"""SQLite 遥测后端(默认): WAL + 单持久连接 + to_thread 桥接。

蓝本 VT `adapters/telemetry.py`: 构造期建连接与表,失败降级为 no-op
(记录基础设施不得拖垮业务调用);`INSERT OR IGNORE` 幂等(call_id 主键);
写入经 threading.Lock 串行化后由 `asyncio.to_thread` 执行,不阻塞事件循环。
"""

from __future__ import annotations

import asyncio
import sqlite3
import threading
from pathlib import Path

from loguru import logger

_DDL = """
CREATE TABLE IF NOT EXISTS llm_calls (
    call_id            TEXT PRIMARY KEY,
    parent_call_id     TEXT,
    session_id         TEXT,
    model              TEXT    NOT NULL,
    provider           TEXT    NOT NULL,
    source_name        TEXT    NOT NULL,
    messages           TEXT    NOT NULL,
    response           TEXT    NOT NULL,
    thinking           TEXT    NOT NULL DEFAULT '',
    prompt_tokens      INTEGER NOT NULL,
    completion_tokens  INTEGER NOT NULL,
    usage_source       TEXT    NOT NULL,
    latency_ms         INTEGER NOT NULL,
    ttft_ms            REAL,
    max_inter_token_ms REAL,
    cache_hit          INTEGER NOT NULL DEFAULT 0,
    error              TEXT,
    cost               REAL,
    created_at         TEXT    NOT NULL DEFAULT (datetime('now'))
);
"""

_COLUMNS = (
    "call_id",
    "parent_call_id",
    "session_id",
    "model",
    "provider",
    "source_name",
    "messages",
    "response",
    "thinking",
    "prompt_tokens",
    "completion_tokens",
    "usage_source",
    "latency_ms",
    "ttft_ms",
    "max_inter_token_ms",
    "cache_hit",
    "error",
    "cost",
)

_INSERT = (
    f"INSERT OR IGNORE INTO llm_calls ({', '.join(_COLUMNS)}) "
    f"VALUES ({', '.join('?' for _ in _COLUMNS)})"
)


class SQLiteRecorder:
    """TelemetryRecorder 端口的 SQLite 实现;初始化/写入失败全降级 warning。"""

    def __init__(self, db_path: Path | str) -> None:
        self._lock = threading.Lock()
        self._conn: sqlite3.Connection | None = None
        try:
            path = Path(db_path)
            path.parent.mkdir(parents=True, exist_ok=True)
            conn = sqlite3.connect(path, check_same_thread=False, timeout=10.0)
            conn.execute("PRAGMA journal_mode=WAL")
            conn.execute("PRAGMA busy_timeout=5000")
            conn.execute(_DDL)
            conn.commit()
            self._conn = conn
        except (OSError, sqlite3.Error) as exc:
            logger.warning("SQLite 遥测初始化失败,后续记录降级为 no-op: {}", exc)

    async def record_llm_call(self, **fields: object) -> None:
        """写一行遥测;字段集合即 18 字段冻结签名(ports.TelemetryRecorder)。"""
        if self._conn is None:
            return
        row = tuple(fields[col] for col in _COLUMNS)
        try:
            await asyncio.to_thread(self._write, row)
        except (OSError, sqlite3.Error) as exc:
            logger.warning("SQLite 遥测写入失败(降级不冒泡): {}", exc)

    def _write(self, row: tuple) -> None:
        assert self._conn is not None  # 内部不变量: 调用方已判空
        with self._lock:
            self._conn.execute(_INSERT, row)
            self._conn.commit()

    def close(self) -> None:
        """幂等关闭持久连接。"""
        conn, self._conn = self._conn, None
        if conn is not None:
            with self._lock:
                conn.close()