wip convert Node Crypto to class

haven't formatted this — will do once contents of class are correct

Use of `satisfies` comes from suggestion in [1].

[1] "Allow specifying interface implements clauses for the static side
of classes": microsoft/TypeScript#33892

Author: lawrence-forooghian

src/platform/nodejs/lib/util/crypto.ts

@@ -4,7 +4,7 @@ import Platform from '../../../../common/platform';
 import crypto from 'crypto';
 import ErrorInfo from '../../../../common/lib/types/errorinfo';
 import * as API from '../../../../../ably';
-import { IGetCipherParams } from 'common/types/ICrypto';
+import ICrypto, { IGetCipherParams } from 'common/types/ICrypto';
 
 var Crypto = (function () {
   var DEFAULT_ALGORITHM = 'aes';
@@ -120,9 +120,9 @@ var Crypto = (function () {
    * concatenated with the resulting raw ciphertext to construct the "ciphertext"
    * data passed to the recipient.
    */
-  function Crypto() {}
+  class Crypto {
 
-  Crypto.CipherParams = CipherParams;
+  static CipherParams = CipherParams;
 
   /**
    * Obtain a complete CipherParams instance from the provided params, filling
@@ -133,7 +133,7 @@ var Crypto = (function () {
    * base64-encoded string. May optionally also contain: algorithm (defaults to
    * AES), mode (defaults to 'cbc')
    */
-  Crypto.getDefaultParams = function (params: API.Types.CipherParamOptions) {
+  static getDefaultParams(params: API.Types.CipherParamOptions) {
     var key;
 
     if (!params.key) {
@@ -163,15 +163,15 @@ var Crypto = (function () {
 
     validateCipherParams(cipherParams);
     return cipherParams;
-  };
+  }
 
   /**
    * Generate a random encryption key from the supplied keylength (or the
    * default keyLength if none supplied) as a Buffer
    * @param keyLength (optional) the required keyLength in bits
    * @param callback (optional) (err, key)
    */
-  Crypto.generateRandomKey = function (keyLength?: number, callback?: API.Types.StandardCallback<API.Types.CipherKey>) {
+  static generateRandomKey(keyLength?: number, callback?: API.Types.StandardCallback<API.Types.CipherKey>) {
     if (arguments.length == 1 && typeof keyLength == 'function') {
       callback = keyLength;
       keyLength = undefined;
@@ -184,14 +184,14 @@ var Crypto = (function () {
     generateRandom((keyLength || DEFAULT_KEYLENGTH) / 8, (err, buf) => {
       callback!(err ? ErrorInfo.fromValues(err) : null, buf);
     });
-  };
+  }
 
   /**
    * Internal; get a ChannelCipher instance based on the given cipherParams
    * @param params either a CipherParams instance or some subset of its
    * fields that includes a key
    */
-  Crypto.getCipher = function (
+  static getCipher(
     params: IGetCipherParams
   ) {
     var cipherParams = isInstCipherParams(params) ? params : Crypto.getDefaultParams(params);
@@ -201,7 +201,11 @@ var Crypto = (function () {
       cipherParams: cipherParams /* CipherOptions.cipher */,
       cipher: new CBCCipher(cipherParams, iv) /* CipherOptions.channelCipher */,
     };
-  };
+  }
+
+  }
+
+  Crypto satisfies ICrypto;
 
   const CBCCipher = function CBCCipher(this: any /* TODO */, params: any /* TODO */, iv: any /* TODO */) {
     var algorithm = (this.algorithm = params.algorithm + '-' + String(params.keyLength) + '-' + params.mode);