1 files changed, 55 insertions, 0 deletions

diff --git a/language-web/src/main/java/org/eclipse/viatra/solver/language/web/CacheControlFilter.java b/language-web/src/main/java/org/eclipse/viatra/solver/language/web/CacheControlFilter.java
new file mode 100644
index 00000000..41b8e5bf
--- /dev/null
+++ b/language-web/src/main/java/org/eclipse/viatra/solver/language/web/CacheControlFilter.java
@@ -0,0 +1,55 @@
+package org.eclipse.viatra.solver.language.web;
+
+import java.io.IOException;
+import java.util.regex.Pattern;
+
+import javax.servlet.Filter;
+import javax.servlet.FilterChain;
+import javax.servlet.FilterConfig;
+import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+public class CacheControlFilter implements Filter {
+
+        private static final String CACHE_CONTROL_HEADER = "Cache-Control";
+
+        private static final String EXPIRES_HEADER = "Expires";
+
+        private static final Pattern CACHE_URI_PATTERN = Pattern.compile(".*\\.(css|gif|js|map|png|svg|woff2)");
+
+        private static final long EXPIRY = 31536000;
+
+        private static final String CACHE_CONTROL_CACHE_VALUE = "public, max-age: " + EXPIRY + ", immutable";
+
+        private static final String CACHE_CONTROL_NO_CACHE_VALUE = "no-cache, no-store, max-age: 0, must-revalidate";
+
+        @Override
+        public void init(FilterConfig filterConfig) throws ServletException {
+                // Nothing to initialize.
+        }
+
+        @Override
+        public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
+                        throws IOException, ServletException {
+                if (request instanceof HttpServletRequest && response instanceof HttpServletResponse) {
+                        var httpRequest = (HttpServletRequest) request;
+                        var httpResponse = (HttpServletResponse) response;
+                        if (CACHE_URI_PATTERN.matcher(httpRequest.getRequestURI()).matches()) {
+                                httpResponse.setHeader(CACHE_CONTROL_HEADER, CACHE_CONTROL_CACHE_VALUE);
+                                httpResponse.setDateHeader(EXPIRES_HEADER, System.currentTimeMillis() + EXPIRY * 1000L);
+                        } else {
+                                httpResponse.setHeader(CACHE_CONTROL_HEADER, CACHE_CONTROL_NO_CACHE_VALUE);
+                                httpResponse.setDateHeader(EXPIRES_HEADER, 0);
+                        }
+                }
+                chain.doFilter(request, response);
+        }
+
+        @Override
+        public void destroy() {
+                // Nothing to dispose.
+        }
+}