# -*- coding: utf-8 -*-
"""配置文件加载与校验。"""
from __future__ import annotations

import sys
from pathlib import Path
from typing import Any

import yaml

_REQUIRED_KEYS = {
    "database": [
        "server", "port", "database", "schema", "username", "password",
        "table", "id_column", "param_column", "connect_timeout", "query_timeout",
    ],
    "llm": [
        "base_url", "api_key", "model", "temperature", "max_tokens",
        "disable_thinking", "timeout", "max_retry", "retry_backoff_seconds",
    ],
    "business": ["max_workers", "log_level", "default_mode", "log_dir", "format_retry"],
}
_VALID_MODES = {"coarse", "fine"}


class ConfigError(Exception):
    """配置文件缺失或格式错误。"""


def load_config(path: str | Path = "config.yaml") -> dict[str, Any]:
    """读取 YAML 配置文件并做基础字段校验。

    校验失败会抛出 ConfigError 并说明缺哪个字段，避免程序运行到一半才因为
    配置缺失而报出难以理解的异常。
    """
    p = Path(path)
    if not p.exists():
        raise ConfigError(f"配置文件不存在: {p.resolve()}")

    with p.open("r", encoding="utf-8") as f:
        try:
            cfg = yaml.safe_load(f)
        except yaml.YAMLError as e:
            raise ConfigError(f"配置文件 YAML 解析失败: {e}") from e

    if not isinstance(cfg, dict):
        raise ConfigError("配置文件顶层必须是一个字典 (database/llm/business)")

    missing_sections = [s for s in _REQUIRED_KEYS if s not in cfg]
    if missing_sections:
        raise ConfigError(f"配置文件缺少顶层配置块: {missing_sections}")

    for section, keys in _REQUIRED_KEYS.items():
        section_cfg = cfg[section]
        if not isinstance(section_cfg, dict):
            raise ConfigError(f"配置块 '{section}' 必须是字典")
        missing = [k for k in keys if k not in section_cfg]
        if missing:
            raise ConfigError(f"配置块 '{section}' 缺少字段: {missing}")

    default_mode = cfg["business"]["default_mode"]
    if default_mode not in _VALID_MODES:
        raise ConfigError(
            f"business.default_mode 必须是 {_VALID_MODES} 之一，实际为: {default_mode!r}"
        )

    # enable_other_category 是后加的可选字段，不放进 _REQUIRED_KEYS——避免
    # 旧配置文件因为没有这个字段就直接报"缺字段"。不写就按 False（关闭）处理；
    # 一旦写了就必须是布尔值，防止 "false"(字符串) 这类误写被当成真值静默生效。
    if "enable_other_category" in cfg["business"]:
        other_flag = cfg["business"]["enable_other_category"]
        if not isinstance(other_flag, bool):
            raise ConfigError(
                f"business.enable_other_category 必须是布尔值 true/false，实际为: {other_flag!r}"
            )

    # 简单的占位符提醒，防止用户忘记改配置直接运行
    placeholders = []
    if cfg["database"]["password"] == "CHANGE_ME":
        placeholders.append("database.password")
    if cfg["llm"]["api_key"] == "CHANGE_ME":
        placeholders.append("llm.api_key")
    if placeholders:
        print(
            f"[警告] 以下配置项仍是占位符，请修改 config.yaml: {placeholders}",
            file=sys.stderr,
        )

    return cfg