//
//  StatusTableViewCell.swift
//  Tusker
//
//  Created by Shadowfacts on 8/16/18.
//  Copyright © 2018 Shadowfacts. All rights reserved.
//

import UIKit
import Combine
import Pachyderm

protocol StatusTableViewCellDelegate: TuskerNavigationDelegate {
    func statusCollapsedStateChanged()
}

class StatusTableViewCell: UITableViewCell {

    var delegate: StatusTableViewCellDelegate? {
        didSet {
            contentLabel.navigationDelegate = delegate
        }
    }
    
    @IBOutlet weak var displayNameLabel: UILabel!
    @IBOutlet weak var usernameLabel: UILabel!
    @IBOutlet weak var contentWarningLabel: UILabel!
    @IBOutlet weak var collapseButton: UIButton!
    @IBOutlet weak var contentLabel: StatusContentLabel!
    @IBOutlet weak var avatarImageView: UIImageView!
    @IBOutlet weak var reblogLabel: UILabel!
    @IBOutlet weak var timestampLabel: UILabel!
    @IBOutlet weak var attachmentsView: AttachmentsContainerView!
    @IBOutlet weak var favoriteButton: UIButton!
    @IBOutlet weak var reblogButton: UIButton!
    
    var statusID: String!
    var accountID: String!
    var reblogStatusID: String?
    var rebloggerID: String?
    
    var favorited: Bool = false {
        didSet {
            favoriteButton.tintColor = favorited ? UIColor(displayP3Red: 1, green: 0.8, blue: 0, alpha: 1) : tintColor
        }
    }
    var reblogged: Bool = false {
        didSet {
            reblogButton.tintColor = reblogged ? UIColor(displayP3Red: 1, green: 0.8, blue: 0, alpha: 1) : tintColor
        }
    }
    
    var collapsible = false {
        didSet {
            collapseButton.isHidden = !collapsible
        }
    }
    var collapsed = false
    
    var avatarURL: URL?
    var updateTimestampWorkItem: DispatchWorkItem?
    var attachmentDataTasks: [URLSessionDataTask] = []
    
    var statusUpdater: Cancellable?
    var accountUpdater: Cancellable?
    var rebloggerAccountUpdater: Cancellable?

    deinit {
        statusUpdater?.cancel()
        accountUpdater?.cancel()
        rebloggerAccountUpdater?.cancel()
    }
    
    override func awakeFromNib() {
        displayNameLabel.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(accountPressed)))
        usernameLabel.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(accountPressed)))
        reblogLabel.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(reblogLabelPressed)))
        avatarImageView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(accountPressed)))
        avatarImageView.layer.masksToBounds = true
        attachmentsView.delegate = self
        attachmentsView.layer.cornerRadius = 5
        attachmentsView.layer.masksToBounds = true
        collapseButton.layer.masksToBounds = true
        collapseButton.layer.cornerRadius = 5
        
        NotificationCenter.default.addObserver(self, selector: #selector(updateUIForPreferences), name: .preferencesChanged, object: nil)
        
        statusUpdater = MastodonCache.statusSubject
            .filter { $0.id == self.statusID }
            .receive(on: DispatchQueue.main)
            .sink(receiveValue: updateStatusState(status:))
        
        accountUpdater = MastodonCache.accountSubject
            .filter { $0.id == self.accountID }
            .receive(on: DispatchQueue.main)
            .sink(receiveValue: updateUI(account:))
        
        rebloggerAccountUpdater = MastodonCache.accountSubject
            .filter { $0.id == self.rebloggerID }
            .receive(on: DispatchQueue.main)
            .sink(receiveValue: { (_) in
                // this method is responsible for setting the reblog label text
                self.updateUIForPreferences()
            })
    }

    func updateUI(statusID: String) {
        guard var status = MastodonCache.status(for: statusID) else { fatalError("Missing cached status \(statusID)") }
        self.statusID = statusID
        
