Wrapper for running Arbtt on macOS Catalina 10.15

ArbttWrapper.swift

////
////  ArbttWrapper
///
//// Starting with macOS Catalina, `arbtt-capture` was not able to read the window titles:
//// https://github.com/nomeata/arbtt/issues/30
///
//// I'm not a Swift programmer and I didn't want to spend too many hours on this, therefore there
//// are a few obvious improvements. The most crucial ones, the ones that are likely to hurt any
//// user who uses this script as is, are:
////        - System signals (e.g. SIGINT) are not handled. You may stop the script, the arbtt process
////        will keep running unless you kill it manually.
////        - User experience isn't polished, as you'll notice below.
///
//// Usage:
////        1. Run this script once with ARBTT_COMMAND set to `arbtt-capture -d`.
////        2. Make sure the prompt for required permissions appear and grant these permissions.
////        3. Change ARBTT_COMMAND to `arbtt-capture <options>`.
////        4. Rerun the script.
////
////  Created by Ozan Ogreden on 10/03/2020.

import Cocoa
import Foundation

import AVFoundation
import CoreGraphics

let ARBTT_COMMAND = "~/.cabal/bin/arbtt-capture -r 10"

func getPermission() -> Bool {
    // Thanks to `brianmario` of StackOverflow.
    // https://stackoverflow.com/q/49413972
    let mainDisplay    = CGMainDisplayID()
    let recordingQueue = DispatchQueue.global(qos: .background)

    let displayStreamProps : [CFString : Any] = [
      CGDisplayStream.minimumFrameTime:    60,
    ]

    let displayStream = CGDisplayStream(
      dispatchQueueDisplay: mainDisplay,
      outputWidth:          1,
      outputHeight:         1,
      pixelFormat:          Int32(kCVPixelFormatType_32BGRA),
      properties:           displayStreamProps as CFDictionary,
      queue:                recordingQueue,

      handler: { status, displayTime, frameSurface, updateRef in
        print("is only called once")
      }
    )

    var hasPermission : Bool
    if displayStream != nil {
        hasPermission = true
        displayStream?.stop()
    } else {
        hasPermission = false
        displayStream?.stop()
    }
    
    return hasPermission
}

func shell(command: String) -> String {
    // Thanks to anonymous user of StackOverflow.
    // https://stackoverflow.com/a/50035059
    let task = Process()
    task.launchPath = "/bin/bash"
    task.arguments = ["-c", command]

    let pipe = Pipe()
    task.standardOutput = pipe
    task.launch()

    let data = pipe.fileHandleForReading.readDataToEndOfFile()
    let output: String = NSString(data: data, encoding: String.Encoding.utf8.rawValue)! as String
    
    return output
}

func runTracker() {
    print(shell(command: ARBTT_COMMAND))
}

let hasPermission = getPermission()
if hasPermission {
    runTracker()
} else {
    print("Screen Recording permissions not granted.")
}