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

import UIKit
import Combine
import Pachyderm

class TimelineStatusTableViewCell: BaseStatusTableViewCell {

    static let relativeDateFormatter: RelativeDateTimeFormatter = {
        let formatter = RelativeDateTimeFormatter()
        formatter.dateTimeStyle = .numeric
        formatter.unitsStyle = .short
        return formatter
    }()
    
    @IBOutlet weak var reblogLabel: EmojiLabel!
    @IBOutlet weak var timestampLabel: UILabel!
    @IBOutlet weak var pinImageView: UIImageView!
    @IBOutlet weak var replyImageView: UIImageView!
    
    var reblogStatusID: String?
    var rebloggerID: String?
    
    var showPinned = false
    var showReplyIndicator = true
    
    var updateTimestampWorkItem: DispatchWorkItem?

    var rebloggerAccountUpdater: Cancellable?

    deinit {
        rebloggerAccountUpdater?.cancel()
        updateTimestampWorkItem?.cancel()
    }
    
    override func awakeFromNib() {
        super.awakeFromNib()
        
        reblogLabel.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(reblogLabelPressed)))

        accessibilityElements!.insert(reblogLabel!, at: 0)
        
        // todo: double check this on RTL layouts
        replyButton.imageView!.leadingAnchor.constraint(equalTo: contentTextView.leadingAnchor).isActive = true
        
        contentTextView.defaultFont = .systemFont(ofSize: 16)
    }
    
    override func createObserversIfNecessary() {
        super.createObserversIfNecessary()
        
        if rebloggerAccountUpdater == nil {
            rebloggerAccountUpdater = mastodonController.persistentContainer.accountSubject
                .filter { [unowned self] in $0 == self.rebloggerID }
                .receive(on: DispatchQueue.main)
                .sink { [unowned self] in
                    if let mastodonController = self.mastodonController,
                       let reblogger = mastodonController.persistentContainer.account(for: $0) {
                        self.updateRebloggerLabel(reblogger: reblogger)
                    }
            }
        }
    }
    
    override func doUpdateUI(status: StatusMO, state: StatusState) {
        var status = status
        
        if let rebloggedStatus = status.reblog {
            reblogStatusID = statusID
            rebloggerID = status.account.id
            reblogLabel.isHidden = false
            updateRebloggerLabel(reblogger: status.account)
            
            status = rebloggedStatus
            statusID = rebloggedStatus.id
        } else {
            reblogStatusID = nil
            rebloggerID = nil
            reblogLabel.isHidden = true
        }
        
        super.doUpdateUI(status: status, state: state)
        
        doUpdateTimestamp(status: status)
        
        let pinned = showPinned && (status.pinned ?? false)
        timestampLabel.isHidden = pinned
        pinImageView.isHidden = !pinned
    }
    
    override func updateGrayscaleableUI(account: AccountMO, status: StatusMO) {
        super.updateGrayscaleableUI(account: account, status: status)
        
        if let rebloggerID = rebloggerID,
           reblogLabel.hasEmojis,
            let reblogger = mastodonController.persistentContainer.account(for: rebloggerID) {
            updateRebloggerLabel(reblogger: reblogger)
        }
    }
    
    private func updateRebloggerLabel(reblogger: AccountMO) {
        if Preferences.shared.hideCustomEmojiInUsernames {
            reblogLabel.text = "Reblogged by \(reblogger.displayNameWithoutCustomEmoji)"
            reblogLabel.removeEmojis()
        } else {
            reblogLabel.text = "Reblogged by \(reblogger.displayOrUserName)"
            reblogLabel.setEmojis(reblogger.emojis, identifier: reblogger.id)
        }
    }
    
    override func updateStatusIconsForPreferences(_ status: StatusMO) {
        super.updateStatusIconsForPreferences(status)
        
        replyImageView.isHidden = !Preferences.shared.showIsStatusReplyIcon || !showReplyIndicator || status.inReplyToID == nil
    }
    
    private func updateTimestamp() {
        // if the mastodonController is nil (i.e. the delegate is nil), then the screen this cell was a part of has been deallocated
        // so we bail out immediately, since there's nothing to update
        // if the status cannot be found, it may have already been discarded due to not being on screen, so we do nothing
        guard let mastodonController = mastodonController,
              let status = mastodonController.persistentContainer.status(for: statusID) else { return }
        
        doUpdateTimestamp(status: status)
    }
    
    private func doUpdateTimestamp(status: StatusMO) {
        timestampLabel.text = status.createdAt.timeAgoString()
        timestampLabel.accessibilityLabel = TimelineStatusTableViewCell.relativeDateFormatter.localizedString(for: status.createdAt, relativeTo: Date())
        
        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 {
            if updateTimestampWorkItem == nil {
                updateTimestampWorkItem = DispatchWorkItem { [weak self] in
                    self?.updateTimestamp()
                }
            }
            DispatchQueue.main.asyncAfter(deadline: .now() + delay, execute: updateTimestampWorkItem!)
        } else {
            updateTimestampWorkItem = nil
        }
    }
    
    func reply() {
        if Preferences.shared.mentionReblogger,
            let rebloggerID = rebloggerID,
            let rebloggerAccount = mastodonController.persistentContainer.account(for: rebloggerID) {
            delegate?.compose(inReplyToID: statusID, mentioningAcct: rebloggerAccount.acct)
        } else {
            delegate?.compose(inReplyToID: statusID)
        }
    }
    
    override func prepareForReuse() {
        super.prepareForReuse()
        updateTimestampWorkItem?.cancel()
        updateTimestampWorkItem = nil
        showPinned = false
    }

