-- +goose Up
-- Weekly recurring rules for class sessions. Rules materialize concrete
-- session rows for a rolling horizon (the service writes them); sessions
-- keep a nullable schedule_id link so regeneration is idempotent via the
-- partial unique index and deleting a rule stops future sessions without
-- touching existing ones.
CREATE TABLE class_schedules (
  id          uuid PRIMARY KEY DEFAULT gen_random_uuid(),
  tenant_id   uuid NOT NULL REFERENCES tenants(id) ON DELETE CASCADE,
  template_id uuid NOT NULL REFERENCES class_templates(id) ON DELETE CASCADE,
  location_id uuid REFERENCES locations(id) ON DELETE SET NULL,
  day_of_week integer NOT NULL CHECK (day_of_week BETWEEN 0 AND 6),
  starts_local time NOT NULL,
  active      boolean NOT NULL DEFAULT true,
  created_at  timestamptz NOT NULL DEFAULT now()
);
CREATE INDEX class_schedules_tenant_idx ON class_schedules (tenant_id);

ALTER TABLE class_sessions
  ADD COLUMN schedule_id uuid REFERENCES class_schedules(id) ON DELETE SET NULL;
CREATE UNIQUE INDEX class_sessions_schedule_start_idx
  ON class_sessions (schedule_id, starts_at)
  WHERE schedule_id IS NOT NULL;

-- +goose Down
ALTER TABLE class_sessions DROP COLUMN IF EXISTS schedule_id;
DROP TABLE IF EXISTS class_schedules;