//
//  ViewController.swift
//  CCCB Display
//
//  Created by Dirk Engling on 26.05.23.
//

import UIKit
import AVFoundation
import CoreImage
import Network

class ViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate, ObservableObject, AVCaptureVideoDataOutputSampleBufferDelegate {

    @IBOutlet weak var frameRateLabel: UILabel!
    @IBOutlet weak var cameraView: UIView!

    var device: AVCaptureDevice?
    var input: AVCaptureDeviceInput?
    var prevLayer: AVCaptureVideoPreviewLayer?

    private let captureSession = AVCaptureSession()
    private let videoDataOutput = AVCaptureVideoDataOutput()
    private let sessionQueue = DispatchQueue(label: "sessionQueue")
    private let context = CIContext()

//    var hostUDP: NWEndpoint.Host = "172.23.42.29"
    var hostUDP: NWEndpoint.Host?
    var portUDP: NWEndpoint.Port = 2342
    var connectionUDP: NWConnection?

    var lastTimeStamp: CFTimeInterval = CACurrentMediaTime()

    /* Physical Display control packet parameters: */
    private let HEADERLEN = 10
    private let WIDTH     = 448
    private let HEIGHT    = 160
    private let VHEIGHT   = 236

    override func viewDidLoad() {
        super.viewDidLoad()

        UserDefaults.standard.addObserver(self, forKeyPath: "Display_Address", options: .new, context: nil)
        constructSocket()

        switch AVCaptureDevice.authorizationStatus(for: .video) {
        case .authorized: // the user has already authorized to access the camera.
            DispatchQueue.main.async {
                self.createSession()
            }
        case .notDetermined:
            AVCaptureDevice.requestAccess (for: .video) { (granted) in
                if granted {
                    print("the user has granted to access the camera")
                    DispatchQueue.main.async {
                        self.createSession ()
                    }
                } else {
                    print("the user has not granted to access the camera")
                    let dialogMessage = UIAlertController(title: "Attention", message: "Can not work without camera access", preferredStyle: .alert)
                    self.present(dialogMessage, animated: true, completion: nil)
                }
            }
        case .denied:
            print("the user has denied previously to access the camera.")
            let dialogMessage = UIAlertController(title: "Attention", message: "Can not work without camera access", preferredStyle: .alert)
            self.present(dialogMessage, animated: true, completion: nil)

        case .restricted:
            print("the user can't give camera access due to some restriction.")
            let dialogMessage = UIAlertController(title: "Attention", message: "Can not work without camera access", preferredStyle: .alert)
            self.present(dialogMessage, animated: true, completion: nil)

        default:
            print("something has wrong due to we can't access the camera.")
            let dialogMessage = UIAlertController(title: "Attention", message: "Can not work without camera access", preferredStyle: .alert)
            self.present(dialogMessage, animated: true, completion: nil)
          }
    }

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        prevLayer?.frame.size = cameraView.frame.size
    }

    func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {

        let now = CACurrentMediaTime()
        let freq = (Int)(1 / (now - lastTimeStamp))
//        print ("Elapsed: \(now - lastTimeStamp) - Frequency: \(1 / (now - lastTimeStamp))")
        lastTimeStamp = now

        guard let pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else { return }

        CVPixelBufferLockBaseAddress(pixelBuffer, .readOnly)
        let bufferWidth = CVPixelBufferGetWidth(pixelBuffer)
        let bufferHeight = CVPixelBufferGetHeight(pixelBuffer)
        let bytesPerRow = CVPixelBufferGetBytesPerRow(pixelBuffer)
        let kBytesPerPixel = 4

        print("\(bufferWidth) \(bufferHeight) \(bytesPerRow)")
        guard let baseAddress = CVPixelBufferGetBaseAddress(pixelBuffer) else { return }

        var packet: [UInt8] = [0, 0x12, 0, 0, 0x23, 0, 0, 0, 0, 0]
        var scratch: [Int] = Array(repeating: 0, count: WIDTH*(2+VHEIGHT))

        let t1 = CACurrentMediaTime()

