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const crc = require('./crc');
const models = require('./models');
const fs = require('fs')
const mcc_codes = require('./mcc_codes.json')
const currencyCode = require('./currencies.json')
const countries = require('./countries.json')
const getDataObjectName = models.getDataObjectName;
const getDataObjectNameSubData = models.getDataObjectNameSubData;
const getDataObjectAdditionalFieldsName = models.getDataObjectAdditionalFieldsName;
const getDataObjectNamePaymentSpecific = models.getDataObjectNamePaymentSpecific;
//
let debug = { log: o => o };
/**
* decode (public|exported)
* receive a text and return a emv parsed object
*/
function decode(emvString) {
const emvObject = {};
// parse emv string
let inputText = emvString;
while (inputText.length > 0) {
debug.log('inputText', inputText);
let { emvItem, remainingText } = readNext(inputText);
if (emvItem.id == 52) {
let translateCode = getObjects(mcc_codes, 'mcc', emvItem.data)
emvItem.data = `${emvItem.data} (${translateCode[0].usda_description})`
}
if (emvItem.id == 53 ){
let currencyTranslate = getObjects(currencyCode,'number',emvItem.data)
emvItem.data = `${emvItem.data} (${currencyTranslate[0].code})`
}
if(emvItem.id == 58){
let countriExplain = getObjects(countries,'Code',emvItem.data)
emvItem.data = `${emvItem.data} (${countriExplain[0].Name})`
}
if (emvItem.name == 'Merchant Account Information') {
emvItem.data = decodeSubData(emvItem.data)
}
if (emvItem.name == 'Additional Data Field Template') {
emvItem.data = decodeAdditionalFields(emvItem.data)
}
emvObject[emvItem.id] = emvItem;
inputText = remainingText;
}
// validate checksum
if (!validateChecksum(emvString)) {
throw new Error('checksum validation failed.');
};
return emvObject;
}
function decodeSubData(emvString) {
const emvObject = {};
// parse emv string
let inputText = emvString;
while (inputText.length > 0) {
debug.log('inputText', inputText);
let { emvItem, remainingText } = readNextSubData(inputText);
emvObject[emvItem.id] = emvItem;
inputText = remainingText;
}
return emvObject;
}
function decodeAdditionalFields(emvString) {
const emvObject = {};
// parse emv string
let inputText = emvString;
while (inputText.length > 0) {
debug.log('inputText', inputText);
let { emvItem, remainingText } = readNextAdditionalFields(inputText);
Iif (emvItem.id == '60') {
emvItem.data = decodePaymentSpecific(emvItem.data)
}
emvObject[emvItem.id] = emvItem;
inputText = remainingText;
}
return emvObject;
}
function decodePaymentSpecific(emvString) {
const emvObject = {};
// parse emv string
let inputText = emvString;
while (inputText.length > 0) {
debug.log('inputText', inputText);
let { emvItem, remainingText } = readNextPaymentSpecific(inputText);
emvObject[emvItem.id] = emvItem;
inputText = remainingText;
}
return emvObject;
}
/**
* readNext (private use)
* read next emvItem, and return the remaining string
*/
function readNext(inputText) {
const id = inputText.substring(0, 2);
const len = checkNumberType(parseInt(inputText.substring(2, 4)));
const data = inputText.substring(4, len + 4);
const emvItem = {
id,
name: getDataObjectName(id),
len,
data
};
const remainingText = inputText.substring(len + 4);
return {
emvItem,
remainingText
};
}
function readNextSubData(inputText) {
const id = inputText.substring(0, 2);
const len = checkNumberType(parseInt(inputText.substring(2, 4)));
const data = inputText.substring(4, len + 4);
const emvItem = {
id,
name: getDataObjectNameSubData(id),
len,
data
};
const remainingText = inputText.substring(len + 4);
return {
emvItem,
remainingText
};
}
function readNextAdditionalFields(inputText) {
const id = inputText.substring(0, 2);
const len = checkNumberType(parseInt(inputText.substring(2, 4)));
const data = inputText.substring(4, len + 4);
const emvItem = {
id,
name: getDataObjectAdditionalFieldsName(id),
len,
data
};
const remainingText = inputText.substring(len + 4);
return {
emvItem,
remainingText
};
}
function readNextPaymentSpecific(inputText) {
const id = inputText.substring(0, 2);
const len = checkNumberType(parseInt(inputText.substring(2, 4)));
const data = inputText.substring(4, len + 4);
const emvItem = {
id,
name: getDataObjectNamePaymentSpecific(id),
len,
data
};
const remainingText = inputText.substring(len + 4);
return {
emvItem,
remainingText
};
}
/**
* validateChecksum (private use)
* you guess
*/
function validateChecksum(emvString) {
const emvData = emvString.substring(0, emvString.length - 4);
const checksum = emvString.substring(emvString.length - 4);
debug.log('emvData', emvData);
debug.log('checksum', checksum);
const expectedCRC = crc.computeCRC(emvData);
return expectedCRC === checksum;
}
function getObjects(obj, key, val) {
var objects = [];
for (var i in obj) {
Iif (!obj.hasOwnProperty(i)) continue;
if (typeof obj[i] == 'object') {
objects = objects.concat(getObjects(obj[i], key, val));
} else
if (i == key && obj[i] == val || i == key && val == '') { //
objects.push(obj);
} else Iif (obj[i] == val && key == '') {
if (objects.lastIndexOf(obj) == -1) {
objects.push(obj);
}
}
}
return objects;
}
function checkNumberType(parsedNo) {
Iif (isNaN(parsedNo)) {
throw new Error('Invalid EMV data');
} else {
return parsedNo
}
}
module.exports = {
decode,
enableDebugLog: () => (debug = console),
decodeSubData,
decodeAdditionalFields,
decodePaymentSpecific
} |