Allow redirection of url to local resources

inspector-vc/src/main/java/org/oneedtech/inspect/vc/util/CachingDocumentLoader.java

@@ -2,8 +2,10 @@ package org.oneedtech.inspect.vc.util;
 
 import java.io.InputStream;
 import java.net.URI;
+import java.net.URISyntaxException;
 import java.net.URL;
 import java.time.Duration;
+import java.util.Map;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -32,10 +34,14 @@ public class CachingDocumentLoader extends ConfigurableDocumentLoader {
 
 
 	public CachingDocumentLoader() {
+		this(null);
+	}
+
+	public CachingDocumentLoader(Map<URI, String> localDomains) {
 		super();
 		setEnableHttp(true);
 		setEnableHttps(true);
-		setDefaultHttpLoader(new HttpLoader());
+		setDefaultHttpLoader(new HttpLoader(localDomains));
 	}
 
 	@Override
@@ -49,16 +55,41 @@ public class CachingDocumentLoader extends ConfigurableDocumentLoader {
 	}
 
 	public class HttpLoader implements DocumentLoader {
+		final Map<URI, String> localDomains;
+
+		public HttpLoader(Map<URI, String> localDomains) {
+			this.localDomains = localDomains;
+		}
+
 		@Override
 		public Document loadDocument(URI url, DocumentLoaderOptions options) throws JsonLdError {
-			Tuple<String, DocumentLoaderOptions> tpl = new Tuple<>(url.toASCIIString(), options);
 			try {
+				// resolve url
+				URI resolvedUrl = resolve(url);
+
+				Tuple<String, DocumentLoaderOptions> tpl = new Tuple<>(resolvedUrl.toASCIIString(), options);
+
 				return documentCache.get(tpl);
 			} catch (Exception e) {
 				logger.error("documentCache not able to load {}", url);
 				throw new JsonLdError(JsonLdErrorCode.INVALID_REMOTE_CONTEXT, e.getMessage());
 			}
 		}
+
+		/**
+		 * Resolved given url. If the url is from one of local domain, a URL of the relative resource will be returned
+		 * @throws URISyntaxException
+		 */
+		private URI resolve(URI url) throws URISyntaxException {
+			if (localDomains != null) {
+				URI base = url.resolve("/");
+				if (localDomains.containsKey(base)) {
+					URL resource = Resources.getResource(localDomains.get(base) + "/" + base.relativize(url).toString());
+					return resource.toURI();
+				}
+			}
+			return url;
+		}
 	}
 
 	static final ImmutableMap<String, URL> bundled = ImmutableMap.<String, URL>builder()

inspector-vc/src/test/java/org/oneedtech/inspect/vc/util/CachingDocumentLoaderTests.java

@@ -1,27 +1,47 @@
 package org.oneedtech.inspect.vc.util;
 
 import java.net.URI;
+import java.net.URL;
+import java.util.Map;
 
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
 import com.apicatalog.jsonld.document.Document;
+import com.apicatalog.jsonld.document.JsonDocument;
 import com.apicatalog.jsonld.loader.DocumentLoader;
 import com.apicatalog.jsonld.loader.DocumentLoaderOptions;
+import com.google.common.io.Resources;
 
 public class CachingDocumentLoaderTests {
 
 	@Test
 	void testStaticCachedDocumentBundled() {
 		Assertions.assertDoesNotThrow(()->{
-			DocumentLoader loader = new CachingDocumentLoader();			
+			DocumentLoader loader = new CachingDocumentLoader();
 			for(String id : CachingDocumentLoader.bundled.keySet()) {
 				Document doc = loader.loadDocument(new URI(id), new DocumentLoaderOptions());
-				Assertions.assertNotNull(doc);	
+				Assertions.assertNotNull(doc);
-			}						
+			}
 		});
 	}
-	
+
+	@Test
+	void testLocalDomainCachedDocument() {
+		Assertions.assertDoesNotThrow(()->{
+			Map<URI, String> localDomains = Map.of(new URI("http://example.org/"), "ob20");
+			DocumentLoader loader = new CachingDocumentLoader(localDomains);
+			URI uri = new URI("http://example.org/basic-assertion.json");
+			Document doc = loader.loadDocument(uri, new DocumentLoaderOptions());
+			Assertions.assertNotNull(doc);
+
+			// assert the returned document is the same as the local resource
+			URL resource = Resources.getResource("ob20/basic-assertion.json");
+			JsonDocument resourceDocument = JsonDocument.of(resource.openStream());
+			Assertions.assertEquals(resourceDocument.getJsonContent().toString(), doc.getJsonContent().toString());
+		});
+	}
+
 	@Test
 	void testStaticCachedDocumentKey() {
 		Assertions.assertDoesNotThrow(()->{
@@ -30,5 +50,5 @@ public class CachingDocumentLoaderTests {
 			Document doc = loader.loadDocument(uri, new DocumentLoaderOptions());
 			Assertions.assertNotNull(doc);
 		});
-	}	
+	}
 }