        // 160 real rows are interleaved with 19 gaps of 4 pixels height on the display
        // so we create 20 virtual blocks of 8 real and 4 virtual pixels
        // we overlay VHEIGHT==236 virtual rows on the image and later skip the 4 invisble rows
        var off = 0
        for row in 0..<VHEIGHT {
            let zeile = (Int)(((Double)(row) / (Double)(VHEIGHT)) * (Double)(bufferHeight)) * bytesPerRow
            for column in 0..<WIDTH {
                let pixel = kBytesPerPixel * (Int)(((Double)(column) / (Double)(WIDTH)) * (Double)(bufferWidth))

                let red   = (Int)(baseAddress.load(fromByteOffset: zeile + pixel + 0, as: UInt8.self)) * 19535
                let green = (Int)(baseAddress.load(fromByteOffset: zeile + pixel + 1, as: UInt8.self)) * 38470
                let blue  = (Int)(baseAddress.load(fromByteOffset: zeile + pixel + 2, as: UInt8.self)) * 7448
                //scratch[row * WIDTH + column] = red + blue + green
                scratch[off] = red + blue + green
                off += 1
            }
        }

        var acc = 0
        var accv = 0

        for row in 0..<VHEIGHT {
            for column in 0..<WIDTH {
                let pixel = scratch[row * WIDTH + column]
                let bwpixel = (pixel < 0x810000) ? 0 : 0xffffff

                // account for gaps on display (virtual lines 9-12)
                if (row % 12) < 8 {
                    acc = (acc << 1) + (bwpixel >> 23)
                    accv += 1
                    if accv == 8 {
                        packet.append((UInt8)(acc))
                        acc =  0
                        accv = 0
                    }
                }

                let err = (pixel - bwpixel) / 42

                func AddSatShift(_ scr: inout Array<Int>, _ X: Int, _ Y: Int, _ SHIFT: Int) {
                    let inner_p = (row + Y) * WIDTH + column + X
                    var r = scr[inner_p] + (err << (16 - SHIFT))
                    if r < 0 {
                        r = 0
                    }
                    if r > 0xffffff {
                        r = 0xffffff
                    }
                    scr[inner_p] = r
                }

                AddSatShift(&scratch, 0, 1, 13)
                AddSatShift(&scratch, 0, 2, 14)
                if (column > 0) {
                    AddSatShift(&scratch, -1, 1, 14)
                    AddSatShift(&scratch, -1, 2, 15)
                }

                if (column > 1) {
                    AddSatShift(&scratch, -2, 1, 15)
                    AddSatShift(&scratch, -2, 2, 16)
                }

                if (column < WIDTH - 1) {
                    AddSatShift(&scratch,  1, 0, 13)
                    AddSatShift(&scratch,  1, 1, 14)
                    AddSatShift(&scratch,  1, 2, 15)
                }

                if (column < WIDTH - 2) {
                    AddSatShift(&scratch,  2, 0, 14)
                    AddSatShift(&scratch,  2, 1, 15)
                    AddSatShift(&scratch,  2, 2, 16)
                }

            }
        }

        let t2 = CACurrentMediaTime()

//        print("dur \(t2 - t1)")
        DispatchQueue.main.async {
            self.frameRateLabel.text = String(format: "%.04f (%d Hz)", t2 - t1, freq)
        }

        self.connectionUDP?.send(content: packet, completion: NWConnection.SendCompletion.contentProcessed(({ (NWError) in
            if (NWError == nil) {
                print("Data was sent to UDP")
            } else {
                print("ERROR! Error when data (Type: Data) sending. NWError: \n \(NWError!)")
                self.constructSocket()
            }
        })))
    }

    func createSession() {
        guard let device = AVCaptureDevice.default(for: AVMediaType.video) else { return }
        do {
            input = try AVCaptureDeviceInput(device: device)
        }
        catch {
            print(error)
        }

        captureSession.sessionPreset = AVCaptureSession.Preset.vga640x480
        if let input = input {
            captureSession.addInput(input)
        }

        prevLayer = AVCaptureVideoPreviewLayer(session: captureSession)
        prevLayer?.frame.size = cameraView.frame.size
        prevLayer?.videoGravity = AVLayerVideoGravity.resizeAspectFill

        cameraView.layer.addSublayer(prevLayer!)
        captureSession.addOutput(videoDataOutput)
        captureSession.commitConfiguration()

