//
//  ProfileTableViewController.swift
//  Tusker
//
//  Created by Shadowfacts on 8/27/18.
//  Copyright © 2018 Shadowfacts. All rights reserved.
//

import UIKit
import Pachyderm
import SafariServices

class ProfileTableViewController: EnhancedTableViewController {
    
    var accountID: String! {
        didSet {
            if shouldLoadOnAccountIDSet {
                DispatchQueue.main.async {
                    self.updateAccountUI()
                }
            }
        }
    }
    
    var timelineSegments: [TimelineSegment<Status>] = [] {
        didSet {
            DispatchQueue.main.async {
                self.tableView.reloadData()
            }
        }
    }
    
    var older: RequestRange?
    var newer: RequestRange?
    
    var shouldLoadOnAccountIDSet = false
    var loadingVC: LoadingViewController? = nil
    
    init(accountID: String?) {
        self.accountID = accountID
        
        super.init(style: .plain)
        
        self.refreshControl = UIRefreshControl()
        refreshControl!.addTarget(self, action: #selector(refreshStatuses(_:)), for: .valueChanged)
        navigationItem.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: .compose, target: self, action: #selector(composePressed(_:)))
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemeneted")
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()

        tableView.rowHeight = UITableView.automaticDimension
        tableView.estimatedRowHeight = 140
        
        tableView.register(UINib(nibName: "StatusTableViewCell", bundle: nil), forCellReuseIdentifier: "statusCell")
        tableView.register(UINib(nibName: "ProfileHeaderTableViewCell", bundle: nil), forCellReuseIdentifier: "headerCell")
        
        tableView.prefetchDataSource = self
        
        if let accountID = accountID {
            if MastodonCache.account(for: accountID) != nil {
                updateAccountUI()
            } else {
                loadingVC = LoadingViewController()
                embedChild(loadingVC!)
                MastodonCache.account(for: accountID) { (account) in
                    guard account != nil else {
                        let alert = UIAlertController(title: "Something Went Wrong", message: "Couldn't load the selected account", preferredStyle: .alert)
                        alert.addAction(UIAlertAction(title: "OK", style: .default, handler: { (_) in
                            self.navigationController!.popViewController(animated: true)
                        }))
                        DispatchQueue.main.async {
                            self.present(alert, animated: true)
                        }
                        return
                    }
                    DispatchQueue.main.async {
                        self.updateAccountUI()
                        self.tableView.reloadData()
                    }
                }
            }
        } else {
            loadingVC = LoadingViewController()
            embedChild(loadingVC!)
            shouldLoadOnAccountIDSet = true
        }
        
        NotificationCenter.default.addObserver(self, selector: #selector(updateUIForPreferences), name: .preferencesChanged, object: nil)
    }

    func updateAccountUI() {
        loadingVC?.removeViewAndController()
        
        updateUIForPreferences()
        
        getStatuses() { response in
            guard case let .success(statuses, pagination) = response else { fatalError() }
            
            MastodonCache.addAll(statuses: statuses)
            self.timelineSegments.append(TimelineSegment(objects: statuses))
            
            self.older = pagination?.older
            self.newer = pagination?.newer
        }
    }
    
    @objc func updateUIForPreferences() {
        guard let account = MastodonCache.account(for: accountID) else { fatalError("Missing cached account \(accountID!)") }
        navigationItem.title = account.realDisplayName
    }
    
    func getStatuses(for range: RequestRange = .default, completion: @escaping Client.Callback<[Status]>) {
        let request = Account.getStatuses(accountID, range: range, onlyMedia: false, pinned: false, excludeReplies: !Preferences.shared.showRepliesInProfiles)
        MastodonController.client.run(request, completion: completion)
    }
    
    func sendMessageMentioning() {
        guard let account = MastodonCache.account(for: accountID) else { fatalError("Missing cached account \(accountID!)") }
        let vc = UINavigationController(rootViewController: ComposeViewController(mentioningAcct: account.acct))
        present(vc, animated: true)
    }
    
