element-ios/Riot/Modules/Room/Views/InputToolbar/VoiceMessageToolbarView.swift

// 
// Copyright 2021 New Vector Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

import UIKit

private enum VoiceMessageToolbarViewState {
    case idle
    case recording
}

class VoiceMessageToolbarView: PassthroughView, Themable, UIGestureRecognizerDelegate {

    @IBOutlet private var backgroundView: UIView!
    
    @IBOutlet private var recordButtonsContainerView: UIView!
    @IBOutlet private var primaryRecordButton: UIButton!
    @IBOutlet private var secondaryRecordButton: UIButton!
    
    @IBOutlet private var slideToCancelContainerView: UIView!
    @IBOutlet private var slideToCancelLabel: UILabel!
    @IBOutlet private var slideToCancelChevron: UIImageView!
    @IBOutlet private var slideToCancelGradient: UIImageView!
    
    private var cancelLabelToRecordButtonDistance: CGFloat = 0.0
    
    private var state: VoiceMessageToolbarViewState = .idle {
        didSet {
            updateUIAnimated(true)
        }
    }
    
    private var currentTheme: Theme? {
        didSet {
            updateUIAnimated(true)
        }
    }
        
    @objc static func instanceFromNib() -> VoiceMessageToolbarView {
        let nib = UINib(nibName: "VoiceMessageToolbarView", bundle: nil)
        guard let view = nib.instantiate(withOwner: nil, options: nil).first as? Self else {
          fatalError("The nib \(nib) expected its root view to be of type \(self)")
        }
        return view
    }
    
    override func awakeFromNib() {
        super.awakeFromNib()
        
        slideToCancelGradient.image = Asset.Images.voiceMessageCancelGradient.image.withRenderingMode(.alwaysTemplate)
        
        let longPressGesture = UILongPressGestureRecognizer(target: self, action: #selector(handleLongPress))
        longPressGesture.delegate = self
        longPressGesture.minimumPressDuration = 0.1
        recordButtonsContainerView.addGestureRecognizer(longPressGesture)
        
        let panGesture = UIPanGestureRecognizer(target: self, action: #selector(handlePan))
        longPressGesture.delegate = self
        recordButtonsContainerView.addGestureRecognizer(panGesture)
        
        updateUIAnimated(false)
    }
    
    // MARK: - Themable
    
    func update(theme: Theme) {
        currentTheme = theme
    }
    
    // MARK: - UIGestureRecognizerDelegate
    
    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
        return true
    }
    
    // MARK: - Private
    
    @objc private func handleLongPress(_ gestureRecognizer: UILongPressGestureRecognizer) {
        switch gestureRecognizer.state {
        case UIGestureRecognizer.State.began:
            state = .recording
            
            let convertedFrame = self.convert(slideToCancelLabel.frame, from: slideToCancelContainerView)
            cancelLabelToRecordButtonDistance = recordButtonsContainerView.frame.minX - convertedFrame.maxX
            
        case UIGestureRecognizer.State.ended:
            state = .idle
        default:
            break
        }
    }
    
    @objc private func handlePan(_ gestureRecognizer: UIPanGestureRecognizer) {
        guard self.state == .recording && gestureRecognizer.state == .changed else {
            return
        }
        
        let translation = gestureRecognizer.translation(in: self)
        
        recordButtonsContainerView.transform = CGAffineTransform(translationX: min(translation.x, 0.0), y: 0.0)
        slideToCancelContainerView.transform = CGAffineTransform(translationX: min(translation.x + cancelLabelToRecordButtonDistance, 0.0), y: 0.0)
    }
    
    private func updateUIAnimated(_ animated: Bool) {
        UIView.animate(withDuration: (animated ? 0.25 : 0.0)) {
            switch self.state {
            case .idle:
                self.slideToCancelContainerView.alpha = 0.0
                self.backgroundView.alpha = 0.0
                self.slideToCancelGradient.alpha = 0.0
                self.recordButtonsContainerView.transform = .identity
                self.slideToCancelContainerView.transform = .identity
                self.primaryRecordButton.alpha = 1.0
                self.secondaryRecordButton.alpha = 0.0
            case .recording:
                self.slideToCancelContainerView.alpha = 1.0
                self.backgroundView.alpha = 1.0
                self.slideToCancelGradient.alpha = 1.0
                self.primaryRecordButton.alpha = 0.0
                self.secondaryRecordButton.alpha = 1.0
            }
            
            guard let theme = self.currentTheme else {
                return
            }
            
            self.backgroundView.backgroundColor = theme.backgroundColor
            self.primaryRecordButton.tintColor = theme.textSecondaryColor
            self.slideToCancelLabel.textColor = theme.textSecondaryColor
            self.slideToCancelChevron.tintColor = theme.textSecondaryColor
            self.slideToCancelGradient.tintColor = theme.backgroundColor
        }
    }
}