        if let rebloggedStatusID = status.reblog?.id,
            let rebloggedStatus = MastodonCache.status(for: rebloggedStatusID) {
            reblogStatusID = statusID
            rebloggerID = status.account.id
            status = rebloggedStatus
            self.statusID = rebloggedStatus.id
            reblogLabel.isHidden = false
        } else {
            reblogStatusID = nil
            rebloggerID = nil
            reblogLabel.isHidden = true
        }
        let account = status.account
        self.accountID = account.id
        updateUI(account: account)

        updateUIForPreferences()

        updateTimestamp()

        attachmentsView.updateUI(status: status)

        let realStatus = status.reblog ?? status
        updateStatusState(status: realStatus)

        contentLabel.statusID = status.id
        
        collapsible = !status.spoilerText.isEmpty
        setCollapsed(collapsible, animated: false)
        contentWarningLabel.text = status.spoilerText
        contentWarningLabel.isHidden = status.spoilerText.isEmpty
    }
    
    private func updateStatusState(status: Status) {
        favorited = status.favourited ?? false
        reblogged = status.reblogged ?? false
    }
    
    private func updateUI(account: Account) {
        usernameLabel.text = "@\(account.acct)"
        avatarImageView.image = nil
        avatarURL = account.avatar
        ImageCache.avatars.get(account.avatar) { (data) in
            guard let data = data else { return }
            DispatchQueue.main.async {
                self.avatarImageView.image = UIImage(data: data)
                self.avatarURL = nil
            }
        }
    }

    @objc func updateUIForPreferences() {
        guard let account = MastodonCache.account(for: accountID) else { fatalError("") }
        avatarImageView.layer.cornerRadius = Preferences.shared.avatarStyle.cornerRadius(for: avatarImageView)
        if let rebloggerID = rebloggerID,
            let reblogger = MastodonCache.account(for: rebloggerID) {
            reblogLabel.text = "Reblogged by \(reblogger.realDisplayName)"
        }
        displayNameLabel.text = account.realDisplayName
    }
    
    func updateTimestamp() {
        guard let status = MastodonCache.status(for: statusID) else { fatalError("Missing cached status \(statusID!)") }
        
        timestampLabel.text = status.createdAt.timeAgoString()
        let delay: DispatchTimeInterval?
        switch status.createdAt.timeAgo().1 {
        case .second:
            delay = .seconds(10)
        case .minute:
            delay = .seconds(60)
        default:
            delay = nil
        }
        if let delay = delay {
            updateTimestampWorkItem = DispatchWorkItem {
                self.updateTimestamp()
            }
            DispatchQueue.main.asyncAfter(deadline: .now() + delay, execute: updateTimestampWorkItem!)
        } else {
            updateTimestampWorkItem = nil
        }
    }
    
    override func prepareForReuse() {
        if let url = avatarURL {
            ImageCache.avatars.cancel(url)
        }
        updateTimestampWorkItem?.cancel()
        updateTimestampWorkItem = nil
        attachmentsView.subviews.forEach { $0.removeFromSuperview() }
    }

    override func setSelected(_ selected: Bool, animated: Bool) {
        super.setSelected(selected, animated: animated)
        
        if selected {
            delegate?.selected(status: statusID)
        }
    }
    
    @IBAction func collapseButtonPressed(_ sender: Any) {
        setCollapsed(!collapsed, animated: true)
        delegate?.statusCollapsedStateChanged()
    }
    
    func setCollapsed(_ collapsed: Bool, animated: Bool) {
        self.collapsed = collapsed

        contentLabel.isHidden = collapsed
        attachmentsView.isHidden = attachmentsView.attachments.count == 0 || collapsed

        let buttonImage = UIImage(systemName: collapsed ? "chevron.down" : "chevron.up")
        
        if animated, let buttonImageView = collapseButton.imageView {
            // we need to use a keyframe animation for this, because we want to control the direction the chevron rotates
            // when rotating ±π, UIKit will always rotate in the same direction
            // using a keyframe to set an intermediate point in the animation allows us to force a specific direction
            UIView.animateKeyframes(withDuration: 0.2, delay: 0, options: .calculationModeLinear, animations: {
                UIView.addKeyframe(withRelativeStartTime: 0, relativeDuration: 0.5) {
                    buttonImageView.transform = CGAffineTransform(rotationAngle: collapsed ? .pi / 2 : -.pi / 2)
                }
                UIView.addKeyframe(withRelativeStartTime: 0.5, relativeDuration: 0.5) {
                    buttonImageView.transform = CGAffineTransform(rotationAngle: .pi)
                }
            }, completion: { (finished) in
                buttonImageView.transform = .identity
                self.collapseButton.setImage(buttonImage, for: .normal)
            })
        } else {
            collapseButton.setImage(buttonImage, for: .normal)
        }
    }
    
