Tusker/Tusker/Screens/Bookmarks/BookmarksTableViewController.swift

//
//  BookmarksTableViewController.swift
//  Tusker
//
//  Created by Shadowfacts on 12/15/19.
//  Copyright © 2019 Shadowfacts. All rights reserved.
//

import UIKit
import Pachyderm

class BookmarksTableViewController: EnhancedTableViewController {
    
    private let statusCell = "statusCell"

    let mastodonController: MastodonController
    
    var statuses: [(id: String, state: StatusState)] = [] {
        didSet {
            DispatchQueue.main.async {
                self.tableView.reloadData()
            }
        }
    }
    
    var newer: RequestRange?
    var older: RequestRange?
    
    init(mastodonController: MastodonController) {
        self.mastodonController = mastodonController
        
        super.init(style: .plain)
        
        title = NSLocalizedString("Bookmarks", comment: "bookmarks screen title")
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()

        tableView.rowHeight = UITableView.automaticDimension
        tableView.estimatedRowHeight = 140
       
        tableView.register(UINib(nibName: "TimelineStatusTableViewCell", bundle: .main), forCellReuseIdentifier: statusCell)
        
        tableView.prefetchDataSource = self
        
        let request = Client.getBookmarks()
        mastodonController.run(request) { (response) in
            guard case let .success(statuses, pagination) = response else { fatalError() }
            self.mastodonController.cache.addAll(statuses: statuses)
            self.statuses.append(contentsOf: statuses.map { ($0.id, .unknown) })
            self.newer = pagination?.newer
            self.older = pagination?.older
        }
        
        userActivity = UserActivityManager.bookmarksActivity()
    }

    // MARK: - Table view data source

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

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return statuses.count
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: statusCell, for: indexPath) as! TimelineStatusTableViewCell
        cell.delegate = self
        let (id, state) = statuses[indexPath.row]
        cell.updateUI(statusID: id, state: state)
        return cell
    }
    
    // MARK: - Table view delegate
    
    override func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
        guard indexPath.row == statuses.count, let older = older else {
            return
        }
        
        let request = Client.getBookmarks(range: older)
        mastodonController.run(request) { (response) in
            guard case let .success(newStatuses, pagination) = response else { fatalError() }
            self.older = pagination?.older
            self.mastodonController.cache.addAll(statuses: newStatuses)
            self.statuses.append(contentsOf: newStatuses.map { ($0.id, .unknown) })
        }
    }
    
    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? {
        let cellConfig = (tableView.cellForRow(at: indexPath) as? TableViewSwipeActionProvider)?.trailingSwipeActionsConfiguration()

        guard let status = mastodonController.cache.status(for: statuses[indexPath.row].id) else {
            return cellConfig
        }
        
        let unbookmarkAction = UIContextualAction(style: .destructive, title: NSLocalizedString("Unbookmark", comment: "unbookmark action title")) { (action, view, completion) in
            let request = Status.unbookmark(status)
            self.mastodonController.run(request) { (response) in
                guard case let .success(newStatus, _) = response else { fatalError() }
                self.mastodonController.cache.add(status: newStatus)
                self.statuses.remove(at: indexPath.row)
            }
        }
        unbookmarkAction.image = UIImage(systemName: "bookmark.fill")
        
        let config: UISwipeActionsConfiguration
        if let cellConfig = cellConfig {
            config = UISwipeActionsConfiguration(actions: cellConfig.actions + [unbookmarkAction])
            config.performsFirstActionWithFullSwipe = cellConfig.performsFirstActionWithFullSwipe
        } else {
            config = UISwipeActionsConfiguration(actions: [unbookmarkAction])
            config.performsFirstActionWithFullSwipe = false
        }
        return config
    }
    
    override func getSuggestedContextMenuActions(tableView: UITableView, indexPath: IndexPath, point: CGPoint) -> [UIAction] {
        guard let status = mastodonController.cache.status(for: statuses[indexPath.row].id) else { return [] }
        return [
            UIAction(title: NSLocalizedString("Unbookmark", comment: "unbookmark action title"), image: UIImage(systemName: "bookmark.fill"), identifier: .init("unbookmark"), discoverabilityTitle: nil, attributes: [], state: .off, handler: { (_) in
                let request = Status.unbookmark(status)
                self.mastodonController.run(request) { (response) in
                    guard case let .success(newStatus, _) = response else { fatalError() }
                    self.mastodonController.cache.add(status: newStatus)
                    self.statuses.remove(at: indexPath.row)
                }
            })
        ]
    }
    
}

extension BookmarksTableViewController: StatusTableViewCellDelegate {
    var apiController: MastodonController { mastodonController }
    
    func statusCellCollapsedStateChanged(_ cell: BaseStatusTableViewCell) {
        tableView.beginUpdates()
        tableView.endUpdates()
    }
}

extension BookmarksTableViewController: UITableViewDataSourcePrefetching {
    func tableView(_ tableView: UITableView, prefetchRowsAt indexPaths: [IndexPath]) {
        for indexPath in indexPaths {
            guard let status = mastodonController.cache.status(for: statuses[indexPath.row].id) else { continue }
            ImageCache.avatars.get(status.account.avatar, completion: nil)
            for attachment in status.attachments where attachment.kind == .image {
                ImageCache.attachments.get(attachment.url, completion: nil)
            }
        }
    }
    
    func tableView(_ tableView: UITableView, cancelPrefetchingForRowsAt indexPaths: [IndexPath]) {
        for indexPath in indexPaths {
            guard let status = mastodonController.cache.status(for: statuses[indexPath.row].id) else { continue }
            ImageCache.avatars.cancel(status.account.avatar)
            for attachment in status.attachments where attachment.kind == .image {
                ImageCache.attachments.cancel(attachment.url)
            }
        }
    }
}