Initial sub-tasks support

In addition to normal dependencies, the application now supports
sub-tasks. Sub-tasks can be added into any existing task (including
other sub-tasks, Inception-style).

Dependencies can only be added between global tasks, or between
sub-tasks of the same task. It is no longer possible to mark a task as
finished if it has incomplete sub-tasks, and conversedly, it is not
possible to reactivate a sub-task if its parent is marked as completed.

A pair of buttons allowing tasks to be moved up and down in the task
hierarachy have been added.

database.sql

@@ -14,8 +14,10 @@ BEGIN;
 \i database/items-functions.sql
 
 -- Task management and task dependencies
+\i database/task-containers.sql
 \i database/tasks-functions.sql
 \i database/task-dependencies.sql
+\i database/tasks-move-sub.sql
 \i database/tasks-view.sql
 
 COMMIT;

database/create-tables.sql

@@ -27,6 +27,43 @@ GRANT SELECT,UPDATE ON task_dependencies_taskdep_id_seq TO :webapp_user;
 -- Tables
 
 
+/*
+ * Task containers
+ * ----------------
+ *
+ * A task container is either an item or a task. Task names within the
+ * same task container are unique.
+ */
+CREATE TABLE task_containers (
+	tc_id		SERIAL NOT NULL PRIMARY KEY ,
+	task_id		INT UNIQUE ,
+	item_id		INT UNIQUE ,
+	CHECK( task_id IS NULL AND item_id IS NOT NULL OR task_id IS NOT NULL AND item_id IS NULL )
+);
+
+GRANT SELECT ON task_containers TO :webapp_user;
+
+
+/*
+ * Logical task containers
+ * ------------------------
+ *
+ * A logical task container is a group of tasks that can depend on each other.
+ * One such container exists for all top-level tasks, and each task defines a
+ * container as well.
+ */
+CREATE TABLE logical_task_containers(
+	ltc_id		SERIAL NOT NULL PRIMARY KEY ,
+	task_id		INT UNIQUE ,
+	CHECK( ltc_id = 1 AND task_id IS NULL OR ltc_id <> 1 AND task_id IS NOT NULL )
+);
+
+INSERT INTO logical_task_containers DEFAULT VALUES;
+
+GRANT SELECT ON logical_task_containers TO :webapp_user;
+
+
+
 --  Table items
 CREATE TABLE items (
 	item_id						INT NOT NULL DEFAULT NEXTVAL('items_item_id_seq'::TEXT),
@@ -51,6 +88,13 @@ ALTER TABLE items ADD FOREIGN KEY (item_id_parent)
 GRANT SELECT,INSERT,UPDATE,DELETE ON items TO :webapp_user;
 
 
+-- Add reference from task containers to items
+ALTER TABLE task_containers
+	ADD FOREIGN KEY ( item_id ) REFERENCES items( item_id )
+		ON UPDATE NO ACTION
+		ON DELETE CASCADE;
+
+
 
 --  Table users
 CREATE TABLE users (
@@ -70,21 +114,38 @@ GRANT SELECT,INSERT,UPDATE ON users TO :webapp_user;
 
 --  Table tasks
 CREATE TABLE tasks (
-	task_id							INT NOT NULL DEFAULT NEXTVAL('tasks_task_id_seq'::TEXT),
+	task_id						INT NOT NULL DEFAULT NEXTVAL('tasks_task_id_seq'::TEXT),
-	item_id						INT NOT NULL REFERENCES items(item_id) ON UPDATE NO ACTION ON DELETE CASCADE,
+	ltc_id						INT NOT NULL REFERENCES logical_task_containers( ltc_id )
-	task_title						VARCHAR(256) NOT NULL,
+								ON UPDATE NO ACTION ON DELETE CASCADE ,
-	task_priority						INT NOT NULL,
+	tc_id						INT NOT NULL REFERENCES task_containers( tc_id )
-	task_description					TEXT NOT NULL,
+								ON UPDATE NO ACTION ON DELETE CASCADE ,
-	task_added						TIMESTAMP WITHOUT TIME ZONE NOT NULL DEFAULT now(),
+	task_title					VARCHAR(256) NOT NULL,
-	user_id							INT NOT NULL REFERENCES users(user_id) ON UPDATE NO ACTION ON DELETE CASCADE,
+	task_priority					INT NOT NULL,
-	user_id_assigned					INT REFERENCES users(user_id) ON UPDATE NO ACTION ON DELETE SET NULL ,
+	task_description				TEXT NOT NULL,
-	PRIMARY KEY(task_id)
+	task_added					TIMESTAMP WITHOUT TIME ZONE NOT NULL DEFAULT now(),
+	user_id						INT NOT NULL REFERENCES users(user_id) ON UPDATE NO ACTION ON DELETE CASCADE,
+	user_id_assigned				INT REFERENCES users(user_id) ON UPDATE NO ACTION ON DELETE SET NULL ,
+
+	PRIMARY KEY( task_id )
 );
 
-CREATE UNIQUE INDEX i_tasks_item_id_task_title ON tasks (item_id,task_title);
+CREATE UNIQUE INDEX i_tasks_title ON tasks (tc_id,task_title);
+CREATE UNIQUE INDEX i_tasks_ltc ON tasks (task_id , ltc_id);
 GRANT SELECT,INSERT,UPDATE,DELETE ON tasks TO :webapp_user;
 
 
+-- Add reference from task containers to tasks
+ALTER TABLE task_containers
+	ADD FOREIGN KEY ( task_id ) REFERENCES tasks( task_id )
+		ON UPDATE NO ACTION
+		ON DELETE CASCADE;
+
+-- Add reference from logical task containers to tasks
+ALTER TABLE logical_task_containers
+	ADD FOREIGN KEY ( task_id ) REFERENCES tasks( task_id )
+		ON UPDATE NO ACTION
+		ON DELETE CASCADE;
+
 
 --  Table items_tree
 CREATE TABLE items_tree (
@@ -112,13 +173,23 @@ GRANT SELECT,INSERT,UPDATE,DELETE ON completed_tasks TO :webapp_user;
 --  Table task_dependencies
 CREATE TABLE task_dependencies (
 	taskdep_id						INT NOT NULL DEFAULT NEXTVAL('task_dependencies_taskdep_id_seq'::TEXT),
-	task_id							INT NOT NULL REFERENCES tasks(task_id) ON UPDATE NO ACTION ON DELETE CASCADE,
+	ltc_id							INT NOT NULL ,
-	task_id_depends						INT NOT NULL REFERENCES tasks(task_id) ON UPDATE NO ACTION ON DELETE CASCADE,
+	task_id							INT NOT NULL ,
+	task_id_depends						INT NOT NULL ,
 	PRIMARY KEY(taskdep_id)
 );
 
 CREATE UNIQUE INDEX i_taskdep_unicity ON task_dependencies (task_id,task_id_depends);
 CREATE INDEX i_taskdep_bydependency ON task_dependencies (task_id_depends);
+
+ALTER TABLE task_dependencies
+	ADD CONSTRAINT fk_taskdep_task
+		FOREIGN KEY ( ltc_id , task_id ) REFERENCES tasks( ltc_id , task_id )
+			ON UPDATE NO ACTION ON DELETE CASCADE ,
+	ADD CONSTRAINT fk_taskdep_dependency
+		FOREIGN KEY ( ltc_id , task_id_depends ) REFERENCES tasks( ltc_id , task_id )
+			ON UPDATE NO ACTION ON DELETE CASCADE;
+
 GRANT SELECT,INSERT,DELETE ON task_dependencies TO :webapp_user;
 
 

database/task-containers.sql

@@ -0,0 +1,43 @@
+/*
+ * Triggers to handle task containers
+ */
+
+
+DROP FUNCTION IF EXISTS tgf_item_tc_ai( ) CASCADE;
+CREATE FUNCTION tgf_item_tc_ai( )
+		RETURNS TRIGGER
+		LANGUAGE PLPGSQL
+		SECURITY DEFINER
+	AS $tgf_item_tc_ai$
+BEGIN
+	INSERT INTO task_containers ( item_id )
+		VALUES ( NEW.item_id );
+	RETURN NEW;
+END;
+$tgf_item_tc_ai$;
+
+REVOKE EXECUTE ON FUNCTION tgf_item_tc_ai( ) FROM PUBLIC;
+
+CREATE TRIGGER tg_item_tc_ai AFTER INSERT ON items
+	FOR EACH ROW EXECUTE PROCEDURE tgf_item_tc_ai( );
+
+
+DROP FUNCTION IF EXISTS tgf_task_tc_ai( ) CASCADE;
+CREATE FUNCTION tgf_task_tc_ai( )
+		RETURNS TRIGGER
+		LANGUAGE PLPGSQL
+		SECURITY DEFINER
+	AS $tgf_task_tc_ai$
+BEGIN
+	INSERT INTO task_containers ( task_id )
+		VALUES ( NEW.task_id );
+	INSERT INTO logical_task_containers ( task_id )
+		VALUES ( NEW.task_id );
+	RETURN NEW;
+END;
+$tgf_task_tc_ai$;
+
+REVOKE EXECUTE ON FUNCTION tgf_task_tc_ai( ) FROM PUBLIC;
+
+CREATE TRIGGER tg_task_tc_ai AFTER INSERT ON tasks
+	FOR EACH ROW EXECUTE PROCEDURE tgf_task_tc_ai( );

database/task-dependencies.sql

@@ -252,12 +252,15 @@ REVOKE EXECUTE ON FUNCTION tgf_taskdep_bi() FROM PUBLIC;
 --
 -- List all dependencies that can be added to a task.
 --
-CREATE OR REPLACE FUNCTION tasks_possible_dependencies( o_id INT )
+DROP FUNCTION IF EXISTS tasks_possible_dependencies( INT );
+CREATE FUNCTION tasks_possible_dependencies( o_id INT )
 	RETURNS SETOF tasks
 	STRICT STABLE
 AS $tasks_possible_dependencies$
-	SELECT * FROM tasks
+	SELECT t.*
-		WHERE task_id NOT IN (
+		FROM tasks t
+			INNER JOIN tasks t2 USING ( ltc_id )
+		WHERE t2.task_id = $1 AND t.task_id NOT IN (
 			SELECT d.task_id_depends AS id
 				FROM taskdep_nodes n1
 					INNER JOIN task_dependencies d
@@ -281,18 +284,28 @@ GRANT EXECUTE ON FUNCTION tasks_possible_dependencies( INT ) TO :webapp_user;
 --
 -- Add a dependency
 --
-CREATE OR REPLACE FUNCTION tasks_add_dependency( t_id INT , t_dependency INT )
+DROP FUNCTION IF EXISTS tasks_add_dependency( INT , INT );
+CREATE FUNCTION tasks_add_dependency( t_id INT , t_dependency INT )
 		RETURNS INT
 		STRICT VOLATILE
 		SECURITY INVOKER
 	AS $tasks_add_dependency$
+
+DECLARE
+	ltc	INT;
+
 BEGIN
-	INSERT INTO task_dependencies( task_id , task_id_depends )
+	SELECT INTO ltc ltc_id FROM tasks WHERE task_id = t_id;
-		VALUES ( t_id , t_dependency );
+	IF NOT FOUND THEN
+		RETURN 1;
+	END IF;
+
+	INSERT INTO task_dependencies( ltc_id , task_id , task_id_depends )
+		VALUES ( ltc , t_id , t_dependency );
 	RETURN 0;
 EXCEPTION
 	WHEN foreign_key_violation THEN
-		RETURN 1;
+		RETURN 3;
 	WHEN check_violation THEN
 		RETURN 2;
 END;

database/tasks-functions.sql

@@ -1,29 +1,109 @@
 -- Create a new task
-CREATE OR REPLACE FUNCTION add_task( t_item INT , t_title TEXT , t_description TEXT , t_priority INT , t_user INT )
+DROP FUNCTION IF EXISTS add_task( INT , TEXT , TEXT , INT , INT ) CASCADE;
+CREATE FUNCTION add_task( t_item INT , t_title TEXT , t_description TEXT , t_priority INT , t_user INT )
 		RETURNS INT
 		STRICT VOLATILE
 		SECURITY INVOKER
 	AS $add_task$
+DECLARE
+	_container		INT;
+	_logical_container	INT;
 BEGIN
-	INSERT INTO tasks ( item_id , task_title , task_description , task_priority , user_id )
+	SELECT INTO _container tc_id
-		VALUES ( t_item , t_title , t_description , t_priority , t_user );
+		FROM task_containers
+		WHERE item_id = t_item;
+	IF NOT FOUND THEN
+		RETURN 2;
+	END IF;
+
+	SELECT INTO _logical_container ltc_id
+		FROM logical_task_containers
+		WHERE task_id IS NULL;
+
+	INSERT INTO tasks ( tc_id , ltc_id , task_title , task_description , task_priority , user_id )
+		VALUES ( _container , _logical_container , t_title , t_description , t_priority , t_user );
 	RETURN 0;
 EXCEPTION
 	WHEN unique_violation THEN
 		RETURN 1;
-	WHEN foreign_key_violation THEN
-		RETURN 2;
 END;
 $add_task$ LANGUAGE plpgsql;
 