    @IBAction func replyPressed(_ sender: Any) {
        delegate?.reply(to: statusID)
    }
    
    @objc func accountPressed() {
        delegate?.selected(account: accountID)
    }
    
    @objc func reblogLabelPressed() {
        guard let rebloggerID = rebloggerID else { return }
        delegate?.selected(account: rebloggerID)
    }
    
    @IBAction func favoritePressed(_ sender: Any) {
        guard let status = MastodonCache.status(for: statusID) else { fatalError("Missing cached status \(statusID!)") }
        
        let oldValue = favorited
        favorited = !favorited
        
        let realStatus: Status = status.reblog ?? status
        let request = (favorited ? Status.favourite : Status.unfavourite)(realStatus)
        MastodonController.client.run(request) { response in
            DispatchQueue.main.async {
                if case let .success(newStatus, _) = response {
                    self.favorited = newStatus.favourited ?? false
                    MastodonCache.add(status: newStatus)
                    UIImpactFeedbackGenerator(style: .light).impactOccurred()
                } else {
                    self.favorited = oldValue
                    print("Couldn't favorite status \(realStatus.id)")
                    // todo: display error message
                    UINotificationFeedbackGenerator().notificationOccurred(.error)
                    return
                }
            }
        }
    }
    
    @IBAction func reblogPressed(_ sender: Any) {
        guard let status = MastodonCache.status(for: statusID) else { fatalError("Missing cached status \(statusID!)") }
        
        let oldValue = reblogged
        reblogged = !reblogged
        
        let realStatus: Status = status.reblog ?? status
        let request = (reblogged ? Status.reblog : Status.unreblog)(realStatus)
        MastodonController.client.run(request) { response in
            DispatchQueue.main.async {
                if case let .success(newStatus, _) = response {
                    self.reblogged = newStatus.reblogged ?? false
                    MastodonCache.add(status: newStatus)
                    UIImpactFeedbackGenerator(style: .light).impactOccurred()
                } else {
                    self.reblogged = oldValue
                    print("Couldn't reblog status \(realStatus.id)")
                    // todo: display error message
                    UINotificationFeedbackGenerator().notificationOccurred(.error)
                }
            }
        }
    }
    
    @IBAction func morePressed(_ sender: Any) {
        delegate?.showMoreOptions(forStatus: statusID)
    }
    
}

extension StatusTableViewCell: TableViewSwipeActionProvider {
    
    func leadingSwipeActionsConfiguration() -> UISwipeActionsConfiguration? {
        guard let status = MastodonCache.status(for: statusID) else { fatalError("Missing cached status \(statusID!)") }
        
        let favoriteTitle: String
        let favoriteRequest: Request<Status>
        let favoriteColor: UIColor
        if status.favourited ?? false {
            favoriteTitle = "Unfavorite"
            favoriteRequest = Status.unfavourite(status)
            favoriteColor = UIColor(displayP3Red: 235/255, green: 77/255, blue: 62/255, alpha: 1)
            
