AuthMethod: add weight to choose when no method was specified

src/auth/AuthController.ts

@@ -7,6 +7,8 @@ import User from "./models/User";
 import UserPasswordComponent from "./password/UserPasswordComponent";
 import UserNameComponent from "./models/UserNameComponent";
 import {UnknownRelationValidationError} from "../db/Validator";
+import AuthMethod from "./AuthMethod";
+import AuthProof from "./AuthProof";
 
 export default class AuthController extends Controller {
     public getRoutesPrefix(): string {
@@ -83,8 +85,23 @@ export default class AuthController extends Controller {
         // Redirect to registration if user not found
         if (methods.length === 0) return await this.redirectToRegistration(req, res, identifier);
 
+        // Choose best matching method
+        let user: User | null = null;
+        let method: AuthMethod<AuthProof<User>> | null = null;
+        let weight = -1;
+
+        for (const entry of methods) {
+            const methodWeight = entry.method.getWeightForRequest(req);
+            if (methodWeight > weight) {
+                user = entry.user;
+                method = entry.method;
+                weight = methodWeight;
+            }
+        }
+
+        if (!method || !user) ({method, user} = methods[0]); // Default to first method
+
         // Login
-        const {user, method} = methods[0];
         return await method.attemptLogin(req, res, user);
     }
 

src/auth/AuthMethod.ts

@@ -9,6 +9,14 @@ export default interface AuthMethod<P extends AuthProof<User>> {
      */
     getName(): string;
 
+    /**
+     * Used for automatic auth method detection. Won't affect forced auth method.
+     *
+     * @return {@code 0} if the request is not conform to this auth method, otherwise the exact count of matching
+     * fields.
+     */
+    getWeightForRequest(req: Request): number;
+
     findUserByIdentifier(identifier: string): Promise<User | null>;
 
     getProofsForSession?(session: Express.Session): Promise<P[]>;

src/auth/magic_link/MagicLinkAuthMethod.ts

@@ -11,7 +11,7 @@ import RedirectBackComponent from "../../components/RedirectBackComponent";
 import Application from "../../Application";
 import {MailTemplate} from "../../mail/Mail";
 import AuthMagicLinkActionType from "./AuthMagicLinkActionType";
-import Validator from "../../db/Validator";
+import Validator, {EMAIL_REGEX} from "../../db/Validator";
 import ModelFactory from "../../db/ModelFactory";
 import UserNameComponent from "../models/UserNameComponent";
 
@@ -26,6 +26,12 @@ export default class MagicLinkAuthMethod implements AuthMethod<MagicLink> {
         return 'magic_link';
     }
 
+    public getWeightForRequest(req: Request): number {
+        return !req.body.identifier || !EMAIL_REGEX.test(req.body.identifier) ?
+            0 :
+            1;
+    }
+
     public async findUserByIdentifier(identifier: string): Promise<User | null> {
         return (await UserEmail.select()
             .with('user.mainEmail')

src/auth/password/PasswordAuthMethod.ts

@@ -24,6 +24,12 @@ export default class PasswordAuthMethod implements AuthMethod<PasswordAuthProof>
         return 'password';
     }
 
+    public getWeightForRequest(req: Request): number {
+        return !req.body.identifier || !req.body.password || req.body.password.length === 0 ?
+            0 :
+            2;
+    }
+
     public async findUserByIdentifier(identifier: string): Promise<User | null> {
         const query = UserEmail.select()
             .with('user')