+REVOKE EXECUTE ON FUNCTION add_task( INT , TEXT , TEXT , INT , INT ) FROM PUBLIC;
+GRANT EXECUTE ON FUNCTION add_task( INT , TEXT , TEXT , INT , INT ) TO :webapp_user;
+
+-- Create a new nested task
+DROP FUNCTION IF EXISTS tasks_add_nested( INT , TEXT , TEXT , INT , INT ) CASCADE;
+CREATE FUNCTION tasks_add_nested( t_parent INT , t_title TEXT , t_description TEXT , t_priority INT , t_user INT )
+		RETURNS INT
+		STRICT VOLATILE
+		SECURITY INVOKER
+	AS $tasks_add_nested$
+DECLARE
+	_container		INT;
+	_logical_container	INT;
+BEGIN
+	SELECT INTO _container tc.tc_id
+		FROM task_containers tc
+			INNER JOIN tasks t USING ( task_id )
+			LEFT OUTER JOIN completed_tasks ct USING ( task_id )
+		WHERE t.task_id = t_parent AND ct.task_id IS NULL;
+	IF NOT FOUND THEN
+		RETURN 2;
+	END IF;
+
+	SELECT INTO _logical_container ltc_id
+		FROM logical_task_containers
+		WHERE task_id = t_parent;
+
+	INSERT INTO tasks ( tc_id , ltc_id , task_title , task_description , task_priority , user_id )
+		VALUES ( _container , _logical_container , t_title , t_description , t_priority , t_user );
+	RETURN 0;
+EXCEPTION
+	WHEN unique_violation THEN
+		RETURN 1;
+END;
+$tasks_add_nested$ LANGUAGE plpgsql;
+
+REVOKE EXECUTE ON FUNCTION tasks_add_nested( INT , TEXT , TEXT , INT , INT ) FROM PUBLIC;
+GRANT EXECUTE ON FUNCTION tasks_add_nested( INT , TEXT , TEXT , INT , INT ) TO :webapp_user;
+
 
 -- Mark a task as finished
-CREATE OR REPLACE FUNCTION finish_task( t_id INT , u_id INT , n_text TEXT )
+DROP FUNCTION IF EXISTS finish_task( INT , INT , TEXT );
+CREATE FUNCTION finish_task( t_id INT , u_id INT , n_text TEXT )
 		RETURNS INT
 		STRICT VOLATILE
 		SECURITY INVOKER
 	AS $finish_task$
 BEGIN
+	PERFORM 1
+		FROM tasks t
+			LEFT OUTER JOIN (
+				SELECT ltc.task_id , COUNT( * ) AS c
+					FROM logical_task_containers ltc
+						INNER JOIN tasks t
+							USING ( ltc_id )
+						LEFT OUTER JOIN completed_tasks ct
+							ON ct.task_id = t.task_id
+					WHERE ltc.task_id = t_id
+						AND ct.task_id IS NULL
+					GROUP BY ltc.task_id
+				) s1 USING ( task_id )
+			LEFT OUTER JOIN (
+				SELECT td.task_id , COUNT( * ) AS c
+					FROM task_dependencies td
+						LEFT OUTER JOIN completed_tasks ct
+							ON ct.task_id = td.task_id_depends
+					WHERE td.task_id = t_id
+						AND ct.task_id IS NULL
+					GROUP BY td.task_id
+				) s2 USING ( task_id )
+		WHERE task_id = t_id AND s1.c IS NULL AND s2.c IS NULL;
+	IF NOT FOUND THEN
+		RETURN 2;
+	END IF;
+
 	BEGIN
 		INSERT INTO completed_tasks ( task_id , user_id )
 			VALUES ( t_id , u_id );
@@ -45,12 +125,33 @@ GRANT EXECUTE ON FUNCTION finish_task( INT , INT , TEXT ) TO :webapp_user;
 
 
 -- Restart a task
-CREATE OR REPLACE FUNCTION restart_task( t_id INT , u_id INT , n_text TEXT )
+DROP FUNCTION IF EXISTS restart_task( INT , INT , TEXT );
+CREATE FUNCTION restart_task( t_id INT , u_id INT , n_text TEXT )
 		RETURNS INT
 		STRICT VOLATILE
 		SECURITY INVOKER
 	AS $restart_task$
 BEGIN
+	PERFORM 1
+		FROM tasks t
+			INNER JOIN logical_task_containers ltc
+				USING ( ltc_id )
+			INNER JOIN completed_tasks ct
+				ON ct.task_id = ltc.task_id
+		WHERE t.task_id = t_id;
+	IF FOUND THEN
+		RETURN 2;
+	END IF;
+
+	PERFORM 1
+		FROM task_dependencies td
+			INNER JOIN completed_tasks ct
+				USING ( task_id )
+		WHERE td.task_id_depends = t_id;
+	IF FOUND THEN
+		RETURN 2;
+	END IF;
+
 	DELETE FROM completed_tasks WHERE task_id = t_id;
 	IF NOT FOUND THEN
 		RETURN 1;
@@ -68,7 +169,62 @@ GRANT EXECUTE ON FUNCTION restart_task( INT , INT , TEXT ) TO :webapp_user;
 
 
 -- Update a task
-CREATE OR REPLACE FUNCTION update_task( t_id INT , p_id INT , t_title TEXT , t_description TEXT , t_priority INT , t_assignee INT )
+DROP FUNCTION IF EXISTS update_task( INT , INT , TEXT , TEXT , INT , INT );
+CREATE FUNCTION update_task( t_id INT , p_id INT , t_title TEXT , t_description TEXT , t_priority INT , t_assignee INT )
+		RETURNS INT
+		STRICT VOLATILE
+		SECURITY INVOKER
+	AS $update_task$
+
+DECLARE
+	tc	INT;
+
+BEGIN
+	PERFORM 1
+		FROM tasks
+			INNER JOIN logical_task_containers
+				USING ( ltc_id )
+			LEFT OUTER JOIN completed_tasks
+				ON tasks.task_id = completed_tasks.task_id
+		WHERE tasks.task_id = t_id
+			AND logical_task_containers.task_id IS NULL
+			AND completed_task_time IS NULL
+		FOR UPDATE OF tasks;
+	IF NOT FOUND THEN
+		RETURN 4;
+	END IF;
+
+	SELECT INTO tc tc_id FROM task_containers
+		WHERE item_id = p_id;
+	IF NOT FOUND THEN
+		RETURN 2;
+	END IF;
+
+	IF t_assignee = 0 THEN
+		t_assignee := NULL;
+	END IF;
+	UPDATE tasks SET tc_id = tc , task_title = t_title ,
+			task_description = t_description ,
+			task_priority = t_priority ,
+			user_id_assigned = t_assignee
+		WHERE task_id = t_id;
+
+	RETURN 0;
+EXCEPTION
+	WHEN unique_violation THEN
+		RETURN 1;
+	WHEN foreign_key_violation THEN
+		RETURN 3;
+END;
+$update_task$ LANGUAGE plpgsql;
+
+REVOKE EXECUTE ON FUNCTION update_task( INT , INT , TEXT , TEXT , INT , INT ) FROM PUBLIC;
+GRANT EXECUTE ON FUNCTION update_task( INT , INT , TEXT , TEXT , INT , INT ) TO :webapp_user;
+
+
+-- Update a nested task
+DROP FUNCTION IF EXISTS update_task( INT , TEXT , TEXT , INT , INT );
+CREATE FUNCTION update_task( t_id INT , t_title TEXT , t_description TEXT , t_priority INT , t_assignee INT )
 		RETURNS INT
 		STRICT VOLATILE
 		SECURITY INVOKER
@@ -76,41 +232,35 @@ CREATE OR REPLACE FUNCTION update_task( t_id INT , p_id INT , t_title TEXT , t_d
 BEGIN
 	PERFORM 1
 		FROM tasks
+			INNER JOIN logical_task_containers
+				USING ( ltc_id )
 			LEFT OUTER JOIN completed_tasks
-				USING( task_id )
+				ON tasks.task_id = completed_tasks.task_id
-		WHERE task_id = t_id AND completed_task_time IS NULL
+		WHERE tasks.task_id = t_id
+			AND logical_task_containers.task_id IS NOT NULL
+			AND completed_task_time IS NULL
 		FOR UPDATE OF tasks;
 	IF NOT FOUND THEN
 		RETURN 4;
 	END IF;
 
-	BEGIN
+	IF t_assignee = 0 THEN
-		IF t_assignee <= 0 THEN
+		t_assignee := NULL;
-			t_assignee := NULL;
+	END IF;
-		END IF;
+	UPDATE tasks
-		BEGIN
+		SET task_title = t_title ,
-			UPDATE tasks SET user_id_assigned = t_assignee WHERE task_id = t_id;
+			task_description = t_description ,
-		EXCEPTION
+			task_priority = t_priority ,
-			WHEN foreign_key_violation THEN
+			user_id_assigned = t_assignee
-				RAISE EXCEPTION 'bad user';
+		WHERE task_id = t_id;
-		END;
-		UPDATE tasks SET item_id = p_id , task_title = t_title ,
-				task_description = t_description ,
-				task_priority = t_priority
-			WHERE task_id = t_id;
-	EXCEPTION
-		WHEN unique_violation THEN
-			RETURN 1;
-		WHEN foreign_key_violation THEN
-			RETURN 2;
-		WHEN raise_exception THEN
-			RETURN 3;
-	END;
-
 	RETURN 0;
+EXCEPTION
+	WHEN unique_violation THEN
+		RETURN 1;
+	WHEN foreign_key_violation THEN
+		RETURN 2;
 END;
 $update_task$ LANGUAGE plpgsql;
 
-
+REVOKE EXECUTE ON FUNCTION update_task( INT , TEXT , TEXT , INT , INT ) FROM PUBLIC;
-REVOKE EXECUTE ON FUNCTION update_task( INT , INT , TEXT , TEXT , INT , INT ) FROM PUBLIC;
+GRANT EXECUTE ON FUNCTION update_task( INT , TEXT , TEXT , INT , INT ) TO :webapp_user;
-GRANT EXECUTE ON FUNCTION update_task( INT , INT , TEXT , TEXT , INT , INT ) TO :webapp_user;

