implement page caching

4 files changed, 96 insertions, 8 deletions

diff --git a/clams-server/src/main/java/no/eliashaugsbakk/clams/server/Main.java b/clams-server/src/main/java/no/eliashaugsbakk/clams/server/App.java
index eba65f8..5910f43 100644
--- a/clams-server/src/main/java/no/eliashaugsbakk/clams/server/Main.java
+++ b/clams-server/src/main/java/no/eliashaugsbakk/clams/server/App.java
@@ -9,15 +9,18 @@ import no.eliashaugsbakk.clams.server.config.AppRoutes;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-public class Main {
-  private static final Logger log = LoggerFactory.getLogger(Main.class);
+public class App {
+  private static final Logger log = LoggerFactory.getLogger(App.class);
   void main() {
     // Initialize dependencies
     AppContext context = new AppContext();
 
     try {
       Javalin.create(config -> {
-        config.staticFiles.add("/public");
+        config.staticFiles.add(staticFiles -> {
+          staticFiles.hostedPath = "/";
+          staticFiles.directory = "/public";
+        });
         config.fileRenderer(new JavalinPebble());
 
         config.routes.error(404, ctx -> {
@@ -51,7 +54,6 @@ public class Main {
         });
 
         config.routes.apiBuilder(new AppRoutes(context));
-
         config.events.serverStopped(context::close);
       }).start(7070);
 
diff --git a/clams-server/src/main/java/no/eliashaugsbakk/clams/server/config/AppContext.java b/clams-server/src/main/java/no/eliashaugsbakk/clams/server/config/AppContext.java
index 2d52374..189edc7 100644
--- a/clams-server/src/main/java/no/eliashaugsbakk/clams/server/config/AppContext.java
+++ b/clams-server/src/main/java/no/eliashaugsbakk/clams/server/config/AppContext.java
@@ -13,6 +13,7 @@ import no.eliashaugsbakk.clams.server.repository.ProjectsRepo;
 import no.eliashaugsbakk.clams.server.repository.ProjectsRepoSqlite;
 import no.eliashaugsbakk.clams.server.repository.SqliteManager;
 import no.eliashaugsbakk.clams.server.service.AuthService;
+import no.eliashaugsbakk.clams.server.service.PageCache;
 import no.eliashaugsbakk.clams.server.service.SlugService;
 
 public class AppContext implements AutoCloseable {
@@ -22,6 +23,7 @@ public class AppContext implements AutoCloseable {
   private final PostController postController;
   private final ProjectsController projectsController;
   private final AuthService authService;
+  private final PageCache pageCache;
 
   public AppContext() {
     AppConfig appConfig = new AppConfig();
@@ -41,6 +43,7 @@ public class AppContext implements AutoCloseable {
     this.projectsController = new ProjectsController(projectsRepo);
     this.postController = new PostController(postsRepo, slugService);
     this.authService = new AuthService(appConfig);
+    this.pageCache = new PageCache(15);
   }
 
   public PostsController getPostsController() { return postsController; }
@@ -48,6 +51,7 @@ public class AppContext implements AutoCloseable {
   public ProjectsController getProjectsController() { return projectsController; }
   public PostController getPostController() { return postController; }
   public AuthService getAuthService() { return authService; }
+  public PageCache pageCache() { return pageCache; }
 
   @Override
   public void close() {
diff --git a/clams-server/src/main/java/no/eliashaugsbakk/clams/server/config/AppRoutes.java b/clams-server/src/main/java/no/eliashaugsbakk/clams/server/config/AppRoutes.java
index abd2926..b296f4f 100644
--- a/clams-server/src/main/java/no/eliashaugsbakk/clams/server/config/AppRoutes.java
+++ b/clams-server/src/main/java/no/eliashaugsbakk/clams/server/config/AppRoutes.java
@@ -1,5 +1,6 @@
 package no.eliashaugsbakk.clams.server.config;
 
+import static io.javalin.apibuilder.ApiBuilder.after;
 import static io.javalin.apibuilder.ApiBuilder.before;
 import static io.javalin.apibuilder.ApiBuilder.delete;
 import static io.javalin.apibuilder.ApiBuilder.get;
@@ -19,6 +20,51 @@ public class AppRoutes implements EndpointGroup {
 
