// 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 "ui/display/screen.h"

#import <ApplicationServices/ApplicationServices.h>
#import <Cocoa/Cocoa.h>
#include <stdint.h>

#include <map>
#include <memory>

#include "base/command_line.h"
#include "base/logging.h"
#include "base/mac/mac_util.h"
#include "base/mac/sdk_forward_declarations.h"
#include "base/macros.h"
#include "base/timer/timer.h"
#include "ui/display/display.h"
#include "ui/display/display_change_notifier.h"
#include "ui/gfx/mac/coordinate_conversion.h"
#include "ui/gfx/switches.h"

extern "C" {
Boolean CGDisplayUsesForceToGray(void);
}

namespace display {
namespace {

// The delay to handle the display configuration changes.
// See comments in ScreenMac::HandleDisplayReconfiguration.
const int64_t kConfigureDelayMs = 500;

NSScreen* GetMatchingScreen(const gfx::Rect& match_rect) {
  // Default to the monitor with the current keyboard focus, in case
  // |match_rect| is not on any screen at all.
  NSScreen* max_screen = [NSScreen mainScreen];
  int max_area = 0;

  for (NSScreen* screen in [NSScreen screens]) {
    gfx::Rect monitor_area = gfx::ScreenRectFromNSRect([screen frame]);
    gfx::Rect intersection = gfx::IntersectRects(monitor_area, match_rect);
    int area = intersection.width() * intersection.height();
    if (area > max_area) {
      max_area = area;
      max_screen = screen;
    }
  }

  return max_screen;
}

Display BuildDisplayForScreen(NSScreen* screen) {
  NSRect frame = [screen frame];

  CGDirectDisplayID display_id = [[[screen deviceDescription]
      objectForKey:@"NSScreenNumber"] unsignedIntValue];

  Display display(display_id, gfx::Rect(NSRectToCGRect(frame)));
  NSRect visible_frame = [screen visibleFrame];
  NSScreen* primary = [[NSScreen screens] firstObject];

  // Convert work area's coordinate systems.
  if ([screen isEqual:primary]) {
    gfx::Rect work_area = gfx::Rect(NSRectToCGRect(visible_frame));
    work_area.set_y(frame.size.height - visible_frame.origin.y -
                    visible_frame.size.height);
    display.set_work_area(work_area);
  } else {
    display.set_bounds(gfx::ScreenRectFromNSRect(frame));
    display.set_work_area(gfx::ScreenRectFromNSRect(visible_frame));
  }
  CGFloat scale = [screen backingScaleFactor];

  if (Display::HasForceDeviceScaleFactor())
    scale = Display::GetForcedDeviceScaleFactor();

  display.set_device_scale_factor(scale);

  // On Sierra, we need to operate in a single screen's color space because
  // IOSurfaces do not opt-out of color correction.
  // https://crbug.com/654488
  CGColorSpaceRef color_space = [[screen colorSpace] CGColorSpace];
  static bool color_correct_rendering_enabled =
      base::CommandLine::ForCurrentProcess()->HasSwitch(
          switches::kEnableColorCorrectRendering);
  if (base::mac::IsAtLeastOS10_12() && !color_correct_rendering_enabled)
    color_space = base::mac::GetSystemColorSpace();

  display.set_icc_profile(gfx::ICCProfile::FromCGColorSpace(color_space));
  display.set_color_depth(NSBitsPerPixelFromDepth([screen depth]));
  display.set_depth_per_component(NSBitsPerSampleFromDepth([screen depth]));
  display.set_is_monochrome(CGDisplayUsesForceToGray());

  // CGDisplayRotation returns a double. Display::SetRotationAsDegree will
  // handle the unexpected situations were the angle is not a multiple of 90.
  display.SetRotationAsDegree(static_cast<int>(CGDisplayRotation(display_id)));
  return display;
}

Display BuildPrimaryDisplay() {
  return BuildDisplayForScreen([[NSScreen screens] firstObject]);
}

