-- mig 094 — tighten paliad.projects.client_number + matter_number CHECK
-- from 7-digit to 6-digit. The "7-Ziffern" rule in mig 018 was wrong;
-- HLC's real Client/Matter format is 6 digits each (m's correction,
-- 2026-05-17). The constraints carry the legacy 'projekte_*_check'
-- name from before the table was renamed (mig 021), so the ALTER
-- TABLE DROP / ADD has to use those names verbatim.
--
-- Existing rows: only test data (2 client_numbers, 1 matter_number),
-- all 7-digit. They violate the new pattern, so we NULL them out
-- before tightening — preserving the project rows themselves, just
-- clearing the wrong-shaped billing identifiers. The rows are
-- snapshotted in projects_pre_094 first so the down migration can
-- restore them byte-identically.
--
-- audit_reason wrapper at top: the trigger on paliad.projects logs
-- every row-level UPDATE; the message persists in the audit table as
-- the permanent record of why those test values were cleared.

SELECT set_config(
    'paliad.audit_reason',
    'mig 094: clear test 7-digit client_number/matter_number values before tightening CHECK to 6-digit (HLC real format correction, 2026-05-17)',
    true);

-- =============================================================================
-- 1. Backup snapshot. Full row copy of every paliad.projects row that
--    has either field populated. Idempotent via CREATE TABLE IF NOT
--    EXISTS — re-running the migration after an aborted run re-uses
--    the existing snapshot.
-- =============================================================================

CREATE TABLE IF NOT EXISTS paliad.projects_pre_094 AS
SELECT *, now() AS snapshotted_at
  FROM paliad.projects
 WHERE client_number IS NOT NULL OR matter_number IS NOT NULL;

COMMENT ON TABLE paliad.projects_pre_094 IS
    'Snapshot of paliad.projects rows that had a client_number or '
    'matter_number set before mig 094 tightened the CHECK from '
    '7-digit to 6-digit. The 094 UPDATE NULL-ed those values out '
    'because they were leftover 7-digit test data. Persists as the '
    'permanent audit anchor; the down migration restores from it.';

-- =============================================================================
-- 2. Clear the 7-digit test values. Only rows that already violate
--    the new pattern are touched — anything that happens to already
--    be 6 digits (none today, but the WHERE keeps the migration
--    re-runnable after future inserts) is left alone.
-- =============================================================================

UPDATE paliad.projects
   SET client_number = NULL
 WHERE client_number IS NOT NULL
   AND client_number !~ '^[0-9]{6}$';

UPDATE paliad.projects
   SET matter_number = NULL
 WHERE matter_number IS NOT NULL
   AND matter_number !~ '^[0-9]{6}$';

-- =============================================================================
-- 3. Replace the legacy 7-digit CHECKs with 6-digit ones. The
--    constraint names carry the pre-rename `projekte_*` prefix from
--    mig 018; keep them stable so external audit tools that scan
--    pg_constraint by name don't drift.
-- =============================================================================

ALTER TABLE paliad.projects
    DROP CONSTRAINT projekte_client_number_check,
    DROP CONSTRAINT projekte_matter_number_check;

ALTER TABLE paliad.projects
    ADD CONSTRAINT projekte_client_number_check
        CHECK (client_number IS NULL OR client_number ~ '^[0-9]{6}$'),
    ADD CONSTRAINT projekte_matter_number_check
        CHECK (matter_number IS NULL OR matter_number ~ '^[0-9]{6}$');

-- =============================================================================
-- 4. Hard assertions. Any row that survived the UPDATE+ALTER must
--    satisfy the new pattern; the count of cleared test rows must
--    match the snapshot.
-- =============================================================================

DO $$
DECLARE
    n_violations int;
BEGIN
    SELECT count(*) INTO n_violations
      FROM paliad.projects
     WHERE (client_number IS NOT NULL AND client_number !~ '^[0-9]{6}$')
        OR (matter_number IS NOT NULL AND matter_number !~ '^[0-9]{6}$');

    IF n_violations > 0 THEN
        RAISE EXCEPTION 'mig 094: % rows still violate the 6-digit pattern after UPDATE — should be 0', n_violations;
    END IF;

    RAISE NOTICE 'mig 094: 6-digit CHECKs in place, all rows compliant';
END $$;