/*

 Copyright (C) 2017 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 A NSViewController subclass showing how to use IBActions to manipulate a view, and how to use UndoManager.

 */

import Cocoa

class ViewController: NSViewController {

    @IBOutlet weak var dotView: DotView!

    // radiusChanged(_:) is an action method which lets you change the radius of the dot.

    // A possible optimization is to check to see if the old and new value is the same,

    // and not do anything if so.

    @IBAction func radiusChanged(_ sender: NSSlider) {

        updateRadius(CGFloat(sender.doubleValue))

    }

    // Having a method which takes the updated radius value as a parameter means that undo can just call this same method

    // with the previous value. This also makes redo work without any extra code.

    private func updateRadius(_ radius: CGFloat) {

        if let undoManager = undoManager {

            undoManager.registerUndo(withTarget: self, handler: { [previousRadius = dotView.radius] (_) -> Void in

                self.updateRadius(previousRadius)

            })

            undoManager.setActionName("Change Radius")

        }

        dotView.radius = radius

    }

    // colorChanged(_:) is an action method which lets you change the color of the dot.

    // A possible optimization is to check to see if the old and new value is the same,

    // and not do anything if so.

    @IBAction func colorChanged(_ sender: NSColorWell) {

        updateColor(sender.color)

    }

    private func updateColor(_ color: NSColor) {

        if let undoManager = undoManager {

            undoManager.registerUndo(withTarget: self, handler: { [previousColor = dotView.color] (_) -> Void in

                self.updateColor(previousColor)

            })

            undoManager.setActionName("Change Color")

        }

        dotView.color = color

    }

    // The recommended way to handle events is to override NSResponder (superclass

    // of NSView) methods in the NSView subclass. One such method is mouseUp(with:).

    // These methods get the event as the argument. The event has the mouse

    // location in window coordinates; use convert(_:from:) (with "nil"

    // as the view argument) to convert this point to view coordinates local

    // to dotView.

    //

    // Note that once we set the new center, needsDisplay is set to true in the center

    // property's didSet observer to mark that the view needs to be redisplayed (which

    // is done automatically by AppKit).

    override func mouseUp(with event: NSEvent) {

        let convertedCenter = dotView.convert(event.locationInWindow, from: nil)

        updateCenter(convertedCenter)

    }

    private func updateCenter(_ center: NSPoint) {

        // Since the previous center was already converted from the window coordinates

        // before setting it as the dotView's center, there is no need to convert

        // previousCenter from window coordinates.

        if let undoManager = undoManager {

            undoManager.registerUndo(withTarget: self, handler: { [previousCenter = dotView.center, unowned self] (_) -> Void in

                self.updateCenter(previousCenter)

            })

            undoManager.setActionName("Change Center")

        }

        dotView.center = center

    }

}