// Returns the minimum Manhattan distance from |point| to corners of |screen|
// frame.
CGFloat GetMinimumDistanceToCorner(const NSPoint& point, NSScreen* screen) {
  NSRect frame = [screen frame];
  CGFloat distance =
      fabs(point.x - NSMinX(frame)) + fabs(point.y - NSMinY(frame));
  distance = std::min(
      distance, fabs(point.x - NSMaxX(frame)) + fabs(point.y - NSMinY(frame)));
  distance = std::min(
      distance, fabs(point.x - NSMinX(frame)) + fabs(point.y - NSMaxY(frame)));
  distance = std::min(
      distance, fabs(point.x - NSMaxX(frame)) + fabs(point.y - NSMaxY(frame)));
  return distance;
}

class ScreenMac : public Screen {
 public:
  ScreenMac()
      : configure_timer_(
            FROM_HERE,
            base::TimeDelta::FromMilliseconds(kConfigureDelayMs),
            base::Bind(&ScreenMac::ConfigureTimerFired, base::Unretained(this)),
            false) {
    old_displays_ = displays_ = BuildDisplaysFromQuartz();
    CGDisplayRegisterReconfigurationCallback(
        ScreenMac::DisplayReconfigurationCallBack, this);
  }

  ~ScreenMac() override {
    CGDisplayRemoveReconfigurationCallback(
        ScreenMac::DisplayReconfigurationCallBack, this);
  }

  gfx::Point GetCursorScreenPoint() override {
    // Flip coordinates to gfx (0,0 in top-left corner) using primary screen.
    return gfx::ScreenPointFromNSPoint([NSEvent mouseLocation]);
  }

  bool IsWindowUnderCursor(gfx::NativeWindow window) override {
    NOTIMPLEMENTED();
    return false;
  }

  gfx::NativeWindow GetWindowAtScreenPoint(const gfx::Point& point) override {
    NOTIMPLEMENTED();
    return gfx::NativeWindow();
  }

  int GetNumDisplays() const override { return GetAllDisplays().size(); }

  const std::vector<Display>& GetAllDisplays() const override {
    return displays_;
  }

  Display GetDisplayNearestWindow(gfx::NativeWindow window) const override {
    EnsureDisplaysValid();
    if (displays_.size() == 1)
      return displays_[0];

    if (!window)
      return GetPrimaryDisplay();

    // Note the following line calls -[NSWindow
    // _bestScreenBySpaceAssignmentOrGeometry] which is quite expensive and
    // performs IPC with the window server process.
    NSScreen* match_screen = [window screen];

    if (!match_screen)
      return GetPrimaryDisplay();
    return GetCachedDisplayForScreen(match_screen);
  }

  Display GetDisplayNearestView(gfx::NativeView view) const override {
    NSWindow* window = [view window];
    if (!window)
      window = [NSApp keyWindow];
    return GetDisplayNearestWindow(window);
  }

  Display GetDisplayNearestPoint(const gfx::Point& point) const override {
    NSArray* screens = [NSScreen screens];
    if ([screens count] <= 1)
      return GetPrimaryDisplay();

    NSPoint ns_point = NSPointFromCGPoint(point.ToCGPoint());
    NSScreen* primary = [screens objectAtIndex:0];
    ns_point.y = NSMaxY([primary frame]) - ns_point.y;
    for (NSScreen* screen in screens) {
      if (NSMouseInRect(ns_point, [screen frame], NO))
        return GetCachedDisplayForScreen(screen);
    }

    NSScreen* nearest_screen = primary;
    CGFloat min_distance = CGFLOAT_MAX;
    for (NSScreen* screen in screens) {
      CGFloat distance = GetMinimumDistanceToCorner(ns_point, screen);
      if (distance < min_distance) {
        min_distance = distance;
        nearest_screen = screen;
      }
    }
    return GetCachedDisplayForScreen(nearest_screen);
  }

  // Returns the display that most closely intersects the provided bounds.
  Display GetDisplayMatching(const gfx::Rect& match_rect) const override {
    NSScreen* match_screen = GetMatchingScreen(match_rect);
    return GetCachedDisplayForScreen(match_screen);
  }

  // Returns the primary display.
  Display GetPrimaryDisplay() const override {
    // Primary display is defined as the display with the menubar,
    // which is always at index 0.
    NSScreen* primary = [[NSScreen screens] firstObject];
    Display display = GetCachedDisplayForScreen(primary);
    return display;
  }

  void AddObserver(DisplayObserver* observer) override {
    change_notifier_.AddObserver(observer);
  }

  void RemoveObserver(DisplayObserver* observer) override {
    change_notifier_.RemoveObserver(observer);
  }

  static void DisplayReconfigurationCallBack(CGDirectDisplayID display,
                                             CGDisplayChangeSummaryFlags flags,
                                             void* userInfo) {
    if (flags & kCGDisplayBeginConfigurationFlag)
      return;

