adding in gg endpoints and basic methods

components/homepage/login.js

@@ -161,6 +161,14 @@ let Login = (props) => {
             : "";
     }, [cookies.pinsUser, router]);
 
+    const govGatwayLoginRedirect = () => {
+        router.replace(
+            props.govGateway.config.authorization_endpoint +
+                "?response_type=code&scope=openid&client_id=5vTukeSpN7d6uBV7YLb7A5wOctzzkZ&redirect_uri=https://pp-planningcasework.service.gov.wales&ui_locales=" +
+                (router.locale == "cy" ? "cy" : "en-GB")
+        );
+    };
+
     return (
         <div className="card" id="login-card">
             <form onSubmit={handleSubmit(onHandleSubmit)}>
@@ -247,6 +255,17 @@ let Login = (props) => {
                                 </a>
                             </Link>
                         </p>
+
+                        <p className="govuk-body-s">
+                            <a
+                                onClick={() => {
+                                    govGatwayLoginRedirect();
+                                }}
+                                className="govuk-link--no-underline"
+                            >
+                                Log in using Government Gateway
+                            </a>
+                        </p>
                     </div>
                 </div>
             </form>
@@ -271,6 +290,7 @@ const mapStateToProps = (state) => {
         watchedCases: state.watchedCases,
         myRepresentations: state.myRepresentations,
         awaitingSubmission: state.awaitingSubmission,
+        govGateway: state.govGateway,
     };
 };