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

import UIKit
import Pachyderm

class FollowNotificationGroupTableViewCell: UITableViewCell {

    weak var delegate: TuskerNavigationDelegate?
    var mastodonController: MastodonController! { delegate?.apiController }
    
    @IBOutlet weak var avatarStackView: UIStackView!
    @IBOutlet weak var timestampLabel: UILabel!
    @IBOutlet weak var actionLabel: UILabel!
    
    var group: NotificationGroup!
    
    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 avatarStackView.arrangedSubviews {
            imageView.layer.cornerRadius = Preferences.shared.avatarStyle.cornerRadius(for: imageView)
        }
    }

    func updateUI(group: NotificationGroup) {
        self.group = group
        
        let people = group.notificationIDs.compactMap(mastodonController.cache.notification(for:)).map { $0.account }
        
        updateActionLabel(people: people)
        updateTimestamp()
        
        avatarStackView.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)
                }
            }
            avatarStackView.addArrangedSubview(imageView)
            NSLayoutConstraint.activate([
                imageView.widthAnchor.constraint(equalToConstant: 30),
                imageView.heightAnchor.constraint(equalToConstant: 30),
            ])
        }
    }
    
    func updateActionLabel(people: [Account]) {
        // todo: update to use managed objects
        // todo: figure out how to localize this
        let peopleStr: String
        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 = "Followed by \(peopleStr)"
    }
    
    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
        }
    }
    
    override func prepareForReuse() {
        super.prepareForReuse()
        
        avatarRequests.values.forEach { $0.cancel() }
        updateTimestampWorkItem?.cancel()
        updateTimestampWorkItem = nil
    }

}

extension FollowNotificationGroupTableViewCell: SelectableTableViewCell {
    func didSelectCell() {
        let people = group.notificationIDs.compactMap(mastodonController.cache.notification(for:)).map { $0.account.id }
        switch people.count {
        case 0:
            return
        case 1:
            delegate?.selected(account: people.first!)
        default:
            delegate?.showFollowedByList(accountIDs: people)
        }
    }
}

extension FollowNotificationGroupTableViewCell: MenuPreviewProvider {
    var navigationDelegate: TuskerNavigationDelegate? { return delegate }
    
    func getPreviewProviders(for location: CGPoint, sourceViewController: UIViewController) -> PreviewProviders? {
        guard let mastodonController = mastodonController else { return nil }
        let accountIDs = self.group.notificationIDs.compactMap(mastodonController.cache.notification(for:)).map { $0.account.id }
        return (content: {
            if accountIDs.count == 1 {
                return ProfileTableViewController(accountID: accountIDs.first!, mastodonController: mastodonController)
            } else {
                return AccountListTableViewController(accountIDs: accountIDs, mastodonController: mastodonController)
            }
        }, actions: {
            if accountIDs.count == 1 {
                return self.actionsForProfile(accountID: accountIDs.first!, sourceView: self)
            } else {
                return []
            }
        })
    }
}