//

// InternalDisplay.swift

// MonitorControl

//

// Created by Joni Van Roost on 24/01/2020.

// Copyright © 2020 Guillaume Broder. All rights reserved.

//

// Most of the code in this file was sourced from:

// https://github.com/fnesveda/ExternalDisplayBrightness

// all credit goes to @fnesveda

import Foundation

class InternalDisplay: Display {

// the queue for dispatching display operations, so they're not performed directly and concurrently

private var displayQueue: DispatchQueue

override init(_ identifier: CGDirectDisplayID, name: String, vendorNumber: UInt32?, modelNumber: UInt32?) {

self.displayQueue = DispatchQueue(label: String("displayQueue-\(identifier)"))

super.init(identifier, name: name, vendorNumber: vendorNumber, modelNumber: modelNumber)

}

func calcNewBrightness(isUp: Bool, isSmallIncrement: Bool) -> Float {

var step: Float = (isUp ? 1 : -1) / 16.0

let delta = step / 4

if isSmallIncrement {

step = delta

}

return min(max(0, ceil((self.getBrightness() + delta) / step) * step), 1)

}

public func getBrightness() -> Float {

self.displayQueue.sync {

Float(type(of: self).CoreDisplayGetUserBrightness?(self.identifier) ?? 0.5)

}

}

override func stepBrightness(isUp: Bool, isSmallIncrement: Bool) {

let value = self.calcNewBrightness(isUp: isUp, isSmallIncrement: isSmallIncrement)

self.displayQueue.sync {

type(of: self).CoreDisplaySetUserBrightness?(self.identifier, Double(value))

type(of: self).DisplayServicesBrightnessChanged?(self.identifier, Double(value))

self.showOsd(command: .brightness, value: Int(value * 64), maxValue: 64)

}

}

// notifies the system that the brightness of a specified display has changed (to update System Preferences etc.)

// unfortunately Apple doesn't provide a public API for this, so we have to manually extract the function from the DisplayServices framework

private static var DisplayServicesBrightnessChanged: ((CGDirectDisplayID, Double) -> Void)? {

let displayServicesPath = CFURLCreateWithString(kCFAllocatorDefault, "/System/Library/PrivateFrameworks/DisplayServices.framework" as CFString, nil)

if let displayServicesBundle = CFBundleCreate(kCFAllocatorDefault, displayServicesPath) {

if let funcPointer = CFBundleGetFunctionPointerForName(displayServicesBundle, "DisplayServicesBrightnessChanged" as CFString) {

typealias DSBCFunctionType = @convention(c) (UInt32, Double) -> Void

return unsafeBitCast(funcPointer, to: DSBCFunctionType.self)

}

}

return nil

}

// reads the brightness of a display through the CoreDisplay framework

// unfortunately Apple doesn't provide a public API for this, so we have to manually extract the function from the CoreDisplay framework

private static var CoreDisplayGetUserBrightness: ((CGDirectDisplayID) -> Double)? {

let coreDisplayPath = CFURLCreateWithString(kCFAllocatorDefault, "/System/Library/Frameworks/CoreDisplay.framework" as CFString, nil)

if let coreDisplayBundle = CFBundleCreate(kCFAllocatorDefault, coreDisplayPath) {

if let funcPointer = CFBundleGetFunctionPointerForName(coreDisplayBundle, "CoreDisplay_Display_GetUserBrightness" as CFString) {

typealias CDGUBFunctionType = @convention(c) (UInt32) -> Double

return unsafeBitCast(funcPointer, to: CDGUBFunctionType.self)

}

}

return nil

}

// sets the brightness of a display through the CoreDisplay framework

// unfortunately Apple doesn't provide a public API for this, so we have to manually extract the function from the CoreDisplay framework

private static var CoreDisplaySetUserBrightness: ((CGDirectDisplayID, Double) -> Void)? {

let coreDisplayPath = CFURLCreateWithString(kCFAllocatorDefault, "/System/Library/Frameworks/CoreDisplay.framework" as CFString, nil)

if let coreDisplayBundle = CFBundleCreate(kCFAllocatorDefault, coreDisplayPath) {

if let funcPointer = CFBundleGetFunctionPointerForName(coreDisplayBundle, "CoreDisplay_Display_SetUserBrightness" as CFString) {

typealias CDSUBFunctionType = @convention(c) (UInt32, Double) -> Void

return unsafeBitCast(funcPointer, to: CDSUBFunctionType.self)

}

}

return nil

}

}