From ea182f0416432c5ce311499df230948d876edaaf Mon Sep 17 00:00:00 2001
From: Adam Retter <adam.retter@googlemail.com>
Date: Tue, 5 Sep 2023 01:00:01 +0200
Subject: [PATCH] [feature] Allow the redirect type (i.e. HTTP Response Status
 Code) to be specified in the URL Rewite Controller (i.e. `controller.xq`) See
 https://github.com/eXist-db/existdb-saml/issues/11

---
 .../org/exist/http/urlrewrite/Redirect.java   | 61 ++++++++++++++++++-
 1 file changed, 58 insertions(+), 3 deletions(-)

diff --git a/exist-core/src/main/java/org/exist/http/urlrewrite/Redirect.java b/exist-core/src/main/java/org/exist/http/urlrewrite/Redirect.java
index 432ea5e0715..c078c3d7300 100644
--- a/exist-core/src/main/java/org/exist/http/urlrewrite/Redirect.java
+++ b/exist-core/src/main/java/org/exist/http/urlrewrite/Redirect.java
@@ -27,14 +27,19 @@
 import jakarta.servlet.ServletException;
 import jakarta.servlet.http.HttpServletRequest;
 import jakarta.servlet.http.HttpServletResponse;
+
+import javax.annotation.Nullable;
 import java.io.IOException;
 
 public class Redirect extends URLRewrite {
 
+    private @Nullable RedirectType redirectType;
+
     public Redirect(final Element config, final String uri) throws ServletException {
         super(config, uri);
+        this.redirectType = parseRedirectType(config.getAttribute("type"));
         final String redirectTo = config.getAttribute("url");
-        if (redirectTo.length() == 0) {
+        if (redirectTo.isEmpty()) {
             throw new ServletException("<exist:redirect> needs an attribute 'url'.");
         }
         if (redirectTo.matches("^\\w+://.*")) {
@@ -47,16 +52,66 @@ public Redirect(final Element config, final String uri) throws ServletException
 
     public Redirect(final Redirect other) {
         super(other);
+        this.redirectType = other.redirectType;
     }
 
     @Override
     public void doRewrite(final HttpServletRequest request, final HttpServletResponse response) throws IOException {
-        setHeaders(new HttpResponseWrapper(response));
-        response.sendRedirect(target);
+        if (redirectType == null) {
+            redirectType =  "GET".equals(request.getMethod()) ? RedirectType.Found : RedirectType.SeeOther;
+        }
+
+        final HttpResponseWrapper responseWrapper = new HttpResponseWrapper(response);
+        setHeaders(responseWrapper);
+        responseWrapper.setStatusCode(redirectType.httpStatusCode);
+        responseWrapper.setHeader("Location", target);
+
+        // commit the response
+        responseWrapper.flushBuffer();
     }
 
     @Override
     protected URLRewrite copy() {
         return new Redirect(this);
     }
+
+    private static @Nullable RedirectType parseRedirectType(@Nullable final String strRedirectType) throws ServletException {
+        // first, if no value use the default
+        if (strRedirectType == null || strRedirectType.isEmpty()) {
+            return null;
+        }
+
+        // second, try to parse by number
+        try {
+            final int intRedirectType = Integer.valueOf(strRedirectType);
+            for (final RedirectType redirectType : RedirectType.values()) {
+                if (redirectType.httpStatusCode == intRedirectType) {
+                    return redirectType;
+                }
+            }
+        } catch (final NumberFormatException e) {
+            // ignore - no op
+        }
+
+        // third, try to parse by name
+        try {
+            return RedirectType.valueOf(strRedirectType);
+        } catch (final IllegalArgumentException e) {
+            throw new ServletException("<exist:redirect type=\"" + strRedirectType + "\" is unsupported.");
+        }
+    }
+
+    private enum RedirectType {
+        MovedPermanently(301),
+        Found(302),
+        SeeOther(303),
+        TemporaryRedirect(307),
+        PermanentRedirect(308);
+
+        public final int httpStatusCode;
+
+        RedirectType(final int httpStatusCode) {
+            this.httpStatusCode = httpStatusCode;
+        }
+    }
 }