   @Override
   public void addEndpoints() {
+    before(ctx -> {
+      String path = ctx.path();
+
+      // Skip non-GET requests and API endpoints
+      if (!ctx.method().name().equalsIgnoreCase("GET")
+          || path.startsWith("/api")
+          || ctx.queryString() != null) {
+        return;
+      }
+
+      String cachedHtml = appContext.pageCache().get(path);
+      if (cachedHtml != null) {
+        ctx.result(cachedHtml);
+        ctx.contentType("text/html");
+        ctx.skipRemainingHandlers();
+      }
+    });
+
+    after(ctx -> {
+      String method = ctx.method().name();
+      String path = ctx.path();
+
+      // Invalidate cache on any modifying request if successful
+      if ((method.equalsIgnoreCase("POST")
+          || method.equalsIgnoreCase("PUT")
+          || method.equalsIgnoreCase("DELETE"))
+          && ctx.status().getCode() >= 200 && ctx.status().getCode() < 300) {
+        appContext.pageCache().clear();
+        return;
+      }
+
+      // 2. Cache GET responses
+      if (method.equalsIgnoreCase("GET")
+          && !path.startsWith("/api") // exclude API responses
+          && ctx.queryString() == null // exclude queried pages
+          && ctx.status().getCode() == 200) { // only cache successful responses
+
+        String renderedHtml = ctx.result();
+        if (renderedHtml != null && !renderedHtml.isBlank()) {
+          appContext.pageCache().put(path, renderedHtml);
+        }
+      }
+    });
+
+
     get("/", ctx -> ctx.redirect("/home"));
     get("/home", ctx -> ctx.render("templates/home.html",
         Map.of("page_title", "Elias Haugsbakk", "page_css", "home")));
@@ -35,8 +81,8 @@ public class AppRoutes implements EndpointGroup {
         String authHeader = ctx.header("Authorization");
 
         if (authHeader == null || !authHeader.startsWith("Bearer ")) {
-          ctx.status(401).json(Map.of("error", "Unauthorized",
-              "message", "Missing or malformed Authorization header."));
+          ctx.status(401).json(Map.of("error", "Unauthorized", "message",
+              "Missing or malformed Authorization header."));
           ctx.skipRemainingHandlers();
           return;
         }
@@ -44,8 +90,7 @@ public class AppRoutes implements EndpointGroup {
         String token = authHeader.substring(7).trim();
         if (!appContext.getAuthService().isValid(token)) {
           ctx.status(403)
-              .json(Map.of("error", "Forbidden",
-                  "message", "Invalid API validation token."));
+              .json(Map.of("error", "Forbidden", "message", "Invalid API validation token."));
           ctx.skipRemainingHandlers();
         }
       });
diff --git a/clams-server/src/main/java/no/eliashaugsbakk/clams/server/service/PageCache.java b/clams-server/src/main/java/no/eliashaugsbakk/clams/server/service/PageCache.java
new file mode 100644
index 0000000..4313cce
--- /dev/null
+++ b/clams-server/src/main/java/no/eliashaugsbakk/clams/server/service/PageCache.java
@@ -0,0 +1,37 @@
+package no.eliashaugsbakk.clams.server.service;
+
+import java.util.Collections;
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+public class PageCache {
+  private final Map<String, String> cache;
+
+  /**
+   * Least Recently Used Cache
+   */
+  public PageCache(int capacity) {
+
+    LinkedHashMap<String, String> map = new LinkedHashMap<>(capacity, 0.75f, true) {
+      @Override
+      protected boolean removeEldestEntry(Map.Entry<String, String> eldest) {
+        return size() > capacity;
+      }
+    };
+
+    // Wrap with synchronizedMap to make thread-safe
+    this.cache = Collections.synchronizedMap(map);
+  }
+
+  public String get(String url) {
+    return cache.get(url);
+  }
+
+  public void put(String url, String html) {
+    cache.put(url, html);
+  }
+
+  public void clear() {
+    cache.clear();
+  }
+}