// 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 "ash/tooltips/tooltip_controller.h"

#include <vector>

#include "ash/ash_switches.h"
#include "ash/shell.h"
#include "base/command_line.h"
#include "base/location.h"
#include "base/string_split.h"
#include "base/time.h"
#include "ui/aura/client/drag_drop_client.h"
#include "ui/aura/event.h"
#include "ui/aura/root_window.h"
#include "ui/aura/window.h"
#include "ui/base/resource/resource_bundle.h"
#include "ui/base/text/text_elider.h"
#include "ui/gfx/font.h"
#include "ui/gfx/point.h"
#include "ui/gfx/rect.h"
#include "ui/gfx/screen.h"
#include "ui/views/background.h"
#include "ui/views/border.h"
#include "ui/views/controls/label.h"
#include "ui/views/widget/widget.h"

namespace {

const SkColor kTooltipBackground = 0xFFFFFFCC;
const SkColor kTooltipBorder = 0xFF646450;
const int kTooltipBorderWidth = 1;
const int kTooltipHorizontalPadding = 3;

// Max visual tooltip width. If a tooltip is greater than this width, it will
// be wrapped.
const int kTooltipMaxWidthPixels = 400;

// Maximum number of lines we allow in the tooltip.
const size_t kMaxLines = 10;

// TODO(derat): This padding is needed on Chrome OS devices but seems excessive
// when running the same binary on a Linux workstation; presumably there's a
// difference in font metrics.  Rationalize this.
const int kTooltipVerticalPadding = 2;
const int kTooltipTimeoutMs = 500;

// FIXME: get cursor offset from actual cursor size.
const int kCursorOffsetX = 10;
const int kCursorOffsetY = 15;

// Maximum number of characters we allow in a tooltip.
const size_t kMaxTooltipLength = 1024;

gfx::Font GetDefaultFont() {
  // TODO(varunjain): implementation duplicated in tooltip_manager_aura. Figure
  // out a way to merge.
  return ui::ResourceBundle::GetSharedInstance().GetFont(
      ui::ResourceBundle::BaseFont);
}

int GetMaxWidth(int x, int y) {
  // TODO(varunjain): implementation duplicated in tooltip_manager_aura. Figure
  // out a way to merge.
  gfx::Rect monitor_bounds =
      gfx::Screen::GetMonitorNearestPoint(gfx::Point(x, y)).bounds();
  return (monitor_bounds.width() + 1) / 2;
}

// Creates a widget of type TYPE_TOOLTIP
views::Widget* CreateTooltip() {
  views::Widget* widget = new views::Widget;
  views::Widget::InitParams params;
  // For aura, since we set the type to TOOLTIP_TYPE, the widget will get
  // auto-parented to the MenuAndTooltipsContainer.
  params.type = views::Widget::InitParams::TYPE_TOOLTIP;
  params.keep_on_top = true;
  params.accept_events = false;
  params.ownership = views::Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET;
  widget->Init(params);
  return widget;
}

}  // namespace

namespace ash {
namespace internal {

// Displays a widget with tooltip using a views::Label.
class TooltipController::Tooltip {
 public:
  Tooltip() {
    label_.set_background(
        views::Background::CreateSolidBackground(kTooltipBackground));
    if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kAuraNoShadows)) {
      label_.set_border(
          views::Border::CreateSolidBorder(kTooltipBorderWidth,
                                           kTooltipBorder));
    }
    label_.set_parent_owned(false);
    widget_.reset(CreateTooltip());
    widget_->SetContentsView(&label_);
    widget_->Activate();
  }

  ~Tooltip() {
    widget_->Close();
  }

  // Updates the text on the tooltip and resizes to fit.
  void SetText(string16 tooltip_text, gfx::Point location) {
    int max_width, line_count;
    TrimTooltipToFit(&tooltip_text, &max_width, &line_count,
                     location.x(), location.y());
    label_.SetText(tooltip_text);

    int width = max_width + 2 * kTooltipHorizontalPadding;
    int height = label_.GetPreferredSize().height() +
        2 * kTooltipVerticalPadding;
    if (CommandLine::ForCurrentProcess()->HasSwitch(
            switches::kAuraNoShadows)) {
      width += 2 * kTooltipBorderWidth;
      height += 2 * kTooltipBorderWidth;
    }
    SetTooltipBounds(location, width, height);
  }

  // Shows the tooltip.
  void Show() {
    widget_->Show();
  }

  // Hides the tooltip.
  void Hide() {
    widget_->Hide();
  }

  bool IsVisible() {
    return widget_->IsVisible();
  }

 private:
  views::Label label_;
  scoped_ptr<views::Widget> widget_;

