Support more PDUs and create Client class

The Client class provides a nice, high-level async API for
client-server communication.

client/src/activities_view.vala

@@ -1,27 +1,6 @@
 namespace StudySystemClient {
-	private struct Activity {
-		public string subject;
-		public ActivityType type;
-	}
-
-	enum ActivityType {
-		EXERCISES,
-		READING;
-
-		public string to_string() {
-			switch (this) {
-			case EXERCISES:
-				return "Exercises";
-			case READING:
-				return "Reading";
-			default:
-				return "Invalid activity type";
-			}
-		}
-	}
-
 	public class ActivitiesView : Gtk.Box {
-		public ActivitiesView(Connection connection)  {
+		public ActivitiesView(Client client)  {
 			margin_top = margin_bottom = margin_start = margin_end = 0;
 
 			var scrolled_window = new Gtk.ScrolledWindow();
@@ -37,15 +16,15 @@ namespace StudySystemClient {
 			scrolled_window.add_css_class("card-container");
 
 			var activities = new Activity[] {
-				{ "Linguistics", ActivityType.EXERCISES },
-				{ "Cybernetics", ActivityType.EXERCISES },
-				{ "Linguistics", ActivityType.READING },
-				{ "Physics", ActivityType.READING },
-				{ "Cybernetics", ActivityType.READING },
-				{ "Physics", ActivityType.EXERCISES },
+				{ 2, "Linguistics", ActivityType.EXERCISES },
+				{ 1, "Cybernetics", ActivityType.EXERCISES },
+				{ 2, "Linguistics", ActivityType.READING },
+				{ 0, "Physics", ActivityType.READING },
+				{ 1, "Cybernetics", ActivityType.READING },
+				{ 0, "Physics", ActivityType.EXERCISES },
 			};
 			foreach (var activity in activities) {
-				var card = new ActivityCard(connection, activity);
+				var card = new ActivityCard(client, activity);
 				card_container.append(card);
 			}
 
@@ -55,7 +34,7 @@ namespace StudySystemClient {
 	}
 
 	private class ActivityCard : Gtk.Frame {
-		public ActivityCard(Connection connection, Activity activity) {
+		public ActivityCard(Client client, Activity activity) {
 			add_css_class("card");
 
 			var content = new Gtk.Box(Gtk.Orientation.HORIZONTAL, 12);
@@ -63,7 +42,7 @@ namespace StudySystemClient {
 			var text = new Gtk.Box(Gtk.Orientation.VERTICAL, 6);
 			text.hexpand = true;
 
-			var subject = new Gtk.Label(activity.subject);
+			var subject = new Gtk.Label(activity.subject_name);
 			subject.halign = Gtk.Align.START;
 			subject.add_css_class("activity-subject");
 			text.append(subject);
@@ -84,7 +63,7 @@ namespace StudySystemClient {
 
 			set_child(content);
 
-			var log_session_popover = new LogSessionPopover(connection);
+			var log_session_popover = new LogSessionPopover(client);
 			log_session_popover.set_parent(button);
 			button.clicked.connect(() => log_session_popover.popup());
 		}
@@ -94,10 +73,10 @@ namespace StudySystemClient {
 		private const int DEFAULT_LENGTH = 30;
 
 		private Gtk.SpinButton input;
-		private Connection connection;
+		private Client client;
 
-		public LogSessionPopover(Connection connection) {
-			this.connection = connection;
+		public LogSessionPopover(Client client) {
+			this.client = client;
 
 			var content = new Gtk.Box(Gtk.Orientation.HORIZONTAL, 6);
 
@@ -126,8 +105,13 @@ namespace StudySystemClient {
 		private async void submit() {
 			reset();
 			popdown();
-			yield connection.send(new Request.Ping());
-			stderr.printf("Got ACK\n");
+
+			try {
+				yield client.ping();
+				stderr.printf("Successfully pinged server\n");
+			} catch (ClientError e) {
+				stderr.printf("Error pinging server: %s\n", e.message);
+			}
 		}
 
 		private void reset() {

client/src/activity.vala

@@ -0,0 +1,24 @@
+namespace StudySystemClient {
+	public struct Activity {
+		public int subject_id;
+		public string subject_name;
+		public ActivityType type;
+		public double priority;
+	}
+
+	public enum ActivityType {
+		EXERCISES,
+		READING;
+
+		public string to_string() {
+			switch (this) {
+			case EXERCISES:
+				return "Exercises";
+			case READING:
+				return "Reading";
+			default:
+				return "Invalid activity type";
+			}
+		}
+	}
+}

