# 2026-03-21 — pg-bulk-insert: bulk INSERT через execute_values.
# Тестирует: большие батчи (до 500 строк), производительность, память.
import os, time, psycopg2, psycopg2.extras

def bulk_insert(event):
    try:
        n = max(0, min(int(event.get("n", 50)), 500))  # cap 500, min 0
    except (TypeError, ValueError):
        n = 50
    prefix = str(event.get("prefix", "bulk"))[:50]
    ts = int(time.time() * 1000)

    # n=0 — граничный случай: вернуть сразу без обращения к PG.
    if n == 0:
        return {"inserted": 0, "first_id": None, "elapsed_sec": 0.0}

    rows = [(f"{prefix}-{ts}-{i}",) for i in range(n)]

    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:
        t0 = time.time()
        with conn.cursor() as cur:
            psycopg2.extras.execute_values(
                cur,
                "INSERT INTO terraform_demo_table (title) VALUES %s RETURNING id",
                rows,
                page_size=100,
            )
            ids = [r[0] for r in cur.fetchall()]
        conn.commit()
        elapsed = round(time.time() - t0, 3)
        return {"inserted": len(ids), "first_id": ids[0] if ids else None, "elapsed_sec": elapsed}
    finally:
        conn.close()