/*

Copyright (C) 2016 Apple Inc. All Rights Reserved.

See LICENSE.txt for this sample’s licensing information

Abstract:

This class manages the presentation of the queued songs and updates when the users context changes.

*/

import UIKit

class SongViewController: UIViewController, UITableViewDataSource, UITableViewDelegate, SongManagerDelegate {

    // MARK: Properties

    static let textCellIdentifier = "SongCell"

    @IBOutlet weak var songTableView: UITableView!

    @IBOutlet weak var albumView: UIImageView!

    let motionManager = MotionManager()

    let songManager = SongManager()

    var cachedSongQueue = [Song]()

    // MARK: View Controller

    override func viewDidLoad() {

        super.viewDidLoad()

        setNeedsStatusBarAppearanceUpdate()

        motionManager.delegate = songManager

        /*

            This is currently needed to allow the Motion Activity Access dialog

            to appear in front of the app, instead of behind it.

        */

        DispatchQueue.main.async {

            self.motionManager.startMonitoring()

        }

        songManager.delegate = self

        // Save the inital queue to present to the user.

        cachedSongQueue = songManager.songQueue

        updateAlbumViewWithSong(nil)

        selectFirstRow()

    }

    func updateAlbumViewWithSong(_ song: Song?) {

        // If no song is passed in, just use the first song in the queue.

        guard let song = song ?? cachedSongQueue.first else { return }

        albumView.image = song.albumImage

    }

    func selectFirstRow() {

        let rowToSelect = IndexPath(row: 0, section: 0)

        songTableView.selectRow(at: rowToSelect, animated: false, scrollPosition: .none)

        tableView(songTableView, didSelectRowAt: rowToSelect)

    }

    // MARK: UITableViewDataSource

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

        return cachedSongQueue.count

    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        let cell = tableView.dequeueReusableCell(withIdentifier: SongViewController.textCellIdentifier, for: indexPath)

        let song = cachedSongQueue[indexPath.row]

        cell.textLabel!.text = song.artist

        cell.detailTextLabel!.text = song.title

        return cell

    }

    func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {

        // Create the header based on the intensity. For example "Low Intensity Music".

        return songManager.contextDescription

    }

    // MARK: UITableViewDelegate

    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {

        let song = cachedSongQueue[indexPath.row]

        updateAlbumViewWithSong(song)

    }

    // MARK: SongManagerDelegate

    func didUpdateSongQueue(_ manager: SongManager) {

        let indexSet = IndexSet(integer: 0)

        // Cache the songs to avoid modifications to the data outside the view controller.

        cachedSongQueue = manager.songQueue

        DispatchQueue.main.async {

            self.songTableView.reloadSections(indexSet, with: .fade)

            self.updateAlbumViewWithSong(nil)

            self.selectFirstRow()

        }

    }

    func didEncounterAuthorizationError(_ manager: SongManager) {

        let title = NSLocalizedString("Motion Activity Not Authorized", comment: "")

        let message = NSLocalizedString("To enable Motion features, please allow access to Motion & Fitness in Settings under Privacy.", comment: "")

        let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)

        let cancelAction = UIAlertAction(title: "Cancel", style: .cancel, handler: nil)

        alert.addAction(cancelAction)

        let openSettingsAction = UIAlertAction(title: "Open Settings", style: .default) { _ in

            // Open the Settings app.

            let url = URL(string: UIApplicationOpenSettingsURLString)!

            UIApplication.shared.openURL(url)

        }

        alert.addAction(openSettingsAction)

        DispatchQueue.main.async {

            self.present(alert, animated: true, completion:nil)

        }

    }

}