configured if tabs keep changing.
  if (!delay_timer_.IsRunning()) {
    configure_timer_.Stop();
    // Note that this pause is kind of a hack: it's just long enough
    // that the overview-mode transitions will have finished happening
    // before we start refreshing snapshots, so we don't bog the CPU
    // while it's trying to animate the overview transitions.
    delay_timer_.Start(
        base::TimeDelta::FromMilliseconds(350), this,
        &WmOverviewController::StartConfiguring);
  }
}

void WmOverviewController::RestoreTabSelections() {
  for (BrowserListenerVector::iterator i = listeners_.begin();
       i != listeners_.end(); ++i) {
    (*i)->RestoreOriginalSelectedTab();
  }
}

void WmOverviewController::SaveTabSelections() {
  for (BrowserListenerVector::iterator i = listeners_.begin();
       i != listeners_.end(); ++i) {
    (*i)->SaveCurrentTab();
  }
}

void WmOverviewController::Show() {
  SaveTabSelections();
  for (BrowserListenerVector::iterator i = listeners_.begin();
       i != listeners_.end(); ++i) {
    (*i)->ShowSnapshots();
  }
  allow_show_snapshots_ = false;
  StartDelayTimer();
}

void WmOverviewController::Hide(bool cancelled) {
  configure_timer_.Stop();
  delay_timer_.Stop();
  if (cancelled) {
    RestoreTabSelections();
  }
}

void WmOverviewController::StartConfiguring() {
  allow_show_snapshots_ = true;
  configure_timer_.Stop();
  configure_timer_.Start(
      base::TimeDelta::FromMilliseconds(10), this,
      &WmOverviewController::ConfigureNextUnconfiguredSnapshot);
}

// Just configure one unconfigured cell.  If there aren't any left,
// then stop the timer.
void WmOverviewController::ConfigureNextUnconfiguredSnapshot() {
  for (BrowserListenerVector::size_type i = 0; i < listeners_.size(); ++i) {
    BrowserListener* listener = listeners_[i].get();
    if (listener->ConfigureNextUnconfiguredSnapshot())
      return;
  }
  configure_timer_.Stop();
}

void WmOverviewController::AddAllBrowsers() {
  // Make a copy so the old ones aren't deleted yet.
  BrowserListenerVector old_listeners;

  listeners_.swap(old_listeners);

  // Iterator through the browser list, adding all the browsers in the
  // new order.  If they were in the old list of listeners, just copy
  // that linked pointer, instead of making a new listener, so that we
  // can avoid lots of spurious destroy/create messages.
  BrowserList::const_iterator iterator = BrowserList::begin();
  while (iterator != BrowserList::end()) {
    // Don't add a browser to the list if that type of browser doesn't
    // have snapshots in overview mode.
    if ((*iterator)->type() != Browser::TYPE_NORMAL &&
        (*iterator)->type() != Browser::TYPE_APP &&
        (*iterator)->type() != Browser::TYPE_EXTENSION_APP) {
      ++iterator;
      continue;
    }

    BrowserListenerVector::value_type item(
        BrowserListenerVector::value_type(NULL));
    for (BrowserListenerVector::iterator old_iter = old_listeners.begin();
         old_iter != old_listeners.end(); ++old_iter) {
      if ((*old_iter)->browser() == *iterator) {
        item = *old_iter;
        break;
      }
    }

    // This browser isn't owned by any listener, so create it.
    if (item.get() == NULL) {
      item = BrowserListenerVector::value_type(
          new BrowserListener(*iterator, this));

      // This browser didn't already exist, and so we haven't been
      // watching it for tab insertions, so we need to create the
      // snapshots associated with it.
      item->RecreateSnapshots();
    }
    listeners_.push_back(item);
    ++iterator;
  }

  // Make sure we get notifications for when browser windows are ready.
  if (registrar_.IsEmpty())
    registrar_.Add(this, NotificationType::BROWSER_WINDOW_READY,
                   NotificationService::AllSources());
}

}  // namespace chromeos