Add beforeLogin trigger with support for auth providers (#5445)

* Add beforeLogin trigger with support for auth providers

* adjust comment that boxed off beforeLogin to a negative use-case only

* add internal error to help future maintainers regarding use of beforeLogin

* let beforeLogin accept className or constructor like other hook types

* add assertions for beforeLogin trigger className validation

src/RestWrite.js

@@ -93,7 +93,7 @@ RestWrite.prototype.execute = function() {
       return this.validateAuthData();
     })
     .then(() => {
-      return this.runBeforeTrigger();
+      return this.runBeforeSaveTrigger();
     })
     .then(() => {
       return this.deleteEmailResetTokenIfNeeded();
@@ -123,7 +123,7 @@ RestWrite.prototype.execute = function() {
       return this.handleFollowup();
     })
     .then(() => {
-      return this.runAfterTrigger();
+      return this.runAfterSaveTrigger();
     })
     .then(() => {
       return this.cleanUserAuthData();
@@ -190,7 +190,7 @@ RestWrite.prototype.validateSchema = function() {
 
 // Runs any beforeSave triggers against this operation.
 // Any change leads to our data being mutated.
-RestWrite.prototype.runBeforeTrigger = function() {
+RestWrite.prototype.runBeforeSaveTrigger = function() {
   if (this.response) {
     return;
   }
@@ -251,6 +251,33 @@ RestWrite.prototype.runBeforeTrigger = function() {
     });
 };
 
+RestWrite.prototype.runBeforeLoginTrigger = async function(userData) {
+  // Avoid doing any setup for triggers if there is no 'beforeLogin' trigger
+  if (
+    !triggers.triggerExists(
+      this.className,
+      triggers.Types.beforeLogin,
+      this.config.applicationId
+    )
+  ) {
+    return;
+  }
+
+  // Cloud code gets a bit of extra data for its objects
+  const extraData = { className: this.className };
+  const user = triggers.inflate(extraData, userData);
+
+  // no need to return a response
+  await triggers.maybeRunTrigger(
+    triggers.Types.beforeLogin,
+    this.auth,
+    user,
+    null,
+    this.config,
+    this.context
+  );
+};
+
 RestWrite.prototype.setRequiredFieldsIfNeeded = function() {
   if (this.data) {
     // Add default fields
@@ -377,7 +404,7 @@ RestWrite.prototype.filteredObjectsByACL = function(objects) {
 
 RestWrite.prototype.handleAuthData = function(authData) {
   let results;
-  return this.findUsersWithAuthData(authData).then(r => {
+  return this.findUsersWithAuthData(authData).then(async r => {
     results = this.filteredObjectsByACL(r);
     if (results.length > 1) {
       // More than 1 user with the passed id's
@@ -421,7 +448,12 @@ RestWrite.prototype.handleAuthData = function(authData) {
             response: userResult,
             location: this.location(),
           };
+          // Run beforeLogin hook before storing any updates
+          // to authData on the db; changes to userResult
+          // will be ignored.
+          await this.runBeforeLoginTrigger(deepcopy(userResult));
         }
+
         // If we didn't change the auth data, just keep going
         if (!hasMutatedAuthData) {
           return;
@@ -430,7 +462,7 @@ RestWrite.prototype.handleAuthData = function(authData) {
         // that can happen when token are refreshed,
         // We should update the token and let the user in
         // We should only check the mutated keys
-        return this.handleAuthDataValidation(mutatedAuthData).then(() => {
+        return this.handleAuthDataValidation(mutatedAuthData).then(async () => {
           // IF we have a response, we'll skip the database operation / beforeSave / afterSave etc...
           // we need to set it up there.
           // We are supposed to have a response only on LOGIN with authData, so we skip those
@@ -441,6 +473,7 @@ RestWrite.prototype.handleAuthData = function(authData) {
               this.response.response.authData[provider] =
                 mutatedAuthData[provider];
             });
+
             // Run the DB update directly, as 'master'
             // Just update the authData part
             // Then we're good for the user, early exit of sorts
@@ -1415,7 +1448,7 @@ RestWrite.prototype.runDatabaseOperation = function() {
 };
 
 // Returns nothing - doesn't wait for the trigger.
-RestWrite.prototype.runAfterTrigger = function() {
+RestWrite.prototype.runAfterSaveTrigger = function() {
   if (!this.response || !this.response.response) {
     return;
   }