    @objc func reblogLabelPressed() {
        guard let rebloggerID = rebloggerID else { return }
        delegate?.selected(account: rebloggerID)
    }
    
    override func replyPressed() {
        reply()
    }

    override func getStatusCellPreviewProviders(for location: CGPoint, sourceViewController: UIViewController) -> BaseStatusTableViewCell.PreviewProviders? {
        guard let mastodonController = mastodonController,
              let status = mastodonController.persistentContainer.status(for: statusID) else {
            return nil
        }
        return (
            content: { ConversationTableViewController(for: self.statusID, state: self.statusState.copy(), mastodonController: mastodonController) },
            actions: { self.actionsForStatus(status, sourceView: self) }
        )
    }

}

extension TimelineStatusTableViewCell: SelectableTableViewCell {
    func didSelectCell() {
        delegate?.selected(status: statusID, state: statusState.copy())
    }
}

extension TimelineStatusTableViewCell: TableViewSwipeActionProvider {
    
    func leadingSwipeActionsConfiguration() -> UISwipeActionsConfiguration? {
        guard let mastodonController = mastodonController,
              mastodonController.loggedIn else { return nil }
        guard let status = mastodonController.persistentContainer.status(for: statusID) else { fatalError("Missing cached status \(statusID!)") }
        
        let favoriteTitle: String
        let favoriteRequest: Request<Status>
        let favoriteColor: UIColor
        if status.favourited {
            favoriteTitle = "Unfavorite"
            favoriteRequest = Status.unfavourite(status.id)
            favoriteColor = UIColor(displayP3Red: 235/255, green: 77/255, blue: 62/255, alpha: 1)
            
        } else {
            favoriteTitle = "Favorite"
            favoriteRequest = Status.favourite(status.id)
            favoriteColor = UIColor(displayP3Red: 1, green: 204/255, blue: 0, alpha: 1)
        }
        let favorite = UIContextualAction(style: .normal, title: favoriteTitle) { (action, view, completion) in
            mastodonController.run(favoriteRequest, completion: { response in
                DispatchQueue.main.async {
                    guard case let .success(status, _) = response else {
                        completion(false)
                        return
                    }
                    completion(true)
                    mastodonController.persistentContainer.addOrUpdate(status: status, incrementReferenceCount: false)
                }
            })
        }
        favorite.image = UIImage(systemName: "star.fill")
        favorite.backgroundColor = favoriteColor
        
        let reblogTitle: String
        let reblogRequest: Request<Status>
        let reblogColor: UIColor
        if status.reblogged {
            reblogTitle = "Unreblog"
            reblogRequest = Status.unreblog(status.id)
            reblogColor = UIColor(displayP3Red: 235/255, green: 77/255, blue: 62/255, alpha: 1)
        } else {
            reblogTitle = "Reblog"
            reblogRequest = Status.reblog(status.id)
            reblogColor = tintColor
        }
        let reblog = UIContextualAction(style: .normal, title: reblogTitle) { (action, view, completion) in
            mastodonController.run(reblogRequest, completion: { response in
                DispatchQueue.main.async {
                    guard case let .success(status, _) = response else {
                        completion(false)
                        return
                    }
                    completion(true)
                    mastodonController.persistentContainer.addOrUpdate(status: status, incrementReferenceCount: false)
                }
            })
        }
        reblog.image = UIImage(systemName: "repeat")
        reblog.backgroundColor = reblogColor
        
        return UISwipeActionsConfiguration(actions: [favorite, reblog])
    }
    
    func trailingSwipeActionsConfiguration() -> UISwipeActionsConfiguration? {
        let share = UIContextualAction(style: .normal, title: "Share") { (action, view, completion) in
            completion(true)
            self.delegate?.showMoreOptions(forStatus: self.statusID, sourceView: self)
        }
        // Bold to more closely match the other action symbols
        let config = UIImage.SymbolConfiguration(weight: .bold)
        share.image = UIImage(systemName: "square.and.arrow.up")!.applyingSymbolConfiguration(config)!
        share.backgroundColor = .lightGray
        
        guard mastodonController.loggedIn else {
            return UISwipeActionsConfiguration(actions: [share])
        }
        
        let reply = UIContextualAction(style: .normal, title: "Reply") { (action, view, completion) in
            completion(true)
            self.reply()
        }
        reply.image = UIImage(systemName: "arrowshape.turn.up.left.fill")
        reply.backgroundColor = tintColor
        
        return UISwipeActionsConfiguration(actions: [reply, share])
    }
    
}

extension TimelineStatusTableViewCell: DraggableTableViewCell {
    func dragItemsForBeginning(session: UIDragSession) -> [UIDragItem] {
        guard let status = mastodonController.persistentContainer.status(for: statusID),
              let accountID = mastodonController.accountInfo?.id else {
            return []
        }
        let provider = NSItemProvider(object: status.url! as NSURL)
        let activity = UserActivityManager.showConversationActivity(mainStatusID: status.id, accountID: accountID)
        provider.registerObject(activity, visibility: .all)
        return [UIDragItem(itemProvider: provider)]
    }
}