Tusker/Tusker/Screens/Conversation/ExpandThreadTableViewCell.swift

//
//  ExpandThreadTableViewCell.swift
//  Tusker
//
//  Created by Shadowfacts on 1/30/21.
//  Copyright © 2021 Shadowfacts. All rights reserved.
//

import UIKit

class ExpandThreadTableViewCell: UITableViewCell {

    @IBOutlet weak var stackViewLeadingConstraint: NSLayoutConstraint!
    @IBOutlet weak var avatarContainerView: UIView!
    @IBOutlet weak var avatarContainerWidthConstraint: NSLayoutConstraint!
    @IBOutlet weak var replyCountLabel: UILabel!
    private var threadLinkView: UIView!
    private var threadLinkViewFullHeightConstraint: NSLayoutConstraint!
    private var threadLinkViewShortHeightConstraint: NSLayoutConstraint!
    private var avatarImageViews: [UIImageView] = []
    
    private var avatarRequests: [ImageCache.Request] = []
    
    override func awakeFromNib() {
        super.awakeFromNib()
        
        threadLinkView = UIView()
        threadLinkView.translatesAutoresizingMaskIntoConstraints = false
        threadLinkView.backgroundColor = tintColor.withAlphaComponent(0.5)
        threadLinkView.layer.cornerRadius = 2.5
        addSubview(threadLinkView)
        threadLinkViewFullHeightConstraint = threadLinkView.bottomAnchor.constraint(equalTo: bottomAnchor)
        threadLinkViewShortHeightConstraint = threadLinkView.bottomAnchor.constraint(equalTo: avatarContainerView.topAnchor, constant: -2)
        NSLayoutConstraint.activate([
            threadLinkView.widthAnchor.constraint(equalToConstant: 5),
            threadLinkView.centerXAnchor.constraint(equalTo: leadingAnchor, constant: 25 + 16 /* system spacing */),
            threadLinkView.topAnchor.constraint(equalTo: topAnchor),
            threadLinkViewFullHeightConstraint,
        ])
        
        NotificationCenter.default.addObserver(self, selector: #selector(preferencesChanged), name: .preferencesChanged, object: nil)
    }
    
    func updateUI(childThreads: [ConversationNode], inline: Bool) {
        stackViewLeadingConstraint.constant = inline ? 50 + 4 : 0
        threadLinkView.layer.maskedCorners = inline ? [] : [.layerMinXMaxYCorner, .layerMaxXMaxYCorner]
        threadLinkViewFullHeightConstraint.isActive = inline
        threadLinkViewShortHeightConstraint.isActive = !inline
        
        let format: String
        if inline {
            format = NSLocalizedString("expand threads inline count", comment: "expnad converstaion threads inline button label")
        } else {
            format = NSLocalizedString("expand threads count", comment: "expand conversation threads button label")
        }
        replyCountLabel.text = String.localizedStringWithFormat(format, childThreads.count)
        
        let accounts = childThreads.map(\.status.account).uniques().prefix(3)
        
        avatarImageViews.forEach { $0.removeFromSuperview() }
        avatarImageViews = []
        
        avatarRequests = []
        
        let avatarImageSize: CGFloat = 44 - 12
        
        if accounts.count == 1 {
            avatarContainerWidthConstraint.constant = avatarImageSize
        } else {
            avatarContainerWidthConstraint.constant = CGFloat(accounts.count) * avatarImageSize * 3 / 4
        }
        
        for (index, account) in accounts.enumerated() {
            let accountImageView = UIImageView()
            accountImageView.translatesAutoresizingMaskIntoConstraints = false
            accountImageView.contentMode = .scaleAspectFit
            accountImageView.layer.cornerRadius = Preferences.shared.avatarStyle.cornerRadiusFraction * avatarImageSize
            accountImageView.layer.masksToBounds = true
            accountImageView.layer.borderWidth = 1
            accountImageView.layer.borderColor = UIColor.secondarySystemBackground.cgColor
            // need a solid background color so semi-transparent avatars don't look bad
            accountImageView.backgroundColor = .secondarySystemBackground
            avatarContainerView.addSubview(accountImageView)
            
            avatarImageViews.append(accountImageView)
                
            accountImageView.layer.zPosition = CGFloat(-index)
            
            let xConstraint: NSLayoutConstraint
            if index == 0 {
                xConstraint = accountImageView.leadingAnchor.constraint(equalTo: avatarContainerView.leadingAnchor)
            } else if index == accounts.count - 1 {
                xConstraint = accountImageView.trailingAnchor.constraint(equalTo: avatarContainerView.trailingAnchor)
            } else {
                xConstraint = accountImageView.centerXAnchor.constraint(equalTo: avatarContainerView.centerXAnchor)
            }
            NSLayoutConstraint.activate([
                accountImageView.widthAnchor.constraint(equalToConstant: avatarImageSize),
                accountImageView.heightAnchor.constraint(equalToConstant: avatarImageSize),
                accountImageView.centerYAnchor.constraint(equalTo: avatarContainerView.centerYAnchor),
                xConstraint
            ])
            
            if let avatar = account.avatar {
                let req = ImageCache.avatars.get(avatar) { [weak accountImageView] (_, image) in
                    DispatchQueue.main.async {
                        accountImageView?.image = image
                    }
                }
                if let req = req {
                    avatarRequests.append(req)
                }
            }
        }
    }
    
    @objc private func preferencesChanged() {
        avatarImageViews.forEach {
            $0.layer.cornerRadius = Preferences.shared.avatarStyle.cornerRadius(for: $0)
        }
    }
    
    override func prepareForReuse() {
        super.prepareForReuse()
        
        avatarRequests.forEach { $0.cancel() }
    }
    
}