/*

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

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    Defines the view controller for the progress scene.

*/

import UIKit

class ProgressViewController: UIViewController {

    // MARK: Properties

    var sourceURL: NSURL?

    var outputURL: NSURL?

    lazy var operationQueue: NSOperationQueue = {

        let operationQueue = NSOperationQueue()

        operationQueue.name = "com.example.apple-samplecode.progressviewcontroller.operationQueue"

        return operationQueue

    }()

    weak var cyanifier: CyanifyOperation?

    static let finishingSegueName = "finishing"

    static let cancelSegueName = "cancel"

    // MARK: IBActions

    @IBAction func cancel() {

        cyanifier?.cancel()

    }

    // MARK: View Controller

    override func viewDidAppear(animated: Bool) {

        super.viewDidAppear(animated)

        guard let outputURL = outputURL, sourceURL = sourceURL else {

            fatalError("`outputURL` and `sourceURL` should not be nil when \(#function) is called.")

        }

        // Create video processing operation and add it to our operation queue.

        let cyanifier = CyanifyOperation(sourceURL: sourceURL, outputURL: outputURL)

        cyanifier.completionBlock = { [weak cyanifier] in

            /*

                Operation must still be alive when it invokes its completion handler.

                It also must have set a non-nil result by the time it finishes.

            */

            let result = cyanifier!.result!

            dispatch_async(dispatch_get_main_queue()) {

                self.cyanificationDidFinish(result)

            }

        }

        operationQueue.addOperation(cyanifier)

        self.cyanifier = cyanifier

    }

    private func cyanificationDidFinish(result: CyanifyOperation.Result) {

        switch result {

            case .Success:

                performSegueWithIdentifier(ProgressViewController.finishingSegueName, sender: self)

            case .Failure(let error):

                presentError(error as NSError)

            case .Cancellation:

                performSegueWithIdentifier(ProgressViewController.cancelSegueName, sender: self)

        }

    }

    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {

        if segue.identifier == ProgressViewController.finishingSegueName {

            let nextViewController = segue.destinationViewController as! ResultViewController

            nextViewController.outputURL = outputURL

        }

    }

    /// Present an `NSError` to the user.

    func presentError(error: NSError) {

        let failureTitle = error.localizedDescription

        let failureMessage = error.localizedRecoverySuggestion ?? error.localizedFailureReason

        let alertController = UIAlertController(title: failureTitle, message: failureMessage, preferredStyle: .Alert)

        let alertAction = UIAlertAction(title: "OK", style: .Default) { _ in

            self.performSegueWithIdentifier("error", sender: self)

        }

        alertController.addAction(alertAction)

        presentViewController(alertController, animated: true, completion: nil)

    }

}