/*

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

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    This file contains the ConfigurationListController class, which is responsible for controlling a list of VPN configurations.

*/

import UIKit

import NetworkExtension

import SimpleTunnelServices

/// The view controller object for the list of packet tunnel configurations.

class ConfigurationListController: ListViewController {

    // MARK: Properties

    /// The image to display for configurations that are disabled.

    let disabledImage = UIImage(named: "GrayDot")

    /// The image to display for configurations that are enabled but are disconnected.

    let disconnectedImage = UIImage(named: "RedDot")

    /// The image to display for configurations that are active (or not disconnected).

    let notDisconnectedImage = UIImage(named: "GreenDot")

    /// A list of NEVPNManager objects for the packet tunnel configurations.

    var managers = [NEVPNManager]()

    // MARK: UIViewController

    /// Handle the event of the view loading into memory.

    override func viewDidLoad() {

        isAddEnabled = true

        super.viewDidLoad()

    }

    /// Handle the event of the view being displayed.

    override func viewWillAppear(_ animated: Bool) {

        super.viewWillAppear(animated)

        // Re-load all of the configurations.

        reloadManagers()

    }

    // MARK: Interface

    /// Re-load all of the packet tunnel configurations from the Network Extension preferences

    func reloadManagers() {

        NETunnelProviderManager.loadAllFromPreferences() { newManagers, error in

            guard let vpnManagers = newManagers else { return }

            self.stopObservingStatus()

            self.managers = vpnManagers

            self.observeStatus()

            // If there are no configurations, automatically go into editing mode.

            if self.managers.count == 0 && !self.isEditing {

                self.setEditing(true, animated: false)

            }

            self.tableView.reloadData()

        }

    }

    /// Register for configuration change notifications.

    func observeStatus() {

        for (index, manager) in managers.enumerated() {

            NotificationCenter.default.addObserver(forName: NSNotification.Name.NEVPNStatusDidChange, object: manager.connection, queue: OperationQueue.main, using: { notification in

                self.tableView.reloadRows(at: [ IndexPath(row: index, section: 0) ], with: .fade)

            })

        }

    }

    /// De-register for configuration change notifications.

    func stopObservingStatus() {

        for manager in managers {

            NotificationCenter.default.removeObserver(self, name: NSNotification.Name.NEVPNStatusDidChange, object: manager.connection)

        }

    }

    /// Unwind segue handler.

    @IBAction func handleUnwind(_ sender: UIStoryboardSegue) {

    }

    // MARK: ListViewController

    /// Set up the destination view controller of a segue away from this view controller.

    override func listSetupSegue(_ segue: UIStoryboardSegue, forItemAtIndex index: Int) {

        guard let identifier = segue.identifier else { return }

        switch identifier {

            case "start-new-configuration":

                // The user tapped on the "Add Configuration..." table row.

                guard let addEditController = segue.destination as? AddEditConfiguration else { break }

                addEditController.setTargetManager(nil, title: "Add Configuration")

            case "edit-configuration":

                // The user tapped on the disclosure button of a configuration while in editing mode.

                guard let addEditController = segue.destination as? AddEditConfiguration , index < managers.count else { break }

                addEditController.setTargetManager(managers[index], title: managers[index].localizedDescription)

            case "introspect-status":

                // The user tapped on a configuration while not in editing mode.

                guard let statusViewController = segue.destination as? StatusViewController , index < managers.count else { break }

                statusViewController.targetManager = managers[index]

            default:

                break

        }

    }

    /// The current number of configurations.

    override var listCount: Int {

        return managers.count

    }

    /// Returns the localized description of the configuration at the given index.

    override func listTextForItemAtIndex(_ index: Int) -> String {

        return managers[index].localizedDescription ?? "NoName"

    }

    /// Returns the appropriate image for the configuration at the given index.

    override func listImageForItemAtIndex(_ index: Int) -> UIImage? {

        let manager = managers[index]

        guard manager.isEnabled else { return disabledImage }

        switch manager.connection.status {

            case .invalid: fallthrough

            case .disconnected: return disconnectedImage

            default: return notDisconnectedImage

        }

    }

    /// Returns UITableViewCellAccessoryType.DisclosureIndicator.

    override var listAccessoryType: UITableViewCellAccessoryType {

        return .disclosureIndicator

    }

    /// Returns UITableViewCellAccessoryType.DetailButton.

    override var listEditingAccessoryType: UITableViewCellAccessoryType {

        return .detailButton

    }

    /// Handle a user tap on the "Delete" button for a configuration.

    override func listRemoveItemAtIndex(_ index: Int) {

        // Remove the configuration from the Network Extension preferences.

        managers[index].removeFromPreferences {

            error in

            if let error = error {

                simpleTunnelLog("Failed to remove manager: \(error)")

            }

        }

        managers.remove(at: index)

    }

}