database/tasks-move-sub.sql

@@ -0,0 +1,148 @@
+/*
+ * View that represents possible "move down" targets for a task
+ */
+DROP VIEW IF EXISTS tasks_move_down_targets;
+CREATE VIEW tasks_move_down_targets
+	AS SELECT t.task_id , tgt.task_id AS target_id , tgt.task_title AS target_title
+		FROM tasks t
+			LEFT OUTER JOIN completed_tasks tct
+				USING ( task_id )
+			INNER JOIN tasks tgt
+				USING ( ltc_id )
+			INNER JOIN logical_task_containers ltc
+				ON ltc.task_id = tgt.task_id
+			LEFT OUTER JOIN tasks tsubs
+				ON tsubs.ltc_id = ltc.ltc_id
+					AND LOWER( tsubs.task_title ) = LOWER( t.task_title )
+			LEFT OUTER JOIN completed_tasks csubs
+				ON csubs.task_id = tgt.task_id
+		WHERE tgt.task_id <> t.task_id
+			AND tsubs.task_id IS NULL
+			AND tct.task_id IS NULL
+			AND csubs.task_id IS NULL;
+
+GRANT SELECT ON tasks_move_down_targets TO :webapp_user;
+
+
+/*
+ * View that represents all tasks which can be moved up one level
+ */
+DROP VIEW IF EXISTS tasks_can_move_up CASCADE;
+CREATE VIEW tasks_can_move_up
+	AS SELECT t.task_id
+		FROM tasks t
+			LEFT OUTER JOIN completed_tasks tct
+				USING ( task_id )
+			INNER JOIN logical_task_containers ptc
+				USING ( ltc_id )
+			INNER JOIN tasks tgt
+				ON tgt.task_id = ptc.task_id
+			LEFT OUTER JOIN tasks psubs
+				ON psubs.ltc_id = tgt.ltc_id
+					AND LOWER( psubs.task_title ) = LOWER( t.task_title )
+		WHERE tct IS NULL
+			AND psubs IS NULL;
+
+
+
+/*
+ * Move the task to its grand-parent, if:
+ * - there are no dependencies and reverse dependencies,
+ * - or the _force parameter is true.
+ */
+DROP FUNCTION IF EXISTS tasks_move_up( _task INT , _force BOOLEAN );
+CREATE FUNCTION tasks_move_up( _task INT , _force BOOLEAN )
+		RETURNS BOOLEAN
+		LANGUAGE PLPGSQL
+		STRICT VOLATILE
+		SECURITY DEFINER
+	AS $tasks_move_up$
+
+DECLARE
+	_gp_container	INT;
+	_gp_lcontainer	INT;
+
+BEGIN
+	PERFORM 1 FROM tasks_can_move_up WHERE task_id = _task;
+	IF NOT FOUND THEN
+		RETURN FALSE;
+	END IF;
+
+	PERFORM 1 FROM task_dependencies
+		WHERE ( task_id = _task OR task_id_depends = _task ) AND NOT _force;
+	IF FOUND THEN
+		RETURN FALSE;
+	END IF;
+
+	SELECT INTO _gp_container , _gp_lcontainer
+		gp.tc_id , gp.ltc_id
+		FROM tasks t 
+			INNER JOIN logical_task_containers lt
+				USING ( ltc_id )
+			INNER JOIN tasks gp
+				ON gp.task_id = lt.task_id
+		WHERE t.task_id = _task;
+
+	DELETE FROM task_dependencies
+		WHERE task_id = _task OR task_id_depends = _task;
+	UPDATE tasks
+		SET tc_id = _gp_container ,
+			ltc_id = _gp_lcontainer
+		WHERE task_id = _task;
+	RETURN TRUE;
+END;
+$tasks_move_up$;
+
+REVOKE EXECUTE ON FUNCTION tasks_move_up( INT , BOOLEAN ) FROM PUBLIC;
+GRANT EXECUTE ON FUNCTION tasks_move_up( INT , BOOLEAN ) TO :webapp_user;
+
+
+/*
+ * Move the task into one of its siblings, if:
+ * - there are no dependencies and reverse dependencies,
+ * - or the _force parameter is true.
+ */
+DROP FUNCTION IF EXISTS tasks_move_down( _task INT , _sibling INT , _force BOOLEAN );
+CREATE FUNCTION tasks_move_down( _task INT , _sibling INT , _force BOOLEAN )
+		RETURNS BOOLEAN
+		LANGUAGE PLPGSQL
+		STRICT VOLATILE
+		SECURITY DEFINER
+	AS $tasks_move_down$
+
+DECLARE
+	_s_container	INT;
+	_s_lcontainer	INT;
+
+BEGIN
+	PERFORM 1 FROM tasks_move_down_targets
+		WHERE task_id = _task AND target_id = _sibling;
+	IF NOT FOUND THEN
+		RETURN FALSE;
+	END IF;
+
+	PERFORM 1 FROM task_dependencies
+		WHERE ( task_id = _task OR task_id_depends = _task ) AND NOT _force;
+	IF FOUND THEN
+		RETURN FALSE;
+	END IF;
+
+	SELECT INTO _s_container tc_id
+		FROM task_containers
+		WHERE task_id = _sibling;
+	SELECT INTO _s_lcontainer ltc_id
+		FROM logical_task_containers
+		WHERE task_id = _sibling;
+
+	DELETE FROM task_dependencies
+		WHERE task_id = _task OR task_id_depends = _task;
+	UPDATE tasks
+		SET tc_id = _s_container ,
+			ltc_id = _s_lcontainer
+		WHERE task_id = _task;
+	RETURN TRUE;
+END;
+$tasks_move_down$;
+
+REVOKE EXECUTE ON FUNCTION tasks_move_down( INT , INT , BOOLEAN ) FROM PUBLIC;
+GRANT EXECUTE ON FUNCTION tasks_move_down( INT , INT , BOOLEAN ) TO :webapp_user;

database/tasks-view.sql

@@ -1,3 +1,29 @@
+/*
+ * Task view
+ *
+ * This view is used by the application when loading individual tasks.
+ */
+DROP VIEW IF EXISTS tasks_single_view;
+CREATE VIEW tasks_single_view
+	AS SELECT t.task_id AS id, t.task_title AS title, tc.item_id AS item , tc.task_id AS parent_task ,
+			t.task_description AS description, t.task_added AS added_at,
+			u1.user_view_name AS added_by, ct.completed_task_time AS completed_at,
+			u2.user_view_name AS assigned_to , u2.user_id AS assigned_id ,
+			u3.user_view_name AS completed_by, t.user_id AS uid ,
+			t.task_priority AS priority ,
+			( cmu IS NOT NULL ) AS can_move_up
+		FROM tasks t
+			INNER JOIN task_containers tc USING ( tc_id )
+			INNER JOIN users_view u1 ON u1.user_id = t.user_id
+			LEFT OUTER JOIN completed_tasks ct ON ct.task_id = t.task_id
+			LEFT OUTER JOIN users_view u2 ON u2.user_id = t.user_id_assigned
+			LEFT OUTER JOIN users_view u3 ON u3.user_id = ct.user_id
+			LEFT OUTER JOIN tasks_can_move_up cmu ON cmu.task_id = t.task_id;
+
+GRANT SELECT ON tasks_single_view TO :webapp_user;
+
+
+
 --
 -- Task list view
 --
@@ -6,7 +32,8 @@
 
 DROP VIEW IF EXISTS tasks_list;
 CREATE VIEW tasks_list
-	AS SELECT t.task_id AS id, t.item_id AS item, t.task_title AS title,
+	AS SELECT t.task_id AS id, tc.item_id AS item , tc.task_id AS parent_task ,
+			t.task_title AS title,
 			t.task_description AS description, t.task_added AS added_at,
 			u1.user_view_name AS added_by,
 			ct.completed_task_time AS completed_at,
@@ -15,8 +42,19 @@ CREATE VIEW tasks_list
 			u3.user_view_name AS completed_by ,
 			t.task_priority AS priority ,
 			bd.bad_deps AS missing_dependencies ,
-			mtd.trans_missing AS total_missing_dependencies
+			bc.bad_children AS missing_subtasks ,
+			( CASE
+				WHEN mtd.trans_missing IS NULL AND bc.bad_children IS NULL THEN
+					NULL::BIGINT
+				WHEN mtd.trans_missing IS NULL THEN
+					bc.bad_children
+				WHEN bc.bad_children IS NULL THEN
+					mtd.trans_missing
+				ELSE
+					bc.bad_children + mtd.trans_missing
+			END ) AS total_missing_dependencies
 		FROM tasks t
+			INNER JOIN task_containers tc USING( tc_id )
 			INNER JOIN users_view u1 ON u1.user_id = t.user_id
 			LEFT OUTER JOIN completed_tasks ct ON ct.task_id = t.task_id
 			LEFT OUTER JOIN users_view u2 ON u2.user_id = t.user_id_assigned
@@ -29,6 +67,16 @@ CREATE VIEW tasks_list
 					WHERE dct.task_id IS NULL
 					GROUP BY td.task_id
 				) AS bd ON bd.task_id = t.task_id
+			LEFT OUTER JOIN (
+				SELECT ltc.task_id , COUNT( * ) AS bad_children
+					FROM logical_task_containers ltc
+						INNER JOIN tasks t
+							USING ( ltc_id )
+						LEFT OUTER JOIN completed_tasks ct
+							ON ct.task_id = t.task_id
+					WHERE ct.task_id IS NULL
+					GROUP BY ltc.task_id
+				) AS bc ON bc.task_id = t.task_id
 			LEFT OUTER JOIN (
 				SELECT tdn.task_id , COUNT( DISTINCT task_id_copyof ) AS trans_missing
 					FROM taskdep_nodes tdn

