// Copyright 2017 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 "AppDelegate.h"

@interface AppDelegate ()
  @property (atomic) uint64_t textureId;
  @property (atomic) int framesProduced;
  @property (atomic) int framesConsumed;
  @property (atomic) int lastFrameConsumed;
  @property (atomic) double startTime;
  @property (atomic) double endTime;
  @property (atomic) double frameRate;
  @property (atomic) double frameStartTime;
  @property (atomic) NSTimer* timer;

  - (void)tick:(NSTimer*)timer;
@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  FlutterViewController* flutterController =
      (FlutterViewController*)self.window.rootViewController;
  FlutterMethodChannel* channel =
      [FlutterMethodChannel methodChannelWithName:@"texture"
                                  binaryMessenger:flutterController];
  [channel setMethodCallHandler:^(FlutterMethodCall* call, FlutterResult result) {
      if ([@"start" isEqualToString:call.method]) {
        _framesProduced = 0;
        _framesConsumed = 0;
        _frameRate = 1.0 / [(NSNumber*) call.arguments intValue];
        _timer = [NSTimer scheduledTimerWithTimeInterval:_frameRate
                                                  target:self
                                                selector:@selector(tick:)
                                                userInfo:nil
                                                 repeats:YES];
        _startTime = [[NSDate date] timeIntervalSince1970];
        result(nil);
      } else if ([@"stop" isEqualToString:call.method]) {
        [_timer invalidate];
        _endTime = [[NSDate date] timeIntervalSince1970];
        result(nil);
      } else if ([@"getProducedFrameRate" isEqualToString:call.method]) {
        result(@(_framesProduced / (_endTime - _startTime)));
      } else if ([@"getConsumedFrameRate" isEqualToString:call.method]) {
        result(@(_framesConsumed / (_endTime - _startTime)));
      } else {
        result(FlutterMethodNotImplemented);
      }
  }];
  _textureId = [flutterController registerTexture:self];
  return [super application:application didFinishLaunchingWithOptions:launchOptions];
}

- (void)tick:(NSTimer*)timer {
  FlutterViewController* flutterController =
      (FlutterViewController*)self.window.rootViewController;
  [flutterController textureFrameAvailable:_textureId];
  _frameStartTime = [[NSDate date] timeIntervalSince1970];
  // We just pretend to be producing a frame.
  _framesProduced++;
}

- (CVPixelBufferRef)copyPixelBuffer {
  double now = [[NSDate date] timeIntervalSince1970];
  if (now < _frameStartTime
      || _frameStartTime + _frameRate < now
      || _framesProduced == _lastFrameConsumed) return nil;
  _framesConsumed++;
  _lastFrameConsumed = _framesProduced;
  // We just pretend to be handing over the produced frame to the consumer.
  return nil;
}
@end
