Add interfaces for social backup recovery tasks.

briar-api/src/main/java/org/briarproject/briar/api/socialbackup/recovery/CustodianTask.java

@@ -0,0 +1,51 @@
+package org.briarproject.briar.api.socialbackup.recovery;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+public interface CustodianTask {
+
+	void start(Observer observer);
+
+	void cancel();
+
+	interface Observer {
+		void onStateChanged(State state);
+	}
+
+	class State {
+
+		static class Connecting extends State {
+		}
+
+		static class SendingShard extends State {
+		}
+
+		static class ReceivingAck extends State {
+		}
+
+		static class Success extends State {
+		}
+
+		static class Failure extends State {
+
+			enum Reason {
+				QR_CODE_INVALID,
+				QR_CODE_TOO_OLD,
+				QR_CODE_TOO_NEW,
+				NO_CONNECTION,
+				OTHER
+			}
+
+			private final Reason reason;
+
+			Failure(Reason reason) {
+				this.reason = reason;
+			}
+
+			public Reason getReason() {
+				return reason;
+			}
+		}
+	}
+}

briar-api/src/main/java/org/briarproject/briar/api/socialbackup/recovery/SecretOwnerTask.java

@@ -0,0 +1,53 @@
+package org.briarproject.briar.api.socialbackup.recovery;
+
+import org.briarproject.bramble.api.crypto.PublicKey;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.net.InetSocketAddress;
+
+@NotNullByDefault
+public interface SecretOwnerTask {
+
+	void start(Observer observer);
+
+	void cancel();
+
+	interface Observer {
+		void onStateChanged(State state);
+	}
+
+	class State {
+
+		static class Listening extends State {
+
+			private final PublicKey publicKey;
+			private final InetSocketAddress socketAddress;
+
+			public Listening(PublicKey publicKey,
+					InetSocketAddress socketAddress) {
+				this.publicKey = publicKey;
+				this.socketAddress = socketAddress;
+			}
+
+			public PublicKey getPublicKey() {
+				return publicKey;
+			}
+
+			public InetSocketAddress getSocketAddress() {
+				return socketAddress;
+			}
+		}
+
+		static class ReceivingShard extends State {
+		}
+
+		static class SendingAck extends State {
+		}
+
+		static class Success extends State {
+		}
+
+		static class Failure extends State {
+		}
+	}
+}