-- ==========================================================
-- 04_fk_policies.sql : normalisation des politiques ON DELETE
-- A exécuter après 01_init.sql et 03_checks.sql
-- ==========================================================

-- Helper: Drop FK d'une table/colonne si elle existe (par son/leurs noms de colonne)
-- puis recrée la contrainte avec la clause fournie
-- Utilise information_schema pour retrouver le nom de contrainte auto-généré
-- NB: schema = public

-- ========== messages.id_expediteur -> utilisateurs.id : SET NULL (au lieu de CASCADE)
DO $$
DECLARE
  conname text;
BEGIN
  SELECT tc.constraint_name INTO conname
  FROM information_schema.table_constraints tc
  JOIN information_schema.key_column_usage kcu
    ON tc.constraint_name = kcu.constraint_name AND tc.table_schema = kcu.table_schema
  WHERE tc.table_schema='public'
    AND tc.table_name='messages'
    AND tc.constraint_type='FOREIGN KEY'
    AND kcu.column_name='id_expediteur';
  IF conname IS NOT NULL THEN
    EXECUTE format('ALTER TABLE public.messages DROP CONSTRAINT %I', conname);
  END IF;
  EXECUTE $sql$
    ALTER TABLE public.messages
    ADD CONSTRAINT fk_messages_id_expediteur
    FOREIGN KEY (id_expediteur) REFERENCES public.utilisateurs(id) ON DELETE SET NULL
  $sql$;
END $$;

-- ========== parents.id_co_parent -> utilisateurs.id : SET NULL
DO $$
DECLARE conname text;
BEGIN
  SELECT tc.constraint_name INTO conname
  FROM information_schema.table_constraints tc
  JOIN information_schema.key_column_usage kcu
    ON tc.constraint_name = kcu.constraint_name AND tc.table_schema = kcu.table_schema
  WHERE tc.table_schema='public'
    AND tc.table_name='parents'
    AND tc.constraint_type='FOREIGN KEY'
    AND kcu.column_name='id_co_parent';
  IF conname IS NOT NULL THEN
    EXECUTE format('ALTER TABLE public.parents DROP CONSTRAINT %I', conname);
  END IF;
  EXECUTE $sql$
    ALTER TABLE public.parents
    ADD CONSTRAINT fk_parents_id_co_parent
    FOREIGN KEY (id_co_parent) REFERENCES public.utilisateurs(id) ON DELETE SET NULL
  $sql$;
END $$;

-- ========== avenants_contrats.initie_par -> utilisateurs.id : SET NULL
DO $$
DECLARE conname text;
BEGIN
  SELECT tc.constraint_name INTO conname
  FROM information_schema.table_constraints tc
  JOIN information_schema.key_column_usage kcu
    ON tc.constraint_name = kcu.constraint_name AND tc.table_schema = kcu.table_schema
  WHERE tc.table_schema='public'
    AND tc.table_name='avenants_contrats'
    AND tc.constraint_type='FOREIGN KEY'
    AND kcu.column_name='initie_par';
  IF conname IS NOT NULL THEN
    EXECUTE format('ALTER TABLE public.avenants_contrats DROP CONSTRAINT %I', conname);
  END IF;
  EXECUTE $sql$
    ALTER TABLE public.avenants_contrats
    ADD CONSTRAINT fk_avenants_contrats_initie_par
    FOREIGN KEY (initie_par) REFERENCES public.utilisateurs(id) ON DELETE SET NULL
  $sql$;
END $$;

-- ========== evenements.id_am -> utilisateurs.id : SET NULL
DO $$
DECLARE conname text;
BEGIN
  SELECT tc.constraint_name INTO conname
  FROM information_schema.table_constraints tc
  JOIN information_schema.key_column_usage kcu
    ON tc.constraint_name = kcu.constraint_name AND tc.table_schema = kcu.table_schema
  WHERE tc.table_schema='public'
    AND tc.table_name='evenements'
    AND tc.constraint_type='FOREIGN KEY'
    AND kcu.column_name='id_am';
  IF conname IS NOT NULL THEN
    EXECUTE format('ALTER TABLE public.evenements DROP CONSTRAINT %I', conname);
  END IF;
  EXECUTE $sql$
    ALTER TABLE public.evenements
    ADD CONSTRAINT fk_evenements_id_am
    FOREIGN KEY (id_am) REFERENCES public.utilisateurs(id) ON DELETE SET NULL
  $sql$;
END $$;

