Introduce CRUD to GCR

[lgpl/argeo-commons.git] / org.argeo.api / src / org / argeo / api / gcr / ContentNamespace.java

diff --git a/org.argeo.api/src/org/argeo/api/gcr/ContentNamespace.java b/org.argeo.api/src/org/argeo/api/gcr/ContentNamespace.java
new file mode 100644 (file)
index 0000000..a595571
--- /dev/null
+++ b/org.argeo.api/src/org/argeo/api/gcr/ContentNamespace.java
@@ -0,0 +1,106 @@
+package org.argeo.api.gcr;
+
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.nio.charset.StandardCharsets;
+import java.util.Objects;
+import java.util.UUID;
+
+/**
+ * An XML-style namespace with a related UUID v3.
+ * 
+ * @see https://www.w3.org/TR/xml-names/
+ */
+public class ContentNamespace {
+       private final UUID uuid;
+       private final URI uri;
+
+       public ContentNamespace(String uri) {
+               try {
+                       this.uri = new URI(uri);
+               } catch (URISyntaxException e) {
+                       throw new IllegalArgumentException("Cannot interpret " + uri + " as URI", e);
+               }
+               this.uuid = namespaceUuid(this.uri);
+       }
+
+       public ContentNamespace(URI uri) {
+               this.uri = uri;
+               this.uuid = namespaceUuid(uri);
+       }
+
+       ContentNamespace(URI uri, UUID uuid) {
+               this.uri = uri;
+               assert uuid.equals(namespaceUuid(uri));
+               this.uuid = uuid;
+       }
+
+       /** Empty namespace */
+       private ContentNamespace() {
+               try {
+                       this.uri = new URI("");
+               } catch (URISyntaxException e) {
+                       throw new IllegalStateException("Cannot create empty URI");
+               }
+               this.uuid = NIL_UUID;
+       }
+
+       public UUID getUuid() {
+               return uuid;
+       }
+
+       public URI getUri() {
+               return uri;
+       }
+
+       public UUID nameUuid(String name) {
+               return nameUuid(getUuid(), name);
+       }
+
+
+       public final static UUID NIL_UUID = UUID.fromString("00000000-0000-0000-0000-000000000000");
+       public final static ContentNamespace EMPTY_NS = new ContentNamespace();
+
+       /**
+        * The UUID v3 of http://www.w3.org/2000/xmlns/ within the standard DNS
+        * namespace, to be used as a base for the namespaces.
+        * 
+        * @see https://www.w3.org/TR/xml-names/#ns-decl
+        */
+       // uuidgen --md5 --namespace @dns --name http://www.w3.org/2000/xmlns/
+       // NOTE : must be declared before default namespaces
+       public final static UUID XMLNS_UUID = UUID.fromString("4b352aad-ba1c-3139-b9d3-41e5816f6088");
+       public final static ContentNamespace CR_NS = new ContentNamespace("http://argeo.org/ns/cr");
+
+
+       public static UUID namespaceUuid(URI namespaceUri) {
+               Objects.requireNonNull(namespaceUri, "Namespace URI cannot be null");
+               return nameUUIDv3(XMLNS_UUID, namespaceUri.toString().getBytes(StandardCharsets.UTF_8));
+       }
+
+       public static UUID nameUuid(UUID namespace, String name) {
+               Objects.requireNonNull(namespace, "Namespace cannot be null");
+               Objects.requireNonNull(namespace, "Name cannot be null");
+               return nameUUIDv3(namespace, name.getBytes(StandardCharsets.UTF_8));
+       }
+
+       /*
+        * CANONICAL IMPLEMENTATION based on java.util.UUID.nameUUIDFromBytes(byte[])
+        */
+       private static UUID nameUUIDv3(UUID namespace, byte[] name) {
+               byte[] arr = new byte[name.length + 16];
+               copyUuidBytes(namespace, arr, 0);
+               System.arraycopy(name, 0, arr, 16, name.length);
+               return UUID.nameUUIDFromBytes(arr);
+       }
+
+       private static void copyUuidBytes(UUID uuid, byte[] arr, int offset) {
+               long msb = uuid.getMostSignificantBits();
+               long lsb = uuid.getLeastSignificantBits();
+               assert arr.length >= 16 + offset;
+               for (int i = offset; i < 8 + offset; i++)
+                       arr[i] = (byte) ((msb >> ((7 - i) * 8)) & 0xff);
+               for (int i = 8 + offset; i < 16 + offset; i++)
+                       arr[i] = (byte) ((lsb >> ((15 - i) * 8)) & 0xff);
+       }
+}