CREATE TABLE IF NOT EXISTS students (
  id SERIAL PRIMARY KEY,
  name VARCHAR(150) NOT NULL UNIQUE,
  created_at TIMESTAMPTZ DEFAULT now()
);

ALTER TABLE students ADD COLUMN IF NOT EXISTS group_id INT REFERENCES groups(id);

CREATE TABLE IF NOT EXISTS settings (
  key TEXT PRIMARY KEY,
  value TEXT
);

INSERT INTO settings (key, value) VALUES ('spam_interval_min', '30')
ON CONFLICT (key) DO NOTHING;

CREATE TABLE IF NOT EXISTS share_links (
  id SERIAL PRIMARY KEY,
  token VARCHAR(40) UNIQUE NOT NULL,
  name VARCHAR(200) NOT NULL,
  group_id INT REFERENCES groups(id),
  student_name VARCHAR(150),
  date_from DATE,
  date_to DATE,
  created_at TIMESTAMPTZ DEFAULT now()
);

DO $$
BEGIN
  INSERT INTO students (name)
  SELECT DISTINCT student_name FROM entries WHERE student_name IS NOT NULL AND student_name <> ''
  ON CONFLICT (name) DO NOTHING;
END $$;