"""SQLite 连接统一配置（WAL + busy_timeout，降低并发锁冲突）。"""
from __future__ import annotations

import os
import sqlite3
import time

DB_PATH = os.path.join(os.path.dirname(os.path.abspath(__file__)), "futures.db")


def connect_db(path: str | None = None) -> sqlite3.Connection:
    db_path = path or DB_PATH
    conn = sqlite3.connect(db_path, timeout=30, check_same_thread=False)
    conn.row_factory = sqlite3.Row
    conn.execute("PRAGMA busy_timeout=30000")
    try:
        conn.execute("PRAGMA journal_mode=WAL")
    except sqlite3.OperationalError:
        pass
    return conn


def execute_retry(
    conn: sqlite3.Connection,
    sql: str,
    params: tuple = (),
    *,
    retries: int = 6,
    base_delay: float = 0.05,
) -> sqlite3.Cursor:
    """遇 database is locked 时短暂退避重试。"""
    last_exc: Exception | None = None
    for attempt in range(retries):
        try:
            return conn.execute(sql, params)
        except sqlite3.OperationalError as exc:
            if "locked" not in str(exc).lower():
                raise
            last_exc = exc
            if attempt < retries - 1:
                time.sleep(base_delay * (attempt + 1))
    if last_exc:
        raise last_exc
    raise sqlite3.OperationalError("database is locked")