  // Adjusts the bounds given by the arguments to fit inside the desktop
  // and applies the adjusted bounds to the label_.
  void SetTooltipBounds(gfx::Point mouse_pos,
                        int tooltip_width,
                        int tooltip_height) {
    gfx::Rect tooltip_rect(mouse_pos.x(), mouse_pos.y(), tooltip_width,
                           tooltip_height);

    tooltip_rect.Offset(kCursorOffsetX, kCursorOffsetY);
    gfx::Rect monitor_bounds =
        gfx::Screen::GetMonitorNearestPoint(tooltip_rect.origin()).bounds();

    // If tooltip is out of bounds on the x axis, we simply shift it
    // horizontally by the offset.
    if (tooltip_rect.right() > monitor_bounds.right()) {
      int h_offset = tooltip_rect.right() - monitor_bounds.right();
      tooltip_rect.Offset(-h_offset, 0);
    }

    // If tooltip is out of bounds on the y axis, we flip it to appear above the
    // mouse cursor instead of below.
    if (tooltip_rect.bottom() > monitor_bounds.bottom())
      tooltip_rect.set_y(mouse_pos.y() - tooltip_height);

    widget_->SetBounds(tooltip_rect.AdjustToFit(monitor_bounds));
  }

};

////////////////////////////////////////////////////////////////////////////////
// TooltipController public:

TooltipController::TooltipController()
    : tooltip_window_(NULL),
      tooltip_window_at_mouse_press_(NULL),
      mouse_pressed_(false),
      tooltip_(new Tooltip),
      tooltips_enabled_(true) {
  tooltip_timer_.Start(FROM_HERE,
      base::TimeDelta::FromMilliseconds(kTooltipTimeoutMs),
      this, &TooltipController::TooltipTimerFired);
  aura::client::SetTooltipClient(Shell::GetRootWindow(), this);
}

TooltipController::~TooltipController() {
  if (tooltip_window_)
    tooltip_window_->RemoveObserver(this);
}

void TooltipController::UpdateTooltip(aura::Window* target) {
  // If tooltip is visible, we may want to hide it. If it is not, we are ok.
  if (tooltip_window_ == target && tooltip_->IsVisible())
    UpdateIfRequired();
}

void TooltipController::SetTooltipsEnabled(bool enable) {
  if (tooltips_enabled_ == enable)
    return;
  tooltips_enabled_ = enable;
  UpdateTooltip(tooltip_window_);
}

bool TooltipController::PreHandleKeyEvent(aura::Window* target,
                                          aura::KeyEvent* event) {
  return false;
}

bool TooltipController::PreHandleMouseEvent(aura::Window* target,
                                            aura::MouseEvent* event) {
  switch (event->type()) {
    case ui::ET_MOUSE_MOVED:
    case ui::ET_MOUSE_DRAGGED:
      if (tooltip_window_ != target) {
        if (tooltip_window_)
          tooltip_window_->RemoveObserver(this);
        tooltip_window_ = target;
        tooltip_window_->AddObserver(this);
      }
      curr_mouse_loc_ = event->location();
      if (tooltip_timer_.IsRunning())
        tooltip_timer_.Reset();

      // We update the tooltip if it is visible, or if we force-hid it due to a
      // mouse press.
      if (tooltip_->IsVisible() || tooltip_window_at_mouse_press_)
        UpdateIfRequired();
      break;
    case ui::ET_MOUSE_PRESSED:
      mouse_pressed_ = true;
      tooltip_window_at_mouse_press_ = target;
      if (target)
        tooltip_text_at_mouse_press_ = aura::client::GetTooltipText(target);
      tooltip_->Hide();
      break;
    case ui::ET_MOUSE_RELEASED:
      mouse_pressed_ = false;
      break;
    case ui::ET_MOUSE_CAPTURE_CHANGED:
      // We will not received a mouse release, so reset mouse pressed state.
      mouse_pressed_ = false;
    case ui::ET_MOUSEWHEEL:
      // Hide the tooltip for click, release, drag, wheel events.
      if (tooltip_->IsVisible())
        tooltip_->Hide();
      break;
    default:
      break;
  }
  return false;
}

ui::TouchStatus TooltipController::PreHandleTouchEvent(
    aura::Window* target,
    aura::TouchEvent* event) {
  // TODO(varunjain): need to properly implement tooltips for
  // touch events.
  // Hide the tooltip for touch events.
  if (tooltip_->IsVisible())
    tooltip_->Hide();
  if (tooltip_window_)
    tooltip_window_->RemoveObserver(this);
  tooltip_window_ = NULL;
  return ui::TOUCH_STATUS_UNKNOWN;
}

ui::GestureStatus TooltipController::PreHandleGestureEvent(
    aura::Window* target,
    aura::GestureEvent* event) {
  return ui::GESTURE_STATUS_UNKNOWN;
}

void TooltipController::OnWindowDestroyed(aura::Window* window) {
  if (tooltip_window_ == window) {
    tooltip_window_->RemoveObserver(this);
    tooltip_window_ = NULL;
  }
}

