space-ios/iOSClient/Login/NCLoginQRCode.swift

//
//  NCLoginQRCode.swift
//  Nextcloud
//
//  Created by Marino Faggiana on 04/03/2019.
//  Copyright © 2019 Marino Faggiana. All rights reserved.
//
//  Author Marino Faggiana <marino.faggiana@nextcloud.com>
//
//  This program is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with this program.  If not, see <http://www.gnu.org/licenses/>.
//

import Foundation
import QRCodeReader

@objc public protocol NCLoginQRCodeDelegate {
    @objc func dismissQRCode(_ value: String?, metadataType: String?)
}

class NCLoginQRCode: NSObject, QRCodeReaderViewControllerDelegate {
    
    lazy var reader: QRCodeReader = QRCodeReader()
    
    weak var delegate: UIViewController?
    
    lazy var readerVC: QRCodeReaderViewController = {
        let builder = QRCodeReaderViewControllerBuilder {
            $0.reader = QRCodeReader(metadataObjectTypes: [.qr], captureDevicePosition: .back)
            $0.showTorchButton = true
            $0.preferredStatusBarStyle = .lightContent
            $0.showOverlayView = true
            $0.rectOfInterest = CGRect(x: 0.2, y: 0.2, width: 0.6, height: 0.6)
            
            $0.reader.stopScanningWhenCodeIsFound = false
        }
        
        return QRCodeReaderViewController(builder: builder)
    }()

    override init() {
        
    }
    
    @objc public init(delegate: UIViewController) {
        self.delegate = delegate
    }
    
    @objc func scan() {
        guard checkScanPermissions() else { return }
        
        readerVC.modalPresentationStyle = .formSheet
        readerVC.delegate = self
        
        readerVC.completionBlock = { (result: QRCodeReaderResult?) in
            if let result = result {
                print("Completion with result: \(result.value) of type \(result.metadataType)")
            } else {
                
            }
            self.readerVC.dismiss(animated: true, completion: nil)
        }
        
        delegate?.present(readerVC, animated: true, completion: nil)
    }
    
    private func checkScanPermissions() -> Bool {
        do {
            return try QRCodeReader.supportsMetadataObjectTypes()
        } catch let error as NSError {
            let alert: UIAlertController
            
            switch error.code {
            case -11852:
                alert = UIAlertController(title: "Error", message: "This app is not authorized to use Back Camera.", preferredStyle: .alert)
                
                alert.addAction(UIAlertAction(title: "Setting", style: .default, handler: { (_) in
                    DispatchQueue.main.async {
                        if let settingsURL = URL(string: UIApplication.openSettingsURLString) {
                            UIApplication.shared.open(settingsURL, options: [:], completionHandler: nil)
                        }
                    }
                }))
                
                alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
            default:
                alert = UIAlertController(title: "Error", message: "Reader not supported by the current device", preferredStyle: .alert)
                alert.addAction(UIAlertAction(title: "OK", style: .cancel, handler: nil))
            }
            
            delegate?.present(alert, animated: true, completion: nil)
            
            return false
        }
    }
    
    func reader(_ reader: QRCodeReaderViewController, didScanResult result: QRCodeReaderResult) {
        reader.stopScanning()
        
        (self.delegate as? NCLoginQRCodeDelegate)?.dismissQRCode(result.value, metadataType: result.metadataType)
    }
    
    func readerDidCancel(_ reader: QRCodeReaderViewController) {
        reader.stopScanning()
        
        (self.delegate as? NCLoginQRCodeDelegate)?.dismissQRCode(nil, metadataType: nil)
    }
}