-- t-paliad-184 / Fristen Phase 3 Slice 3 — wrap paliad.event_deadlines
-- in a read-only trigger so nobody can edit either side mid-cutover.
--
-- Slice 3 just moved 77 rows from event_deadlines → deadline_rules (mig
-- 085). Until Slice 4 cuts every reader over and Slice 9 drops the
-- legacy table, event_deadlines stays in place as the audit anchor and
-- (briefly) a compat-read source. We must not let any writer mutate it
-- behind the unified backend's back — diverging the two sides would
-- silently regress "Was kommt nach…" parity.
--
-- The trigger fires AFTER INSERT / UPDATE / DELETE and raises an
-- EXCEPTION with a clear message pointing the writer at the unified
-- table. SELECT is unaffected — the legacy EventDeadlineService's
-- pre-Slice-3 SELECT path keeps working until Slice 4 swaps it.
--
-- The supabase service_role bypasses RLS but NOT triggers — so
-- direct DB maintenance (psql, migration scripts) is also blocked.
-- This is intentional: any further edit to event_deadlines is a
-- mistake until Slice 9 drops the table.
--
-- Removed by Slice 9 (Step E, mig ~090) when paliad.event_deadlines is
-- dropped. Until then the trigger is the only thing keeping the two
-- tables in sync.

CREATE OR REPLACE FUNCTION paliad.event_deadlines_readonly_trigger()
RETURNS trigger
LANGUAGE plpgsql
AS $$
BEGIN
    RAISE EXCEPTION
        'paliad.event_deadlines is read-only after Phase 3 Slice 3 — '
        'writes must go through paliad.deadline_rules (Pipeline C is '
        'unified; the source table is preserved as an audit anchor '
        'until Slice 9 drops it). Operation: %', TG_OP;
END;
$$;

COMMENT ON FUNCTION paliad.event_deadlines_readonly_trigger() IS
    'BEFORE INSERT/UPDATE/DELETE trigger function that raises on any '
    'write to paliad.event_deadlines. Lives only between Slice 3 and '
    'Slice 9 — removed when the source table is dropped.';

-- BEFORE-trigger so the write is blocked before any row image is
-- captured. AFTER would still raise but the surrounding tx would
-- have already taken row locks.
DROP TRIGGER IF EXISTS event_deadlines_readonly ON paliad.event_deadlines;

CREATE TRIGGER event_deadlines_readonly
    BEFORE INSERT OR UPDATE OR DELETE ON paliad.event_deadlines
    FOR EACH ROW
    EXECUTE FUNCTION paliad.event_deadlines_readonly_trigger();

-- Defensive INSERT-row-level trigger covers the COPY path too; same
-- function, identical behaviour.

COMMENT ON TRIGGER event_deadlines_readonly ON paliad.event_deadlines IS
    'Phase 3 Slice 3 read-only wrapper. Blocks every INSERT/UPDATE/DELETE '
    'until Slice 9 drops the table. SELECT unaffected.';