-- 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 )
		RETURNS INT
		STRICT VOLATILE
		SECURITY INVOKER
	AS $add_task$
BEGIN
	INSERT INTO tasks ( item_id , task_title , task_description , task_priority , user_id )
		VALUES ( t_item , 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;


-- Mark a task as finished
CREATE OR REPLACE FUNCTION finish_task( t_id INT , u_id INT , n_text TEXT )
		RETURNS INT
		STRICT VOLATILE
		SECURITY INVOKER
	AS $finish_task$
BEGIN
	BEGIN
		INSERT INTO completed_tasks ( task_id , user_id )
			VALUES ( t_id , u_id );
	EXCEPTION
		WHEN unique_violation THEN
			RETURN 1;
	END;

	INSERT INTO notes ( task_id , user_id , note_text )
		VALUES ( t_id , u_id , n_text );
	RETURN 0;
END;
$finish_task$ LANGUAGE plpgsql;


-- Restart a task
CREATE OR REPLACE FUNCTION restart_task( t_id INT , u_id INT , n_text TEXT )
		RETURNS INT
		STRICT VOLATILE
		SECURITY INVOKER
	AS $restart_task$
BEGIN
	DELETE FROM completed_tasks WHERE task_id = t_id;
	IF NOT FOUND THEN
		RETURN 1;
	END IF;
	INSERT INTO notes ( task_id , user_id , note_text )
		VALUES ( t_id , u_id , n_text );
	RETURN 0;
END;
$restart_task$ LANGUAGE plpgsql;


-- Update a task
CREATE OR REPLACE FUNCTION update_task( t_id INT , p_id INT , t_title TEXT , t_description TEXT , t_priority INT )
		RETURNS INT
		STRICT VOLATILE
		SECURITY INVOKER
	AS $update_task$
BEGIN
	UPDATE tasks SET item_id = p_id , task_title = t_title ,
			task_description = t_description ,
			task_priority = t_priority
		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;