database/upgrade/from-49cc53e31f80084bd5f530f0f37d6f8d219ea3b0.sql

@@ -0,0 +1,612 @@
+--
+-- Upgrade the database from commit ID 49cc53e31f80084bd5f530f0f37d6f8d219ea3b0
+--
+-- Run this from the top-level directory
+--
+
+\i database/config.sql
+\c :db_name
+
+BEGIN;
+
+	CREATE TABLE task_containers (
+		tc_id		SERIAL NOT NULL PRIMARY KEY ,
+		task_id		INT UNIQUE ,
+		item_id		INT UNIQUE ,
+		CHECK( task_id IS NULL AND item_id IS NOT NULL OR task_id IS NOT NULL AND item_id IS NULL )
+	);
+	GRANT SELECT ON task_containers TO :webapp_user;
+	ALTER TABLE task_containers
+		ADD FOREIGN KEY ( item_id ) REFERENCES items( item_id )
+			ON UPDATE NO ACTION
+			ON DELETE CASCADE ,
+		ADD FOREIGN KEY ( task_id ) REFERENCES tasks( task_id )
+			ON UPDATE NO ACTION
+			ON DELETE CASCADE;
+	INSERT INTO task_containers ( item_id )
+		SELECT item_id FROM items;
+	INSERT INTO task_containers ( task_id )
+		SELECT task_id FROM tasks;
+
+	CREATE TABLE logical_task_containers(
+		ltc_id		SERIAL NOT NULL PRIMARY KEY ,
+		task_id		INT UNIQUE ,
+		CHECK( ltc_id = 1 AND task_id IS NULL OR ltc_id <> 1 AND task_id IS NOT NULL )
+	);
+	INSERT INTO logical_task_containers DEFAULT VALUES;
+	ALTER TABLE logical_task_containers
+		ADD FOREIGN KEY ( task_id ) REFERENCES tasks( task_id )
+			ON UPDATE NO ACTION
+			ON DELETE CASCADE;
+	GRANT SELECT ON logical_task_containers TO :webapp_user;
+	INSERT INTO logical_task_containers (task_id)
+		SELECT task_id FROM tasks;
+
+	ALTER TABLE tasks
+		ADD tc_id INT ,
+		ADD ltc_id INT;
+	UPDATE tasks t
+		SET ltc_id = 1 , tc_id = tc.tc_id
+		FROM task_containers tc
+		WHERE tc.item_id = t.item_id;
+	ALTER TABLE tasks
+		ALTER tc_id SET NOT NULL ,
+		ALTER ltc_id SET NOT NULL ,
+		ADD FOREIGN KEY ( tc_id ) REFERENCES task_containers ( tc_id )
+			ON UPDATE NO ACTION ON DELETE CASCADE ,
+		ADD FOREIGN KEY ( ltc_id ) REFERENCES logical_task_containers ( ltc_id )
+			ON UPDATE NO ACTION ON DELETE CASCADE ,
+		DROP COLUMN item_id CASCADE;
+	CREATE UNIQUE INDEX i_tasks_title ON tasks (tc_id, task_title);
+	CREATE UNIQUE INDEX i_tasks_ltc ON tasks (task_id , ltc_id);
+
+	ALTER TABLE task_dependencies ADD ltc_id INT;
+	UPDATE task_dependencies SET ltc_id = 1;
+	ALTER TABLE task_dependencies
+		ALTER ltc_id SET NOT NULL ,
+		DROP CONSTRAINT task_dependencies_task_id_depends_fkey ,
+		DROP CONSTRAINT task_dependencies_task_id_fkey ,
+		ADD CONSTRAINT fk_taskdep_task
+			FOREIGN KEY ( ltc_id , task_id ) REFERENCES tasks( ltc_id , task_id )
+				ON UPDATE NO ACTION ON DELETE CASCADE ,
+		ADD CONSTRAINT fk_taskdep_dependency
+			FOREIGN KEY ( ltc_id , task_id_depends ) REFERENCES tasks( ltc_id , task_id )
+				ON UPDATE NO ACTION ON DELETE CASCADE;
+
+	CREATE FUNCTION tgf_item_tc_ai( )
+			RETURNS TRIGGER
+			LANGUAGE PLPGSQL
+			SECURITY DEFINER
+		AS $tgf_item_tc_ai$
+	BEGIN
+		INSERT INTO task_containers ( item_id )
+			VALUES ( NEW.item_id );
+		RETURN NEW;
+	END;
+	$tgf_item_tc_ai$;
+	REVOKE EXECUTE ON FUNCTION tgf_item_tc_ai( ) FROM PUBLIC;
+	CREATE TRIGGER tg_item_tc_ai AFTER INSERT ON items
+		FOR EACH ROW EXECUTE PROCEDURE tgf_item_tc_ai( );
+
+	CREATE FUNCTION tgf_task_tc_ai( )
+			RETURNS TRIGGER
+			LANGUAGE PLPGSQL
+			SECURITY DEFINER
+		AS $tgf_task_tc_ai$
+	BEGIN
+		INSERT INTO task_containers ( task_id )
+			VALUES ( NEW.task_id );
+		INSERT INTO logical_task_containers ( task_id )
+			VALUES ( NEW.task_id );
+		RETURN NEW;
+	END;
+	$tgf_task_tc_ai$;
+	REVOKE EXECUTE ON FUNCTION tgf_task_tc_ai( ) FROM PUBLIC;
+	CREATE TRIGGER tg_task_tc_ai AFTER INSERT ON tasks
+		FOR EACH ROW EXECUTE PROCEDURE tgf_task_tc_ai( );
+
+	DROP FUNCTION add_task( INT , TEXT , TEXT , INT , INT ) CASCADE;
+	CREATE FUNCTION add_task( t_item INT , t_title TEXT , t_description TEXT , t_priority INT , t_user INT )
+			RETURNS INT
+			STRICT VOLATILE
+			SECURITY INVOKER
+		AS $add_task$
+	DECLARE
+		_container		INT;
+		_logical_container	INT;
+	BEGIN
+		SELECT INTO _container tc_id
+			FROM task_containers
+			WHERE item_id = t_item;
+		IF NOT FOUND THEN
+			RETURN 2;
+		END IF;
+
+		SELECT INTO _logical_container ltc_id
+			FROM logical_task_containers
+			WHERE task_id IS NULL;
+
+		INSERT INTO tasks ( tc_id , ltc_id , task_title , task_description , task_priority , user_id )
+			VALUES ( _container , _logical_container , t_title , t_description , t_priority , t_user );
+		RETURN 0;
+	EXCEPTION
+		WHEN unique_violation THEN
+			RETURN 1;
+	END;
+	$add_task$ LANGUAGE plpgsql;
+	REVOKE EXECUTE ON FUNCTION add_task( INT , TEXT , TEXT , INT , INT ) FROM PUBLIC;
+	GRANT EXECUTE ON FUNCTION add_task( INT , TEXT , TEXT , INT , INT ) TO :webapp_user;
+
+	CREATE FUNCTION tasks_add_nested( t_parent INT , t_title TEXT , t_description TEXT , t_priority INT , t_user INT )
+			RETURNS INT
+			STRICT VOLATILE
+			SECURITY INVOKER
+		AS $tasks_add_nested$
+	DECLARE
+		_container		INT;
+		_logical_container	INT;
+	BEGIN
+		SELECT INTO _container tc.tc_id
+			FROM task_containers tc
+				INNER JOIN tasks t USING ( task_id )
+				LEFT OUTER JOIN completed_tasks ct USING ( task_id )
+			WHERE t.task_id = t_parent AND ct.task_id IS NULL;
+		IF NOT FOUND THEN
+			RETURN 2;
+		END IF;
+
+		SELECT INTO _logical_container ltc_id
+			FROM logical_task_containers
+			WHERE task_id = t_parent;
+
+		INSERT INTO tasks ( tc_id , ltc_id , task_title , task_description , task_priority , user_id )
+			VALUES ( _container , _logical_container , t_title , t_description , t_priority , t_user );
+		RETURN 0;
+	EXCEPTION
+		WHEN unique_violation THEN
+			RETURN 1;
+	END;
+	$tasks_add_nested$ LANGUAGE plpgsql;
+	REVOKE EXECUTE ON FUNCTION tasks_add_nested( INT , TEXT , TEXT , INT , INT ) FROM PUBLIC;
+	GRANT EXECUTE ON FUNCTION tasks_add_nested( INT , TEXT , TEXT , INT , INT ) TO :webapp_user;
+
+
+	DROP FUNCTION finish_task( INT , INT , TEXT );
+	CREATE FUNCTION finish_task( t_id INT , u_id INT , n_text TEXT )
+			RETURNS INT
+			STRICT VOLATILE
+			SECURITY INVOKER
+		AS $finish_task$
+	BEGIN
+		PERFORM 1
+			FROM tasks t
+				LEFT OUTER JOIN (
+					SELECT ltc.task_id , COUNT( * ) AS c
+						FROM logical_task_containers ltc
+							INNER JOIN tasks t
+								USING ( ltc_id )
+							LEFT OUTER JOIN completed_tasks ct
+								ON ct.task_id = t.task_id
+						WHERE ltc.task_id = t_id
+							AND ct.task_id IS NULL
+						GROUP BY ltc.task_id
+					) s1 USING ( task_id )
+				LEFT OUTER JOIN (
+					SELECT td.task_id , COUNT( * ) AS c
+						FROM task_dependencies td
+							LEFT OUTER JOIN completed_tasks ct
+								ON ct.task_id = td.task_id_depends
+						WHERE td.task_id = t_id
+							AND ct.task_id IS NULL
+						GROUP BY td.task_id
+					) s2 USING ( task_id )
+			WHERE task_id = t_id AND s1.c IS NULL AND s2.c IS NULL;
+		IF NOT FOUND THEN
+			RETURN 2;
+		END IF;
+
+		BEGIN
+			INSERT INTO completed_tasks ( task_id , user_id )
+				VALUES ( t_id , u_id );
+		EXCEPTION
+			WHEN unique_violation THEN
+				RETURN 1;
+		END;
+
+		UPDATE tasks SET user_id_assigned = NULL WHERE task_id = t_id;
+
+		INSERT INTO notes ( task_id , user_id , note_text )
+			VALUES ( t_id , u_id , n_text );
+		RETURN 0;
+	END;
+	$finish_task$ LANGUAGE plpgsql;
+	REVOKE EXECUTE ON FUNCTION finish_task( INT , INT , TEXT ) FROM PUBLIC;
+	GRANT EXECUTE ON FUNCTION finish_task( INT , INT , TEXT ) TO :webapp_user;
+
+	DROP FUNCTION restart_task( INT , INT , TEXT );
+	CREATE FUNCTION restart_task( t_id INT , u_id INT , n_text TEXT )
+			RETURNS INT
+			STRICT VOLATILE
+			SECURITY INVOKER
+		AS $restart_task$
+	BEGIN
+		PERFORM 1
+			FROM tasks t
+				INNER JOIN logical_task_containers ltc
+					USING ( ltc_id )
+				INNER JOIN completed_tasks ct
+					ON ct.task_id = ltc.task_id
+			WHERE t.task_id = t_id;
+		IF FOUND THEN
+			RETURN 2;
+		END IF;
+
+		PERFORM 1
+			FROM task_dependencies td
+				INNER JOIN completed_tasks ct
+					USING ( task_id )
+			WHERE td.task_id_depends = t_id;
+		IF FOUND THEN
+			RETURN 2;
+		END IF;
+
+		DELETE FROM completed_tasks WHERE task_id = t_id;
+		IF NOT FOUND THEN
+			RETURN 1;
+		END IF;
+		UPDATE tasks SET user_id_assigned = u_id
+			WHERE task_id = t_id;
+		INSERT INTO notes ( task_id , user_id , note_text )
+			VALUES ( t_id , u_id , n_text );
+		RETURN 0;
+	END;
+	$restart_task$ LANGUAGE plpgsql;
+	REVOKE EXECUTE ON FUNCTION restart_task( INT , INT , TEXT ) FROM PUBLIC;
+	GRANT EXECUTE ON FUNCTION restart_task( INT , INT , TEXT ) TO :webapp_user;
+
+	DROP FUNCTION update_task( INT , INT  , TEXT , TEXT , INT , INT );
+	CREATE FUNCTION update_task( t_id INT , p_id INT , t_title TEXT , t_description TEXT , t_priority INT , t_assignee INT )
+			RETURNS INT
+			STRICT VOLATILE
+			SECURITY INVOKER
+		AS $update_task$
+
+	DECLARE
+		tc	INT;
+
+	BEGIN
+		PERFORM 1
+			FROM tasks
+				INNER JOIN logical_task_containers
+					USING ( ltc_id )
+				LEFT OUTER JOIN completed_tasks
+					ON tasks.task_id = completed_tasks.task_id
+			WHERE tasks.task_id = t_id
+				AND logical_task_containers.task_id IS NULL
+				AND completed_task_time IS NULL
+			FOR UPDATE OF tasks;
+		IF NOT FOUND THEN
+			RETURN 4;
+		END IF;
+
+		SELECT INTO tc tc_id FROM task_containers
+			WHERE item_id = p_id;
+		IF NOT FOUND THEN
+			RETURN 2;
+		END IF;
+
+		IF t_assignee = 0 THEN
+			t_assignee := NULL;
+		END IF;
+		UPDATE tasks SET tc_id = tc , task_title = t_title ,
+				task_description = t_description ,
+				task_priority = t_priority ,
+				user_id_assigned = t_assignee
+			WHERE task_id = t_id;
+
+		RETURN 0;
+	EXCEPTION
+		WHEN unique_violation THEN
+			RETURN 1;
+		WHEN foreign_key_violation THEN
+			RETURN 3;
+	END;
+	$update_task$ LANGUAGE plpgsql;
+	REVOKE EXECUTE ON FUNCTION update_task( INT , INT , TEXT , TEXT , INT , INT ) FROM PUBLIC;
+	GRANT EXECUTE ON FUNCTION update_task( INT , INT , TEXT , TEXT , INT , INT ) TO :webapp_user;
+
+
+	-- Update a nested task
+	CREATE FUNCTION update_task( t_id INT , t_title TEXT , t_description TEXT , t_priority INT , t_assignee INT )
+			RETURNS INT
+			STRICT VOLATILE
+			SECURITY INVOKER
+		AS $update_task$
+	BEGIN
+		PERFORM 1
+			FROM tasks
+				INNER JOIN logical_task_containers
+					USING ( ltc_id )
+				LEFT OUTER JOIN completed_tasks
+					ON tasks.task_id = completed_tasks.task_id
+			WHERE tasks.task_id = t_id
+				AND logical_task_containers.task_id IS NOT NULL
+				AND completed_task_time IS NULL
+			FOR UPDATE OF tasks;
+		IF NOT FOUND THEN
+			RETURN 4;
+		END IF;
+
+		IF t_assignee = 0 THEN
+			t_assignee := NULL;
+		END IF;
+		UPDATE tasks
+			SET task_title = t_title ,
+				task_description = t_description ,
+				task_priority = t_priority ,
+				user_id_assigned = t_assignee
+			WHERE task_id = t_id;
+		RETURN 0;
+	EXCEPTION
+		WHEN unique_violation THEN
+			RETURN 1;
+		WHEN foreign_key_violation THEN
+			RETURN 2;
+	END;
+	$update_task$ LANGUAGE plpgsql;
+	REVOKE EXECUTE ON FUNCTION update_task( INT , TEXT , TEXT , INT , INT ) FROM PUBLIC;
+	GRANT EXECUTE ON FUNCTION update_task( INT , TEXT , TEXT , INT , INT ) TO :webapp_user;
+
+	DROP FUNCTION tasks_possible_dependencies( INT );
+	CREATE FUNCTION tasks_possible_dependencies( o_id INT )
+		RETURNS SETOF tasks
+		STRICT STABLE
+	AS $tasks_possible_dependencies$
+		SELECT t.*
+			FROM tasks t
+				INNER JOIN tasks t2 USING ( ltc_id )
+			WHERE t2.task_id = $1 AND t.task_id NOT IN (
+				SELECT d.task_id_depends AS id
+					FROM taskdep_nodes n1
+						INNER JOIN task_dependencies d
+							ON d.task_id = n1.task_id_copyof
+					WHERE n1.task_id = $1 AND n1.tnode_reverse
+				UNION ALL SELECT n.task_id_copyof AS id
+					FROM task_dependencies d1
+						INNER JOIN taskdep_nodes n
+							ON n.task_id = d1.task_id_depends
+					WHERE d1.task_id = $1 AND n.tnode_reverse
+				UNION ALL SELECT task_id_copyof AS id
+					FROM taskdep_nodes
+					WHERE task_id = $1
+			);
+	$tasks_possible_dependencies$ LANGUAGE sql;
+	REVOKE EXECUTE ON FUNCTION tasks_possible_dependencies( INT ) FROM PUBLIC;
+	GRANT EXECUTE ON FUNCTION tasks_possible_dependencies( INT ) TO :webapp_user;
+
+	DROP FUNCTION tasks_add_dependency( INT , INT );
+	CREATE FUNCTION tasks_add_dependency( t_id INT , t_dependency INT )
+			RETURNS INT
+			STRICT VOLATILE
+			SECURITY INVOKER
+		AS $tasks_add_dependency$
+
+	DECLARE
+		ltc	INT;
+
+	BEGIN
+		SELECT INTO ltc ltc_id FROM tasks WHERE task_id = t_id;
+		IF NOT FOUND THEN
+			RETURN 1;
+		END IF;
+
+		INSERT INTO task_dependencies( ltc_id , task_id , task_id_depends )
+			VALUES ( ltc , t_id , t_dependency );
+		RETURN 0;
+	EXCEPTION
+		WHEN foreign_key_violation THEN
+			RETURN 3;
+		WHEN check_violation THEN
+			RETURN 2;
+	END;
+	$tasks_add_dependency$ LANGUAGE plpgsql;
+	REVOKE EXECUTE ON FUNCTION tasks_add_dependency( INT , INT ) FROM PUBLIC;
+	GRANT EXECUTE ON FUNCTION tasks_add_dependency( INT , INT ) TO :webapp_user;
+
+	CREATE VIEW tasks_move_down_targets
+		AS SELECT t.task_id , tgt.task_id AS target_id , tgt.task_title AS target_title
+			FROM tasks t
+				LEFT OUTER JOIN completed_tasks tct
+					USING ( task_id )
+				INNER JOIN tasks tgt
+					USING ( ltc_id )
+				INNER JOIN logical_task_containers ltc
+					ON ltc.task_id = tgt.task_id
+				LEFT OUTER JOIN tasks tsubs
+					ON tsubs.ltc_id = ltc.ltc_id
+						AND LOWER( tsubs.task_title ) = LOWER( t.task_title )
+				LEFT OUTER JOIN completed_tasks csubs
+					ON csubs.task_id = tgt.task_id
+			WHERE tgt.task_id <> t.task_id
+				AND tsubs.task_id IS NULL
+				AND tct.task_id IS NULL
+				AND csubs.task_id IS NULL;
+	GRANT SELECT ON tasks_move_down_targets TO :webapp_user;
+	CREATE VIEW tasks_can_move_up
+		AS SELECT t.task_id
+			FROM tasks t
+				LEFT OUTER JOIN completed_tasks tct
+					USING ( task_id )
+				INNER JOIN logical_task_containers ptc
+					USING ( ltc_id )
+				INNER JOIN tasks tgt
+					ON tgt.task_id = ptc.task_id
+				LEFT OUTER JOIN tasks psubs
+					ON psubs.ltc_id = tgt.ltc_id
+						AND LOWER( psubs.task_title ) = LOWER( t.task_title )
+			WHERE tct IS NULL
+				AND psubs IS NULL;
+
+	CREATE FUNCTION tasks_move_up( _task INT , _force BOOLEAN )
+			RETURNS BOOLEAN
+			LANGUAGE PLPGSQL
+			STRICT VOLATILE
+			SECURITY DEFINER
+		AS $tasks_move_up$
+
+	DECLARE
+		_gp_container	INT;
+		_gp_lcontainer	INT;
+
+	BEGIN
+		PERFORM 1 FROM tasks_can_move_up WHERE task_id = _task;
+		IF NOT FOUND THEN
+			RETURN FALSE;
+		END IF;
+
+		PERFORM 1 FROM task_dependencies
+			WHERE ( task_id = _task OR task_id_depends = _task ) AND NOT _force;
+		IF FOUND THEN
+			RETURN FALSE;
+		END IF;
+
+		SELECT INTO _gp_container , _gp_lcontainer
+			gp.tc_id , gp.ltc_id
+			FROM tasks t 
+				INNER JOIN logical_task_containers lt
+					USING ( ltc_id )
+				INNER JOIN tasks gp
+					ON gp.task_id = lt.task_id
+			WHERE t.task_id = _task;
+
+		DELETE FROM task_dependencies
+			WHERE task_id = _task OR task_id_depends = _task;
+		UPDATE tasks
+			SET tc_id = _gp_container ,
+				ltc_id = _gp_lcontainer
+			WHERE task_id = _task;
+		RETURN TRUE;
+	END;
+	$tasks_move_up$;
+	REVOKE EXECUTE ON FUNCTION tasks_move_up( INT , BOOLEAN ) FROM PUBLIC;
+	GRANT EXECUTE ON FUNCTION tasks_move_up( INT , BOOLEAN ) TO :webapp_user;
+
+	CREATE FUNCTION tasks_move_down( _task INT , _sibling INT , _force BOOLEAN )
+			RETURNS BOOLEAN
+			LANGUAGE PLPGSQL
+			STRICT VOLATILE
+			SECURITY DEFINER
+		AS $tasks_move_down$
+
+	DECLARE
+		_s_container	INT;
+		_s_lcontainer	INT;
+
+	BEGIN
+		PERFORM 1 FROM tasks_move_down_targets
+			WHERE task_id = _task AND target_id = _sibling;
+		IF NOT FOUND THEN
+			RETURN FALSE;
+		END IF;
+
+		PERFORM 1 FROM task_dependencies
+			WHERE ( task_id = _task OR task_id_depends = _task ) AND NOT _force;
+		IF FOUND THEN
+			RETURN FALSE;
+		END IF;
+
+		SELECT INTO _s_container tc_id
+			FROM task_containers
+			WHERE task_id = _sibling;
+		SELECT INTO _s_lcontainer ltc_id
+			FROM logical_task_containers
+			WHERE task_id = _sibling;
+
+		DELETE FROM task_dependencies
+			WHERE task_id = _task OR task_id_depends = _task;
+		UPDATE tasks
+			SET tc_id = _s_container ,
+				ltc_id = _s_lcontainer
+			WHERE task_id = _task;
+		RETURN TRUE;
+	END;
+	$tasks_move_down$;
+	REVOKE EXECUTE ON FUNCTION tasks_move_down( INT , INT , BOOLEAN ) FROM PUBLIC;
+	GRANT EXECUTE ON FUNCTION tasks_move_down( INT , INT , BOOLEAN ) TO :webapp_user;
+
+	CREATE VIEW tasks_single_view
+		AS SELECT t.task_id AS id, t.task_title AS title, tc.item_id AS item , tc.task_id AS parent_task ,
+				t.task_description AS description, t.task_added AS added_at,
+				u1.user_view_name AS added_by, ct.completed_task_time AS completed_at,
+				u2.user_view_name AS assigned_to , u2.user_id AS assigned_id ,
+				u3.user_view_name AS completed_by, t.user_id AS uid ,
+				t.task_priority AS priority ,
+				( cmu IS NOT NULL ) AS can_move_up
+			FROM tasks t
+				INNER JOIN task_containers tc USING ( tc_id )
+				INNER JOIN users_view u1 ON u1.user_id = t.user_id
+				LEFT OUTER JOIN completed_tasks ct ON ct.task_id = t.task_id
+				LEFT OUTER JOIN users_view u2 ON u2.user_id = t.user_id_assigned
+				LEFT OUTER JOIN users_view u3 ON u3.user_id = ct.user_id
+				LEFT OUTER JOIN tasks_can_move_up cmu ON cmu.task_id = t.task_id;
+	GRANT SELECT ON tasks_single_view TO :webapp_user;
+
+	CREATE VIEW tasks_list
+		AS SELECT t.task_id AS id, tc.item_id AS item , tc.task_id AS parent_task ,
+				t.task_title AS title,
+				t.task_description AS description, t.task_added AS added_at,
+				u1.user_view_name AS added_by,
+				ct.completed_task_time AS completed_at,
+				u2.user_view_name AS assigned_to ,
+				u2.user_id AS assigned_to_id ,
+				u3.user_view_name AS completed_by ,
+				t.task_priority AS priority ,
+				bd.bad_deps AS missing_dependencies ,
+				bc.bad_children AS missing_subtasks ,
+				( CASE
+					WHEN mtd.trans_missing IS NULL AND bc.bad_children IS NULL THEN
+						NULL::BIGINT
+					WHEN mtd.trans_missing IS NULL THEN
+						bc.bad_children
+					WHEN bc.bad_children IS NULL THEN
+						mtd.trans_missing
+					ELSE
+						bc.bad_children + mtd.trans_missing
+				END ) AS total_missing_dependencies
+			FROM tasks t
+				INNER JOIN task_containers tc USING( tc_id )
+				INNER JOIN users_view u1 ON u1.user_id = t.user_id
+				LEFT OUTER JOIN completed_tasks ct ON ct.task_id = t.task_id
+				LEFT OUTER JOIN users_view u2 ON u2.user_id = t.user_id_assigned
+				LEFT OUTER JOIN users_view u3 ON u3.user_id = ct.user_id
+				LEFT OUTER JOIN (
+					SELECT td.task_id , COUNT(*) AS bad_deps
+						FROM task_dependencies td
+							LEFT OUTER JOIN completed_tasks dct
+								ON dct.task_id = td.task_id_depends
+						WHERE dct.task_id IS NULL
+						GROUP BY td.task_id
+					) AS bd ON bd.task_id = t.task_id
+				LEFT OUTER JOIN (
+					SELECT ltc.task_id , COUNT( * ) AS bad_children
+						FROM logical_task_containers ltc
+							INNER JOIN tasks t
+								USING ( ltc_id )
+							LEFT OUTER JOIN completed_tasks ct
+								ON ct.task_id = t.task_id
+						WHERE ct.task_id IS NULL
+						GROUP BY ltc.task_id
+					) AS bc ON bc.task_id = t.task_id
+				LEFT OUTER JOIN (
+					SELECT tdn.task_id , COUNT( DISTINCT task_id_copyof ) AS trans_missing
+						FROM taskdep_nodes tdn
+							LEFT OUTER JOIN completed_tasks ct
+								ON ct.task_id = task_id_copyof
+						WHERE NOT tnode_reverse AND ct.task_id IS NULL
+							AND tdn.task_id <> tdn.task_id_copyof
+						GROUP BY tdn.task_id
+					) AS mtd ON mtd.task_id = t.task_id;
+
+	GRANT SELECT ON tasks_list TO :webapp_user;
+
+COMMIT;