    ScreenMac* screen_mac = static_cast<ScreenMac*>(userInfo);

    // Timer::Reset() ensures at least another interval passes before the
    // associated task runs, effectively coalescing these events.
    screen_mac->configure_timer_.Reset();
    screen_mac->displays_require_update_ = true;
  }

 private:
  Display GetCachedDisplayForScreen(NSScreen* screen) const {
    EnsureDisplaysValid();
    const CGDirectDisplayID display_id = [[[screen deviceDescription]
        objectForKey:@"NSScreenNumber"] unsignedIntValue];
    for (const Display& display : displays_) {
      if (display_id == display.id())
        return display;
    }
    NOTREACHED();  // Asked for a hidden/sleeping/mirrored screen?
    return BuildDisplayForScreen(screen);
  }

  void EnsureDisplaysValid() const {
    if (displays_require_update_) {
      displays_ = BuildDisplaysFromQuartz();
      displays_require_update_ = false;
    }
  }

  void ConfigureTimerFired() {
    EnsureDisplaysValid();
    change_notifier_.NotifyDisplaysChanged(old_displays_, displays_);
    old_displays_ = displays_;
  }

  std::vector<Display> BuildDisplaysFromQuartz() const {
    // Don't just return all online displays.  This would include displays
    // that mirror other displays, which are not desired in this list.  It's
    // tempting to use the count returned by CGGetActiveDisplayList, but active
    // displays exclude sleeping displays, and those are desired.

    // It would be ridiculous to have this many displays connected, but
    // CGDirectDisplayID is just an integer, so supporting up to this many
    // doesn't hurt.
    CGDirectDisplayID online_displays[128];
    CGDisplayCount online_display_count = 0;
    if (CGGetOnlineDisplayList(arraysize(online_displays), online_displays,
                               &online_display_count) != kCGErrorSuccess) {
      return std::vector<Display>(1, BuildPrimaryDisplay());
    }

    typedef std::map<int64_t, NSScreen*> ScreenIdsToScreensMap;
    ScreenIdsToScreensMap screen_ids_to_screens;
    for (NSScreen* screen in [NSScreen screens]) {
      NSDictionary* screen_device_description = [screen deviceDescription];
      int64_t screen_id = [[screen_device_description
          objectForKey:@"NSScreenNumber"] unsignedIntValue];
      screen_ids_to_screens[screen_id] = screen;
    }

    std::vector<Display> displays;
    for (CGDisplayCount online_display_index = 0;
         online_display_index < online_display_count; ++online_display_index) {
      CGDirectDisplayID online_display = online_displays[online_display_index];
      if (CGDisplayMirrorsDisplay(online_display) == kCGNullDirectDisplay) {
        // If this display doesn't mirror any other, include it in the list.
        // The primary display in a mirrored set will be counted, but those that
        // mirror it will not be.
        ScreenIdsToScreensMap::iterator foundScreen =
            screen_ids_to_screens.find(online_display);
        if (foundScreen != screen_ids_to_screens.end()) {
          displays.push_back(BuildDisplayForScreen(foundScreen->second));
        }
      }
    }

    return displays.empty() ? std::vector<Display>(1, BuildPrimaryDisplay())
                            : displays;
  }

  // The displays currently attached to the device. Cached.
  mutable std::vector<Display> displays_;

  // Set whenever the CGDisplayRegisterReconfigurationCallback is invoked and
  // cleared when |displays_| is updated by BuildDisplaysFromQuartz().
  mutable bool displays_require_update_ = false;

  // The displays last communicated to DisplayChangeNotifier.
  std::vector<Display> old_displays_;

  // The timer to delay configuring outputs and notifying observers.
  base::Timer configure_timer_;

  DisplayChangeNotifier change_notifier_;

  DISALLOW_COPY_AND_ASSIGN(ScreenMac);
};

}  // namespace

// static
gfx::NativeWindow Screen::GetWindowForView(gfx::NativeView view) {
  NSWindow* window = nil;
#if !defined(USE_AURA)
  window = [view window];
#endif
  return window;
}

#if !defined(USE_AURA)
Screen* CreateNativeScreen() {
  return new ScreenMac;
}
#endif

}  // namespace display