        } else {
            favoriteTitle = "Favorite"
            favoriteRequest = Status.favourite(status)
            favoriteColor = UIColor(displayP3Red: 1, green: 204/255, blue: 0, alpha: 1)
        }
        let favorite = UIContextualAction(style: .normal, title: favoriteTitle) { (action, view, completion) in
            MastodonController.client.run(favoriteRequest, completion: { response in
                DispatchQueue.main.async {
                    guard case let .success(status, _) = response else {
                        completion(false)
                        return
                    }
                    completion(true)
                    MastodonCache.add(status: status)
                }
            })
        }
        favorite.image = UIImage(systemName: "star.fill")
        favorite.backgroundColor = favoriteColor
        
        let reblogTitle: String
        let reblogRequest: Request<Status>
        let reblogColor: UIColor
        if status.reblogged ?? false {
            reblogTitle = "Unreblog"
            reblogRequest = Status.unreblog(status)
            reblogColor = UIColor(displayP3Red: 235/255, green: 77/255, blue: 62/255, alpha: 1)
        } else {
            reblogTitle = "Reblog"
            reblogRequest = Status.reblog(status)
            reblogColor = tintColor
        }
        let reblog = UIContextualAction(style: .normal, title: reblogTitle) { (action, view, completion) in
            MastodonController.client.run(reblogRequest, completion: { response in
                DispatchQueue.main.async {
                    guard case let .success(status, _) = response else {
                        completion(false)
                        return
                    }
                    completion(true)
                    MastodonCache.add(status: status)
                }
            })
        }
        reblog.image = UIImage(systemName: "repeat")
        reblog.backgroundColor = reblogColor
        
        return UISwipeActionsConfiguration(actions: [favorite, reblog])
    }
    
    func trailingSwipeActionsConfiguration() -> UISwipeActionsConfiguration? {
        let reply = UIContextualAction(style: .normal, title: "Reply") { (action, view, completion) in
            completion(true)
            self.delegate?.reply(to: self.statusID)
        }
        reply.image = UIImage(systemName: "arrowshape.turn.up.left.fill")
        reply.backgroundColor = tintColor
        let more = UIContextualAction(style: .normal, title: "More") { (action, view, completion) in
            completion(true)
            self.delegate?.showMoreOptions(forStatus: self.statusID)
        }
        more.image = UIImage(systemName: "ellipsis")
        more.backgroundColor = .gray
        return UISwipeActionsConfiguration(actions: [reply, more])
    }
    
}

extension StatusTableViewCell: AttachmentViewDelegate {
    func showAttachmentsGallery(startingAt index: Int) {
        guard let status = MastodonCache.status(for: statusID) else { fatalError("Missing cached status \(statusID!)") }
        let sourceViews = status.attachments.map(attachmentsView.getAttachmentView(for:))
        delegate?.showGallery(attachments: status.attachments, sourceViews: sourceViews, startIndex: index)
    }
}

extension StatusTableViewCell: MenuPreviewProvider {
    
    func getPreviewProviders(for location: CGPoint, sourceViewController: UIViewController) -> PreviewProviders? {
        if avatarImageView.frame.contains(location) {
            return (content: { ProfileTableViewController(accountID: self.accountID) }, actions: { self.actionsForProfile(accountID: self.accountID) })
        } else if attachmentsView.frame.contains(location) {
            let attachmentsViewLocation = attachmentsView.convert(location, from: self)
            if let attachmentView = attachmentsView.subviews.first(where: { $0.frame.contains(attachmentsViewLocation) }) as? AttachmentView {
                let image = attachmentView.image!
                let description = attachmentView.attachment.description
                return (content: { self.delegate?.largeImage(image, description: description, sourceView: attachmentView) }, actions: { [] })
            }
        } else if contentLabel.frame.contains(location),
            let link = contentLabel.getLink(atPoint: contentLabel.convert(location, from: self)) {
            return (
                content: { self.contentLabel.getViewController(forLink: link.url, inRange: link.range) },
                actions: {
                    let text = (self.contentLabel.text! as NSString).substring(with: link.range)
                    if let mention = self.contentLabel.getMention(for: link.url, text: text) {
                        return self.actionsForProfile(accountID: mention.id)
                    } else if let hashtag = self.contentLabel.getHashtag(for: link.url, text: text) {
                        return self.actionsForHashtag(hashtag)
                    } else {
                        return self.actionsForURL(link.url)
                    }
                }
            )
        }
        return (content: { ConversationTableViewController(for: self.statusID) }, actions: { self.actionsForStatus(statusID: self.statusID) })
    }
    
}