-- ========== evenements.id_parent -> parents.id_utilisateur : SET NULL
DO $$
DECLARE conname text;
BEGIN
  SELECT tc.constraint_name INTO conname
  FROM information_schema.table_constraints tc
  JOIN information_schema.key_column_usage kcu
    ON tc.constraint_name = kcu.constraint_name AND tc.table_schema = kcu.table_schema
  WHERE tc.table_schema='public'
    AND tc.table_name='evenements'
    AND tc.constraint_type='FOREIGN KEY'
    AND kcu.column_name='id_parent';
  IF conname IS NOT NULL THEN
    EXECUTE format('ALTER TABLE public.evenements DROP CONSTRAINT %I', conname);
  END IF;
  EXECUTE $sql$
    ALTER TABLE public.evenements
    ADD CONSTRAINT fk_evenements_id_parent
    FOREIGN KEY (id_parent) REFERENCES public.parents(id_utilisateur) ON DELETE SET NULL
  $sql$;
END $$;

-- ========== evenements.cree_par -> utilisateurs.id : SET NULL
DO $$
DECLARE conname text;
BEGIN
  SELECT tc.constraint_name INTO conname
  FROM information_schema.table_constraints tc
  JOIN information_schema.key_column_usage kcu
    ON tc.constraint_name = kcu.constraint_name AND tc.table_schema = kcu.table_schema
  WHERE tc.table_schema='public'
    AND tc.table_name='evenements'
    AND tc.constraint_type='FOREIGN KEY'
    AND kcu.column_name='cree_par';
  IF conname IS NOT NULL THEN
    EXECUTE format('ALTER TABLE public.evenements DROP CONSTRAINT %I', conname);
  END IF;
  EXECUTE $sql$
    ALTER TABLE public.evenements
    ADD CONSTRAINT fk_evenements_cree_par
    FOREIGN KEY (cree_par) REFERENCES public.utilisateurs(id) ON DELETE SET NULL
  $sql$;
END $$;

-- ========== signalements_bugs.id_utilisateur -> utilisateurs.id : SET NULL
DO $$
DECLARE conname text;
BEGIN
  SELECT tc.constraint_name INTO conname
  FROM information_schema.table_constraints tc
  JOIN information_schema.key_column_usage kcu
    ON tc.constraint_name = kcu.constraint_name AND tc.table_schema = kcu.table_schema
  WHERE tc.table_schema='public'
    AND tc.table_name='signalements_bugs'
    AND tc.constraint_type='FOREIGN KEY'
    AND kcu.column_name='id_utilisateur';
  IF conname IS NOT NULL THEN
    EXECUTE format('ALTER TABLE public.signalements_bugs DROP CONSTRAINT %I', conname);
  END IF;
  EXECUTE $sql$
    ALTER TABLE public.signalements_bugs
    ADD CONSTRAINT fk_signalements_bugs_id_utilisateur
    FOREIGN KEY (id_utilisateur) REFERENCES public.utilisateurs(id) ON DELETE SET NULL
  $sql$;
END $$;

-- ========== validations.id_utilisateur -> utilisateurs.id : SET NULL
DO $$
DECLARE conname text;
BEGIN
  SELECT tc.constraint_name INTO conname
  FROM information_schema.table_constraints tc
  JOIN information_schema.key_column_usage kcu
    ON tc.constraint_name = kcu.constraint_name AND tc.table_schema = kcu.table_schema
  WHERE tc.table_schema='public'
    AND tc.table_name='validations'
    AND tc.constraint_type='FOREIGN KEY'
    AND kcu.column_name='id_utilisateur';
  IF conname IS NOT NULL THEN
    EXECUTE format('ALTER TABLE public.validations DROP CONSTRAINT %I', conname);
  END IF;
  EXECUTE $sql$
    ALTER TABLE public.validations
    ADD CONSTRAINT fk_validations_id_utilisateur
    FOREIGN KEY (id_utilisateur) REFERENCES public.utilisateurs(id) ON DELETE SET NULL
  $sql$;
END $$;

-- NB:
-- D'autres FK déjà correctes : CASCADE (assistantes_maternelles, parents, enfants_parents, dossiers, messages.id_dossier, contrats, avenants_contrats.id_contrat, evenements.id_enfant), SET NULL (uploads).
-- On laisse ON UPDATE par défaut (NO ACTION), car les UUID ne changent pas.