Tusker/Tusker/Screens/Status Action Account List/StatusActionAccountListTableViewController.swift

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

import UIKit
import Pachyderm

class StatusActionAccountListTableViewController: EnhancedTableViewController {
        
    private let statusCell = "statusCell"
    private let accountCell = "accountCell"
    
    weak var mastodonController: MastodonController!
    
    let actionType: ActionType
    let statusID: String
    var statusState: StatusState
    var accountIDs: [String]? {
        didSet {
            tableView.reloadData()
        }
    }
    
    /// If `true`, a warning will be shown below the account list describing that the total favs/reblogs may be innacurate.
    var showInacurateCountWarning = false
    
    /**
     Creates a new view controller showing the accounts that performed the given action on the given status.
     
     - Parameter actionType The action that this VC is for.
     - Parameter statusID The ID of the status to show.
     - Parameter accountIDs The accounts that will be shown. If `nil` is passed, a request will be performed to load the accounts.
     - Parameter mastodonController The `MastodonController` instance this view controller uses.
     */
    init(actionType: ActionType, statusID: String, statusState: StatusState, accountIDs: [String]?, mastodonController: MastodonController) {
        self.mastodonController = mastodonController
        
        self.actionType = actionType
        self.statusID = statusID
        self.statusState = statusState
        self.accountIDs = accountIDs
        
        super.init(style: .grouped)
        
        switch actionType {
        case .favorite:
            title = NSLocalizedString("Favorited By", comment: "status favorited by accounts list title")
        case .reblog:
            title = NSLocalizedString("Reblogged By", comment: "status reblogged by accounts list title")
        }
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    deinit {
        if let accountIDs = self.accountIDs, let container = mastodonController?.persistentContainer {
            container.backgroundContext.perform {
                for id in accountIDs {
                    container.account(for: id, in: container.backgroundContext)?.decrementReferenceCount()
                }
            }
        }
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()

        tableView.register(UINib(nibName: "TimelineStatusTableViewCell", bundle: .main), forCellReuseIdentifier: statusCell)
        tableView.register(UINib(nibName: "AccountTableViewCell", bundle: .main), forCellReuseIdentifier: accountCell)
        
        tableView.rowHeight = UITableView.automaticDimension
        tableView.estimatedRowHeight = 66 // height of account cell, which will be the most common
        
        tableView.alwaysBounceVertical = true
        
        tableView.tableHeaderView = UIView(frame: CGRect(x: 0, y: 0, width: 0, height: CGFloat.leastNormalMagnitude))
        
        if let accountIDs = accountIDs {
            accountIDs.forEach { (id) in
                self.mastodonController.persistentContainer.account(for: id)?.incrementReferenceCount()
            }
        } else {
            // account IDs haven't been set, so perform a request to load them
            guard let status = mastodonController.persistentContainer.status(for: statusID) else {
                fatalError("Missing cached status \(statusID)")
            }

            tableView.tableFooterView = UIActivityIndicatorView(style: .large)
            
            let request = actionType == .favorite ? Status.getFavourites(status.id) : Status.getReblogs(status.id)
            mastodonController.run(request) { (response) in
                guard case let .success(accounts, _) = response else { fatalError() }
                self.mastodonController.persistentContainer.addAll(accounts: accounts) {
                    DispatchQueue.main.async {
                        self.accountIDs = accounts.map { $0.id }
                        self.tableView.tableFooterView = nil
                    }
                }
            }
        }
    }

    // MARK: - Table view data source

    override func numberOfSections(in tableView: UITableView) -> Int {
        return 2
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        switch section {
        case 0: // status
            return 1
        case 1: // accounts
            if let accountIDs = accountIDs {
                return accountIDs.count
            } else {
                return 0
            }
        default:
            fatalError("Invalid section \(section)")
        }
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        switch indexPath.section {
        case 0:
            guard let cell = tableView.dequeueReusableCell(withIdentifier: statusCell, for: indexPath) as? TimelineStatusTableViewCell else { fatalError() }
            cell.delegate = self
            cell.updateUI(statusID: statusID, state: statusState)
            return cell
        case 1:
            guard let accountIDs = accountIDs,
                let cell = tableView.dequeueReusableCell(withIdentifier: accountCell, for: indexPath) as? AccountTableViewCell else { fatalError() }
            cell.delegate = self
            cell.updateUI(accountID: accountIDs[indexPath.row])
            return cell
        default:
            fatalError("Invalid section \(indexPath.section)")
        }
    }
    
    override func tableView(_ tableView: UITableView, titleForFooterInSection section: Int) -> String? {
        guard section == 1, showInacurateCountWarning else { return nil }
        return NSLocalizedString("Favorite and reblog counts for posts originating from instances other than your own may not be accurate.", comment: "shown on lists of status total actions")
    }
    
    enum ActionType {
        case favorite, reblog
    }
    
}

extension StatusActionAccountListTableViewController: StatusTableViewCellDelegate {
    var apiController: MastodonController { mastodonController }
    func statusCellCollapsedStateChanged(_ cell: BaseStatusTableViewCell) {
        // causes the table view to recalculate the cell heights
        tableView.beginUpdates()
        tableView.endUpdates()
    }
}