/*

     File: AVSEAddWatermarkCommand.m

 Abstract: A subclass of AVSECommand which handles CALayer. This tool adds a title layer (CALayer) on top of an existing AVMutableComposition or an AVAsset.

  Version: 1.1

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 */

#import "AVSEAddWatermarkCommand.h"

@interface AVSEAddWatermarkCommand (Internal)

-(CALayer*)watermarkLayerForSize:(CGSize)videoSize;

@end

@implementation AVSEAddWatermarkCommand

- (void)performWithAsset:(AVAsset*)asset

{

    self.watermarkLayer = nil;

    CGSize videoSize;

    AVAssetTrack *assetVideoTrack = nil;

    AVAssetTrack *assetAudioTrack = nil;

    // Check if the asset contains video and audio tracks

    if ([[asset tracksWithMediaType:AVMediaTypeVideo] count] != 0) {

        assetVideoTrack = [asset tracksWithMediaType:AVMediaTypeVideo][0];

    }

    if ([[asset tracksWithMediaType:AVMediaTypeAudio] count] != 0) {

        assetAudioTrack = [asset tracksWithMediaType:AVMediaTypeAudio][0];

    }

    CMTime insertionPoint = kCMTimeZero;

    NSError *error = nil;

    // Step 1

    // Create a composition with the given asset and insert audio and video tracks into it from the asset

    if(!self.mutableComposition) {

        // Check if a composition already exists, else create a composition using the input asset

        self.mutableComposition = [AVMutableComposition composition];

        // Insert the video and audio tracks from AVAsset

        if (assetVideoTrack != nil) {

            AVMutableCompositionTrack *compositionVideoTrack = [self.mutableComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];

            [compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, [asset duration]) ofTrack:assetVideoTrack atTime:insertionPoint error:&error];

        }

        if (assetAudioTrack != nil) {

            AVMutableCompositionTrack *compositionAudioTrack = [self.mutableComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];

            [compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, [asset duration]) ofTrack:assetAudioTrack atTime:insertionPoint error:&error];

        }

    }

    // Step 2

    // Create a water mark layer of the same size as that of a video frame from the asset

    if ([[self.mutableComposition tracksWithMediaType:AVMediaTypeVideo] count] != 0) {

        if(!self.mutableVideoComposition) {

            // build a pass through video composition

            self.mutableVideoComposition = [AVMutableVideoComposition videoComposition];

            self.mutableVideoComposition.frameDuration = CMTimeMake(1, 30); // 30 fps

            self.mutableVideoComposition.renderSize = assetVideoTrack.naturalSize;

            AVMutableVideoCompositionInstruction *passThroughInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];

            passThroughInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, [self.mutableComposition duration]);

            AVAssetTrack *videoTrack = [self.mutableComposition tracksWithMediaType:AVMediaTypeVideo][0];

            AVMutableVideoCompositionLayerInstruction *passThroughLayer = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];

            passThroughInstruction.layerInstructions = @[passThroughLayer];

            self.mutableVideoComposition.instructions = @[passThroughInstruction];

        }

        videoSize = self.mutableVideoComposition.renderSize;

        self.watermarkLayer = [self watermarkLayerForSize:videoSize];

    }

    // Step 3

    // Notify AVSEViewController about add watermark operation completion

    [[NSNotificationCenter defaultCenter] postNotificationName:AVSEEditCommandCompletionNotification object:self];

}

- (CALayer*)watermarkLayerForSize:(CGSize)videoSize

{

    // Create a layer for the title

    CALayer *_watermarkLayer = [CALayer layer];

    // Create a layer for the text of the title.

    CATextLayer *titleLayer = [CATextLayer layer];

    titleLayer.string = @"AVSE";

    titleLayer.foregroundColor = [[UIColor whiteColor] CGColor];

    titleLayer.shadowOpacity = 0.5;

    titleLayer.alignmentMode = kCAAlignmentCenter;

    titleLayer.bounds = CGRectMake(0, 0, videoSize.width/2, videoSize.height/2);

    // Add it to the overall layer.

    [_watermarkLayer addSublayer:titleLayer];

    return _watermarkLayer;

}

@end