    // MARK: - Table view data source

    override func numberOfSections(in tableView: UITableView) -> Int {
        return 1 + timelineSegments.count
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        if section == 0 {
            return accountID == nil || MastodonCache.account(for: accountID) == nil ? 0 : 1
        } else {
            return timelineSegments[section - 1].count
        }
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        if indexPath.section == 0 {
            guard let cell = tableView.dequeueReusableCell(withIdentifier: "headerCell", for: indexPath) as? ProfileHeaderTableViewCell else { fatalError() }
            cell.selectionStyle = .none
            cell.delegate = self
            cell.updateUI(for: accountID)
            return cell
        } else {
            guard let cell = tableView.dequeueReusableCell(withIdentifier: "statusCell", for: indexPath) as? StatusTableViewCell else { fatalError() }
            let statusID = timelineSegments[indexPath.section - 1][indexPath.row]
            cell.updateUI(statusID: statusID)
            cell.delegate = self
            return cell
        }
    }
    
    override func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
        if timelineSegments.count > 0 && indexPath.section == timelineSegments.count && indexPath.row == timelineSegments[indexPath.section - 1].count - 1 {
            let older = self.older ?? RequestRange.after(id: timelineSegments.last!.last!, count: nil)

            getStatuses(for: older) { response in
                guard case let .success(newStatuses, pagination) = response else { fatalError() }
                
                MastodonCache.addAll(statuses: newStatuses)
                self.timelineSegments[indexPath.section - 1].append(objects: newStatuses)

                self.older = pagination?.older
            }
        }
    }

    override func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
        return true
    }
    
    override func tableView(_ tableView: UITableView, leadingSwipeActionsConfigurationForRowAt indexPath: IndexPath) -> UISwipeActionsConfiguration? {
        return (tableView.cellForRow(at: indexPath) as? TableViewSwipeActionProvider)?.leadingSwipeActionsConfiguration()
    }
    
    override func tableView(_ tableView: UITableView, trailingSwipeActionsConfigurationForRowAt indexPath: IndexPath) -> UISwipeActionsConfiguration? {
        return (tableView.cellForRow(at: indexPath) as? TableViewSwipeActionProvider)?.trailingSwipeActionsConfiguration()
    }
    
    @objc func refreshStatuses(_ sender: Any) {
        let newer = self.newer ?? RequestRange.after(id: timelineSegments.first!.first!, count: nil)

        getStatuses(for: newer) { response in
            guard case let .success(newStatuses, pagination) = response else { fatalError() }
            
            MastodonCache.addAll(statuses: newStatuses)
            self.timelineSegments[0].insertAtBeginning(objects: newStatuses)

            self.newer = pagination?.newer

            DispatchQueue.main.async {
                self.refreshControl?.endRefreshing()
            }
        }
    }
    
    @objc func composePressed(_ sender: Any) {
        sendMessageMentioning()
    }
    
}

extension ProfileTableViewController: StatusTableViewCellDelegate {
    func statusCollapsedStateChanged() {
        // causes the table view to recalculate the cell heights
        tableView.beginUpdates()
        tableView.endUpdates()
    }
}

extension ProfileTableViewController: ProfileHeaderTableViewCellDelegate {
    func showMoreOptions() {
        let account = MastodonCache.account(for: accountID)!
        
        MastodonCache.relationship(for: account.id) { [weak self] (relationship) in
            guard let self = self else { return }
            
            let customActivities: [UIActivity]
            if let relationship = relationship {
                let toggleFollowActivity = relationship.following ? UnfollowAccountActivity() : FollowAccountActivity()
                customActivities = [
                    SendMessageActivity(),
                    toggleFollowActivity,
                    OpenInSafariActivity()
                ]
            } else {
                customActivities = [
                    SendMessageActivity(),
                    OpenInSafariActivity()
                ]
            }
            
            DispatchQueue.main.async {
                let activityController = UIActivityViewController(activityItems: [account.url, account], applicationActivities: customActivities)
                activityController.completionWithItemsHandler = OpenInSafariActivity.completionHandler(viewController: self, url: account.url)
                self.present(activityController, animated: true)
            }
        }
    }
}

extension ProfileTableViewController: UITableViewDataSourcePrefetching {
    func tableView(_ tableView: UITableView, prefetchRowsAt indexPaths: [IndexPath]) {
        for indexPath in indexPaths where indexPath.section > 0 {
            let statusID = timelineSegments[indexPath.section - 1][indexPath.row]
            guard let status = MastodonCache.status(for: statusID) else { continue }
            ImageCache.avatars.get(status.account.avatar, completion: nil)
            for attachment in status.attachments {
                ImageCache.attachments.get(attachment.url, completion: nil)
            }
        }
    }
    
    func tableView(_ tableView: UITableView, cancelPrefetchingForRowsAt indexPaths: [IndexPath]) {
        for indexPath in indexPaths where indexPath.section > 0 {
            let statusID = timelineSegments[indexPath.section - 1][indexPath.row]
            guard let status = MastodonCache.status(for: statusID) else { continue }
            ImageCache.avatars.cancel(status.account.avatar)
            for attachment in status.attachments {
                ImageCache.attachments.cancel(attachment.url)
            }
        }
    }
}