CGSSpace.swift

// -----------------------------------------------------------------------------
//  CGSSpace.swift by Julian Schiavo
//  Originally from avaidyam/Parrot
//
//  This file is a lightly modified derivative of the original CGSSpace.swift
//  file from the “Parrot” repository by avaidyam, made available under the
//  Mozilla Public License, Version 2.0 (“MPL‑2.0”).
//
//  All modifications herein are governed by MPL‑2.0. You are granted the rights
//  to use, modify, and redistribute this file in accordance with the license’s
//  terms and conditions. Any use of this file, in source or binary form, must
//  reproduce this header and include a copy of the full MPL‑2.0 text.
//
//  Original Source:
//    https://github.com/avaidyam/Parrot/
//      blob/6cf7ba419176c386ed8f18e838690a7272fe57ee/
//      MochaUI/CGSSpace.swift
//  Full License Text:
//    https://github.com/avaidyam/Parrot/
//      blob/6cf7ba419176c386ed8f18e838690a7272fe57ee/LICENSE.md
//
//  When distributing public app releases, you must include a copy of the MPL‑2.0
//  license text and a link to (this) Github Gist in the distributed app.
// -----------------------------------------------------------------------------

import AppKit

final class CGSSpace {
    private let identifier: CGSSpaceID
    
    public var windows: Set<NSWindow> = [] {
        didSet {
            let remove = oldValue.subtracting(windows)
            let add = windows.subtracting(oldValue)
            
            CGSRemoveWindowsFromSpaces(
                _CGSDefaultConnection(),
                remove.map { $0.windowNumber } as NSArray,
                [identifier]
            )
            CGSAddWindowsToSpaces(
                _CGSDefaultConnection(),
                add.map { $0.windowNumber } as NSArray,
                [identifier])
        }
    }
    
    public init(level: Int = 0) {
        let flag = 0x1 // this value MUST be 1, otherwise, Finder decides to draw desktop icons
        self.identifier = CGSSpaceCreate(_CGSDefaultConnection(), flag, nil)
        CGSSpaceSetAbsoluteLevel(_CGSDefaultConnection(), identifier, level)
        CGSShowSpaces(_CGSDefaultConnection(), [identifier])
    }
    
    deinit {
        CGSHideSpaces(_CGSDefaultConnection(), [self.identifier])
        CGSSpaceDestroy(_CGSDefaultConnection(), self.identifier)
    }
}

fileprivate typealias CGSConnectionID = UInt
fileprivate typealias CGSSpaceID = UInt64

@_silgen_name("_CGSDefaultConnection")
fileprivate func _CGSDefaultConnection() -> CGSConnectionID

@_silgen_name("CGSSpaceCreate")
fileprivate func CGSSpaceCreate(_ cid: CGSConnectionID, _ unknown: Int, _ options: NSDictionary?) -> CGSSpaceID

@_silgen_name("CGSSpaceDestroy")
fileprivate func CGSSpaceDestroy(_ cid: CGSConnectionID, _ space: CGSSpaceID)

@_silgen_name("CGSSpaceSetAbsoluteLevel")
fileprivate func CGSSpaceSetAbsoluteLevel(_ cid: CGSConnectionID, _ space: CGSSpaceID, _ level: Int)

@_silgen_name("CGSAddWindowsToSpaces")
fileprivate func CGSAddWindowsToSpaces(_ cid: CGSConnectionID, _ windows: NSArray, _ spaces: NSArray)

@_silgen_name("CGSRemoveWindowsFromSpaces")
fileprivate func CGSRemoveWindowsFromSpaces(_ cid: CGSConnectionID, _ windows: NSArray, _ spaces: NSArray)

@_silgen_name("CGSHideSpaces")
fileprivate func CGSHideSpaces(_ cid: CGSConnectionID, _ spaces: NSArray)

@_silgen_name("CGSShowSpaces")
fileprivate func CGSShowSpaces(_ cid: CGSConnectionID, _ spaces: NSArray)