Add method to get a pending contact.

bramble-api/src/main/java/org/briarproject/bramble/api/contact/ContactManager.java

@@ -87,6 +87,12 @@ public interface ContactManager {
 	PendingContact addPendingContact(String link, String alias)
 			throws DbException, FormatException;
 
+	/**
+	 * Returns the pending contact with the given ID.
+	 */
+	PendingContact getPendingContact(Transaction txn, PendingContactId p)
+			throws DbException;
+
 	/**
 	 * Returns a list of {@link PendingContact PendingContacts} and their
 	 * {@link PendingContactState states}.

bramble-api/src/main/java/org/briarproject/bramble/api/db/DatabaseComponent.java

@@ -411,6 +411,14 @@ public interface DatabaseComponent extends TransactionManager {
 	 */
 	long getNextSendTime(Transaction txn, ContactId c) throws DbException;
 
+	/**
+	 * Returns the pending contact with the given ID.
+	 * <p/>
+	 * Read-only.
+	 */
+	PendingContact getPendingContact(Transaction txn, PendingContactId p)
+			throws DbException;
+
 	/**
 	 * Returns all pending contacts.
 	 * <p/>

bramble-core/src/main/java/org/briarproject/bramble/contact/ContactManagerImpl.java

@@ -127,6 +127,12 @@ class ContactManagerImpl implements ContactManager {
 		return p;
 	}
 
+	@Override
+	public PendingContact getPendingContact(Transaction txn, PendingContactId p)
+			throws DbException {
+		return db.getPendingContact(txn, p);
+	}
+
 	@Override
 	public Collection<Pair<PendingContact, PendingContactState>> getPendingContacts()
 			throws DbException {

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

@@ -496,6 +496,14 @@ interface Database<T> {
 	 */
 	long getNextSendTime(T txn, ContactId c) throws DbException;
 
+	/**
+	 * Returns the pending contact with the given ID.
+	 * <p/>
+	 * Read-only.
+	 */
+	PendingContact getPendingContact(T txn, PendingContactId p)
+			throws DbException;
+
 	/**
 	 * Returns all pending contacts.
 	 * <p/>

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

@@ -712,6 +712,15 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return db.getNextSendTime(txn, c);
 	}
 
+	@Override
+	public PendingContact getPendingContact(Transaction transaction,
+			PendingContactId p) throws DbException {
+		T txn = unbox(transaction);
+		if (!db.containsPendingContact(txn, p))
+			throw new NoSuchPendingContactException();
+		return db.getPendingContact(txn, p);
+	}
+
 	@Override
 	public Collection<PendingContact> getPendingContacts(
 			Transaction transaction) throws DbException {

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

@@ -2205,6 +2205,30 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public PendingContact getPendingContact(Connection txn, PendingContactId p)
+			throws DbException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT publicKey, alias, timestamp"
+					+ " FROM pendingContacts"
+					+ " WHERE pendingContactId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setBytes(1, p.getBytes());
+			rs = ps.executeQuery();
+			if (!rs.next()) throw new DbStateException();
+			PublicKey publicKey = new AgreementPublicKey(rs.getBytes(1));
+			String alias = rs.getString(2);
+			long timestamp = rs.getLong(3);
+			return new PendingContact(p, publicKey, alias, timestamp);
+		} catch (SQLException e) {
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public Collection<PendingContact> getPendingContacts(Connection txn)
 			throws DbException {

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

@@ -763,12 +763,12 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 			throws Exception {
 		context.checking(new Expectations() {{
 			// Check whether the pending contact is in the DB (which it's not)
-			exactly(3).of(database).startTransaction();
+			exactly(4).of(database).startTransaction();
 			will(returnValue(txn));
-			exactly(3).of(database).containsPendingContact(txn,
+			exactly(4).of(database).containsPendingContact(txn,
 					pendingContactId);
 			will(returnValue(false));
-			exactly(3).of(database).abortTransaction(txn);
+			exactly(4).of(database).abortTransaction(txn);
 		}});
 		DatabaseComponent db = createDatabaseComponent(database, eventBus,
 				eventExecutor, shutdownManager);
@@ -791,6 +791,14 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 			// Expected
 		}
 
+		try {
+			db.transaction(false, transaction ->
+					db.getPendingContact(transaction, pendingContactId));
+			fail();
+		} catch (NoSuchPendingContactException expected) {
+			// Expected
+		}
+
 		try {
 			db.transaction(false, transaction ->
 					db.removePendingContact(transaction, pendingContactId));

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

@@ -2204,14 +2204,14 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertEquals(emptyList(), db.getPendingContacts(txn));
 
 		db.addPendingContact(txn, pendingContact);
+		PendingContact retrieved =
+				db.getPendingContact(txn, pendingContact.getId());
+		assertPendingContactEquals(pendingContact, retrieved);
+
 		Collection<PendingContact> pendingContacts = db.getPendingContacts(txn);
 		assertEquals(1, pendingContacts.size());
-		PendingContact retrieved = pendingContacts.iterator().next();
-		assertEquals(pendingContact.getId(), retrieved.getId());
-		assertEquals(pendingContact.getAlias(), retrieved.getAlias());
-		assertArrayEquals(pendingContact.getPublicKey().getEncoded(),
-				retrieved.getPublicKey().getEncoded());
-		assertEquals(pendingContact.getTimestamp(), retrieved.getTimestamp());
+		retrieved = pendingContacts.iterator().next();
+		assertPendingContactEquals(pendingContact, retrieved);
 
 		db.removePendingContact(txn, pendingContact.getId());
 		assertEquals(emptyList(), db.getPendingContacts(txn));
@@ -2220,6 +2220,15 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		db.close();
 	}
 
+	private void assertPendingContactEquals(PendingContact expected,
+			PendingContact actual) {
+		assertEquals(expected.getId(), actual.getId());
+		assertArrayEquals(expected.getPublicKey().getEncoded(),
+				actual.getPublicKey().getEncoded());
+		assertEquals(expected.getAlias(), actual.getAlias());
+		assertEquals(expected.getTimestamp(), actual.getTimestamp());
+	}
+
 	@Test
 	public void testTransferKeys() throws Exception {
 		boolean alice = random.nextBoolean();