#708 wip, initial stubs/code

src/main/java/alfio/controller/IndexController.java

@@ -21,7 +21,10 @@
 import alfio.manager.system.ConfigurationLevel;
 import alfio.manager.system.ConfigurationManager;
 import alfio.manager.user.UserManager;
+import alfio.repository.EventRepository;
+import alfio.util.RequestUtils;
 import alfio.util.TemplateManager;
+import ch.digitalfondue.jfiveparse.*;
 import lombok.AllArgsConstructor;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.core.env.Environment;
@@ -37,6 +40,9 @@
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
 import java.security.Principal;
 import java.util.EnumSet;
 import java.util.Map;
@@ -53,6 +59,7 @@ public class IndexController {
     private static final String UTF_8 = "UTF-8";
 
     private final ConfigurationManager configurationManager;
+    private final EventRepository eventRepository;
     private final Environment environment;
     private final UserManager userManager;
     private final TemplateManager templateManager;
@@ -98,14 +105,37 @@ public ResponseEntity<String> replyToK8s() {
         "/event/{eventShortName}/reservation/{reservationId}/success",
         "/event/{eventShortName}/ticket/{ticketId}/view"
     })
-    public void replyToIndex(HttpServletResponse response) throws IOException {
+    public void replyToIndex(@PathVariable(value = "eventShortName", required = false) String eventShortName,
+                             @RequestHeader(value = "User-Agent", required = false) String userAgent,
+                             HttpServletResponse response) throws IOException {
+
         response.setContentType(TEXT_HTML_CHARSET_UTF_8);
         response.setCharacterEncoding(UTF_8);
-        try (var is = new ClassPathResource("alfio-public-frontend-index.html").getInputStream(); var os = response.getOutputStream()) {
-            is.transferTo(os);
+
+        if (eventShortName != null && RequestUtils.isSocialMediaShareUA(userAgent) && eventRepository.existsByShortName(eventShortName)) {
+            try (var is = new ClassPathResource("alfio/web-templates/event-open-graph-page.html").getInputStream(); var os = response.getOutputStream()) {
+                var res = getOpenGraphPage(is, eventShortName);
+                os.write(res);
+            }
+        } else {
+            try (var is = new ClassPathResource("alfio-public-frontend-index.html").getInputStream(); var os = response.getOutputStream()) {
+                is.transferTo(os);
+            }
         }
     }
 
+    private byte[] getOpenGraphPage(InputStream is, String eventShortName) {
+        var event = eventRepository.findByShortName(eventShortName);
+        var eventOpenGraph = new Parser().parse(new InputStreamReader(is, StandardCharsets.UTF_8));
+        eventOpenGraph.getElementsByTagName("title").get(0).appendChild(new Text(event.getDisplayName()));
+        getMetaElement(eventOpenGraph, "og:image").setAttribute("content", "file/" + event.getFileBlobId());
+        return eventOpenGraph.getOuterHTML().getBytes(StandardCharsets.UTF_8);
+    }
+
+    private static Element getMetaElement(Document document, String propertyValue) {
+        return (Element) document.getAllNodesMatching(Selector.select().element("meta").attrValEq("property", "og:image").toMatcher(), true).get(0);
+    }
+
     @GetMapping("/event/{eventShortName}/code/{code}")
     public String redirectCode(@PathVariable("eventShortName") String eventName,
                              @PathVariable("code") String code) {
@@ -114,7 +144,6 @@ public String redirectCode(@PathVariable("eventShortName") String eventName,
             .toString();
     }
 
-
     // login related
     @GetMapping("/authentication")
     public void getLoginPage(@RequestParam(value="failed", required = false) String failed, @RequestParam(value = "recaptchaFailed", required = false) String recaptchaFailed,

src/main/java/alfio/util/RequestUtils.java

@@ -23,6 +23,7 @@
 import javax.servlet.http.HttpServletRequest;
 import java.nio.charset.StandardCharsets;
 import java.util.Optional;
+import java.util.regex.Pattern;
 
 @Log4j2
 @UtilityClass
@@ -36,4 +37,10 @@ public static Optional<String> readRequest(HttpServletRequest request) {
             return Optional.empty();
         }
     }
+
+    private static final Pattern SOCIAL_MEDIA_UA = Pattern.compile("facebookexternalhit/|XING-contenttabreceiver/|LinkedInBot/|Twitterbot/");
+
+    public static boolean isSocialMediaShareUA(String ua) {
+        return ua != null && SOCIAL_MEDIA_UA.matcher(ua).find();
+    }
 }

src/main/resources/alfio/web-templates/event-open-graph-page.html

@@ -0,0 +1,10 @@
+<!DOCTYPE html>
+<html lang="" prefix="og: http://ogp.me/ns#">
+    <head>
+        <meta charset="UTF-8">
+        <title></title>
+        <meta property="og:type" content="website" />
+        <meta property="og:image" content="" />
+        <meta property="og:description" content="" />
+    </head>
+</html>

src/test/java/alfio/util/RequestUtilsTest.java

@@ -0,0 +1,32 @@
+/**
+ * This file is part of alf.io.
+ *
+ * alf.io is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * alf.io is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with alf.io.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package alfio.util;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class RequestUtilsTest {
+
+    @Test
+    public void testUA() {
+        Assertions.assertTrue(RequestUtils.isSocialMediaShareUA("facebookexternalhit/1.1 (+http://www.facebook.com/externalhit_uatext.php)"));
+        Assertions.assertTrue(RequestUtils.isSocialMediaShareUA("XING-contenttabreceiver/2.0"));
+        Assertions.assertTrue(RequestUtils.isSocialMediaShareUA("LinkedInBot/1.0 (compatible; Mozilla/5.0; Jakarta Commons-HttpClient/3.1 +http://www.linkedin.com)"));
+        Assertions.assertTrue(RequestUtils.isSocialMediaShareUA("Twitterbot/1.0"));
+        Assertions.assertFalse(RequestUtils.isSocialMediaShareUA("Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36"));
+    }
+}