ViewOnceMessageViewController.swift

//
// Copyright 2019 Signal Messenger, LLC
// SPDX-License-Identifier: AGPL-3.0-only
//

import CoreMedia
import SDWebImage
import SignalServiceKit
import SignalUI

class ViewOnceMessageViewController: OWSViewController {

    typealias Content = ViewOnceContent

    // MARK: - Properties

    private let content: Content

    private var mediaView: UIView!
    private var scrollView: ZoomableMediaView!

    // MARK: - Initializers

    init(content: Content) {
        self.content = content

        super.init()
    }

    // MARK: -

    class func tryToPresent(
        interaction: TSInteraction,
        from fromViewController: UIViewController,
    ) {
        AssertIsOnMainThread()

        ModalActivityIndicatorViewController.present(
            fromViewController: fromViewController,
            canCancel: false,
        ) { modal in
            DispatchQueue.main.async {
                let content: Content? = loadContentForPresentation(interaction: interaction)

                modal.dismiss(completion: {
                    guard let content else {
                        owsFailDebug("Could not present interaction")
                        // TODO: Show an alert.
                        return
                    }

                    let view = ViewOnceMessageViewController(content: content)
                    fromViewController.presentFullScreen(view, animated: true)
                })
            }
        }
    }

    private class func loadContentForPresentation(interaction: TSInteraction) -> Content? {
        guard let message = interaction as? TSMessage else {
            return nil
        }
        return DependenciesBridge.shared.attachmentViewOnceManager.prepareViewOnceContentForDisplay(message)
    }

    // MARK: - View Lifecycle

    override func loadView() {
        self.view = UIView()
        view.backgroundColor = UIColor.ows_black

        let defaultMediaView = UIView()
        defaultMediaView.backgroundColor = Theme.darkThemeWashColor

        let accessoryView: UIView?
        if let (mediaView, _accessoryView) = buildMediaView() {
            self.mediaView = mediaView
            accessoryView = _accessoryView
        } else {
            self.mediaView = defaultMediaView
            accessoryView = nil
        }

        self.scrollView = ZoomableMediaView(mediaView: mediaView)
        scrollView.delegate = self
        view.addSubview(scrollView)
        scrollView.autoPinEdgesToSuperviewEdges()

        if let accessoryView {
            view.addSubview(accessoryView)
            accessoryView.autoPinEdge(toSuperviewMargin: .trailing, withInset: 16)
            accessoryView.autoPinEdge(toSuperviewMargin: .top, withInset: 30)
        }

        let dismissButton = OWSButton(imageName: Theme.iconName(.buttonX), tintColor: Theme.darkThemePrimaryColor) { [weak self] in
            self?.dismissButtonPressed()
        }
        dismissButton.layer.shadowColor = Theme.darkThemeBackgroundColor.cgColor
        dismissButton.layer.shadowOffset = .zero
        dismissButton.layer.shadowOpacity = 0.7
        dismissButton.layer.shadowRadius = 3.0
        dismissButton.setShadow(opacity: 0.66)
        view.addSubview(dismissButton)
        dismissButton.autoPinEdge(toSuperviewMargin: .leading, withInset: 16)
        dismissButton.autoPinEdge(toSuperviewMargin: .top, withInset: 30)

        setupDatabaseObservation()
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        scrollView.updateZoomScaleForLayout()
        scrollView.zoomScale = scrollView.minimumZoomScale
    }

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        scrollView.updateZoomScaleForLayout()
    }

    // MARK: -

    private func buildMediaView() -> (
        UIView,
        accessoryView: UIView?,
    )? {
        switch content.type {
        case .loopingVideo:
            guard let asset = try? content.loadAVAsset() else {
                owsFailDebug("Could not load attachment.")
                return nil
            }
            let video = LoopingVideo(asset: asset)
            let view = LoopingVideoView()
            view.contentMode = .scaleAspectFit
            view.video = video
            return (view, accessoryView: nil)
        case .animatedImage:
            guard let image = try? content.loadYYImage() else {
                owsFailDebug("Could not load attachment.")
                return nil
            }
            guard
                image.size.width > 0,
                image.size.height > 0
            else {
                owsFailDebug("Attachment has invalid size.")
                return nil
            }
            let animatedImageView = SDAnimatedImageView()
            // We need to specify a contentMode since the size of the image
            // might not match the aspect ratio of the view.
            animatedImageView.contentMode = .scaleAspectFit
            // Use trilinear filters for better scaling quality at
            // some performance cost.
            animatedImageView.layer.minificationFilter = .trilinear
            animatedImageView.layer.magnificationFilter = .trilinear
            animatedImageView.layer.allowsEdgeAntialiasing = true
            animatedImageView.image = image
            return (animatedImageView, accessoryView: nil)
        case .stillImage:
            guard let image = try? content.loadImage() else {
                owsFailDebug("Could not load attachment.")
                return nil
            }
            guard
                image.size.width > 0,
                image.size.height > 0
            else {
                owsFailDebug("Attachment has invalid size.")
                return nil
            }

