Add BadgeController and FaviconController, integrate Javadoc badge display in index page

src/main/java/codes/thischwa/jdvs/web/BadgeController.java

@@ -0,0 +1,34 @@
+package codes.thischwa.jdvs.web;
+
+import codes.thischwa.jdvs.jpa.GitRepositoryRepository;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.HttpStatus;
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.server.ResponseStatusException;
+
+@Controller
+@RequiredArgsConstructor
+public class BadgeController {
+
+  private static final String BADGE_URL_PREFIX =
+      "https://img.shields.io/badge/javadoc%40JdVS-";
+
+  private static final String BADGE_URL_SUFFIX = "-green";
+
+  private final GitRepositoryRepository repository;
+
+  @GetMapping("/badge/{repositoryName}")
+  public String badge(@PathVariable String repositoryName) {
+    String tag =
+        repository
+            .findByName(repositoryName)
+            .map(r -> r.getLastTag() != null ? r.getLastTag() : "unknown")
+            .orElseThrow(
+                () ->
+                    new ResponseStatusException(
+                        HttpStatus.NOT_FOUND, "Repository not found: " + repositoryName));
+    return "redirect:" + BADGE_URL_PREFIX + tag + BADGE_URL_SUFFIX;
+  }
+}

src/main/java/codes/thischwa/jdvs/web/FaviconController.java

@@ -0,0 +1,16 @@
+package codes.thischwa.jdvs.web;
+
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+/**
+ * Controller for favicon.ico, just for reducing 404 errors in the logs.
+ */
+@RestController
+public class FaviconController {
+
+  @GetMapping("favicon.ico")
+  void returnNoFavicon() {
+    // see class comment
+  }
+}

src/main/resources/templates/index.html

@@ -13,7 +13,7 @@
             <th>Name</th>
             <th>Latest Version</th>
             <th>Last Update</th>
-            <th>Action</th>
+            <th>Javadoc link</th>
         </tr>
         </thead>
         <tbody>
@@ -22,7 +22,9 @@
             <td th:text="${repo.lastTag}">-</td>
             <td th:text="${#temporals.format(repo.updated, 'dd.MM.yyyy HH:mm')}">-</td>
             <td>
-                <a th:if="${repo.lastTag != null}" th:href="@{/{name}/index.html(name=${repo.name})}" class="btn btn-primary btn-sm">Open Javadoc</a>
+                <a th:if="${repo.lastTag != null}" th:href="@{/{name}/index.html(name=${repo.name})}">
+                    <img th:src="@{/badge/{name}(name=${repo.name})}" alt="javadoc badge">
+                </a>
                 <span th:if="${repo.lastTag == null}" class="badge bg-secondary">Not yet generated</span>
             </td>
         </tr>