[bramble-core] Add DB method for getting contact by handshake key

bramble-core/src/main/java/org/briarproject/bramble/db/Database.java

@@ -267,6 +267,16 @@ interface Database<T> {
 	 */
 	Collection<ContactId> getContacts(T txn, AuthorId local) throws DbException;
 
+	/**
+	 * Returns the contact with the given {@code handshakePublicKey}
+	 * for the given local pseudonym or {@code null} if none exists.
+	 * <p/>
+	 * Read-only.
+	 */
+	@Nullable
+	Contact getContact(T txn, PublicKey handshakePublicKey, AuthorId local)
+			throws DbException;
+
 	/**
 	 * Returns the group with the given ID.
 	 * <p/>

bramble-core/src/main/java/org/briarproject/bramble/db/JdbcDatabase.java

@@ -1465,6 +1465,43 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Nullable
+	@Override
+	public Contact getContact(Connection txn, PublicKey handshakePublicKey,
+			AuthorId localAuthorId) throws DbException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT contactId, authorId, formatVersion, name,"
+					+ " alias, publicKey, verified"
+					+ " FROM contacts"
+					+ " WHERE handshakePublicKey = ? AND localAuthorId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setBytes(1, handshakePublicKey.getEncoded());
+			ps.setBytes(2, localAuthorId.getBytes());
+			rs = ps.executeQuery();
+			if (!rs.next()) return null;
+			ContactId contactId = new ContactId(rs.getInt(1));
+			AuthorId authorId = new AuthorId(rs.getBytes(2));
+			int formatVersion = rs.getInt(3);
+			String name = rs.getString(4);
+			String alias = rs.getString(5);
+			PublicKey publicKey = new SignaturePublicKey(rs.getBytes(6));
+			boolean verified = rs.getBoolean(7);
+			if (rs.next()) throw new DbException();
+			rs.close();
+			ps.close();
+			Author author =
+					new Author(authorId, formatVersion, name, publicKey);
+			return new Contact(contactId, author, localAuthorId, alias,
+					handshakePublicKey, verified);
+		} catch (SQLException e) {
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public Group getGroup(Connection txn, GroupId g) throws DbException {
 		PreparedStatement ps = null;

bramble-core/src/test/java/org/briarproject/bramble/db/JdbcDatabaseTest.java

@@ -34,6 +34,7 @@ import org.briarproject.bramble.test.BrambleTestCase;
 import org.briarproject.bramble.test.SettableClock;
 import org.briarproject.bramble.test.TestDatabaseConfig;
 import org.briarproject.bramble.test.TestMessageFactory;
+import org.briarproject.bramble.test.TestUtils;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
@@ -1149,6 +1150,43 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		db.close();
 	}
 
+	@Test
+	public void testGetContactsByHandshakePublicKey() throws Exception {
+		Database<Connection> db = open(false);
+		Connection txn = db.startTransaction();
+
+		// Add an identity for a local author - no contacts should be
+		// associated
+		db.addIdentity(txn, identity);
+		PublicKey handshakePublicKey = TestUtils.getSignaturePublicKey();
+		Contact contact =
+				db.getContact(txn, handshakePublicKey, localAuthor.getId());
+		assertNull(contact);
+
+		// Add a contact associated with the local author
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
+				handshakePublicKey, true));
+		contact = db.getContact(txn, handshakePublicKey, localAuthor.getId());
+		assertNotNull(contact);
+		assertEquals(contactId, contact.getId());
+		assertEquals(author, contact.getAuthor());
+		assertNull(contact.getAlias());
+		assertEquals(handshakePublicKey, contact.getHandshakePublicKey());
+		assertTrue(contact.isVerified());
+		assertEquals(author.getName(), contact.getAuthor().getName());
+		assertEquals(author.getPublicKey(), contact.getAuthor().getPublicKey());
+		assertEquals(author.getFormatVersion(),
+				contact.getAuthor().getFormatVersion());
+
+		// Ensure no contacts are returned after contact was deleted
+		db.removeContact(txn, contactId);
+		contact = db.getContact(txn, handshakePublicKey, localAuthor.getId());
+		assertNull(contact);
+
+		db.commitTransaction(txn);
+		db.close();
+	}
+
 	@Test
 	public void testOfferedMessages() throws Exception {
 		Database<Connection> db = open(false);