DeviceCheckPlugin.swift

//
//  DeviceCheckPlugin.swift
//  Runner
//
//  Created by Avo Sukiasyan on 26.12.21.
//

import UIKit
import DeviceCheck
import Flutter
import CryptoKit

class DeviceCheckPlugin {

    let curDevice = DCDevice.current
    var token = ""
    
    var channelMethod:FlutterMethodChannel?
    
    init(channelMethod: FlutterMethodChannel) {
        self.channelMethod = channelMethod
        self.setup()
    }

    func setup() {
        channelMethod?.setMethodCallHandler { call, result in
            switch call.method {
            case "attest":
                let args = call.arguments as? [String: Any]

                if #available(iOS 14, *) {
                    let service = DCAppAttestService.shared
                    service.generateKey { (keyIdentifier, error) in
                        guard error == nil  else {
                            result(nil)
                            return
                        }

                        let legitimationId = args?["nonce"] as? String ?? ""
                        let challenge = legitimationId.data(using: .utf8)!
                        let hash = Data(SHA256.hash(data: challenge))
                        service.attestKey(keyIdentifier!, clientDataHash: hash) { attestation, error in
                            guard error == nil else {
                                result(nil)
                                return
                            }

                            let attestationString = attestation?.base64EncodedString()
                            result(["attestation":attestationString])
                        }
                    }
                } else {
                    self.curDevice.generateToken { data, error in
                                    if let data = data {
                                           self.token = data.base64EncodedString(options: [])
                                           result(["attestation":self.token])
                                       }
                                   }
                }
                
            case "isSupported":
                result(["isSupported":self.curDevice.isSupported])
            default:
                break
        }
    }
    }
}