-- migrate:up
CREATE TABLE courses (
    id SERIAL PRIMARY KEY,
    "name" TEXT NOT NULL,
    -- e.g. CS-477
    code TEXT,
    -- At least one teacher, checked by the backend
    teachers TEXT[] NOT NULL DEFAULT '{}',
    -- Main page of the course (usually moodle)
    main_page_url TEXT
);

-- Kind of a time slot (lecture, exercises, lab, ...). A table rather than an enum so
-- new kinds can be added without a migration of the slots.
CREATE TABLE slot_tags (
    id SERIAL PRIMARY KEY,
    "name" JSONB NOT NULL,
    -- Hex color used to display the slots of this kind, e.g. #2563eb
    color TEXT NOT NULL
);

INSERT INTO slot_tags ("name", color) VALUES
    ('{"fr": "Cours", "en": "Lecture"}', '#2563eb'),
    ('{"fr": "Exercices", "en": "Exercises"}', '#16a34a'),
    ('{"fr": "Lab", "en": "Lab"}', '#ea580c');

-- Weekly recurring slot of a course. Slots of different courses may overlap.
CREATE TABLE time_slots (
    id SERIAL PRIMARY KEY,
    course_id INTEGER NOT NULL REFERENCES courses (id) ON DELETE CASCADE,
    tag_id INTEGER NOT NULL REFERENCES slot_tags (id),
    -- ISO weekday: 1 = monday ... 7 = sunday
    weekday SMALLINT NOT NULL CHECK (weekday BETWEEN 1 AND 7),
    start_time TIME NOT NULL,
    end_time TIME NOT NULL,
    CHECK (start_time < end_time)
);

CREATE INDEX time_slots_course_id_idx ON time_slots (course_id);

-- migrate:down
DROP TABLE IF EXISTS time_slots;
DROP TABLE IF EXISTS slot_tags;
DROP TABLE IF EXISTS courses;