includes/t-data/dao_items.inc.php

@@ -177,8 +177,9 @@ class DAO_Items
 		$query = $this->query(
 			'SELECT p.item_id , p.item_name , p.item_description , COUNT(*) AS t_count '
 			.	'FROM items p '
-			.		'INNER JOIN tasks t USING( item_id ) '
+			.		'INNER JOIN task_containers USING ( item_id ) '
-			.		'LEFT OUTER JOIN completed_tasks c USING( task_id ) '
+			.		'INNER JOIN tasks t USING( tc_id ) '
+			.		'LEFT OUTER JOIN completed_tasks c ON t.task_id = c.task_id '
 			.	'WHERE c.task_id IS NULL '
 			.	'GROUP BY item_id, p.item_name' );
 		$results = $query->execute( );

includes/t-data/dao_tasks.inc.php

@@ -35,6 +35,7 @@ class DAO_Tasks
 		return $this->query(
 			'SELECT * FROM tasks_list '
 			.	'WHERE completed_at IS NULL AND missing_dependencies IS NULL '
+			.		'AND missing_subtasks IS NULL '
 			.	'ORDER BY priority DESC , added_at DESC' )->execute( );
 	}
 
@@ -42,7 +43,8 @@ class DAO_Tasks
 	{
 		return $this->query(
 			'SELECT * FROM tasks_list '
-			.	'WHERE completed_at IS NULL AND missing_dependencies IS NOT NULL '
+			.	'WHERE completed_at IS NULL '
+			.		'AND ( missing_dependencies IS NOT NULL OR missing_subtasks IS NOT NULL ) '
 			.	'ORDER BY priority DESC , total_missing_dependencies ASC , added_at DESC' )->execute( );
 	}
 
