//
//  ScanViewController.swift
//  BlockEQ
//
//  Created by Satraj Bambra on 2018-03-11.
//  Copyright © 2018 Satraj Bambra. All rights reserved.
//

import AVFoundation
import UIKit

protocol ScanViewControllerDelegate: class {
    func setQR(value: String)
}

class ScanViewController: UIViewController {
    var captureSession = AVCaptureSession()
    var videoPreviewLayer: AVCaptureVideoPreviewLayer?
    var qrCodeFrameView: UIView?
    
    weak var delegate: ScanViewControllerDelegate?
    
    private let supportedCodeTypes = [AVMetadataObject.ObjectType.upce,
                                      AVMetadataObject.ObjectType.code39,
                                      AVMetadataObject.ObjectType.code39Mod43,
                                      AVMetadataObject.ObjectType.code93,
                                      AVMetadataObject.ObjectType.code128,
                                      AVMetadataObject.ObjectType.ean8,
                                      AVMetadataObject.ObjectType.ean13,
                                      AVMetadataObject.ObjectType.aztec,
                                      AVMetadataObject.ObjectType.pdf417,
                                      AVMetadataObject.ObjectType.itf14,
                                      AVMetadataObject.ObjectType.dataMatrix,
                                      AVMetadataObject.ObjectType.interleaved2of5,
                                      AVMetadataObject.ObjectType.qr]
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
    
    init() {
        super.init(nibName: String(describing: ScanViewController.self), bundle: nil)
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        
        setupView()
        setupCamera()
    }
    
    func setupView() {
        navigationItem.title = "Scanning..."
        
        let image = UIImage(named:"close")
        let leftBarButtonItem = UIBarButtonItem(image: image, style: .plain, target: self, action: #selector(self.dismissView))
        navigationItem.leftBarButtonItem = leftBarButtonItem
        
        view.backgroundColor = Colors.primaryDark
    }
    
    @objc func dismissView() {
        captureSession.stopRunning()
        videoPreviewLayer?.removeFromSuperlayer()
        
        dismiss(animated: true, completion: nil)
    }
    
    func setupCamera() {
        let deviceDiscoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInDualCamera, .builtInWideAngleCamera], mediaType: AVMediaType.video, position: .back)
        
        guard let captureDevice = deviceDiscoverySession.devices.first else {
            print("No Camera Found.")
            return
        }
        
        do {
            let input = try AVCaptureDeviceInput(device: captureDevice)
            captureSession.addInput(input)
            
            let captureMetadataOutput = AVCaptureMetadataOutput()
            captureSession.addOutput(captureMetadataOutput)
            captureMetadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
            captureMetadataOutput.metadataObjectTypes = supportedCodeTypes
        } catch {
            print(error)
            return
        }
        
        videoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
        videoPreviewLayer?.videoGravity = AVLayerVideoGravity.resizeAspectFill
        videoPreviewLayer?.frame = view.layer.bounds
        view.layer.addSublayer(videoPreviewLayer!)
        
        captureSession.startRunning()
        
        qrCodeFrameView = UIView()
        
        if let qrCodeFrameView = qrCodeFrameView {
            qrCodeFrameView.layer.borderColor = Colors.primaryDark.cgColor
            qrCodeFrameView.layer.borderWidth = 3.0
            view.addSubview(qrCodeFrameView)
            view.bringSubview(toFront: qrCodeFrameView)
        }
    }
}

extension ScanViewController: AVCaptureMetadataOutputObjectsDelegate {
    func metadataOutput(_ output: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject], from connection: AVCaptureConnection) {
        if metadataObjects.count == 0 {
            qrCodeFrameView?.frame = CGRect.zero
            return
        }
        
        let metadataObj = metadataObjects[0] as! AVMetadataMachineReadableCodeObject
        
        if supportedCodeTypes.contains(metadataObj.type) {
            let barCodeObject = videoPreviewLayer?.transformedMetadataObject(for: metadataObj)
            qrCodeFrameView?.frame = barCodeObject!.bounds
            
            if let qrValue =  metadataObj.stringValue {
                delegate?.setQR(value: qrValue)
                
                navigationItem.title = "Valid QR Code Found"
                perform(#selector(self.dismissView), with: nil, afterDelay: 0.8)
            }
        }
    }
}