# 2026-03-21 — pg-dedup: удаляет дубликаты по title, оставляет первый (min id).
# Тестирует: DELETE с subquery, CTE, idempotency (повторный вызов безопасен).
import os, psycopg2

def dedup(event):
    dry_run = str(event.get("dry_run", "false")).lower() in ("true", "1", "yes")
    conn = psycopg2.connect(
        host=os.environ["PGHOST"], port=int(os.environ.get("PGPORT", 5432)),
        dbname=os.environ["PGDATABASE"], user=os.environ["PGUSER"],
        password=os.environ["PGPASSWORD"], sslmode=os.environ.get("PGSSLMODE", "require"),
    )
    try:
        with conn.cursor() as cur:
            # Считаем сколько дублей есть
            cur.execute("""
                SELECT COUNT(*) FROM terraform_demo_table t1
                WHERE EXISTS (
                    SELECT 1 FROM terraform_demo_table t2
                    WHERE t2.title = t1.title AND t2.id < t1.id
                )
            """)
            dupes_count = cur.fetchone()[0]

            if not dry_run and dupes_count > 0:
                cur.execute("""
                    DELETE FROM terraform_demo_table
                    WHERE id NOT IN (
                        SELECT MIN(id) FROM terraform_demo_table GROUP BY title
                    )
                """)
                deleted = cur.rowcount
                conn.commit()
            else:
                deleted = 0

        return {"duplicates_found": dupes_count, "deleted": deleted, "dry_run": dry_run}
    finally:
        conn.close()