Tusker/Tusker/Views/Notifications/FollowRequestNotificationTableViewCell.swift

//
//  FollowRequestNotificationTableViewCell.swift
//  Tusker
//
//  Created by Shadowfacts on 1/4/20.
//  Copyright © 2020 Shadowfacts. All rights reserved.
//

import UIKit
import Pachyderm

class FollowRequestNotificationTableViewCell: UITableViewCell {

    weak var delegate: TuskerNavigationDelegate?
    var mastodonController: MastodonController! { delegate?.apiController }
    
    @IBOutlet weak var stackView: UIStackView!
    @IBOutlet weak var avatarImageView: UIImageView!
    @IBOutlet weak var timestampLabel: UILabel!
    @IBOutlet weak var actionLabel: EmojiLabel!
    @IBOutlet weak var actionButtonsStackView: UIStackView!
    @IBOutlet weak var acceptButton: UIButton!
    @IBOutlet weak var rejectButton: UIButton!
    
    var notification: Pachyderm.Notification?
    var account: Account!
    
    private var avatarRequest: ImageCache.Request?
    private var updateTimestampWorkItem: DispatchWorkItem?
    private var isGrayscale = false
    
    deinit {
        updateTimestampWorkItem?.cancel()
    }
    
    override func awakeFromNib() {
        super.awakeFromNib()
        
        avatarImageView.layer.masksToBounds = true
        
        NotificationCenter.default.addObserver(self, selector: #selector(updateUIForPreferences), name: .preferencesChanged, object: nil)
        updateUIForPreferences()
    }
    
    @objc func updateUIForPreferences() {
        avatarImageView.layer.cornerRadius = Preferences.shared.avatarStyle.cornerRadiusFraction * 30
        
        if isGrayscale != Preferences.shared.grayscaleImages,
           let account = self.account {
            updateUI(account: account)
        }
    }

    func updateUI(notification: Pachyderm.Notification) {
        self.notification = notification
        updateUI(account: notification.account)
        updateTimestamp()
    }
    
    func updateUI(account: Account) {
        // todo: update to use managed objects
        self.account = account
        if Preferences.shared.hideCustomEmojiInUsernames {
            actionLabel.text = "Request to follow from \(account.displayName)"
            actionLabel.removeEmojis()
        } else {
            actionLabel.text = "Request to follow from \(account.displayName)"
            actionLabel.setEmojis(account.emojis, identifier: account.id)
        }
        let avatarURL = account.avatar
        avatarRequest = ImageCache.avatars.get(avatarURL) { [weak self] (data) in
            guard let self = self, self.account == account, let data = data else { return }
            self.avatarRequest = nil
            
            let image: UIImage?
            if self.isGrayscale {
                image = ImageGrayscalifier.convert(url: avatarURL, data: data)
            } else {
                image = UIImage(data: data)
            }
            
            if let image = image {
                DispatchQueue.main.async {
                    self.avatarImageView.image = image
                }
            }
        }
    }
    
    private func updateTimestamp() {
        guard let notification = notification else { return }
        
        timestampLabel.text = notification.createdAt.timeAgoString()
        
        let delay: DispatchTimeInterval?
        switch notification.createdAt.timeAgo().1 {
        case .second:
            delay = .seconds(10)
        case .minute:
            delay = .seconds(60)
        default:
            delay = nil
        }
        if let delay = delay {
            if updateTimestampWorkItem == nil {
                updateTimestampWorkItem = DispatchWorkItem { [weak self] in
                    self?.updateTimestamp()
                }
            }
            DispatchQueue.main.asyncAfter(deadline: .now() + delay, execute: updateTimestampWorkItem!)
        } else {
            updateTimestampWorkItem = nil
        }
    }
    
    override func prepareForReuse() {
        super.prepareForReuse()
        
        avatarRequest?.cancel()
        updateTimestampWorkItem?.cancel()
        updateTimestampWorkItem = nil
    }
    
    private func addLabel(_ text: String) {
        let label = UILabel()
        label.textAlignment = .center
        label.font = .boldSystemFont(ofSize: 17)
        label.text = text
        self.stackView.addArrangedSubview(label)
    }
    
    // MARK: - Interaction
    
    @IBAction func rejectButtonPressed() {
        acceptButton.isEnabled = false
        rejectButton.isEnabled = false
        
        let request = Account.rejectFollowRequest(account)
        mastodonController.run(request) { (response) in
            guard case .success(_, _) = response else { fatalError() }
            DispatchQueue.main.async {
                UINotificationFeedbackGenerator().notificationOccurred(.success)
                self.actionButtonsStackView.isHidden = true
                self.addLabel(NSLocalizedString("Rejected", comment: "rejected follow request label"))
            }
        }
    }
    
    @IBAction func acceptButtonPressed() {
        acceptButton.isEnabled = false
        rejectButton.isEnabled = false
        
        let request = Account.authorizeFollowRequest(account)
        mastodonController.run(request) { (response) in
            guard case .success(_, _) = response else { fatalError() }
            DispatchQueue.main.async {
                UINotificationFeedbackGenerator().notificationOccurred(.success)
                self.actionButtonsStackView.isHidden = true
                self.addLabel(NSLocalizedString("Accepted", comment: "accepted follow request label"))
            }
        }
    }
    
}

extension FollowRequestNotificationTableViewCell: SelectableTableViewCell {
    func didSelectCell() {
        delegate?.selected(account: account.id)
    }
}

extension FollowRequestNotificationTableViewCell: MenuPreviewProvider {
    var navigationDelegate: TuskerNavigationDelegate? { return delegate }
    
    func getPreviewProviders(for location: CGPoint, sourceViewController: UIViewController) -> PreviewProviders? {
        guard let mastodonController = mastodonController else { return nil }
        return (content: {
            return ProfileViewController(accountID: self.account.id, mastodonController: mastodonController)
        }, actions: {
            return []
        })
    }
}