Jerboa.swift

//
//  main.swift
//  Jerboa
//
//  Created by Emil Johansen on 19/01/2019.
//  Copyright © 2019 AngryAnt. All rights reserved.
//
//  https://en.wikipedia.org/wiki/Jerboa
//

import Foundation


class Jerboa
{
	static let supportedDisplayCount: UInt32 = 64;
	private static let displayKey = "DisplayID";
	private static let userDefaults = UserDefaults.standard;

	private static var workingDisplays = [CGDirectDisplayID] (repeating: 0, count: Int (supportedDisplayCount));
	private static var current: CGDirectDisplayID = 0;
	private static var displayCount = 0;


	private class func readDisplays ()
	{
		current = CGDirectDisplayID (userDefaults.integer (forKey: displayKey));

		var result: UInt32 = 0;
		CGGetActiveDisplayList (Jerboa.supportedDisplayCount, &Jerboa.workingDisplays, &result);
		displayCount = Int (result);
	}


	private class func jumpBy (delta: Int)
	{
		readDisplays ();
		var currentIndex = Jerboa.workingDisplays.firstIndex (of: current) ?? 0;

		currentIndex += delta;
		if (currentIndex < 0)
		{
			currentIndex = displayCount - 1;
		}
		else if (currentIndex >= displayCount)
		{
			currentIndex = 0;
		}

		jumpTo (targetIndex: currentIndex);
	}


	private class func jumpTo (targetIndex : Int)
	{
		current = Jerboa.workingDisplays[targetIndex];

		CGDisplayMoveCursorToPoint (
			current,
			CGPoint.init (x: CGDisplayPixelsWide (current) / 2,
						  y: CGDisplayPixelsHigh (current) / 2)
		);
		CGDisplayShowCursor (current);
		CGDisplayShowCursor (current);
		CGDisplayShowCursor (current);

		userDefaults.set (current, forKey: displayKey);
	}


	class func startup ()
	{
		userDefaults.synchronize ();
		userDefaults.integer (forKey: displayKey);
	}


	class func teardown ()
	{
		userDefaults.synchronize ();
	}


	class func forward ()
	{
		jumpBy (delta: 1);
	}


	class func backward ()
	{
		jumpBy (delta: -1);
	}


	class func first ()
	{
		readDisplays ();
		jumpTo (targetIndex: 0);
	}


	class func last ()
	{
		readDisplays ();
		jumpTo (targetIndex: displayCount - 1);
	}
}


Jerboa.startup ();

for argument in CommandLine.arguments
{
	switch (argument)
	{
		case "forward":
			Jerboa.forward ();
		break;
		case "backward":
			Jerboa.backward ();
		break;
		case "first":
			Jerboa.first ();
		break;
		case "last":
			Jerboa.last ();
		break;
		default:
			Jerboa.forward ();
		break;
	}
}

Jerboa.teardown ();