self/app/ios/PassportReader.swift

//
//  PassportReader.swift
//  ProofOfPassport
//
//  Created by Y E on 27/07/2023.
//

import Foundation
import React
import NFCPassportReader

@available(iOS 15, *)
@objc(PassportReader)
class PassportReader: NSObject{
  
  private let passportReader = NFCPassportReader.PassportReader()
  
  func getMRZKey(passportNumber: String, dateOfBirth: String, dateOfExpiry: String ) -> String {
    
    // Pad fields if necessary
    let pptNr = pad( passportNumber, fieldLength:9)
    let dob = pad( dateOfBirth, fieldLength:6)
    let exp = pad( dateOfExpiry, fieldLength:6)
    
    // Calculate checksums
    let passportNrChksum = calcCheckSum(pptNr)
    let dateOfBirthChksum = calcCheckSum(dob)
    let expiryDateChksum = calcCheckSum(exp)
    
    let mrzKey = "\(pptNr)\(passportNrChksum)\(dob)\(dateOfBirthChksum)\(exp)\(expiryDateChksum)"
    
    return mrzKey
  }
  
  func pad( _ value : String, fieldLength:Int ) -> String {
    // Pad out field lengths with < if they are too short
    let paddedValue = (value + String(repeating: "<", count: fieldLength)).prefix(fieldLength)
    return String(paddedValue)
  }
      
  func calcCheckSum( _ checkString : String ) -> Int {
    let characterDict  = ["0" : "0", "1" : "1", "2" : "2", "3" : "3", "4" : "4", "5" : "5", "6" : "6", "7" : "7", "8" : "8", "9" : "9", "<" : "0", " " : "0", "A" : "10", "B" : "11", "C" : "12", "D" : "13", "E" : "14", "F" : "15", "G" : "16", "H" : "17", "I" : "18", "J" : "19", "K" : "20", "L" : "21", "M" : "22", "N" : "23", "O" : "24", "P" : "25", "Q" : "26", "R" : "27", "S" : "28","T" : "29", "U" : "30", "V" : "31", "W" : "32", "X" : "33", "Y" : "34", "Z" : "35"]
    
    var sum = 0
    var m = 0
    let multipliers : [Int] = [7, 3, 1]
    for c in checkString {
      guard let lookup = characterDict["\(c)"],
            let number = Int(lookup) else { return 0 }
      let product = number * multipliers[m]
      sum += product
      m = (m+1) % 3
    }
    
    return (sum % 10)
  }
  
  @objc(scanPassport:dateOfBirth:dateOfExpiry:resolve:reject:)
  func scanPassport(_ passportNumber: String, dateOfBirth: String, dateOfExpiry: String, resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) {
    let customMessageHandler : (NFCViewDisplayMessage)->String? = { (displayMessage) in
                    switch displayMessage {
                        case .requestPresentPassport:
                            return "Hold your iPhone near ann NFC enabled passport."
                        default:
                            // Return nil for all other messages so we use the provided default
                            return nil
                    }
                }

    Task { [weak self] in
            guard let self = self else {
              return
            }

            do {
                let mrzKey = getMRZKey( passportNumber: passportNumber, dateOfBirth: dateOfBirth, dateOfExpiry: dateOfExpiry)
                let masterListURL = Bundle.main.url(forResource: "masterList", withExtension: ".pem")
              passportReader.setMasterListURL( masterListURL! )

                let passport = try await passportReader.readPassport( mrzKey: mrzKey, customDisplayMessage: customMessageHandler)

              let passportData = passport.lastName
                resolve(passportData)
            } catch {
                reject("E_PASSPORT_READ", "Failed to read passport", error)
            }
        }
  }
  
//  @objc(scanPassport:dateOfBirth:dateOfExpiry:resolve:reject:)
//  func scanPassport(_ passportNumber: String, dateOfBirth: String, dateOfExpiry: String, resolve: @escaping RCTPromiseResolveBlock, reject: @escaping RCTPromiseRejectBlock) {
//    let concatenatedString = "\(passportNumber), \(dateOfBirth), \(dateOfExpiry)"
//        resolve(concatenatedString)
//  }

  
  @objc
  static func requiresMainQueueSetup() -> Bool {
    return true
  }
}