@@ -57,7 +59,7 @@ class DAO_Tasks
 			.				'priority '
 			.			'ELSE '
 			.				'-1 '
-			.		'END ) DESC , missing_dependencies ASC NULLS FIRST , added_at DESC'
+			.		'END ) DESC , total_missing_dependencies ASC NULLS FIRST , added_at DESC'
 		)->execute( $item->id );
 	}
 
@@ -80,21 +82,17 @@ class DAO_Tasks
 	}
 
 
+	public function addNestedTask( $parent , $title , $priority , $description )
+	{
+		$result = $this->query( 'SELECT tasks_add_nested( $1 , $2 , $3 , $4 , $5 ) AS error' )
+			->execute( $parent , $title , $description , $priority , $_SESSION[ 'uid' ] );
+		return $result[0]->error;
+	}
+
+
 	public function get( $id )
 	{
-		$result = $this->query(
+		$result = $this->query( 'SELECT * FROM tasks_single_view WHERE id = $1' )->execute( $id );
-			'SELECT t.task_id AS id, t.task_title AS title, t.item_id AS item ,'
-			.		't.task_description AS description, t.task_added AS added_at, '
-			.		'u1.user_view_name AS added_by, ct.completed_task_time AS completed_at, '
-			.		'u2.user_view_name AS assigned_to , u2.user_id AS assigned_id , '
-			.		'u3.user_view_name AS completed_by, t.user_id AS uid , '
-			.		't.task_priority AS priority '
-			.	'FROM tasks t '
-			.		'INNER JOIN users_view u1 ON u1.user_id = t.user_id '
-			.		'LEFT OUTER JOIN completed_tasks ct ON ct.task_id = t.task_id '
-			.		'LEFT OUTER JOIN users_view u2 ON u2.user_id = t.user_id_assigned '
-			.		'LEFT OUTER JOIN users_view u3 ON u3.user_id = ct.user_id '
-			.	'WHERE t.task_id = $1' )->execute( $id );
 		if ( empty( $result ) ) {
 			return null;
 		}
@@ -107,33 +105,50 @@ class DAO_Tasks
 			.		'INNER JOIN users_view u USING (user_id) '
 			.	'WHERE n.task_id = $1 '
 			.	'ORDER BY n.note_added DESC' )->execute( $id );
+		$task->subtasks = $this->query(
+			'SELECT * FROM tasks_list '
+			.	'WHERE parent_task = $1 '
+			.	'ORDER BY ( CASE '
+			.			'WHEN completed_at IS NULL THEN '
+			.				'priority '
+			.			'ELSE '
+			.				'-1 '
+			.		'END ) DESC , missing_dependencies ASC NULLS FIRST , added_at DESC'
+		)->execute( $id );
+		$task->moveDownTargets = $this->query(
+			'SELECT * FROM tasks_move_down_targets '
+			.	'WHERE task_id = $1 '
+			.	'ORDER BY target_title' )->execute( $id );
 		$task->dependencies = $this->query(
-			'SELECT t.task_id AS id , t.task_title AS title , t.item_id AS item , '
+			'SELECT t.task_id AS id , t.task_title AS title , tc.item_id AS item , '
 			.		'i.item_name AS item_name , '
 			.		'( ct.completed_task_time IS NOT NULL ) AS completed , '
 			.		'tl.total_missing_dependencies AS missing_dependencies '
 			.	'FROM task_dependencies td '
 			.		'INNER JOIN tasks t ON t.task_id = td.task_id_depends '
-			.		'INNER JOIN items i USING ( item_id ) '
+			.		'INNER JOIN task_containers tc USING ( tc_id ) '
 			.		'INNER JOIN tasks_list tl ON tl.id = t.task_id '
+			.		'LEFT OUTER JOIN items i USING ( item_id ) '
 			.		'LEFT OUTER JOIN completed_tasks ct ON ct.task_id = t.task_id '
 			.	'WHERE td.task_id = $1 '
 			.	'ORDER BY i.item_name , t.task_priority DESC , t.task_title' )->execute( $id );
 		$task->reverseDependencies = $this->query(
-			'SELECT t.task_id AS id , t.task_title AS title , t.item_id AS item , '
+			'SELECT t.task_id AS id , t.task_title AS title , tc.item_id AS item , '
 			.		'i.item_name AS item_name , '
 			.		'( ct.completed_task_time IS NOT NULL ) AS completed '
 			.	'FROM task_dependencies td '
 			.		'INNER JOIN tasks t USING( task_id ) '
-			.		'INNER JOIN items i USING ( item_id ) '
+			.		'INNER JOIN task_containers tc USING ( tc_id ) '
-			.		'LEFT OUTER JOIN completed_tasks ct USING ( task_id ) '
+			.		'LEFT OUTER JOIN items i USING ( item_id ) '
+			.		'LEFT OUTER JOIN completed_tasks ct ON t.task_id = ct.task_id '
 			.	'WHERE td.task_id_depends = $1 '
 			.	'ORDER BY i.item_name , t.task_priority DESC , t.task_title' )->execute( $id );
 		$task->possibleDependencies = $this->query(
-			'SELECT t.task_id AS id , t.task_title AS title , t.item_id AS item , '
+			'SELECT t.task_id AS id , t.task_title AS title , tc.item_id AS item , '
 			.		'i.item_name AS item_name '
 			.	'FROM tasks_possible_dependencies( $1 ) t '
-			.		'INNER JOIN items i USING ( item_id ) '
+			.		'INNER JOIN task_containers tc USING ( tc_id ) '
+			.		'LEFT OUTER JOIN items i USING ( item_id ) '
 			.	'ORDER BY i.item_name , t.task_priority , t.task_title' )->execute( $id );
 
 		return $task;
@@ -159,6 +174,11 @@ class DAO_Tasks
 				return false;
 			}
 		}
+		foreach ( $task->subtasks as $subtask ) {
+			if ( $subtask->completed_at === null ) {
+				return false;
+			}
+		}
 		return true;
 	}
 
@@ -171,7 +191,12 @@ class DAO_Tasks
 				return false;
 			}
 		}
-		return true;
+
+		if ( $task->parent_task === null ) {
+			return true;
+		}
+		$parent = ( $task->parent_task instanceof StdClass ) ? $task->parent_task : $this->get( $task->parent_task );
+		return $parent->completed_by === null;
 	}
 
 
@@ -201,6 +226,13 @@ class DAO_Tasks
 		return $result[0]->error;
 	}
 
+	public function updateNestedTask( $id , $title , $priority , $description , $assignee )
+	{
+		$result = $this->query( 'SELECT update_task( $1 , $2 , $3 , $4 , $5 ) AS error' )
+			->execute( $id , $title , $description , $priority , $assignee );
+		return $result[0]->error;
+	}
+
 	public function addNote( $task , $note )
 	{
 		$this->query( 'INSERT INTO notes ( task_id , user_id , note_text ) VALUES ( $1 , $2 , $3 )' )
@@ -258,4 +290,18 @@ class DAO_Tasks
 			.	'WHERE _task2.task_id = _task.task_id AND _completed.task_id IS NULL AND _task.task_id = $1'
 		)->execute( $task , $user );
 	}
+
+	public function moveUp( $task , $force = false )
+	{
+		$result = $this->query( 'SELECT tasks_move_up( $1 , $2 ) AS success')
+			->execute( $task->id , $force ? 't' : 'f' );
+		return ( $result[0]->success == 't' );
+	}
+
+	public function moveDown( $task , $sibling , $force )
+	{
+		$result = $this->query( 'SELECT tasks_move_down( $1 , $2 , $3 ) AS success')
+			->execute( $task->id , $sibling , $force ? 't' : 'f' );
+		return ( $result[0]->success == 't' );
+	}
 }

includes/t-items/controllers.inc.php

@@ -280,6 +280,6 @@ class Ctrl_ItemTasks
 		return Loader::View( 'box' , 'Tasks' , Loader::View( 'tasks_list' , $tasks , array(
 					'deps' , 'assigned' , 'completed' ) ) )
 				->addButton( BoxButton::create( 'Add task' , 'tasks/add?to=' . $this->item->id )
-				->setClass( 'list-add' ) );
+					->setClass( 'list-add' ) );
 	}
 }

includes/t-tasks/controllers.inc.php

@@ -13,6 +13,15 @@ class Ctrl_AddTask
 	}
 
 	public function handle( Page $page )
+	{
+		$nested = $this->form->field( 'nested' )->value( );
+		if ( 0 === (int) $nested ) {
+			return $this->addTopLevelTask( );
+		}
+		return $this->addNestedTask( );
+	}
+
+	private function addTopLevelTask( )
 	{
 		$item = $this->form->field( 'item' );
 		$name = $this->form->field( 'title' );
@@ -41,6 +50,32 @@ class Ctrl_AddTask
 
 		return null;
 	}
+
+	private function addNestedTask( )
+	{
+		$parent = $this->form->field( 'parent' );
+		$name = $this->form->field( 'title' );
+		$priority = $this->form->field( 'priority' );
+		$description = $this->form->field( 'description' );
+
+		$error = Loader::DAO( 'tasks' )->addNestedTask( (int) $parent->value( ) ,
+			$name->value( ) , (int) $priority->value( ) , $description->value( ) );
+		switch ( $error ) {
+
+		case 0:
+			return true;
+
+		case 1:
+			$name->putError( 'Duplicate sub-task name.' );
+			break;
+
+		default:
+			$name->putError( "An unknown error occurred ($error)" );
+			break;
+		}
+
+		return null;
+	}
 }
 
 
@@ -62,8 +97,13 @@ class Ctrl_TaskDetails
 		} else {
 			$bTitle = "Active task";
 		}
-		$items = Loader::DAO( 'items' );
+
-		$items->getLineage( $this->task->item = $items->get( $this->task->item ) );
+		if ( $this->task->item !== null ) {
+			$items = Loader::DAO( 'items' );
+			$items->getLineage( $this->task->item = $items->get( $this->task->item ) );
+		} else {
+			$this->task->parent_task = Loader::DAO( 'tasks' )->get( $this->task->parent_task );
+		}
 
 		$box = Loader::View( 'box' , $bTitle , Loader::View( 'task_details' , $this->task ) );
 
@@ -81,6 +121,15 @@ class Ctrl_TaskDetails
 				$box->addButton( BoxButton::create( 'Claim task' , 'tasks/claim?id=' . $this->task->id )
 						->setClass( 'icon claim' ) );
 			}
+
+			if ( $this->task->can_move_up == 't' ) {
+				$box->addButton( BoxButton::create( 'Move task to grandparent' ,
+					'tasks/move/up?id=' . $this->task->id )->setClass( 'icon move-up' ) );
+			}
+			if ( ! empty( $this->task->moveDownTargets ) ) {
+				$box->addButton( BoxButton::create( 'Move task to sibling' ,
+					'tasks/move/down?id=' . $this->task->id )->setClass( 'icon move-down' ) );
+			}
 		} else {
 			if ( $tasks->canRestart( $this->task ) ) {
 				$box->addButton( BoxButton::create( 'Re-activate' , 'tasks/restart?id=' . $this->task->id )
@@ -99,6 +148,32 @@ class Ctrl_TaskDetails
 }
 
 
+class Ctrl_TaskListSubtasks
+	extends Controller
+{
+	private $task;
+
+	public function __construct( $task )
+	{
+		$this->task = $task;
+	}
+
+
+	public function handle( Page $page )
+	{
+		$box = Loader::View( 'box' , 'Sub-tasks' ,
+			Loader::View( 'tasks_list' , $this->task->subtasks , array( 'deps' , 'assigned' , 'completed' ) ) );
+
+		if ( $this->task->completed_by === null ) {
+			$box->addButton( BoxButton::create( 'Add sub-task' , 'tasks/add?parent=' . $this->task->id )
+				->setClass( 'list-add' ) );
+		}
+
+		return $box;
+	}
+}
+
+
 class Ctrl_TaskDependencies
 	extends Controller
 {
@@ -112,14 +187,17 @@ class Ctrl_TaskDependencies
 
 	public function handle( Page $page )
 	{
-		$views = array(
+		$views = array( );
-			$depBox = Loader::View( 'box' , 'Dependencies' ,
-				Loader::View( 'task_dependencies' , $this->task , false ) )
-		);
 
