Tusker/Tusker/Views/Notifications/ActionNotificationGroupTableViewCell.swift

//
//  ActionNotificationGroupTableViewCell.swift
//  Tusker
//
//  Created by Shadowfacts on 9/5/19.
//  Copyright © 2019 Shadowfacts. All rights reserved.
//

import UIKit
import Pachyderm
import SwiftSoup

class ActionNotificationGroupTableViewCell: UITableViewCell {

    weak var delegate: TuskerNavigationDelegate?
    var mastodonController: MastodonController! { delegate?.apiController }
    
    @IBOutlet weak var actionImageView: UIImageView!
    @IBOutlet weak var actionAvatarStackView: UIStackView!
    @IBOutlet weak var timestampLabel: UILabel!
    @IBOutlet weak var actionLabel: UILabel!
    @IBOutlet weak var statusContentLabel: UILabel!

    var group: NotificationGroup!
    var statusID: String!
    
    var avatarRequests = [String: ImageCache.Request]()
    var updateTimestampWorkItem: DispatchWorkItem?
    
    deinit {
        updateTimestampWorkItem?.cancel()
    }
    
    override func awakeFromNib() {
        super.awakeFromNib()
        
        NotificationCenter.default.addObserver(self, selector: #selector(updateUIForPreferences), name: .preferencesChanged, object: nil)
    }

    @objc func updateUIForPreferences() {
        let people = group.notificationIDs.compactMap(mastodonController.cache.notification(for:)).map { $0.account }
        updateActionLabel(people: people)
        
        for case let imageView as UIImageView in actionAvatarStackView.arrangedSubviews {
            imageView.layer.cornerRadius = Preferences.shared.avatarStyle.cornerRadius(for: imageView)
        }
    }
    
    func updateUI(group: NotificationGroup) {
        guard group.kind == .favourite || group.kind == .reblog else {
            fatalError("Invalid notification type \(group.kind) for ActionNotificationGroupTableViewCell")
        }
        self.group = group
        
        guard let firstNotification = mastodonController.cache.notification(for: group.notificationIDs.first!) else { fatalError() }
        let status = firstNotification.status!
        self.statusID = status.id
        
        updateUIForPreferences()
        
        switch group.kind {
        case .favourite:
            actionImageView.image = UIImage(systemName: "star.fill")
        case .reblog:
            actionImageView.image = UIImage(systemName: "repeat")
        default:
            fatalError()
        }
        
        let people = group.notificationIDs.compactMap(mastodonController.cache.notification(for:)).map { $0.account }

        actionAvatarStackView.arrangedSubviews.forEach { $0.removeFromSuperview() }
        for account in people {
            let imageView = UIImageView()
            imageView.translatesAutoresizingMaskIntoConstraints = false
            imageView.layer.masksToBounds = true
            imageView.layer.cornerRadius = Preferences.shared.avatarStyle.cornerRadiusFraction * 30
            avatarRequests[account.id] = ImageCache.avatars.get(account.avatar) { [weak self] (data) in
                guard let self = self, let data = data, self.group.id == group.id else { return }
                DispatchQueue.main.async {
                    self.avatarRequests.removeValue(forKey: account.id)
                    imageView.image = UIImage(data: data)
                }
            }
            actionAvatarStackView.addArrangedSubview(imageView)
            NSLayoutConstraint.activate([
                imageView.widthAnchor.constraint(equalToConstant: 30),
                imageView.heightAnchor.constraint(equalToConstant: 30)
            ])
        }
        
        updateTimestamp()

        updateActionLabel(people: people)
        
        let doc = try! SwiftSoup.parse(status.content)
        statusContentLabel.text = try! doc.text()
    }
    
    func updateTimestamp() {
        guard let id = group.notificationIDs.first,
            let notification = mastodonController.cache.notification(for: id) else {
            fatalError("Missing cached notification")
        }
        
        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
        }
    }
    
    func updateActionLabel(people: [Account]) {
        let verb: String
        switch group.kind {
        case .favourite:
            verb = "Favorited"
        case .reblog:
            verb = "Reblogged"
        default:
            fatalError()
        }
        let peopleStr: String
        // todo: figure out how to localize this
        // todo: update to use managed objects
        switch people.count {
        case 1:
            peopleStr = people.first!.displayName
        case 2:
            peopleStr = people.first!.displayName + " and " + people.last!.displayName
        default:
            peopleStr = people.dropLast().map { $0.displayName }.joined(separator: ", ") + ", and " + people.last!.displayName
        }
        actionLabel.text = "\(verb) by \(peopleStr)"
    }
    
    override func prepareForReuse() {
        super.prepareForReuse()
        
        avatarRequests.values.forEach { $0.cancel() }
        updateTimestampWorkItem?.cancel()
        updateTimestampWorkItem = nil
    }

}

extension ActionNotificationGroupTableViewCell: SelectableTableViewCell {
    func didSelectCell() {
        guard let delegate = delegate else { return }
        let notifications = group.notificationIDs.compactMap(mastodonController.cache.notification(for:))
        let accountIDs = notifications.map { $0.account.id }
        let action: StatusActionAccountListTableViewController.ActionType
        switch notifications.first!.kind {
        case .favourite:
            action = .favorite
        case .reblog:
            action = .reblog
        default:
            fatalError()
        }
        let vc = delegate.statusActionAccountList(action: action, statusID: statusID, statusState: .unknown, accountIDs: accountIDs)
        delegate.show(vc)
    }
}

extension ActionNotificationGroupTableViewCell: MenuPreviewProvider {
    var navigationDelegate: TuskerNavigationDelegate? { return delegate }
    
    func getPreviewProviders(for location: CGPoint, sourceViewController: UIViewController) -> PreviewProviders? {
        return (content: {
            let notifications = self.group.notificationIDs.compactMap(self.mastodonController.cache.notification(for:))
            let accountIDs = notifications.map { $0.account.id }
            let action: StatusActionAccountListTableViewController.ActionType
            switch notifications.first!.kind {
            case .favourite:
                action = .favorite
            case .reblog:
                action = .reblog
            default:
                fatalError()
            }
            return self.delegate?.statusActionAccountList(action: action, statusID: self.statusID, statusState: .unknown, accountIDs: accountIDs)
        }, actions: {
            return []
        })
    }
}