element-ios/Riot/Modules/SlidingModal/SlidingModalContainerView.swift

/*
Copyright 2019-2024 New Vector Ltd.

SPDX-License-Identifier: AGPL-3.0-only
Please see LICENSE in the repository root for full details.
 */

import UIKit
import Reusable

protocol SlidingModalContainerViewDelegate: AnyObject {
    func slidingModalContainerViewDidTapBackground(_ view: SlidingModalContainerView)
}

/// `SlidingModalContainerView` is a custom UIView used as a `UIViewControllerContextTransitioning.containerView` subview to embed a `SlidingModalPresentable` during presentation.
class SlidingModalContainerView: UIView, Themable, NibLoadable {
    
    // MARK: - Constants
    
    private enum Constants {
        static let cornerRadius: CGFloat = 12.0
        static let dimmingColorAlpha: CGFloat = 0.7
    }
    
    private enum Sizing {
        static let view = SlidingModalContainerView.loadFromNib()
        static var widthConstraint: NSLayoutConstraint?
        static var heightConstraint: NSLayoutConstraint?
    }
    
    // MARK: - Properties
    
    private weak var blurView: UIVisualEffectView?
    var blurBackground: Bool = false {
        didSet {
            if blurBackground {
                let blurView = UIVisualEffectView(effect: UIBlurEffect(style: .dark))
                blurView.frame = self.dimmingView.bounds
                blurView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
                self.dimmingView.addSubview(blurView)
                self.blurView = blurView
                self.dimmingView.backgroundColor = .clear
            } else {
                self.blurView?.removeFromSuperview()
                self.dimmingView.backgroundColor = UIColor.black.withAlphaComponent(Constants.dimmingColorAlpha)
            }
        }
    }
    
    var centerInScreen: Bool = false
    
    // MARK: Outlets
    
    @IBOutlet private weak var dimmingView: UIView!
    @IBOutlet private weak var contentView: UIView!
    
    @IBOutlet private weak var contentViewHeightConstraint: NSLayoutConstraint!
    @IBOutlet private weak var contentViewBottomConstraint: NSLayoutConstraint!
    
    // MARK: Private
    
    private var dismissContentViewBottomConstant: CGFloat {
        let bottomSafeAreaHeight: CGFloat
        
        bottomSafeAreaHeight = self.contentView.safeAreaInsets.bottom
        
        return -(self.contentViewHeightConstraint.constant + bottomSafeAreaHeight)
    }
    
    // used to avoid changing constraint during animations
    private var lastBounds: CGRect?
    
    // MARK: Public
    
    var contentViewFrame: CGRect {
        return self.contentView.frame
    }
    
    weak var delegate: SlidingModalContainerViewDelegate?
    
    // MARK: - Setup
    
    static func instantiate() -> SlidingModalContainerView {
        return self.loadFromNib()
    }
        
    // MARK: - Life cycle
    
    override func awakeFromNib() {
        super.awakeFromNib()
        
        self.contentView.layer.masksToBounds = true
        self.dimmingView.backgroundColor = UIColor.black.withAlphaComponent(Constants.dimmingColorAlpha)

        self.setupBackgroundTapGestureRecognizer()
        
        self.update(theme: ThemeService.shared().theme)
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        
        self.contentView.layer.cornerRadius = Constants.cornerRadius
        
        guard lastBounds != nil else {
            lastBounds = bounds
            return
        }
        
        if UIDevice.current.userInterfaceIdiom == .pad && lastBounds != bounds {
            lastBounds = bounds
            self.contentViewBottomConstraint.constant = (UIScreen.main.bounds.height + self.dismissContentViewBottomConstant) / 2
        }
    }
    
    // MARK: - Public
    
    func preparePresentAnimation() {
        if UIDevice.current.userInterfaceIdiom == .pad {
            self.contentViewBottomConstraint.constant = (UIScreen.main.bounds.height + self.dismissContentViewBottomConstant) / 2
        } else {
            if centerInScreen {
                contentViewBottomConstraint.constant = (bounds.height - contentViewHeightConstraint.constant)/2
            } else {
                contentViewBottomConstraint.constant = 0
            }
        }
    }
    
    func prepareDismissAnimation() {
        self.contentViewBottomConstraint.constant = self.dismissContentViewBottomConstant
    }
    
    func update(theme: Theme) {
        self.contentView.backgroundColor = theme.headerBackgroundColor
    }
    
    func updateContentViewMaxHeight(_ maxHeight: CGFloat) {
        self.contentViewHeightConstraint.constant = maxHeight
    }
    
    func updateContentViewLayout() {
        self.layoutIfNeeded()
    }
    
    func setContentView(_ contentView: UIView) {
        for subView in self.contentView.subviews {
            subView.removeFromSuperview()
        }
        self.contentView.vc_addSubViewMatchingParent(contentView)
    }
    
    func updateDimmingViewAlpha(_ alpha: CGFloat) {
        self.dimmingView.alpha = alpha
    }
    
    func contentViewWidthFittingSize(_ size: CGSize) -> CGFloat {
        let sizingView = SlidingModalContainerView.Sizing.view
        
        if let widthConstraint = SlidingModalContainerView.Sizing.widthConstraint {
            widthConstraint.constant = size.width
        } else {
            let widthConstraint = sizingView.widthAnchor.constraint(equalToConstant: size.width)
            widthConstraint.isActive = true
            SlidingModalContainerView.Sizing.widthConstraint = widthConstraint
        }
        
        if let heightConstraint = SlidingModalContainerView.Sizing.heightConstraint {
            heightConstraint.constant = size.height
        } else {
            let heightConstraint = sizingView.heightAnchor.constraint(equalToConstant: size.width)
            heightConstraint.isActive = true
            SlidingModalContainerView.Sizing.heightConstraint = heightConstraint
        }        
        
        sizingView.setNeedsLayout()
        sizingView.layoutIfNeeded()                
        
        return sizingView.contentViewFrame.width
    }
    
    // MARK: - Private
    
    private func setupBackgroundTapGestureRecognizer() {
        let tapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(handleBackgroundTap(_:)))
        self.dimmingView.addGestureRecognizer(tapGestureRecognizer)
    }
    
    @objc private func handleBackgroundTap(_ gestureRecognizer: UITapGestureRecognizer) {
        self.delegate?.slidingModalContainerViewDidTapBackground(self)
    }
}