WIP identify suspected cheaters

services/headless-lms/migrations/20240312115600_add_suspected_cheaters.down.sql

@@ -0,0 +1,2 @@
+DROP TABLE suspected_cheaters;
+DROP TABLE cheater_thresholds;

services/headless-lms/migrations/20240312115600_add_suspected_cheaters.up.sql

@@ -0,0 +1,40 @@
+CREATE TABLE suspected_cheaters (
+  id UUID DEFAULT uuid_generate_v4() PRIMARY KEY,
+  user_id UUID NOT NULL REFERENCES users,
+  created_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT now(),
+  updated_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT now(),
+  deleted_at TIMESTAMP WITH TIME ZONE,
+  total_duration_seconds INTEGER,
+  total_points INTEGER NOT NULL
+);
+CREATE TRIGGER set_timestamp BEFORE
+UPDATE ON suspected_cheaters FOR EACH ROW EXECUTE PROCEDURE trigger_set_timestamp();
+-- The suspected_cheaters table is a that contains a student that are suspected of cheating because they meet the cheating requirement (i.e. score > threshold && duration > average_duration)
+COMMENT ON TABLE suspected_cheaters IS 'This table stores data regarding student that are suspected of cheating in a course instance.';
+COMMENT ON COLUMN suspected_cheaters.id IS 'A unique, stable identifier for the record.';
+COMMENT ON COLUMN suspected_cheaters.user_id IS 'The user_id of the student being suspected.';
+COMMENT ON COLUMN suspected_cheaters.created_at IS 'Timestamp when the record was created.';
+COMMENT ON COLUMN suspected_cheaters.updated_at IS 'Timestamp when the record was updated.';
+COMMENT ON COLUMN suspected_cheaters.deleted_at IS 'Timestamp when the record was deleted. If null, the record is not deleted.';
+COMMENT ON COLUMN suspected_cheaters.total_duration_seconds IS 'The total duration the student spent completing the course.';
+COMMENT ON COLUMN suspected_cheaters.total_points IS 'The total points earned by the student in the course.';
+-- The cheater_thresholds table contains thresholds set by the instructor, representing the maximum score or duration a student can surpass before being suspected of cheating.
+CREATE TABLE cheater_thresholds (
+  id UUID DEFAULT uuid_generate_v4() PRIMARY KEY,
+  course_instance_id UUID NOT NULL REFERENCES course_instances,
+  created_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT now(),
+  updated_at TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT now(),
+  deleted_at TIMESTAMP WITH TIME ZONE,
+  points INTEGER NOT NULL,
+  duration_seconds INTEGER
+);
+CREATE TRIGGER set_timestamp BEFORE
+UPDATE ON cheater_thresholds FOR EACH ROW EXECUTE PROCEDURE trigger_set_timestamp();
+COMMENT ON TABLE cheater_thresholds IS 'This table stores thresholds set by the instructor, representing the maximum score or duration a student can surpass before being suspected of cheating cheaters.';
+COMMENT ON COLUMN cheater_thresholds.id IS 'A unique, stable identifier for the record.';
+COMMENT ON COLUMN cheater_thresholds.course_instance_id IS 'The course_instance_id of the course.';
+COMMENT ON COLUMN cheater_thresholds.created_at IS 'Timestamp when the record was created.';
+COMMENT ON COLUMN cheater_thresholds.updated_at IS 'Timestamp when the record was updated.';
+COMMENT ON COLUMN cheater_thresholds.deleted_at IS 'Timestamp when the record was deleted. If null, the record is not deleted.';
+COMMENT ON COLUMN cheater_thresholds.points IS 'The score threshold of the course.';
+COMMENT ON COLUMN cheater_thresholds.duration_seconds IS 'The duration threshold of the course.';

services/headless-lms/models/src/course_instances.rs

@@ -746,6 +746,54 @@ WHERE user_id = $1
     Ok(())
 }
 
+pub async fn get_course_average_duration(
+    conn: &mut PgConnection,
+    course_instance_id: Uuid,
+) -> ModelResult<Option<i64>> {
+    let res = sqlx::query!(
+        "
+SELECT
+    AVG(EXTRACT(EPOCH FROM cmc.completion_date - ce.created_at))::int8 AS average_duration_seconds
+FROM course_instance_enrollments ce
+JOIN course_module_completions cmc ON cmc.course_instance_id = ce.course_instance_id
+WHERE ce.course_instance_id = $1
+    AND ce.deleted_at IS NULL
+    AND cmc.deleted_at IS NULL;
+        ",
+        course_instance_id
+    )
+    .fetch_one(conn)
+    .await?;
+
+    Ok(res.average_duration_seconds)
+}
+
+pub async fn get_student_duration(
+    conn: &mut PgConnection,
+    user_id: Uuid,
+    course_instance_id: Uuid,
+) -> ModelResult<Option<i64>> {
+    let res = sqlx::query!(
+        "
+SELECT
+    COALESCE(EXTRACT(EPOCH FROM cmc.completion_date - ce.created_at)::int8, 0) AS student_duration_seconds
+FROM course_instance_enrollments ce
+JOIN course_module_completions cmc ON cmc.course_instance_id = ce.course_instance_id
+AND cmc.user_id = ce.user_id
+WHERE ce.course_instance_id = $1
+    AND ce.user_id = $2
+    AND ce.deleted_at IS NULL
+    AND cmc.deleted_at IS NULL;
+        ",
+        course_instance_id,
+        user_id
+    )
+    .fetch_one(conn)
+    .await?;
+
+    Ok(res.student_duration_seconds)
+}
+
 #[cfg(test)]
 mod test {
     use super::*;