-- Charakter-Verknüpfungen auch bei DELETEs außerhalb der Worker bereinigen.
-- Löscht bestehende verwaiste Beziehungen; vorher auf der Ziel-DB sichern.
BEGIN;

LOCK TABLE falukant_data.character, falukant_data.relationship,
    falukant_data.relationship_state, falukant_data.child_relation
    IN SHARE ROW EXCLUSIVE MODE;

DELETE FROM falukant_data.relationship_state rs
WHERE NOT EXISTS (
    SELECT 1 FROM falukant_data.relationship r WHERE r.id = rs.relationship_id
)
OR EXISTS (
    SELECT 1 FROM falukant_data.relationship r
    WHERE r.id = rs.relationship_id
      AND ((r.character1_id IS NOT NULL AND NOT EXISTS (
                SELECT 1 FROM falukant_data.character c WHERE c.id = r.character1_id))
        OR (r.character2_id IS NOT NULL AND NOT EXISTS (
                SELECT 1 FROM falukant_data.character c WHERE c.id = r.character2_id)))
);

DELETE FROM falukant_data.relationship r
WHERE (r.character1_id IS NOT NULL AND NOT EXISTS (
    SELECT 1 FROM falukant_data.character c WHERE c.id = r.character1_id
)) OR (r.character2_id IS NOT NULL AND NOT EXISTS (
    SELECT 1 FROM falukant_data.character c WHERE c.id = r.character2_id
));

DELETE FROM falukant_data.child_relation cr
WHERE (cr.child_character_id IS NOT NULL AND NOT EXISTS (
    SELECT 1 FROM falukant_data.character c WHERE c.id = cr.child_character_id
)) OR (cr.father_character_id IS NOT NULL AND NOT EXISTS (
    SELECT 1 FROM falukant_data.character c WHERE c.id = cr.father_character_id
)) OR (cr.mother_character_id IS NOT NULL AND NOT EXISTS (
    SELECT 1 FROM falukant_data.character c WHERE c.id = cr.mother_character_id
));

-- Vorhandene einspaltige FKs ersetzen (deren Namen sind je nach Backend verschieden).
-- Auch relationship_state absichern, damit es die Kaskade nicht blockieren kann.
DO $$
DECLARE
    target record;
    existing_fk record;
BEGIN
    FOR target IN
        SELECT * FROM (VALUES
            ('relationship', 'character1_id', 'character'),
            ('relationship', 'character2_id', 'character'),
            ('child_relation', 'child_character_id', 'character'),
            ('child_relation', 'father_character_id', 'character'),
            ('child_relation', 'mother_character_id', 'character'),
            ('relationship_state', 'relationship_id', 'relationship')
        ) AS targets(table_name, column_name, referenced_table)
    LOOP
        FOR existing_fk IN
            SELECT con.conname
            FROM pg_constraint con
            JOIN pg_attribute att ON att.attrelid = con.conrelid
                AND con.conkey = ARRAY[att.attnum]
            WHERE con.contype = 'f'
              AND con.conrelid = format('falukant_data.%I', target.table_name)::regclass
              AND con.confrelid = format('falukant_data.%I', target.referenced_table)::regclass
              AND att.attname = target.column_name
        LOOP
            EXECUTE format('ALTER TABLE falukant_data.%I DROP CONSTRAINT %I',
                target.table_name, existing_fk.conname);
        END LOOP;

        EXECUTE format(
            'ALTER TABLE falukant_data.%I ADD CONSTRAINT %I FOREIGN KEY (%I) REFERENCES falukant_data.%I (id) ON DELETE CASCADE',
            target.table_name, target.table_name || '_' || target.column_name || '_fkey',
            target.column_name, target.referenced_table);
    END LOOP;
END;
$$;

COMMIT;