client/src/client.vala

@@ -0,0 +1,62 @@
+namespace StudySystemClient {
+	public errordomain ClientError {
+		ERROR_RESPONSE,
+		UNEXPECTED_RESPONSE,
+	}
+
+	public class Client {
+		private Connection connection;
+
+		public Client(string cert_dir) throws Error {
+			connection = new Connection(cert_dir);
+		}
+
+		public async void ping() throws ClientError {
+			var response = yield connection.send(new Request.Ping());
+			if (response is Response.Ack) {
+				return;
+			} else if (response is Response.Error) {
+				throw new ClientError.ERROR_RESPONSE(
+					"Error response to Ping: %s",
+					response.value.to_string());
+			} else {
+				throw new ClientError.UNEXPECTED_RESPONSE(
+					"Unexpected response to Ping");
+			}
+		}
+
+		public async Array<Activity> list_activities()
+				throws ClientError {
+			var request = new Request.ListActivities();
+			var response = yield connection.send(request);
+			if (response is Response.Activities) {
+				return response.value;
+			} else if (response is Response.Error) {
+				throw new ClientError.ERROR_RESPONSE(
+					"Error response to ListActivities: %s",
+					response.value.to_string());
+			} else {
+				throw new ClientError.UNEXPECTED_RESPONSE(
+					"Unexpected response to ListActivities");
+			}
+		}
+
+		public async void log_session(int subject_id, ActivityType type,
+									  int minutes) throws ClientError {
+			var timestamp = new DateTime.now_utc().to_unix();
+			var request = new Request.LogSession(subject_id, type,
+												 timestamp, minutes);
+			var response = yield connection.send(request);
+			if (response is Response.Ack) {
+				return;
+			} else if (response is Response.Error) {
+				throw new ClientError.ERROR_RESPONSE(
+					"Error response to LogSession: %s",
+					response.value.to_string());
+			} else {
+				throw new ClientError.UNEXPECTED_RESPONSE(
+					"Unexpected response to LogSession");
+			}
+		}
+	}
+}

client/src/main.vala

@@ -14,8 +14,8 @@ namespace StudySystemClient {
 					css_provider,
 					Gtk.STYLE_PROVIDER_PRIORITY_APPLICATION);
 
-				var connection = new Connection(Config.CERT_DIR);
-				var main_window = new MainWindow(this, connection);
+				var client = new Client(Config.CERT_DIR);
+				var main_window = new MainWindow(this, client);
 				main_window.present();
 			} catch (Error e) {
 				stderr.printf("Failed to initialize: %s\n", e.message);

client/src/main_window.vala

@@ -1,22 +1,18 @@
 namespace StudySystemClient {
 	public class MainWindow : Gtk.ApplicationWindow {
-		private Connection connection;
-
-		public MainWindow(Gtk.Application app, Connection connection) {
+		public MainWindow(Gtk.Application app, Client client) {
 			Object(application: app);
 
 			default_width = 360;
 			default_height = 580;
 
-			this.connection = connection;
-
 			var header_bar = new Gtk.HeaderBar();
 			var title = new Gtk.Label("Study System Client");
 			title.add_css_class("title");
 			header_bar.title_widget = title;
 			set_titlebar(header_bar);
 
-			var activities_view = new ActivitiesView(connection);
+			var activities_view = new ActivitiesView(client);
 			set_child(activities_view);
 		}
 	}

client/src/meson.build

@@ -10,7 +10,9 @@ configure_file(
 lib = library(
   'study-system-client',
   sources: files(
+    'activity.vala',
     'activities_view.vala',
+    'client.vala',
     'connection.vala',
     'der.vala',
     'main_window.vala',

client/src/request.vala

@@ -15,16 +15,40 @@ namespace StudySystemClient.Request {
 	public abstract class Body {
 		protected enum Tag {
 			PING = 0,
-			LIST_PRIORITIZED_ACTIVITIES = 1,
+			LIST_ACTIVITIES = 1,
 			LOG_SESSION = 2,
 		}
 
 		internal Der.Datum datum;
+
+		protected Body(Tag tag, Der.Datum datum) {
+			this.datum = new Der.Choice(tag, datum);
+		}
 	}
 