-		if ( ! empty( $this->task->possibleDependencies ) ) {
+		if ( ! empty( $this->task->dependencies )
-			$depBox->addButton( BoxButton::create( 'Add dependency' , 'tasks/deps/add?to=' . $this->task->id )
+				|| ( $this->task->completed_by === null && ! empty( $this->task->possibleDependencies ) ) ) {
-					->setClass( 'list-add' ) );
+			$views[] = ( $depBox = Loader::View( 'box' , 'Dependencies' ,
+				Loader::View( 'task_dependencies' , $this->task , false ) ) );
+
+			if ( ! empty( $this->task->possibleDependencies ) ) {
+				$depBox->addButton( BoxButton::create( 'Add dependency' , 'tasks/deps/add?to=' . $this->task->id )
+						->setClass( 'list-add' ) );
+			}
 		}
 
 		if ( ! empty( $this->task->reverseDependencies ) ) {
@@ -230,12 +308,54 @@ class Ctrl_EditTask
 	public function handle( Page $page )
 	{
 		$id = $this->form->field( 'id' );
-		$item = $this->form->field( 'item' );
+
+		$nested = $this->form->field( 'nested' )->value( );
+		if ( 0 == (int) $nested ) {
+			$item = $this->form->field( 'item' );
+		} else {
+			$item = null;
+		}
+
 		$name = $this->form->field( 'title' );
 		$priority = $this->form->field( 'priority' );
 		$description = $this->form->field( 'description' );
 		$assignee = $this->form->field( 'assigned-to' );
 
+		if ( $item != null ) {
+			return $this->handleTopLevelTask( $id , $item , $name , $priority , $description , $assignee );
+		}
+		return $this->handleNestedTask(  $id , $name , $priority , $description , $assignee );
+	}
+
+	private function handleNestedTask( $id , $name , $priority , $description , $assignee )
+	{
+		$error = Loader::DAO( 'tasks' )->updateNestedTask( (int) $id->value( ) , $name->value( ) ,
+			(int) $priority->value( ) , $description->value( ) ,
+			(int) $assignee->value( ) );
+
+		switch ( $error ) {
+
+		case 0:
+			return true;
+
+		case 1:
+			$name->putError( 'Another sub-task already uses this title.' );
+			break;
+
+		case 2:
+			$assignee->putError( 'This user has been deleted.' );
+			break;
+
+		default:
+			$name->putError( "An unknown error occurred ($error)" );
+			break;
+		}
+
+		return null;
+	}
+
+	private function handleTopLevelTask( $id , $item , $name , $priority , $description , $assignee )
+	{
 		$error = Loader::DAO( 'tasks' )->updateTask( (int) $id->value( ) ,
 			(int) $item->value( ) , $name->value( ) ,
 			(int) $priority->value( ) , $description->value( ) ,
@@ -373,8 +493,8 @@ class Ctrl_DependencyAdd
 	public function handle( Page $page )
 	{
 		$id = (int) $this->form->field( 'to' )->value( );
-		$dependency = $this->form->field( 'dependency' )->value( );
+		$dependency = $this->form->field( 'dependency' );
-		$error = Loader::DAO( 'tasks' )->addDependency( $id , $dependency );
+		$error = Loader::DAO( 'tasks' )->addDependency( $id , $dependency->value( ) );
 
 		switch ( $error ) {
 
@@ -382,15 +502,19 @@ class Ctrl_DependencyAdd
 			return true;
 
 		case 1:
-			$name->putError( 'The task you selected has been deleted.' );
+			$dependency->putError( 'The task you selected has been deleted.' );
 			break;
 
 		case 2:
-			$item->putError( 'This dependency is no longer possible.' );
+			$dependency->putError( 'This dependency is no longer possible.' );
+			break;
+
+		case 3:
+			$dependency->putError( 'These tasks are no longer at the same level.' );
 			break;
 
 		default:
-			$name->putError( "An unknown error occurred ($error)" );
+			$dependency->putError( "An unknown error occurred ($error)" );
 			break;
 		}
 

includes/t-tasks/package.inc.php

@@ -26,9 +26,12 @@ $package[ 'ctrls' ][] = 'edit_note_form';
 $package[ 'ctrls' ][] = 'edit_note';
 $package[ 'ctrls' ][] = 'edit_task_form';
 $package[ 'ctrls' ][] = 'edit_task';
+$package[ 'ctrls' ][] = 'task_claim';
 $package[ 'ctrls' ][] = 'task_dependencies';
 $package[ 'ctrls' ][] = 'task_details';
-$package[ 'ctrls' ][] = 'task_claim';
+$package[ 'ctrls' ][] = 'task_list_subtasks';
+$package[ 'ctrls' ][] = 'task_move_down';
+$package[ 'ctrls' ][] = 'task_move_up';
 $package[ 'ctrls' ][] = 'task_notes';
 $package[ 'ctrls' ][] = 'toggle_task';
 $package[ 'ctrls' ][] = 'view_task';

includes/t-tasks/page_controllers.inc.php

@@ -75,8 +75,15 @@ class Ctrl_AddTaskForm
 	{
 		try {
 			$target = (int) $this->getParameter( 'to' );
+			$targetIsItem = true;
 		} catch ( ParameterException $e ) {
-			$target = null;
+			try {
+				$target = (int) $this->getParameter( 'parent' );
+				$targetIsItem = false;
+			} catch ( ParameterException $e ) {
+				$target = null;
+				$targetIsItem = null;
+			}
 		}
 
 		$form = Loader::Create( 'Form' , 'Add this task' , 'create-task' );
@@ -86,20 +93,43 @@ class Ctrl_AddTaskForm
 			if ( ! $this->addItemSelector( $form ) ) {
 				return 'items';
 			}
-		} else {
+			$form->addField( Loader::Create( 'Field' , 'nested' , 'hidden' )
+				->setDefaultValue( 0 ) );
+		} elseif ( $targetIsItem ) {
 			$item = Loader::DAO( 'items' )->get( $target );
 			if ( $item === null ) {
-				return 'items';
+				return 'tasks';
 			}
 			$returnURL = 'items/view?id=' . $target;
 
 			$form->addField( Loader::Create( 'Field' , 'to' , 'hidden' )
 					->setDefaultValue( $target ) )
+				->addField( Loader::Create( 'Field' , 'nested' , 'hidden' )
+					->setDefaultValue( 0 ) )
 				->addField( Loader::Create( 'Field' , 'item' , 'hidden' )
 					->setDefaultValue( $target ) )
 				->addField( Loader::Create( 'Field' , 'item-name' , 'label' )
+					->setMandatory( false )
 					->setDescription( 'Item:' )
 					->setDefaultValue( $item->name ) );
+		} else {
+			$parent = Loader::DAO( 'tasks' )->get( $target );
+			if ( $parent === null ) {
+				return 'tasks';
+			}
+			$returnURL = 'tasks/view?id=' . $target;
+			if ( $parent->completed_by !== null ) {
+				return $returnURL;
+			}
+
+			$form->addField( Loader::Create( 'Field' , 'parent' , 'hidden' )
+					->setDefaultValue( $target ) )
+				->addField( Loader::Create( 'Field' , 'nested' , 'hidden' )
+					->setDefaultValue( 1 ) )
+				->addField( Loader::Create( 'Field' , 'item-name' , 'label' )
+					->setMandatory( false )
+					->setDescription( 'Sub-task of:' )
+					->setDefaultValue( $parent->title ) );
 		}
 
 		$page->setTitle( 'New task' );
@@ -159,10 +189,13 @@ class Ctrl_ViewTask
 		$page->setTitle( $task->title . ' (task)' );
 
 		$result = array(
-			Loader::Ctrl( 'task_details' , $task ) ,
+			Loader::Ctrl( 'task_details' , $task )
-			Loader::Ctrl( 'task_dependencies' , $task ) ,
 		);
 
+		if ( $task->completed_by === null || ! empty( $task->subtasks ) ) {
+			$result[] = Loader::Ctrl( 'task_list_subtasks' , $task );
+		}
+		$result[] = Loader::Ctrl( 'task_dependencies' , $task );
 		if ( $task->completed_by === null ) {
 			array_push( $result , Loader::Ctrl( 'add_task_note_form' , $task ) );
 		}
@@ -197,6 +230,13 @@ class Ctrl_DeleteTaskForm
 		}
 		$page->setTitle( $task->title . ' (task)' );
 
+		// Create parent URL from either the item or parent task
+		if ( $task->parent_task === null ) {
+			$parentURL = 'items/view?id=' . $task->item;
+		} else {
+			$parentURL = 'tasks/view?id=' . $task->parent_task;
+		}
+
 		// Generate confirmation text
 		$confText = HTML::make( 'div' )
 			->appendElement( HTML::make( 'p' )
@@ -210,7 +250,7 @@ class Ctrl_DeleteTaskForm
 				->setDefaultValue( $task->id ) )
 			->addField( Loader::Create( 'Field' , 'confirm' , 'html' )->setDefaultValue( $confText ) )
 			->setCancelURL( 'tasks/view?id=' . $task->id )
-			->setSuccessURL( 'items/view?id=' . $task->item )
+			->setSuccessURL( $parentURL )
 			->addController( Loader::Ctrl( 'delete_task' ) )
 			->controller( );
 
@@ -242,13 +282,19 @@ class Ctrl_EditTaskForm
 		$page->setTitle( $task->title . ' (task)' );
 
 
-		return Loader::Create( 'Form' , 'Update task' , 'edit-task' , 'Editing task' )
+		$form = Loader::Create( 'Form' , 'Update task' , 'edit-task' , 'Editing task' )
 			->setURL( 'tasks/view?id=' . $task->id )
 			->addField( Loader::Create( 'Field' , 'id' , 'hidden' )
 				->setDefaultValue( $task->id ) )
-			->addField( $this->createItemSelector( )
+			->addField( Loader::Create( 'Field' , 'nested' , 'hidden' )
-				->setDefaultValue( $task->item ) )
+				->setDefaultValue( $task->item === null ? 1 : 0 ) );
-			->addField( Loader::Create( 'Field' , 'title' , 'text' )
+
+		if ( $task->item !== null ) {
+			$form->addField( $this->createItemSelector( )
+				->setDefaultValue( $task->item ) );
+		}
+
+		return $form->addField( Loader::Create( 'Field' , 'title' , 'text' )
 				->setDescription( 'Title:' )
 				->setModifier( Loader::Create( 'Modifier_TrimString' ) )
 				->setValidator( Loader::Create( 'Validator_StringLength' , 'This title' , 5 , 256 ) )
@@ -411,31 +457,37 @@ class Ctrl_DependencyAddForm
 		$form = Loader::Create( 'Form' , 'Add dependency' , 'add-dep' )
 			->addField( Loader::Create( 'Field' , 'to' , 'hidden' )
 			->setDefaultValue( $id ) );
-		$this->addDependencySelector( $form , $task->possibleDependencies );
+		$this->addDependencySelector( $form , $task->possibleDependencies , $task->item !== null );
 		return $form->setURL( 'tasks/view?id=' . $id )
 			->addController( Loader::Ctrl( 'dependency_add' ) )
 			->controller( );
 
 	}
 
-	private function addDependencySelector( $form , $possibleDependencies )
+	private function addDependencySelector( $form , $possibleDependencies , $topLevel )
 	{
 		$form->addField( $select = Loader::Create( 'Field' , 'dependency' , 'select' )
 			->setDescription( 'Dependency to add:' )
 			->addOption( '' , '(please select a task)' ) );
 
-		$depsByItem = $this->getDependenciesByItem( $possibleDependencies );
+		if ( $topLevel ) {
-		$items = $this->getItemsToDisplay( $depsByItem );
+			$depsByItem = $this->getDependenciesByItem( $possibleDependencies );
-		foreach ( $items as $item ) {
+			$items = $this->getItemsToDisplay( $depsByItem );
-			$prefix = '-' . str_repeat( '--' , $item->depth );
+			foreach ( $items as $item ) {
-			$name = $prefix . ' ' . $item->name;
+				$prefix = '-' . str_repeat( '--' , $item->depth );
-			$select->addOption( 'I' . $item->id , $name , true );
+				$name = $prefix . ' ' . $item->name;
-			if ( ! array_key_exists( $item->id , $depsByItem ) ) {
+				$select->addOption( 'I' . $item->id , $name , true );
-				continue;
+				if ( ! array_key_exists( $item->id , $depsByItem ) ) {
-			}
+					continue;
+				}
 
