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/*** @file utility.ts* @author tngan* @desc  Library for some common functions (e.g. de/inflation, en/decoding)*/import { pki, util, asn1 } from 'node-forge';import { inflate, deflate } from 'pako';
const BASE64_STR = 'base64';
/** * @desc Mimic lodash.zipObject * @param arr1 {string[]} * @param arr2 {[]} */export function zipObject(arr1: string[], arr2: any[], skipDuplicated = true) {  return arr1.reduce((res, l, i) => {        if (skipDuplicated) {      res[l] = arr2[i];      return res;    }    // if key exists, aggregate with array in order to get rid of duplicate key    if (res[l] !== undefined) {      res[l] = Array.isArray(res[l])        ? res[l].concat(arr2[i])        : [res[l]].concat(arr2[i]);      return res;    }
    res[l] = arr2[i];    return res;
  }, {});}/** * @desc Alternative to lodash.flattenDeep * @reference https://github.com/you-dont-need/You-Dont-Need-Lodash-Underscore#_flattendeep * @param input {[]} */export function flattenDeep(input: any[]) {  return Array.isArray(input)  ? input.reduce( (a, b) => a.concat(flattenDeep(b)) , [])  : [input];}/** * @desc Alternative to lodash.last * @reference https://github.com/you-dont-need/You-Dont-Need-Lodash-Underscore#_last * @param input {[]} */export function last(input: any[]) {  return input.slice(-1)[0];}/** * @desc Alternative to lodash.uniq * @reference https://github.com/you-dont-need/You-Dont-Need-Lodash-Underscore#_uniq * @param input {string[]} */export function uniq(input: string[]) {  const set = new Set(input);  return [... set];}/** * @desc Alternative to lodash.get  * @reference https://github.com/you-dont-need/You-Dont-Need-Lodash-Underscore#_get * @param obj  * @param path  * @param defaultValue  */export function get(obj, path, defaultValue) {  return path.split('.')  .reduce((a, c) => (a && a[c] ? a[c] : (defaultValue || null)), obj);}/** * @desc Check if the input is string  * @param {any} input  */export function isString(input: any) {  return typeof input === 'string';}/*** @desc Encode string with base64 format* @param  {string} message                       plain-text message* @return {string} base64 encoded string*/function base64Encode(message: string | number[]) {  return Buffer.from(message as string).toString(BASE64_STR);}/*** @desc Decode string from base64 format* @param  {string} base64Message                 encoded string* @param  {boolean} isBytes                      determine the return value type (True: bytes False: string)* @return {bytes/string}  decoded bytes/string depends on isBytes, default is {string}*/export function base64Decode(base64Message: string, isBytes?: boolean): string | Buffer {  const bytes = Buffer.from(base64Message, BASE64_STR);  return Boolean(isBytes) ? bytes : bytes.toString();}/*** @desc Compress the string* @param  {string} message* @return {string} compressed string*/function deflateString(message: string): number[] {  const input = Array.prototype.map.call(message, char => char.charCodeAt(0));  return Array.from(deflate(input, { raw: true }));}/*** @desc Decompress the compressed string* @param  {string} compressedString* @return {string} decompressed string*/export function inflateString(compressedString: string): string {  const inputBuffer = Buffer.from(compressedString, BASE64_STR);  const input = Array.prototype.map.call(inputBuffer.toString('binary'), char => char.charCodeAt(0));  return Array.from(inflate(input, { raw: true }))    .map((byte: number) => String.fromCharCode(byte))    .join('');}/*** @desc Abstract the normalizeCerString and normalizePemString* @param {buffer} File stream or string* @param {string} String for header and tail* @return {string} A formatted certificate string*/function _normalizeCerString(bin: string | Buffer, format: string) {  return bin.toString().replace(/\n/g, '').replace(/\r/g, '').replace(`-----BEGIN ${format}-----`, '').replace(`-----END ${format}-----`, '').replace(/ /g, '').replace(/\t/g, '');}/*** @desc Parse the .cer to string format without line break, header and footer* @param  {string} certString     declares the certificate contents* @return {string} certificiate in string format*/function normalizeCerString(certString: string | Buffer) {  return _normalizeCerString(certString, 'CERTIFICATE');}/*** @desc Normalize the string in .pem format without line break, header and footer* @param  {string} pemString* @return {string} private key in string format*/function normalizePemString(pemString: string | Buffer) {  return _normalizeCerString(pemString.toString(), 'RSA PRIVATE KEY');}/*** @desc Return the complete URL* @param  {object} req                   HTTP request* @return {string} URL*/function getFullURL(req) {  return `${req.protocol}://${req.get('host')}${req.originalUrl}`;}/*** @desc Parse input string, return default value if it is undefined* @param  {string/boolean}* @return {boolean}*/function parseString(str, defaultValue = '') {  return str || defaultValue;}/*** @desc Override the object by another object (rtl)* @param  {object} default object* @param  {object} object applied to the default object* @return {object} result object*/function applyDefault(obj1, obj2) {  return Object.assign({}, obj1, obj2);}/*** @desc Get public key in pem format from the certificate included in the metadata* @param {string} x509 certificate* @return {string} public key fetched from the certificate*/function getPublicKeyPemFromCertificate(x509Certificate: string) {  const certDerBytes = util.decode64(x509Certificate);  const obj = asn1.fromDer(certDerBytes);  const cert = pki.certificateFromAsn1(obj);  return pki.publicKeyToPem(cert.publicKey);}/*** @desc Read private key from pem-formatted string* @param {string | Buffer} keyString pem-formattted string* @param {string} protected passphrase of the key* @return {string} string in pem format* If passphrase is used to protect the .pem content (recommend)*/export function readPrivateKey(keyString: string | Buffer, passphrase: string | undefined, isOutputString?: boolean) {  return isString(passphrase) ? this.convertToString(pki.privateKeyToPem(pki.decryptRsaPrivateKey(String(keyString), passphrase)), isOutputString) : keyString;}/*** @desc Inline syntax sugar*/function convertToString(input, isOutputString) {  return Boolean(isOutputString) ? String(input) : input;}/** * @desc Check if the input is an array with non-zero size */export function isNonEmptyArray(a) {  return Array.isArray(a) && a.length > 0;}
export function notEmpty<TValue>(value: TValue | null | undefined): value is TValue {  return value !== null && value !== undefined;}
const utility = {  isString,  base64Encode,  base64Decode,  deflateString,  inflateString,  normalizeCerString,  normalizePemString,  getFullURL,  parseString,  applyDefault,  getPublicKeyPemFromCertificate,  readPrivateKey,  convertToString,  isNonEmptyArray,};
export default utility;