            let imageView = UIImageView()
            // We need to specify a contentMode since the size of the image
            // might not match the aspect ratio of the view.
            imageView.contentMode = .scaleAspectFit
            // Use trilinear filters for better scaling quality at
            // some performance cost.
            imageView.layer.minificationFilter = .trilinear
            imageView.layer.magnificationFilter = .trilinear
            imageView.layer.allowsEdgeAntialiasing = true
            imageView.image = image
            return (imageView, accessoryView: nil)
        case .video:
            guard let asset = try? content.loadAVAsset() else {
                owsFailDebug("Could not load attachment.")
                return nil
            }
            let player = VideoPlayer(avPlayer: .init(playerItem: .init(asset: asset)), shouldLoop: true)
            self.videoPlayer = player
            player.delegate = self

            let playerView = VideoPlayerView()
            playerView.player = player.avPlayer

            let label = UILabel()
            label.textColor = Theme.darkThemePrimaryColor
            label.font = UIFont.dynamicTypeBody.monospaced()
            label.setShadow()

            let formatter = DateComponentsFormatter()
            formatter.unitsStyle = .positional
            formatter.allowedUnits = [.minute, .second]
            formatter.zeroFormattingBehavior = [.pad]

            let avPlayer = player.avPlayer
            self.videoPlayerProgressObserver = avPlayer.addPeriodicTimeObserver(forInterval: CMTime(seconds: 0.1, preferredTimescale: 100), queue: nil) { _ in

                guard let item = avPlayer.currentItem else {
                    owsFailDebug("item was unexpectedly nil")
                    label.text = "0:00"
                    return
                }

                let position = avPlayer.currentTime()
                let duration: CMTime = item.asset.duration
                let remainingTime = duration - position
                let remainingSeconds = CMTimeGetSeconds(remainingTime)

                guard let remainingString = formatter.string(from: remainingSeconds) else {
                    owsFailDebug("unable to format time remaining")
                    label.text = "0:00"
                    return
                }

                label.text = remainingString
            }

            return (playerView, accessoryView: label)
        }
    }

    // MARK: Video

    var videoPlayerProgressObserver: Any?
    var videoPlayer: VideoPlayer?

    func setupDatabaseObservation() {
        DependenciesBridge.shared.databaseChangeObserver.appendDatabaseChangeDelegate(self)

        NotificationCenter.default.addObserver(
            self,
            selector: #selector(applicationWillEnterForeground),
            name: .OWSApplicationWillEnterForeground,
            object: nil,
        )
    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)

        self.videoPlayer?.play()
    }

    override var preferredStatusBarStyle: UIStatusBarStyle {
        return .lightContent
    }

    // MARK: - Video

    // Once open, this view only dismisses if the message is deleted
    // (e.g. by per-conversation expiration).
    private func dismissIfRemoved() {
        AssertIsOnMainThread()

        let shouldDismiss: Bool = SSKEnvironment.shared.databaseStorageRef.read { transaction in
            let uniqueId = self.content.messageId
            guard TSInteraction.fetchViaCache(uniqueId: uniqueId, transaction: transaction) != nil else {
                return true
            }
            return false
        }

        if shouldDismiss {
            self.dismiss(animated: true)
        }
    }

    // MARK: - Events

    @objc
    private func applicationWillEnterForeground() throws {
        AssertIsOnMainThread()

        Logger.debug("")

        dismissIfRemoved()
    }

    @objc
    private func dismissButtonPressed() {
        AssertIsOnMainThread()

        dismiss(animated: true)
    }
}

// MARK: -

extension ViewOnceMessageViewController: DatabaseChangeDelegate {

    func databaseChangesDidUpdate(databaseChanges: DatabaseChanges) {
        dismissIfRemoved()
    }

    func databaseChangesDidUpdateExternally() {
        dismissIfRemoved()
    }

    func databaseChangesDidReset() {
        dismissIfRemoved()
    }
}

extension ViewOnceMessageViewController: VideoPlayerDelegate {
    func videoPlayerDidPlayToCompletion(_ videoPlayer: VideoPlayer) {
        // no-op
    }
}

// MARK: -

extension ViewOnceMessageViewController: UIScrollViewDelegate {
    func viewForZooming(in scrollView: UIScrollView) -> UIView? {
        return mediaView
    }

    func scrollViewDidZoom(_ scrollView: UIScrollView) {
        (scrollView as? ZoomableMediaView)?.updateZoomScaleForLayout()
        view.layoutIfNeeded()
    }
}