Auth Strategies (#1257)

* auth strategies

* default to no auth

* rename base auth strategy

* rename base strategy cont.

* refactor auth strategy methods and LocalAuth

* activate old session options even if is falsy value

* move restartOnAuthFail to LegacyAuthStrategy option

* add link to guide item

* update example/shell

* types

src/authStrategies/LocalAuth.js

@@ -0,0 +1,54 @@
+'use strict';
+
+const path = require('path');
+const fs = require('fs');
+const BaseAuthStrategy = require('./BaseAuthStrategy');
+
+/**
+ * Local directory-based authentication
+ * @param {object} options - options
+ * @param {string} options.clientId - Client id to distinguish instances if you are using multiple, otherwise keep null if you are using only one instance
+ * @param {string} options.dataPath - Change the default path for saving session files, default is: "./.wwebjs_auth/" 
+*/
+class LocalAuth extends BaseAuthStrategy {
+    constructor({ clientId, dataPath }={}) {
+        super();
+
+        const idRegex = /^[-_\w]+$/i;
+        if(clientId && !idRegex.test(clientId)) {
+            throw new Error('Invalid clientId. Only alphanumeric characters, underscores and hyphens are allowed.');
+        }
+
+        this.dataPath = path.resolve(dataPath || './.wwebjs_auth/');
+        this.clientId = clientId;
+    }
+
+    async beforeBrowserInitialized() {
+        const puppeteerOpts = this.client.options.puppeteer;
+
+        if(puppeteerOpts.userDataDir) {
+            throw new Error('LocalAuth is not compatible with a user-supplied userDataDir.');
+        }
+
+        const sessionDirName = this.clientId ? `session-${this.clientId}` : 'session';
+        const dirPath = path.join(this.dataPath, sessionDirName);
+
+        fs.mkdirSync(dirPath, { recursive: true });
+        
+        this.client.options.puppeteer = {
+            ...puppeteerOpts,
+            userDataDir: dirPath
+        };
+
+        this.userDataDir = dirPath;
+    }
+
+    async logout() {
+        if (this.userDataDir) {
+            return (fs.rmSync ? fs.rmSync : fs.rmdirSync).call(this.userDataDir, { recursive: true });
+        }
+    }
+
+}
+
+module.exports = LocalAuth;