Caps-iOS/Caps/Camera/CameraManager.swift

import Foundation
import AVFoundation

class CameraManager: ObservableObject {
    enum Status {
        case unconfigured
        case configured
        case unauthorized
        case failed
    }

    static let shared = CameraManager()

    @Published var error: CameraError?

    let session = AVCaptureSession()

    private let sessionQueue = DispatchQueue(label: "de.christophhagen.cam")
    private let videoOutput = AVCaptureVideoDataOutput()
    private let photoOutput = AVCapturePhotoOutput()
    private var status = Status.unconfigured

    private init() {
        configure()
    }

    private func set(error: CameraError?) {
        DispatchQueue.main.async {
            self.error = error
        }
    }

    private func checkPermissions() {
        switch AVCaptureDevice.authorizationStatus(for: .video) {
        case .notDetermined:
            sessionQueue.suspend()
            AVCaptureDevice.requestAccess(for: .video) { authorized in
                if !authorized {
                    self.status = .unauthorized
                    self.set(error: .deniedAuthorization)
                }
                self.sessionQueue.resume()
            }
        case .restricted:
            status = .unauthorized
            set(error: .restrictedAuthorization)
        case .denied:
            status = .unauthorized
            set(error: .deniedAuthorization)
        case .authorized:
            break
        @unknown default:
            status = .unauthorized
            set(error: .unknownAuthorization)
        }
    }

    private func configureCaptureSession() {
        guard status == .unconfigured else {
            return
        }

        session.beginConfiguration()
        session.sessionPreset = .photo

        defer {
            session.commitConfiguration()
        }

        let device = AVCaptureDevice.default(
            .builtInWideAngleCamera,
            for: .video,
            position: .back)
        guard let camera = device else {
            set(error: .cameraUnavailable)
            status = .failed
            return
        }

        let cameraInput: AVCaptureDeviceInput
        do {
            cameraInput = try AVCaptureDeviceInput(device: camera)
        } catch {
            set(error: .createCaptureInput(error))
            status = .failed
            return
        }
        guard session.canAddInput(cameraInput) else {
            set(error: .cannotAddInput)
            status = .failed
            return
        }
        session.addInput(cameraInput)


        if session.canAddOutput(videoOutput) {
            session.addOutput(videoOutput)

            videoOutput.videoSettings =
            [kCVPixelBufferPixelFormatTypeKey as String: kCVPixelFormatType_32BGRA]

            let videoConnection = videoOutput.connection(with: .video)
            videoConnection?.videoOrientation = .portrait
        } else {
            set(error: .cannotAddOutput)
            status = .failed
            return
        }

        guard session.canAddOutput(photoOutput) else {
            set(error: .cannotAddOutput)
            status = .failed
            return
        }
        session.addOutput(photoOutput)
        photoOutput.isHighResolutionCaptureEnabled = true
        photoOutput.isDepthDataDeliveryEnabled = false
        photoOutput.isLivePhotoCaptureEnabled = false

        status = .configured
    }

    private func configure() {
        checkPermissions()

        sessionQueue.async {
            self.configureCaptureSession()
            self.session.startRunning()
        }
    }

    func setVideoDelegate(_ delegate: AVCaptureVideoDataOutputSampleBufferDelegate,
             queue: DispatchQueue) {
        sessionQueue.async {
            self.videoOutput.setSampleBufferDelegate(delegate, queue: queue)
        }
    }

    func stopVideoCaptureSession() {
        sessionQueue.async {
            guard self.status == .configured else {
                return
            }
            guard self.session.isRunning else {
                return
            }
            self.session.stopRunning()
        }
    }

    func startVideoCapture() {
        guard status == .configured else {
            return
        }
        sessionQueue.async {
            guard !self.session.isRunning else {
                return
            }
            self.session.startRunning()
        }
    }

    // MARK: Photo Capture

    func capturePhoto(delegate: AVCapturePhotoCaptureDelegate) {
        sessionQueue.async {
            let photoSettings = AVCapturePhotoSettings()
            photoSettings.flashMode = .off
            self.photoOutput.capturePhoto(with: photoSettings, delegate: delegate)
        }
    }
}