-- Enforce immutable tracecoin ledger: no UPDATE/DELETE allowed.

CREATE OR REPLACE FUNCTION prevent_tracecoin_ledger_mutation()
RETURNS trigger AS $$
BEGIN
    RAISE EXCEPTION 'tracecoin_ledger is immutable; % is not allowed', TG_OP;
END;
$$ LANGUAGE plpgsql;

DROP TRIGGER IF EXISTS trg_prevent_tracecoin_ledger_update ON tracecoin_ledger;
CREATE TRIGGER trg_prevent_tracecoin_ledger_update
BEFORE UPDATE ON tracecoin_ledger
FOR EACH ROW
EXECUTE FUNCTION prevent_tracecoin_ledger_mutation();

DROP TRIGGER IF EXISTS trg_prevent_tracecoin_ledger_delete ON tracecoin_ledger;
CREATE TRIGGER trg_prevent_tracecoin_ledger_delete
BEFORE DELETE ON tracecoin_ledger
FOR EACH ROW
EXECUTE FUNCTION prevent_tracecoin_ledger_mutation();