/**
* Copyright (c) 2015-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*/

#import "RCTDisplayLink.h"

#import <Foundation/Foundation.h>
#import <QuartzCore/CADisplayLink.h>

#import "RCTAssert.h"
#import "RCTBridgeModule.h"
#import "RCTFrameUpdate.h"
#import "RCTModuleData.h"
#import "RCTProfile.h"

#define RCTAssertRunLoop() \
RCTAssert(_runLoop == [NSRunLoop currentRunLoop], \
@"This method must be called on the CADisplayLink run loop")

@implementation RCTDisplayLink
{
CADisplayLink *_jsDisplayLink;
NSMutableSet<RCTModuleData *> *_frameUpdateObservers;
NSRunLoop *_runLoop;
}

- (instancetype)init
{
if ((self = [super init])) {
_frameUpdateObservers = [NSMutableSet new];
_jsDisplayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(_jsThreadUpdate:)];
}

return self;
}

- (void)registerModuleForFrameUpdates:(id<RCTBridgeModule>)module
withModuleData:(RCTModuleData *)moduleData
{
if (![moduleData.moduleClass conformsToProtocol:@protocol(RCTFrameUpdateObserver)] ||
[_frameUpdateObservers containsObject:moduleData]) {
return;
}

[_frameUpdateObservers addObject:moduleData];

// Don't access the module instance via moduleData, as this will cause deadlock
id<RCTFrameUpdateObserver> observer = (id<RCTFrameUpdateObserver>)module;
__weak typeof(self) weakSelf = self;
observer.pauseCallback = ^{
typeof(self) strongSelf = weakSelf;
if (!strongSelf) {
return;
}

CFRunLoopRef cfRunLoop = [strongSelf->_runLoop getCFRunLoop];
if (!cfRunLoop) {
return;
}

if ([NSRunLoop currentRunLoop] == strongSelf->_runLoop) {
[weakSelf updateJSDisplayLinkState];
} else {
CFRunLoopPerformBlock(cfRunLoop, kCFRunLoopDefaultMode, ^{
[weakSelf updateJSDisplayLinkState];
});
CFRunLoopWakeUp(cfRunLoop);
}
};

// Assuming we're paused right now, we only need to update the display link's state
// when the new observer is not paused. If it not paused, the observer will immediately
// start receiving updates anyway.
if (![observer isPaused] && _runLoop) {
CFRunLoopPerformBlock([_runLoop getCFRunLoop], kCFRunLoopDefaultMode, ^{
[self updateJSDisplayLinkState];
});
}
}

- (void)addToRunLoop:(NSRunLoop *)runLoop
{
_runLoop = runLoop;
[_jsDisplayLink addToRunLoop:runLoop forMode:NSRunLoopCommonModes];
}

- (void)invalidate
{
[_jsDisplayLink invalidate];
}

- (void)dispatchBlock:(dispatch_block_t)block
queue:(dispatch_queue_t)queue
{
if (queue == RCTJSThread) {
block();
} else if (queue) {
dispatch_async(queue, block);
}
}

- (void)_jsThreadUpdate:(CADisplayLink *)displayLink
{
RCTAssertRunLoop();

RCT_PROFILE_BEGIN_EVENT(RCTProfileTagAlways, @"-[RCTDisplayLink _jsThreadUpdate:]", nil);

RCTFrameUpdate *frameUpdate = [[RCTFrameUpdate alloc] initWithDisplayLink:displayLink];
for (RCTModuleData *moduleData in _frameUpdateObservers) {
id<RCTFrameUpdateObserver> observer = (id<RCTFrameUpdateObserver>)moduleData.instance;
if (!observer.paused) {
RCTProfileBeginFlowEvent();

[self dispatchBlock:^{
RCTProfileEndFlowEvent();
[observer didUpdateFrame:frameUpdate];
} queue:moduleData.methodQueue];
}
}

[self updateJSDisplayLinkState];

RCTProfileImmediateEvent(RCTProfileTagAlways, @"JS Thread Tick", displayLink.timestamp, 'g');

RCT_PROFILE_END_EVENT(RCTProfileTagAlways, @"objc_call");
}

- (void)updateJSDisplayLinkState
{
RCTAssertRunLoop();

BOOL pauseDisplayLink = YES;
for (RCTModuleData *moduleData in _frameUpdateObservers) {
id<RCTFrameUpdateObserver> observer = (id<RCTFrameUpdateObserver>)moduleData.instance;
if (!observer.paused) {
pauseDisplayLink = NO;
break;
}
}

_jsDisplayLink.paused = pauseDisplayLink;
}

@end