        videoDataOutput.videoSettings.updateValue(kCVPixelFormatType_32BGRA, forKey: "PixelFormatType")
        videoDataOutput.setSampleBufferDelegate(self, queue: self.sessionQueue)

        do {
            try device.lockForConfiguration()
            device.activeVideoMaxFrameDuration = CMTimeMake(value: 1, timescale: 60)
            device.activeVideoMinFrameDuration = CMTimeMake(value: 1, timescale: 60)
            device.unlockForConfiguration()
        } catch {
            print(error)
        }

        let captureConnection = videoDataOutput.connection(with: .video)
        captureConnection?.isEnabled = true
        deviceOrientationDidChange(Notification(name: UIDevice.orientationDidChangeNotification))
        // captureConnection?.videoOrientation = .landscapeRight

        sessionQueue.async { self.captureSession.startRunning() }
    }

    func cameraWithPosition(position: AVCaptureDevice.Position) -> AVCaptureDevice? {
        if #available(iOS 11.1, *) {
        let deviceDiscoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInDualCamera, .builtInTelephotoCamera, .builtInTrueDepthCamera, .builtInWideAngleCamera, ], mediaType: .video, position: position)

        if let device = deviceDiscoverySession.devices.first {
            return device
        }
            else {
                //add code here
            }
        return nil
        }

        return device
    }

    func transformOrientation(orientation: UIInterfaceOrientation) -> AVCaptureVideoOrientation {
        switch orientation {
        case .landscapeLeft:
            return .landscapeLeft
        case .landscapeRight:
            return .landscapeRight
        case .portraitUpsideDown:
            return .portraitUpsideDown
        default:
            return .portrait
        }
    }

    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        if keyPath == "Display_Address" {
            constructSocket()
        }
    }

    func constructSocket() {
        let defaults = UserDefaults.standard
        if let ip = defaults.string(forKey: "Display_Address") {
            hostUDP = NWEndpoint.Host(ip)
        } else {
            hostUDP = NWEndpoint.Host("172.23.42.29")
            // hostUDP = NWEndpoint.Host("84.200.61.9")
            // hostUDP = NWEndpoint.Host("192.168.178.69")
        }
//        hostUDP = NWEndpoint.Host("192.168.178.69")

        self.connectionUDP = NWConnection(host: hostUDP!, port: portUDP, using: .udp)
        self.connectionUDP?.start(queue: .global())
    }

    @IBAction func switchCameraSide(sender: AnyObject) {
        let currentCameraInput: AVCaptureInput = captureSession.inputs[0]
        captureSession.removeInput(currentCameraInput)
        var newCamera: AVCaptureDevice
        if (currentCameraInput as! AVCaptureDeviceInput).device.position == .back {
            newCamera = self.cameraWithPosition(position: .front)!
        } else {
            newCamera = self.cameraWithPosition(position: .back)!
        }

        var newVideoInput: AVCaptureDeviceInput?
        do{
            newVideoInput = try AVCaptureDeviceInput(device: newCamera)
        }
        catch{
            print(error)
        }

        if let newVideoInput = newVideoInput{
            captureSession.addInput(newVideoInput)
            deviceOrientationDidChange(Notification(name: UIDevice.orientationDidChangeNotification))
        }
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)

        NotificationCenter.default.addObserver(self, selector: #selector(deviceOrientationDidChange),
                                               name: UIDevice.orientationDidChangeNotification, object: nil)
        deviceOrientationDidChange(Notification(name: UIDevice.orientationDidChangeNotification))

        sessionQueue.async { self.captureSession.startRunning() }
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)

        sessionQueue.async { self.captureSession.stopRunning() }
        NotificationCenter.default.removeObserver(self)
    }

    @objc func deviceOrientationDidChange(_ notification: Notification) {
        let orientation = UIDevice.current.orientation
        let captureConnection = videoDataOutput.connection(with: .video)

        if orientation == .landscapeLeft {
            self.prevLayer?.connection?.videoOrientation = .landscapeRight
            captureConnection?.videoOrientation = .landscapeRight
        } else {
            self.prevLayer?.connection?.videoOrientation = .landscapeLeft
            captureConnection?.videoOrientation = .landscapeLeft
        }
    }
}