//
//  CameraView.swift
//  im-client-ios
//
//  Created by 北京居家科技有限公司 on 2022/3/10.
//

import SwiftUI
import AVFoundation

let cameraPreview = CameraPreview()
 
fileprivate var captureSession = AVCaptureSession()
 
fileprivate var videoDataOutput = AVCaptureVideoDataOutput()


struct CameraPreviewHolder: ContentView{
    
    typealias NSViewType = CameraPreview
 
    func makeNSView(context: NSViewRepresentableContext<CameraPreviewHolder>) -> CameraPreview {
 
        let cameraPreview = CameraPreview()
        return cameraPreview
    }
    
    func updateNSView(_ nsView: CameraPreview, context: NSViewRepresentableContext<CameraPreviewHolder>) {
    }
}
final class CameraPreview: NSView {
 
    private var tmp:URL?
    
    init() {
        super.init(frame: .zero)
        
        var allowedAccess = false
        let blocker = DispatchGroup()
        blocker.enter()
        
        AVCaptureDevice.requestAccess(for: .video) { flag in
            allowedAccess = flag
            blocker.leave()
        }
        blocker.wait()
 
        guard allowedAccess else {
            print("No camera access")
            return
        }
        
        showCameraViewSeting()
    }
    
    func showCameraViewSeting() {
 
        let session = captureSession
        
        session.beginConfiguration()
 
        //分辨率
        session.sessionPreset = AVCaptureSession.Preset.high
 
        guard let videoDevice = AVCaptureDevice.default(for: .video) else {
            print("No video device")
            return
        }
 
        guard let videoDeviceInput = try? AVCaptureDeviceInput(device: videoDevice),
            session.canAddInput(videoDeviceInput)
            else {
            print("Unable to determine video device input")
            return
        }
 
        session.addInput(videoDeviceInput)
 
        let videoOutput = videoDataOutput
        videoOutput.alwaysDiscardsLateVideoFrames = true
 
        if session.canAddOutput(videoOutput) {
            session.addOutput(videoOutput)
        }
 
        session.commitConfiguration()
        captureSession = session
        
        self.wantsLayer = true
        
        self.layer = AVCaptureVideoPreviewLayer()
    }
 
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    var videoPreviewLayer: AVCaptureVideoPreviewLayer {
        return self.layer as! AVCaptureVideoPreviewLayer
    }
 
    override func viewDidMoveToSuperview() { // on iOS .didMoveToSuperview
        super.viewDidMoveToSuperview()
 
        if nil != self.superview {
            self.videoPreviewLayer.session = captureSession
            self.videoPreviewLayer.videoGravity = .resizeAspect
            captureSession.startRunning()
        } else {
            captureSession.stopRunning()
        }
    }
    
    func scan(){
        videoDataOutput.setSampleBufferDelegate(cameraCaptureDelegate, queue: DispatchQueue.main)
    }
 
    func removeCameraPreview() {
        self.removeFromSuperview()
    }
}
 
class CameraCaptureDelegate: NSObject, AVCaptureVideoDataOutputSampleBufferDelegate{
    
    func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
 
        let cgImage:CGImage = imageFromSampleBuffer(sampleBuffer: sampleBuffer)
        print("\(cgImage)")
        
        //获取的图片经过EFQRCode（GitHub上搜这个库）识别，如果含有二维码，即可识别出二维码数据
//        let result = EFQRCode.recognize(image: cgImage)
//        print("didOutput : \(String(describing: result))")
 
    }
 
    func captureOutput(_ output: AVCaptureOutput, didDrop sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
        print("didDrop sampleBuffer")
    }
}
 
func imageFromSampleBuffer(sampleBuffer: CMSampleBuffer) -> CGImage {
 
    let imageBuffer: CVPixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)!
    let ciImage : CIImage = CIImage(cvPixelBuffer: imageBuffer)
    let context:CIContext = CIContext.init(options: nil)
    let cgImage:CGImage = context.createCGImage(ciImage, from: ciImage.extent)!
 
    return cgImage
}