/*
     File: SimpleEditor.m
 Abstract: Demonstrates construction of AVComposition, AVAudioMix, and AVVideoComposition. 
 
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 */

#import "SimpleEditor.h"

#import <CoreMedia/CoreMedia.h>
#import <AVFoundation/AVFoundation.h>

@implementation SimpleEditor

- (id)init
{
	if (self = [super init]) {
		_songStartTime = CMTimeMake(0, 1); // Default start time for the song is two seconds.
		_videoStartTime = CMTimeMake(0, 1); // Default start time for the video is two seconds.
	}
	return self;
}

// Configuration

@synthesize video = _video, videoStartTime = _videoStartTime;
@synthesize song = _song, songStartTime = _songStartTime;
@synthesize videoComposition = _videoComposition;

// Composition objects.

@synthesize composition = _composition;
@synthesize audioMix = _audioMix;
@synthesize playerItem = _playerItem;

- (void)addSongTrackToComposition:(AVMutableComposition *)composition withAudioMix:(AVMutableAudioMix *)audioMix
{	
	// Clip song duration to composition duration.
	CMTimeRange songTimeRange = CMTimeRangeMake(self.songStartTime, self.video.duration);
	if (CMTIME_COMPARE_INLINE(CMTimeRangeGetEnd(songTimeRange), >, [composition duration]))
		songTimeRange.duration = CMTimeSubtract([composition duration], songTimeRange.start);
	
	// Add the song track.
	AVMutableCompositionTrack *compositionSongTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
	[compositionSongTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, songTimeRange.duration) ofTrack:[[self.song tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:songTimeRange.start error:nil];

	// Ramp tracks down and up at beginning and end.
	NSMutableArray *trackMixArray = [NSMutableArray array];

    CMTime rampDuration = CMTimeMake(1, 2); // half-second ramp-ups
    CMTime endRampDuration = CMTimeMake(4, 2); // two-second ramp-downs
    
    // Ramp song down and up
    AVMutableAudioMixInputParameters *trackMix = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:compositionSongTrack];
    // CMTimeRangeMake(CMTimeSubtract(songTimeRange.start, rampDuration)
    [trackMix setVolumeRampFromStartVolume:0.3 toEndVolume:0.5 timeRange:CMTimeRangeMake(songTimeRange.start, rampDuration)];
    [trackMix setVolumeRampFromStartVolume:0.5 toEndVolume:0.0 timeRange:CMTimeRangeMake(CMTimeSubtract(CMTimeRangeGetEnd(songTimeRange), endRampDuration), endRampDuration)];
    [trackMixArray addObject:trackMix];

	audioMix.inputParameters = trackMixArray;
}

- (void)addVideoTrackToComposition:(AVMutableComposition *)composition
{
    AVAssetTrack *videoTrack = nil;
    if ([[self.video tracksWithMediaType:AVMediaTypeVideo] count] > 0)
       videoTrack = [[self.video tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];

    AVMutableCompositionTrack *compositionVideoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
    CMTimeRange videoTimeRange = CMTimeRangeMake(self.videoStartTime, self.video.duration);

    [compositionVideoTrack insertTimeRange:videoTimeRange ofTrack:videoTrack atTime:videoTimeRange.start error:nil];
}
- (void)addAudioTrackToComposition:(AVMutableComposition *)composition
{
    AVAssetTrack *audioTrack = nil;
    if ([[self.video tracksWithMediaType:AVMediaTypeAudio] count] > 0)
       audioTrack = [[self.video tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];

    AVMutableCompositionTrack *compositionAudioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
    CMTimeRange audioTimeRange = CMTimeRangeMake(self.videoStartTime, self.video.duration);

    [compositionAudioTrack insertTimeRange:audioTimeRange ofTrack:audioTrack atTime:audioTimeRange.start error:nil];
}

// Combines self.video and self.song (if available) into a video composition
// If parameter forPlayback is true, also builds player self.playeritem
- (void)buildNewCompositionForPlayback:(BOOL)forPlayback
{
	AVMutableComposition *composition = [[AVMutableComposition alloc]init];
	AVMutableAudioMix *audioMix = nil;

    
    // to suppress warning, get size of specific track instead
	CGSize videoSize = [[[self.video tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] naturalSize];
    
	composition.naturalSize = videoSize;

    if (self.video) {
        [self addVideoTrackToComposition:composition];
        [self addAudioTrackToComposition:composition];
    }

	if (self.song) {
		// Add the song track and duck all other audio during it.
		audioMix = [AVMutableAudioMix audioMix];
		[self addSongTrackToComposition:composition withAudioMix:audioMix];
	}

	self.composition = composition;
	self.audioMix = audioMix;

	if (forPlayback) {
//#if TARGET_OS_EMBEDDED
//		// Render high-def movies at half scale for real-time playback (device-only).
//		if (videoSize.width > 640)
//			composition.renderScale = 0.5;
//#endif // TARGET_OS_EMBEDDED
		
		AVPlayerItem *playerItem = [AVPlayerItem playerItemWithAsset:self.composition];
		playerItem.audioMix = audioMix;
		self.playerItem = playerItem;
	}
}

- (AVAssetImageGenerator*)assetImageGenerator
{
	AVAssetImageGenerator *generator = [AVAssetImageGenerator assetImageGeneratorWithAsset:self.composition];
	return generator;
}

- (AVAssetExportSession*)assetExportSessionWithPreset:(NSString*)presetName
{
	AVAssetExportSession *session = [[AVAssetExportSession alloc] initWithAsset:self.composition presetName:presetName];

//    session.videoComposition = self.videoComposition;
	session.audioMix = self.audioMix;
    return session;
}

@end