/*

 Copyright (C) 2017 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 Custom video composition instruction class implementing AVVideoCompositionInstruction protocol.

 */

import AVFoundation

import Foundation

import CoreMedia

class APLCustomVideoCompositionInstruction: NSObject, AVVideoCompositionInstructionProtocol {

    /// ID used by subclasses to identify the foreground frame.

    var foregroundTrackID: CMPersistentTrackID = kCMPersistentTrackID_Invalid

    /// ID used by subclasses to identify the background frame.

    var backgroundTrackID: CMPersistentTrackID = kCMPersistentTrackID_Invalid

    /// The timeRange during which instructions will be effective.

    var overrideTimeRange: CMTimeRange = CMTimeRange()

    /// Indicates whether post-processing should be skipped for the duration of the instruction.

    var overrideEnablePostProcessing = false

    /// Indicates whether to avoid some duplicate processing when rendering a frame from the same source and destinatin at different times.

    var overrideContainsTweening = false

    /// The track IDs required to compose frames for the instruction.

    var overrideRequiredSourceTrackIDs: [NSValue]?

    /// Track ID of the source frame when passthrough is in effect.

    var overridePassthroughTrackID: CMPersistentTrackID = 0

    /*

     If for the duration of the instruction, the video composition result is one of the source frames, this property

     should return the corresponding track ID. The compositor won't be run for the duration of the instruction and

     the proper source frame will be used instead.

     */

    var passthroughTrackID: CMPersistentTrackID {

        get {

            return self.overridePassthroughTrackID

        }

        set {

            self.overridePassthroughTrackID = newValue

        }

    }

    /*

     List of video track IDs required to compose frames for this instruction. If the value of this property

     is nil, all source tracks will be considered required for composition.

     */

    var requiredSourceTrackIDs: [NSValue]? {

        get {

            return self.overrideRequiredSourceTrackIDs

        }

        set {

            self.overrideRequiredSourceTrackIDs = newValue

        }

    }

    // Indicates the timeRange during which the instruction is effective.

    var timeRange: CMTimeRange {

        get {

            return self.overrideTimeRange

        }

        set(newTimeRange) {

            self.overrideTimeRange = newTimeRange

        }

    }

    // If NO, indicates that post-processing should be skipped for the duration of this instruction.

    var enablePostProcessing: Bool {

        get {

            return self.overrideEnablePostProcessing

        }

        set(newPostProcessing) {

            self.overrideEnablePostProcessing = newPostProcessing

        }

    }

    /*

     If YES, rendering a frame from the same source buffers and the same composition instruction at 2 different

     compositionTime may yield different output frames. If NO, 2 such compositions would yield the

     same frame. The media pipeline may me able to avoid some duplicate processing when containsTweening is NO.

     */

    var containsTweening: Bool {

        get {

            return self.overrideContainsTweening

        }

        set(newContainsTweening) {

            self.overrideContainsTweening = newContainsTweening

        }

    }

    init(thePassthroughTrackID: CMPersistentTrackID, forTimeRange theTimeRange: CMTimeRange) {

        super.init()

        passthroughTrackID = thePassthroughTrackID

        timeRange = theTimeRange

        requiredSourceTrackIDs = [NSValue]()

        containsTweening = false

        enablePostProcessing = false

    }

    init(theSourceTrackIDs: [NSValue], forTimeRange theTimeRange: CMTimeRange) {

        super.init()

        requiredSourceTrackIDs = theSourceTrackIDs

        timeRange = theTimeRange

        passthroughTrackID = kCMPersistentTrackID_Invalid

        containsTweening = true

        enablePostProcessing = false

    }

}