"""
PostgreSQL 运行账连接与迁移。

本包职责：解析 PG_DSN、安全拒绝现网库名、执行版本化 SQL。
禁止：智能体经本包写 MySQL 工单表；禁止 FLUSH / 删现网库。
"""

from __future__ import annotations

import logging
import re
from pathlib import Path
from typing import Optional
from urllib.parse import urlparse

from agent.config import Settings, get_settings

logger = logging.getLogger(__name__)

# 现网运行账库名：新系统迁移脚本绝对不能碰
_FORBIDDEN_DB_NAMES = frozenset({"ytd_runtime"})


def migrations_dir() -> Path:
    """返回 inquiry-agent/migrations 目录。"""
    return Path(__file__).resolve().parents[2] / "migrations"


def assert_safe_database(dsn: str) -> str:
    """
    从 DSN 解析库名并校验。

    返回库名；若为 ytd_runtime 则抛错。
    """
    if not dsn:
        raise RuntimeError("PG_DSN 为空，无法迁移")
    parsed = urlparse(dsn)
    db = (parsed.path or "").lstrip("/").split("?")[0]
    if not db:
        raise RuntimeError(f"无法从 DSN 解析库名: {dsn[:32]}...")
    if db in _FORBIDDEN_DB_NAMES:
        raise RuntimeError(f"禁止对现网库执行迁移: {db}")
    return db


def connect_psycopg(dsn: str):
    """
    打开 psycopg 连接（调用方负责 close）。

    副作用：网络连库。
    """
    import psycopg

    return psycopg.connect(dsn, connect_timeout=5)


def apply_migrations(settings: Optional[Settings] = None) -> list[str]:
    """
    按文件名顺序执行尚未应用的 *.sql。

    返回：本次新执行的 version 列表。
    无 DSN：抛错（自检可用 --dry-list）。
    """
    cfg = settings or get_settings()
    dsn = cfg.resolve_pg_dsn()
    db_name = assert_safe_database(dsn)
    logger.info("准备迁移 database=%s", db_name)

    sql_files = sorted(migrations_dir().glob("*.sql"))
    if not sql_files:
        logger.warning("migrations 目录无 .sql 文件")
        return []

    applied: list[str] = []
    with connect_psycopg(dsn) as conn:
        conn.execute(
            """
            CREATE TABLE IF NOT EXISTS schema_migrations (
                version TEXT PRIMARY KEY,
                applied_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
                description TEXT NOT NULL DEFAULT ''
            )
            """
        )
        conn.commit()
        for path in sql_files:
            version = path.stem
            row = conn.execute(
                "SELECT 1 FROM schema_migrations WHERE version = %s",
                (version,),
            ).fetchone()
            if row:
                logger.info("跳过已应用 migration=%s", version)
                continue
            sql = path.read_text(encoding="utf-8")
            # 去掉纯注释行后的空脚本保护
            body = "\n".join(
                ln for ln in sql.splitlines() if not ln.strip().startswith("--")
            ).strip()
            if not body:
                continue
            logger.info("执行 migration=%s", version)
            conn.execute(sql)
            # 若脚本未自行写入 schema_migrations，补写
            exists = conn.execute(
                "SELECT 1 FROM schema_migrations WHERE version = %s",
                (version,),
            ).fetchone()
            if not exists:
                conn.execute(
                    "INSERT INTO schema_migrations(version, description) VALUES (%s, %s)",
                    (version, path.name),
                )
            conn.commit()
            applied.append(version)
    return applied


def list_migration_files() -> list[str]:
    """列出迁移文件名（不连库）。"""
    return [p.name for p in sorted(migrations_dir().glob("*.sql"))]


# 会话 / 停等仓储壳（表已在 001；本包只提供读写空实现）
from agent.runtime_db.session_store import (  # noqa: E402
    MemorySessionStore,
    SessionRecord,
    create_session_store,
)
from agent.runtime_db.suspend_store import (  # noqa: E402
    MemorySuspendStore,
    SuspendRecord,
    create_suspend_store,
)