"""配置加载与设置模型。

优先级（高 -> 低）：
1. 环境变量 SMARTEDT_CONFIG 指定的配置文件
2. 在若干候选位置寻找 config.ini（兼容 PyInstaller 打包运行态）
3. 环境变量的 fallback
4. 内置默认值
"""

from __future__ import annotations

import configparser
import os
from dataclasses import dataclass
from pathlib import Path


@dataclass(frozen=True)
class ServerSettings:
    """服务监听配置。"""

    host: str = "0.0.0.0"
    port: int = 5000
    debug: bool = False


@dataclass(frozen=True)
class FileSettings:
    """文件存储相关配置。"""

    root_path: Path


@dataclass(frozen=True)
class DatabaseSettings:
    """数据库连接相关配置。"""

    url: str
    timescaledb: bool = True


@dataclass(frozen=True)
class UnitySettings:
    host: str = "127.0.0.1"
    port: int = 6000


@dataclass(frozen=True)
class AppSettings:
    """应用聚合配置。"""

    server: ServerSettings
    files: FileSettings
    database: DatabaseSettings
    unity: UnitySettings


import sys

def _find_config_file() -> Path | None:
    """尝试从若干候选位置定位 config.ini（包含 PyInstaller 运行态）。"""
    # Handle PyInstaller frozen state
    if getattr(sys, 'frozen', False):
        # If onefile, _MEIPASS. If onedir, executable dir or _internal
        # With onedir, the exe is in root, internal files in _internal.
        # But our spec put config in backend/config
        
        # Check relative to executable
        exe_dir = Path(sys.executable).parent
        candidates = [
            exe_dir / "backend" / "config" / "config.ini",
            exe_dir / "_internal" / "backend" / "config" / "config.ini",
            exe_dir / "config.ini",
        ]
        for path in candidates:
            if path.exists():
                return path

    candidates = [
        Path(__file__).resolve().parent / "config.ini",
        Path(__file__).resolve().parents[1] / "config.ini",
        Path(__file__).resolve().parents[2] / "config.ini",
    ]
    for path in candidates:
        if path.exists():
            return path
    return None


def load_settings() -> AppSettings:
    """加载并返回应用配置。"""
    config = configparser.ConfigParser()
    config_path = os.getenv("SMARTEDT_CONFIG")
    if config_path:
        config.read(config_path, encoding="utf-8")
    else:
        found = _find_config_file()
        if found:
            config.read(found, encoding="utf-8")

    server = ServerSettings(
        host=config.get("SERVER", "host", fallback=os.getenv("SMARTEDT_HOST", "0.0.0.0")),
        port=config.getint("SERVER", "port", fallback=int(os.getenv("SMARTEDT_PORT", "5000"))),
        debug=config.getboolean("SERVER", "debug", fallback=os.getenv("SMARTEDT_DEBUG", "False").lower() == "true"),
    )

    default_root = Path(os.getenv("SMARTEDT_FILE_ROOT", "data"))
    root_value = config.get("FILEPATH", "path", fallback=str(default_root))
    root_path = Path(root_value)
    if not root_path.is_absolute():
        root_path = (Path(__file__).resolve().parents[1] / root_path).resolve()

    database_url = config.get("DATABASE", "url", fallback=os.getenv("SMARTEDT_DATABASE_URL", "")).strip()
    if not database_url:
        database_url = "postgresql+psycopg://smartedt:CHANGE_ME@127.0.0.1:5432/smartedt"
    timescaledb = config.getboolean(
        "DATABASE",
        "timescaledb",
        fallback=os.getenv("SMARTEDT_TIMESCALEDB", "True").lower() == "true",
    )

    unity = UnitySettings(
        host=config.get("UNITY", "host", fallback=os.getenv("SMARTEDT_UNITY_HOST", "127.0.0.1")),
        port=config.getint("UNITY", "port", fallback=int(os.getenv("SMARTEDT_UNITY_PORT", "6000"))),
    )

    return AppSettings(
        server=server,
        files=FileSettings(root_path=root_path),
        database=DatabaseSettings(url=database_url, timescaledb=timescaledb),
        unity=unity,
    )