////////////////////////////////////////////////////////////////////////////////
// TooltipController private:

// static
void TooltipController::TrimTooltipToFit(string16* text,
                                         int* max_width,
                                         int* line_count,
                                         int x,
                                         int y) {
  *max_width = 0;
  *line_count = 0;

  // Clamp the tooltip length to kMaxTooltipLength so that we don't
  // accidentally DOS the user with a mega tooltip.
  if (text->length() > kMaxTooltipLength)
    *text = text->substr(0, kMaxTooltipLength);

  // Determine the available width for the tooltip.
  int available_width = std::min(kTooltipMaxWidthPixels, GetMaxWidth(x, y));

  std::vector<string16> lines;
  base::SplitString(*text, '\n', &lines);
  std::vector<string16> result_lines;

  // Format each line to fit.
  gfx::Font font = GetDefaultFont();
  for (std::vector<string16>::iterator l = lines.begin(); l != lines.end();
      ++l) {
    // We break the line at word boundaries, then stuff as many words as we can
    // in the available width to the current line, and move the remaining words
    // to a new line.
    std::vector<string16> words;
    base::SplitStringDontTrim(*l, ' ', &words);
    int current_width = 0;
    string16 line;
    for (std::vector<string16>::iterator w = words.begin(); w != words.end();
        ++w) {
      string16 word = *w;
      if (w + 1 != words.end())
        word.push_back(' ');
      int word_width = font.GetStringWidth(word);
      if (current_width + word_width > available_width) {
        // Current width will exceed the available width. Must start a new line.
        if (!line.empty())
          result_lines.push_back(line);
        current_width = 0;
        line.clear();
      }
      current_width += word_width;
      line.append(word);
    }
    result_lines.push_back(line);
  }

  // Clamp number of lines to |kMaxLines|.
  if (result_lines.size() > kMaxLines) {
    result_lines.resize(kMaxLines);
    // Add ellipses character to last line.
    result_lines[kMaxLines - 1] = ui::TruncateString(
        result_lines.back(), result_lines.back().length() - 1);
  }
  *line_count = result_lines.size();

  // Flatten the result.
  string16 result;
  for (std::vector<string16>::iterator l = result_lines.begin();
      l != result_lines.end(); ++l) {
    if (!result.empty())
      result.push_back('\n');
    int line_width = font.GetStringWidth(*l);
    // Since we only break at word boundaries, it could happen that due to some
    // very long word, line_width is greater than the available_width. In such
    // case, we simply truncate at available_width and add ellipses at the end.
    if (line_width > available_width) {
      *max_width = available_width;
      result.append(ui::ElideText(*l, font, available_width, ui::ELIDE_AT_END));
    } else {
      *max_width = std::max(*max_width, line_width);
      result.append(*l);
    }
  }
  *text = result;
}

void TooltipController::TooltipTimerFired() {
  UpdateIfRequired();
}

void TooltipController::UpdateIfRequired() {
  if (!tooltips_enabled_ || mouse_pressed_ || IsDragDropInProgress() ||
      !Shell::GetRootWindow()->cursor_shown()) {
    tooltip_->Hide();
    return;
  }

  string16 tooltip_text;
  if (tooltip_window_)
    tooltip_text = aura::client::GetTooltipText(tooltip_window_);

  // If the user pressed a mouse button. We will hide the tooltip and not show
  // it until there is a change in the tooltip.
  if (tooltip_window_at_mouse_press_) {
    if (tooltip_window_ == tooltip_window_at_mouse_press_ &&
        tooltip_text == tooltip_text_at_mouse_press_) {
      tooltip_->Hide();
      return;
    }
    tooltip_window_at_mouse_press_ = NULL;
  }

  // We add the !tooltip_->IsVisible() below because when we come here from
  // TooltipTimerFired(), the tooltip_text may not have changed but we still
  // want to update the tooltip because the timer has fired.
  // If we come here from UpdateTooltip(), we have already checked for tooltip
  // visibility and this check below will have no effect.
  if (tooltip_text_ != tooltip_text || !tooltip_->IsVisible()) {
    tooltip_text_ = tooltip_text;
    if (tooltip_text_.empty()) {
      tooltip_->Hide();
    } else {
      string16 tooltip_text(tooltip_text_);
      gfx::Point widget_loc = curr_mouse_loc_;
      widget_loc = widget_loc.Add(
          tooltip_window_->GetBoundsInRootWindow().origin());
      tooltip_->SetText(tooltip_text, widget_loc);
      tooltip_->Show();
    }
  }
}

bool TooltipController::IsTooltipVisible() {
  return tooltip_->IsVisible();
}

bool TooltipController::IsDragDropInProgress() {
  aura::client::DragDropClient* client = aura::client::GetDragDropClient(
      Shell::GetRootWindow());
  if (client)
    return client->IsDragDropInProgress();
  return false;
}

}  // namespace internal
}  // namespace ash