Start Matrix client authentication

matrixgw_backend/src/controllers/matrix_link_controller.rs

@@ -0,0 +1,14 @@
+use crate::controllers::HttpResult;
+use crate::extractors::matrix_client_extractor::MatrixClientExtractor;
+use actix_web::HttpResponse;
+
+#[derive(serde::Serialize)]
+struct StartAuthResponse {
+    url: String,
+}
+
+/// Start user authentication on Matrix server
+pub async fn start_auth(client: MatrixClientExtractor) -> HttpResult {
+    let url = client.client.initiate_login().await?.to_string();
+    Ok(HttpResponse::Ok().json(StartAuthResponse { url }))
+}