Tusker/Tusker/Screens/Gallery/VideoOverlayViewController.swift

//
//  VideoOverlayViewController.swift
//  Tusker
//
//  Created by Shadowfacts on 3/26/24.
//  Copyright © 2024 Shadowfacts. All rights reserved.
//

import UIKit
import AVFoundation

class VideoOverlayViewController: UIViewController {
    
    private static let playImage = UIImage(systemName: "play.fill")!
    private static let pauseImage = UIImage(systemName: "pause.fill")!

    private let player: AVPlayer
    @Box private var playbackSpeed: Float
    
    private var dimmingView: UIView!
    private var controlsStack: UIStackView!
    private var skipBackButton: VideoOverlayButton!
    private var skipForwardButton: VideoOverlayButton!

    private var rateObservation: NSKeyValueObservation?
    
    init(player: AVPlayer, playbackSpeed: Box<Float>) {
        self.player = player
        self._playbackSpeed = playbackSpeed
        super.init(nibName: nil, bundle: nil)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()

        dimmingView = UIView()
        dimmingView.backgroundColor = .black
        dimmingView.alpha = 0.2
        dimmingView.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(dimmingView)
        NSLayoutConstraint.activate([
            dimmingView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            dimmingView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            dimmingView.topAnchor.constraint(equalTo: view.topAnchor),
            dimmingView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
        ])
        
        skipBackButton = VideoOverlayButton(image: UIImage(systemName: "gobackward.10")!)
        skipBackButton.addTarget(self, action: #selector(skipBackPressed), for: .touchUpInside)
        
        let playPauseButton = VideoOverlayButton(image: VideoOverlayViewController.pauseImage)
        playPauseButton.addTarget(self, action: #selector(playPausePressed), for: .touchUpInside)

        skipForwardButton = VideoOverlayButton(image: UIImage(systemName: "goforward.10")!)
        skipForwardButton.addTarget(self, action: #selector(skipForwardPressed), for: .touchUpInside)

        controlsStack = UIStackView(arrangedSubviews: [
            skipBackButton,
            playPauseButton,
            skipForwardButton,
        ])
        controlsStack.axis = .horizontal
        controlsStack.alignment = .center
        controlsStack.spacing = 24
        controlsStack.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(controlsStack)
        NSLayoutConstraint.activate([
            controlsStack.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            controlsStack.centerYAnchor.constraint(equalTo: view.centerYAnchor),
            
            skipBackButton.widthAnchor.constraint(equalToConstant: 50),
            skipBackButton.heightAnchor.constraint(equalToConstant: 50),
            playPauseButton.widthAnchor.constraint(equalToConstant: 66),
            playPauseButton.heightAnchor.constraint(equalToConstant: 66),
            skipForwardButton.widthAnchor.constraint(equalToConstant: 50),
            skipForwardButton.heightAnchor.constraint(equalToConstant: 50),
        ])
        
        rateObservation = player.observe(\.rate, changeHandler: { player, _ in
            MainActor.runUnsafely {
                playPauseButton.image = player.rate > 0 ? VideoOverlayViewController.pauseImage : VideoOverlayViewController.playImage
            }
        })
    }
    
    func setVisible(_ visible: Bool) {
        loadViewIfNeeded()
        
        view.alpha = visible ? 1 : 0
    }
    
    @objc private func playPausePressed() {
        if player.rate > 0 {
            player.rate = 0
        } else {
            player.rate = playbackSpeed
        }
    }
    
    @objc private func skipBackPressed() {
        player.seek(to: player.currentTime() - CMTime(value: 10, timescale: 1))
    }
    
    @objc private func skipForwardPressed() {
        player.seek(to: player.currentTime() + CMTime(value: 10, timescale: 1))
    }

}

private class VideoOverlayButton: UIControl {
    var image: UIImage? {
        get {
            imageView.image
        }
        set {
            imageView.image = newValue
        }
    }
    
    private let backgroundView = UIView()
    private let imageView = UIImageView()

    private var animator: UIViewPropertyAnimator?
    
    override var isEnabled: Bool {
        didSet {
            imageView.tintColor = isEnabled ? .white : .lightGray
        }
    }
    
    init(image: UIImage) {
        super.init(frame: .zero)
        
        backgroundView.alpha = 0
        backgroundView.backgroundColor = .lightGray.withAlphaComponent(0.5)
        backgroundView.translatesAutoresizingMaskIntoConstraints = false
        addSubview(backgroundView)
        NSLayoutConstraint.activate([
            backgroundView.leadingAnchor.constraint(equalTo: leadingAnchor),
            backgroundView.trailingAnchor.constraint(equalTo: trailingAnchor),
            backgroundView.topAnchor.constraint(equalTo: topAnchor),
            backgroundView.bottomAnchor.constraint(equalTo: bottomAnchor),
        ])
        
        imageView.image = image
        imageView.tintColor = .white
        imageView.contentMode = .scaleAspectFit
        imageView.preferredSymbolConfiguration = .init(scale: .large)
        imageView.translatesAutoresizingMaskIntoConstraints = false
        addSubview(imageView)
        NSLayoutConstraint.activate([
            imageView.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 8),
            imageView.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -8),
            imageView.topAnchor.constraint(equalTo: topAnchor, constant: 8),
            imageView.bottomAnchor.constraint(equalTo: bottomAnchor, constant: -8),
        ])
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        
        backgroundView.layer.cornerRadius = bounds.height / 2
    }
    
    override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
        bounds.contains(point) ? self : nil
    }
    
    override func beginTracking(_ touch: UITouch, with event: UIEvent?) -> Bool {
        UIView.animate(withDuration: 0.2) {
            self.backgroundView.alpha = 1
            self.backgroundView.transform = CGAffineTransform(scaleX: 1/0.8, y: 1/0.8)
            self.transform = CGAffineTransform(scaleX: 0.8, y: 0.8)
        }
        return super.beginTracking(touch, with: event)
    }
    
    override func endTracking(_ touch: UITouch?, with event: UIEvent?) {
        UIView.animate(withDuration: 0.2) {
            self.backgroundView.alpha = 0
            self.backgroundView.transform = .identity
            self.transform = .identity
        }
    }
    
    override func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
        if gestureRecognizer is UITapGestureRecognizer {
            return false
        }
        return true
    }
}