const crypto = require('crypto');

const jt = require('@tsmx/json-traverse');

function createOrderedObjectString(obj) {

let attributes = [];

const callbacks = {

processValue: (key, value, _level, path, _isObjectRoot, _isArrayElement, _cbSetValue) => {

attributes.push((path.length > 0 ? (path.join('.') + '.') : '') + key + '=' + value);

}

};

jt.traverse(obj, callbacks);

attributes.sort();

return attributes.join('|');

}

function createHmac(obj, key, hmacAttribute = '__hmac') {

const hmac = calculateHmac(obj, key);

obj[hmacAttribute] = hmac;

}

function calculateHmac(obj, key) {

let hmac = crypto.createHmac('sha256', key);

hmac.update(createOrderedObjectString(obj));

return hmac.digest('hex');

}

function verifyHmac(obj, key, hmacAttribute = '__hmac') {

if (!obj) return false;

const providedHmac = obj[hmacAttribute];

let hmacObj = { ...obj };

delete hmacObj[hmacAttribute];

const calculatedHmac = calculateHmac(hmacObj, key);

return calculatedHmac === providedHmac;

}

module.exports.createHmac = createHmac;

module.exports.calculateHmac = calculateHmac;

module.exports.verifyHmac = verifyHmac;