 	public class Ping : Body {
 		public Ping() {
-			datum = new Der.Choice(Tag.PING, new Der.Null());
+			base(Tag.PING, new Der.Null());
+		}
+	}
+
+	public class ListActivities : Body {
+		public ListActivities() {
+			base(Tag.LIST_ACTIVITIES, new Der.Null());
+		}
+	}
+
+	public class LogSession : Body {
+		public LogSession(int subject_id, ActivityType type,
+						  int64 timestamp, int minutes)
+		{
+			var fields = new Der.Datum[] {
+				new Der.Integer(subject_id),
+				new Der.Enumerated((int)type),
+				new Der.Integer(timestamp),
+				new Der.Integer(minutes),
+			};
+			base(Tag.LOG_SESSION, new Der.Sequence(fields));
 		}
 	}
 }

client/src/response.vala

@@ -15,9 +15,9 @@ namespace StudySystemClient.Response {
 				throw new DecodeError.INVALID_RESPONSE(
 					"Response was not a SEQUENCE");
 			}
-			if (sequence.value.length != 2) {
+			if (sequence.value.length < 2) {
 				throw new DecodeError.INVALID_RESPONSE(
-					"Response sequnce contained %u fields (expected 2)",
+					"Too few fields in Response: %u (expected 2)",
 					sequence.value.length);
 			}
 			var id_datum = sequence.value[0] as Der.Integer;
@@ -68,7 +68,20 @@ namespace StudySystemClient.Response {
 		public enum Value {
 			INVALID_REQUEST = 0,
 			INVALID_ARGUMENTS = 1,
-			SERVER_ERROR = 2,
+			SERVER_ERROR = 2;
+
+			public string to_string() {
+				switch (this) {
+				case INVALID_REQUEST:
+					return "Invalid request";
+				case INVALID_ARGUMENTS:
+					return "Invalid arguments";
+				case SERVER_ERROR:
+					return "Server error";
+				default:
+					return "Unknown error";
+				}
+			}
 		}
 
 		public Value value { get; private set; }
@@ -95,4 +108,71 @@ namespace StudySystemClient.Response {
 			}
 		}
 	}
+
+	public class Activities : Body {
+		public Array<Activity> value { get; private set; }
+
+		internal Activities.from_datum(Der.Datum datum) throws DecodeError {
+			value = new Array<Activity>();
+			if (datum is Der.Sequence) {
+				foreach (var activity_datum in datum.value)
+					value.append_val(activity_from_datum(activity_datum));
+			} else {
+				throw new DecodeError.INVALID_BODY(
+					"Activities was not a SEQUENCE");
+			}
+		}
+
+		private static Activity activity_from_datum(Der.Datum datum)
+			throws DecodeError {
+			if (datum is Der.Sequence) {
+				var fields = datum.value;
+				if (fields.length < 4) {
+					throw new DecodeError.INVALID_BODY(
+						"Too few fields in Activity: %u (expected 4)",
+						fields.length);
+				}
+				var subject_id = get_int("Activity.subjectId", fields[0]);
+				var subject_name
+					= get_string("Activity.subjectName", fields[1]);
+				var activity_type
+					= get_activity_type("Activity.type", fields[2]);
+				var int_priority = get_int("Activity.priority", fields[3]);
+				var priority = (double)int_priority / 100.0;
+				return { subject_id, subject_name, activity_type, priority };
+
+			} else {
+				throw new DecodeError.INVALID_BODY(
+					"Activity was not a SEQUENCE");
+			}
+		}
+
+		private static int get_int(string name, Der.Datum datum)
+			throws DecodeError {
+			if (datum is Der.Integer)
+				return (int)datum.value;
+			throw new DecodeError.INVALID_BODY(@"$name was not an INTEGER");
+		}
+
+		private static string get_string(string name, Der.Datum datum)
+			throws DecodeError {
+			if (datum is Der.Utf8String)
+				return datum.value;
+			throw new DecodeError.INVALID_BODY(
+				@"$name was not a UTF8String");
+		}
+
+		private static ActivityType get_activity_type(
+			string name, Der.Datum datum) throws DecodeError {
+			if (datum is Der.Enumerated) {
+				var value = datum.value;
+				if (0 <= value <= 1)
+					return (ActivityType)value;
+				throw new DecodeError.INVALID_BODY(
+					"Invalid value for ActivityType: %lld", value);
+			}
+			throw new DecodeError.INVALID_BODY(
+				@"$name was not an ENUMERATED");
+		}
+	}
 }