KEYCLOAK-581 Add login_hint query param to login

services/src/main/java/org/keycloak/services/resources/TokenService.java

@@ -2,6 +2,7 @@ package org.keycloak.services.resources;
 
 import org.jboss.logging.Logger;
 import org.jboss.resteasy.annotations.cache.NoCache;
+import org.jboss.resteasy.specimpl.MultivaluedMapImpl;
 import org.jboss.resteasy.spi.BadRequestException;
 import org.jboss.resteasy.spi.HttpRequest;
 import org.jboss.resteasy.spi.HttpResponse;
@@ -789,7 +790,8 @@ public class TokenService {
     @GET
     public Response loginPage(final @QueryParam("response_type") String responseType,
                               @QueryParam("redirect_uri") String redirect, final @QueryParam("client_id") String clientId,
-                              final @QueryParam("scope") String scopeParam, final @QueryParam("state") String state, final @QueryParam("prompt") String prompt) {
+                              final @QueryParam("scope") String scopeParam, final @QueryParam("state") String state, final @QueryParam("prompt") String prompt,
+                              final @QueryParam("login_hint") String loginHint) {
         logger.info("TokenService.loginPage");
 
         audit.event(EventType.LOGIN).client(clientId).detail(Details.REDIRECT_URI, redirect).detail(Details.RESPONSE_TYPE, "code");
@@ -845,8 +847,17 @@ public class TokenService {
         if (prompt != null && prompt.equals("none")) {
             return oauth.redirectError(client, "access_denied", state, redirect);
         }
-        logger.info("createLogin() now...");
+
-        return Flows.forms(session, realm, uriInfo).createLogin();
+        LoginFormsProvider forms = Flows.forms(session, realm, uriInfo);
+
+        if (loginHint != null) {
+            MultivaluedMap<String, String> formData = new MultivaluedMapImpl<String, String>();
+            formData.add(AuthenticationManager.FORM_USERNAME, loginHint);
+
+            forms.setFormData(formData);
+        }
+
+        return forms.createLogin();
     }
 
     /**

testsuite/integration/src/test/java/org/keycloak/testsuite/forms/LoginTest.java

@@ -120,6 +120,20 @@ public class LoginTest {
         events.expectLogin().user(userId).detail(Details.USERNAME, "login-test").assertEvent();
     }
 
+    @Test
+    public void loginLoginHint() {
+        String loginFormUrl = oauth.getLoginFormUrl() + "&login_hint=login-test";
+        driver.navigate().to(loginFormUrl);
+
+        Assert.assertEquals("login-test", loginPage.getUsername());
+        loginPage.login("password");
+
+        Assert.assertEquals(RequestType.AUTH_RESPONSE, appPage.getRequestType());
+        Assert.assertNotNull(oauth.getCurrentQuery().get(OAuth2Constants.CODE));
+
+        events.expectLogin().user(userId).detail(Details.USERNAME, "login-test").assertEvent();
+    }
+
     @Test
     public void loginWithEmailSuccess() {
         loginPage.open();

testsuite/integration/src/test/java/org/keycloak/testsuite/pages/LoginPage.java

@@ -75,6 +75,17 @@ public class LoginPage extends AbstractPage {
         submitButton.click();
     }
 
+    public void login(String password) {
+        passwordInput.clear();
+        passwordInput.sendKeys(password);
+
+        submitButton.click();
+    }
+
+    public String getUsername() {
+        return usernameInput.getAttribute("value");
+    }
+
     public void cancel() {
         cancelButton.click();
     }