/*

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

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    This is the View Controller which manages our Shape Views when editing an individual document.

*/

import UIKit

/**

    The `DocumentViewController` handles opening / closing of our shape document

    as well as managing the UISegmentedControl for selecting new shapes.

*/

class DocumentViewController: UIViewController {

    // MARK: - Properties

    var document: ShapeDocument!

    var documentURL: NSURL? {

        didSet {

            guard let url = documentURL else { return }

            document = ShapeDocument(fileURL: url)

            do {

                var displayName: AnyObject?

                try url.getPromisedItemResourceValue(&displayName, forKey: NSURLLocalizedNameKey)

                title = displayName as? String

            }

            catch {

                // Ignore a failure here. We'll just keep the old display name.

            }

        }

    }

    @IBOutlet var shapeView: ShapeView!

    @IBOutlet var shapeSelector: UISegmentedControl!

    @IBOutlet var progressView: UIProgressView!

    var documentObserver: NSObjectProtocol?

    // MARK: - View Controller

    override func viewWillAppear(animated: Bool) {

        super.viewWillAppear(animated)

        shapeSelector.selectedSegmentIndex = UISegmentedControlNoSegment

        shapeSelector.userInteractionEnabled = false

        progressView.hidden = false

        documentObserver = NSNotificationCenter.defaultCenter().addObserverForName(UIDocumentStateChangedNotification, object: document, queue: nil) { _ in

            if self.document.documentState.contains(.ProgressAvailable) {

                self.progressView.observedProgress = self.document.progress

            }

        }

        document.openWithCompletionHandler { success in

            if success {

                self.updateView()

                guard let navigation = self.navigationController else {

                    return

                }

                guard let documentBrowserController = navigation.viewControllers.first as? DocumentBrowserController else {

                    return

                }

                documentBrowserController.documentWasOpenedSuccessfullyAtURL(self.document.fileURL)

            }

            else {

                let title = self.title!

                let alert = UIAlertController(title: "Unable to Load \"\(title)\"", message: "Opening the document failed", preferredStyle: .Alert)

                let alertAction = UIAlertAction(title: "Dismiss", style: .Default) { action in

                    self.navigationController?.popToRootViewControllerAnimated(true)

                }

                alert.addAction(alertAction)

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

            }

            if let observer = self.documentObserver {

                NSNotificationCenter.defaultCenter().removeObserver(observer)

                self.documentObserver = nil

            }

            self.progressView.hidden = true

        }

    }

    override func viewDidDisappear(animated: Bool) {

        super.viewDidDisappear(animated)

        document.closeWithCompletionHandler(nil)

    }

    private var segmentedControllerTintColor: UIColor {

        let originalColor = document.color

        var red:   CGFloat = 0

        var green: CGFloat = 0

        var blue:  CGFloat = 0

        originalColor.getRed(&red, green: &green, blue: &blue, alpha: nil)

        return UIColor(red: red * 0.7, green: green * 0.7, blue: blue * 0.7, alpha: 1)

    }

    @IBAction func shapeChanged(sender: UISegmentedControl?) {

        // The shape was modified using the shapeSelector, so save the selected value.

        let shapeRawValue = shapeSelector.selectedSegmentIndex

        guard let shape = ShapeDocument.Shape(rawValue: shapeRawValue) else { return }

        document.shape = shape

        document.updateChangeCount(.Done)

        shapeSelector.tintColor = segmentedControllerTintColor

        updateView()

    }

    func updateView() {

        // Update the selected segment to be what we loaded from disk.

        if let index = document.shape?.rawValue {

            shapeSelector.selectedSegmentIndex = index

            shapeSelector.userInteractionEnabled = true

        }

        else {

            shapeSelector.selectedSegmentIndex = UISegmentedControlNoSegment

        }

        shapeSelector.tintColor = segmentedControllerTintColor

        shapeView.document = document

    }

}