Auth Adapters refactoring (#3177)

* Moves all authentication providers to Adapter/Auth

* refactors specs

* Deprecates oauth option in favor of auth option

- Deprecates facebookAppIds option (in favor of auth.facebook.appIds)
- Adds warnings about the deprecated options

* nits

src/Adapters/Auth/index.js

@@ -0,0 +1,99 @@
+import loadAdapter from '../AdapterLoader';
+
+const facebook = require('./facebook');
+const instagram = require("./instagram");
+const linkedin = require("./linkedin");
+const meetup = require("./meetup");
+const google = require("./google");
+const github = require("./github");
+const twitter = require("./twitter");
+const spotify = require("./spotify");
+const digits = require("./twitter"); // digits tokens are validated by twitter
+const janrainengage = require("./janrainengage");
+const janraincapture = require("./janraincapture");
+const vkontakte = require("./vkontakte");
+const qq = require("./qq");
+const wechat = require("./wechat");
+const weibo = require("./weibo");
+
+const anonymous = {
+  validateAuthData: () => {
+    return Promise.resolve();
+  },
+  validateAppId: () => {
+    return Promise.resolve();
+  }
+}
+
+const providers = {
+  facebook,
+  instagram,
+  linkedin,
+  meetup,
+  google,
+  github,
+  twitter,
+  spotify,
+  anonymous,
+  digits,
+  janrainengage,
+  janraincapture,
+  vkontakte,
+  qq,
+  wechat,
+  weibo
+}
+
+function authDataValidator(adapter, appIds, options) {
+  return function(authData) {
+    return adapter.validateAuthData(authData, options).then(() => {
+      if (appIds) {
+        return adapter.validateAppId(appIds, authData, options);
+      }
+      return Promise.resolve();
+    });
+  }
+}
+
+module.exports = function(authOptions = {}, enableAnonymousUsers = true) {
+  let _enableAnonymousUsers = enableAnonymousUsers;
+  let setEnableAnonymousUsers = function(enable) {
+    _enableAnonymousUsers = enable;
+  }
+  // To handle the test cases on configuration
+  let getValidatorForProvider = function(provider) {
+
+    if (provider === 'anonymous' && !_enableAnonymousUsers) {
+      return;
+    }
+
+    const defaultAdapter = providers[provider];
+    let adapter = defaultAdapter;
+    const providerOptions = authOptions[provider];
+
+    if (!defaultAdapter && !providerOptions) {
+      return;
+    }
+
+    const appIds = providerOptions ? providerOptions.appIds : undefined;
+
+    // Try the configuration methods
+    if (providerOptions) {
+      const optionalAdapter = loadAdapter(providerOptions, undefined, providerOptions);
+      if (optionalAdapter) {
+        adapter = optionalAdapter;
+      }
+    }
+
+    if (!adapter.validateAuthData || !adapter.validateAppId) {
+      return;
+    }
+
+    return authDataValidator(adapter, appIds, providerOptions);
+  }
+
+  return Object.freeze({
+    getValidatorForProvider,
+    setEnableAnonymousUsers,
+  })
+}