Merge pull request 'Added max amount of tasks on contest' (#7) from feature/max_tasks_on_contest into develop

Reviewed-on: #7
Reviewed-by: Vyacheslav Birin <vyacheslav1557@noreply.localhost>

migrations/20240727123308_initial.sql

@@ -9,6 +9,24 @@ BEGIN
 END;
 $$;
 
+CREATE FUNCTION check_max_tasks() RETURNS TRIGGER
+    LANGUAGE plpgsql AS
+$$
+DECLARE
+    max_on_contest_tasks_amount integer := 50;
+BEGIN
+    IF  (
+        SELECT count(*) FROM tasks
+        WHERE contest_id = NEW.contest_id
+    ) >= (
+        max_on_contest_tasks_amount
+    ) THEN
+    RAISE EXCEPTION 'Exceeded max tasks for this contest';
+END IF;
+    RETURN NEW;
+END;
+$$;
+
 CREATE TABLE IF NOT EXISTS problems
 (
     id                 serial         NOT NULL,
@@ -73,6 +91,11 @@ CREATE TABLE IF NOT EXISTS tasks
     CHECK (position >= 0)
 );
 
+CREATE TRIGGER max_tasks_on_contest_check
+    BEFORE INSERT ON tasks
+    FOR EACH STATEMENT
+EXECUTE FUNCTION check_max_tasks();
+
 CREATE TRIGGER on_tasks_update
     BEFORE UPDATE
     ON tasks
@@ -98,6 +121,7 @@ CREATE TRIGGER on_participants_update
     FOR EACH ROW
 EXECUTE PROCEDURE updated_at_update();
 
+
 CREATE TABLE IF NOT EXISTS solutions
 (
     id             serial           NOT NULL,
@@ -125,15 +149,17 @@ EXECUTE PROCEDURE updated_at_update();
 
 -- +goose Down
 -- +goose StatementBegin
+DROP TRIGGER IF EXISTS on_solutions_update ON solutions;
+DROP TABLE IF EXISTS solutions;
+DROP TRIGGER IF EXISTS on_participants_update ON participants;
+DROP TABLE IF EXISTS participants;
+DROP TRIGGER IF EXISTS on_tasks_update ON tasks;
+DROP TRIGGER IF EXISTS max_tasks_on_contest_check ON tasks;
+DROP TABLE IF EXISTS tasks;
 DROP TRIGGER IF EXISTS on_problems_update ON problems;
 DROP TABLE IF EXISTS problems;
 DROP TRIGGER IF EXISTS on_contests_update ON contests;
 DROP TABLE IF EXISTS contests;
-DROP TRIGGER IF EXISTS on_tasks_update ON tasks;
-DROP TABLE IF EXISTS tasks;
-DROP TRIGGER IF EXISTS on_participants_update ON participants;
-DROP TABLE IF EXISTS participants;
-DROP TRIGGER IF EXISTS on_solutions_update ON solutions;
-DROP TABLE IF EXISTS solutions;
-DROP FUNCTION updated_at_update();
+DROP FUNCTION IF EXISTS  updated_at_update();
+DROP FUNCTION IF EXISTS check_max_tasks();
 -- +goose StatementEnd