-			foreach ( $depsByItem[ $item->id ] as $task ) {
+				foreach ( $depsByItem[ $item->id ] as $task ) {
-				$select->addOption( $task->id , $prefix . '-> ' . $task->title );
+					$select->addOption( $task->id , $prefix . '-> ' . $task->title );
+				}
+			}
+		} else {
+			foreach ( $possibleDependencies as $task ) {
+				$select->addOption( $task->id , $task->title );
 			}
 		}
 		return true;
@@ -546,3 +598,155 @@ class Ctrl_DependencyDeleteForm
 }
 
 
+
+class Ctrl_TaskMoveDown
+	extends Controller
+{
+
+	public function __construct( )
+	{
+		$this->dao = Loader::DAO( 'tasks' );
+	}
+
+	public function handle( Page $page )
+	{
+		try {
+			$id = (int) $this->getParameter( 'id' );
+		} catch ( ParameterException $e ) {
+			return 'tasks';
+		}
+
+		$task = $this->dao->get( $id );
+		if ( $task === null ) {
+			return 'tasks';
+		}
+
+		if ( empty( $task->moveDownTargets ) ) {
+			return 'tasks/view?id=' . $id;
+		}
+
+		$page->setTitle( $task->title . ' (task)' );
+		$sibling = $this->getSibling( $task );
+		if ( $sibling != null ) {
+			if ( $this->handleSelectedSibling( $task , $sibling ) ) {
+				return 'tasks/view?id=' . $id;
+			} else {
+				return $this->confirmationForm( $task , $sibling );
+			}
+		}
+		return $this->siblingSelectionForm( $task );
+	}
+
+	private function getSibling( $task )
+	{
+		try {
+			$sibling = (int) $this->getParameter( 'sibling' );
+			$okSiblings = array_map( function( $item ) { return $item->target_id; } , $task->moveDownTargets );
+			if ( ! in_array( $sibling , $okSiblings ) ) {
+				$sibling = null;
+			}
+		} catch ( ParameterException $e ) {
+			$sibling = null;
+		}
+		return $sibling;
+	}
+
+	private function handleSelectedSibling( $task , $sibling )
+	{
+		try {
+			$force = (bool) $this->getParameter( 'force' );
+		} catch ( ParameterException $e ) {
+			$force = false;
+		}
+
+		return $this->dao->moveDown( $task , $sibling , $force );
+	}
+
+	private function confirmationForm( $task , $sibling )
+	{
+		$sibling = $this->dao->get( $sibling );
+		$confText = HTML::make( 'div' )
+			->appendElement( HTML::make( 'p' )
+				->appendText( 'All dependencies and reverse dependencies of the '
+					. 'selected task will be lost when it is moved into ' )
+				->appendElement( HTML::make( 'strong' )->appendText( $sibling->title ) )
+				->appendText( '.' ) )
+			->appendElement( HTML::make( 'p' )
+				->appendText( 'Please confirm.' ) );
+
+		return Loader::Create( 'Form' , 'Move task' , 'move-down' )
+			->addField( Loader::Create( 'Field' , 'id' , 'hidden' )
+				->setDefaultValue( $task->id ) )
+			->addField( Loader::Create( 'Field' , 'sibling' , 'hidden' )
+				->setDefaultValue( $sibling->id ) )
+			->addField( Loader::Create( 'Field' , 'force' , 'hidden' )
+				->setDefaultValue( 1 ) )
+			->addField( Loader::Create( 'Field' , 'confirm' , 'html' )->setDefaultValue( $confText ) )
+			->setURL( 'tasks/view?id=' . $task->id )
+			->controller( );
+	}
+
+	private function siblingSelectionForm( $task )
+	{
+		$selector = Loader::Create( 'Field' , 'sibling' , 'select' )
+			->setDescription( 'Move task into: ' );
+		foreach ( $task->moveDownTargets as $target ) {
+			$selector->addOption( $target->target_id , $target->target_title );
+		}
+		return Loader::Create( 'Form' , 'Move task' , 'move-down' , 'Move task to sibling' )
+			->addField( Loader::Create( 'Field' , 'id' , 'hidden' )
+				->setDefaultValue( $task->id ) )
+			->addField( $selector )
+			->setURL( 'tasks/view?id=' . $task->id )
+			->controller( );
+	}
+}
+
+
+class Ctrl_TaskMoveUp
+	extends Controller
+{
+
+	public function handle( Page $page )
+	{
+		try {
+			$id = (int) $this->getParameter( 'id' );
+		} catch ( ParameterException $e ) {
+			return 'tasks';
+		}
+
+		$dao = Loader::DAO( 'tasks' );
+		$task = $dao->get( $id );
+		if ( $task === null ) {
+			return 'tasks';
+		}
+
+		try {
+			$force = (bool) $this->getParameter( 'force' );
+		} catch ( ParameterException $e ) {
+			$force = false;
+		}
+
+		if ( ! $task->can_move_up || $dao->moveUp( $task , $force ) ) {
+			return 'tasks/view?id=' . $id;
+		}
+
+		$confText = HTML::make( 'div' )
+			->appendElement( HTML::make( 'p' )
+				->appendText( 'All dependencies and reverse dependencies of the '
+					. 'selected task will be lost when it is moved.' ) )
+			->appendElement( HTML::make( 'p' )
+				->appendText( 'Please confirm.' ) );
+
+		$page->setTitle( $task->title . ' (task)' );
+		return Loader::Create( 'Form' , 'Move task' , 'move-up' )
+			->addField( Loader::Create( 'Field' , 'id' , 'hidden' )
+				->setDefaultValue( $id ) )
+			->addField( Loader::Create( 'Field' , 'force' , 'hidden' )
+				->setDefaultValue( 1 ) )
+			->addField( Loader::Create( 'Field' , 'confirm' , 'html' )->setDefaultValue( $confText ) )
+			->setURL( 'tasks/view?id=' . $id )
+			->controller( );
+	}
+
+}

includes/t-tasks/pages.inc.php

@@ -15,10 +15,12 @@ class Page_TasksTasks
 			'finish'	=> array( 'toggle_task' , false ) ,
 			'restart'	=> array( 'toggle_task' , true ) ,
 			'view'		=> 'view_task' ,
-			'notes/edit'	=> 'edit_note_form' ,
-			'notes/delete'	=> 'delete_note_form' ,
 			'deps/add'	=> 'dependency_add_form' ,
 			'deps/delete'	=> 'dependency_delete_form' ,
+			'move/down'	=> 'task_move_down' ,
+			'move/up'	=> 'task_move_up' ,
+			'notes/edit'	=> 'edit_note_form' ,
+			'notes/delete'	=> 'delete_note_form' ,
 		));
 	}
 

includes/t-tasks/views.inc.php

@@ -60,7 +60,7 @@ class View_TasksList
 			->appendElement( HTML::make( 'a' )
 				->setAttribute( 'href' , $this->base . '/tasks/view?id=' . $task->id )
 				->appendText( $task->title ) ) );
-		$this->addItem( $cell , $task );
+		$this->addParent( $cell , $task );
 		$classes = array( );
 
 		$addedAt = strtotime( $task->added_at );
@@ -75,6 +75,9 @@ class View_TasksList
 			if ( $task->missing_dependencies !== null ) {
 				$this->generateMissingDependencies( $cell , $classes , $task );
 			}
+			if ( $task->missing_subtasks !== null ) {
+				$this->generateMissingSubtasks( $cell , $classes , $task );
+			}
 			if ( $task->assigned_to !== null ) {
 				$this->generateAssignedTask( $cell , $classes , $task );
 			}
@@ -82,19 +85,28 @@ class View_TasksList
 
 		if ( ! empty( $classes ) ) {
 			foreach ( $cell as $entry ) {
-				$entry->setAttribute( 'class' , join( ' ' , $classes ) );
+				$entry->setAttribute( 'class' , join( ' ' , array_unique( $classes ) ) );
 			}
 		}
 
 		return $cell;
 	}
 
-	protected function addItem( &$cell , $task )
+	protected function addParent( &$cell , $task )
 	{
 		if ( ! array_key_exists( 'item' , $this->features ) ) {
 			return;
 		}
 
+		if ( $task->item !== null ) {
+			$this->addItem( $cell , $task );
+		} else {
+			$this->addParentTask( $cell , $task );
+		}
+	}
+
+	protected function addItem( &$cell , $task )
+	{
 		$itemsDao = Loader::DAO( 'items' );
 		$item = $itemsDao->get( $task->item );
 		$lineage = $itemsDao->getLineage( $item );
@@ -114,6 +126,17 @@ class View_TasksList
 		array_push( $cell , HTML::make( 'dd' )->append( $contents ) );
 	}
 
+	protected function addParentTask( &$cell , $task )
+	{
+		$parent = $this->dao->get( $task->parent_task );
+
+		array_push( $cell , HTML::make( 'dd' )
+			->appendText( 'Sub-task of ' )
+			->appendElement( HTML::make( 'a' )
+				->setAttribute( 'href' , $this->base . '/tasks/view?id=' . $parent->id )
+				->appendText( $parent->title ) ) );
+	}
+
 	protected function generateMissingDependencies( &$cell , &$classes , $task )
 	{
 		if ( ! array_key_exists( 'deps' , $this->features ) ) {
@@ -134,6 +157,23 @@ class View_TasksList
 		array_push( $classes , 'missing-deps' );
 	}
 
+	protected function generateMissingSubtasks( &$cell , &$classes , $task )
+	{
+		if ( ! array_key_exists( 'deps' , $this->features ) ) {
+			return;
+		}
+
+		if ( $task->missing_subtasks > 1 ) {
+			$end = 's';
+		} else {
+			$end = '';
+		}
+		array_push( $cell ,
+			$md = HTML::make( 'dd' )->appendText( "{$task->missing_subtasks} incomplete sub-task$end" ) );
+
+		array_push( $classes , 'missing-deps' );
+	}
+
 	protected function generateAssignedTask( &$cell , &$classes , $task )
 	{
 		if ( ! array_key_exists( 'assigned' , $this->features ) ) {
@@ -173,11 +213,22 @@ class View_TaskDetails
 	public function render( )
 	{
 		$list = HTML::make( 'dl' )
-			->setAttribute( 'class' , 'tasks' )
+			->setAttribute( 'class' , 'tasks' );
-			->appendElement( HTML::make( 'dt' )
+
-				->appendText( 'On item:' ) )
+		if ( $this->task->item !== null ) {
-			->appendElement( HTML::make( 'dd' )
+			$list->appendElement( HTML::make( 'dt' )
-				->append( $this->formatPlaceLineage( $this->task->item ) ) );
+					->appendText( 'On item:' ) )
+				->appendElement( HTML::make( 'dd' )
+					->append( $this->formatPlaceLineage( $this->task->item ) ) );
+		} else {
+			$list->appendElement( HTML::make( 'dt' )
+					->appendText( 'Sub-task of:' ) )
+				->appendElement( HTML::make( 'dd' )
+					->appendElement( HTML::make( 'a' )
+						->setAttribute( 'href' , $this->base .
+							'/tasks/view?id=' . $this->task->parent_task->id )
+						->appendText( $this->task->parent_task->title ) ) );
+		}
 
 		if ( $this->task->description != '' ) {
 			$list->appendElement( HTML::make( 'dt' )
@@ -317,6 +368,8 @@ class View_TaskDependencies
 						->appendText( $dependency->item_name ) )
 					->appendElement( $itemList ) );
 				$prevItem = $dependency->item;
+			} elseif ( $itemList === null ) {
+				$itemList = $list;
 			}
 
 			$entry = HTML::make( 'li' )->appendElement(

site/style.css

@@ -360,6 +360,12 @@ div.box-buttons a.start:hover { background-position: -18px -90px }
 div.box-buttons a.claim { background-position: 0px -108px }
 div.box-buttons a.claim:hover { background-position: -18px -108px }
 
+div.box-buttons a.move-up { background-position: 0px -126px }
+div.box-buttons a.move-up:hover { background-position: -18px -126px }
+
+div.box-buttons a.move-down { background-position: 0px -144px }
+div.box-buttons a.move-down:hover { background-position: -18px -144px }
+
 div.box-buttons a.list-add::after {
 	content: '+';
 	font-weight: bold;