import json
import os
from typing import Dict, Optional

CONFIG_PATH = os.path.join(os.path.dirname(__file__), "proxy_settings.json")

DEFAULT_CONFIG = {
    "enabled": True,
    "tunnel": "t133.kdltps.com:15818",
    "username": "t16766298346583",
    "password": "zyn0vb20",
    "scheme": "http",
}

_PROXY_STATUS_REPORTED = False


def _normalize_bool(value, default: bool = True) -> bool:
    if value is None:
        return default
    if isinstance(value, bool):
        return value
    text = str(value).strip().lower()
    return text not in ("0", "false", "no", "off", "")


def _env_proxy_override() -> Optional[bool]:
    """
    环境变量覆盖代理开关：
    - PROXY_ENABLED 未设置：返回 None（不覆盖，仍读取 proxy_settings.json）
    - PROXY_ENABLED=0/false/off：强制关闭代理
    - PROXY_ENABLED=1/true/on：强制开启代理（前提是配置字段齐全）
    """
    raw = os.getenv("PROXY_ENABLED")
    if raw is None:
        return None
    return _normalize_bool(raw, True)


def _load_config() -> Dict[str, str]:
    if not os.path.exists(CONFIG_PATH):
        return dict(DEFAULT_CONFIG)
    try:
        with open(CONFIG_PATH, "r", encoding="utf-8") as f:
            data = json.load(f) or {}
    except Exception as exc:
        print(f"[proxy] 配置读取失败: {exc}, 使用默认配置")
        return dict(DEFAULT_CONFIG)

    config = dict(DEFAULT_CONFIG)
    for key, value in data.items():
        if value is not None:
            config[key] = value
    return config


def report_proxy_status() -> None:
    global _PROXY_STATUS_REPORTED
    if _PROXY_STATUS_REPORTED:
        return
    _PROXY_STATUS_REPORTED = True

    config = _load_config()
    override = _env_proxy_override()
    if override is False:
        print("[proxy] disabled by env (PROXY_ENABLED=0)")
        return

    enabled = _normalize_bool(config.get("enabled"), True) if override is None else True
    if not enabled:
        print("[proxy] disabled by config")
        return

    missing = [key for key in ("tunnel", "username", "password") if not config.get(key)]
    if missing:
        print(f"[proxy] enabled but missing fields: {', '.join(missing)}")
        return
    print(f"[proxy] enabled=True tunnel={config.get('tunnel')}")


def get_proxies() -> Optional[Dict[str, str]]:
    """
    返回统一的代理配置；当配置 enabled=false 时返回 None。
    代理配置从 proxy_settings.json 读取，不依赖环境变量。
    """
    config = _load_config()
    override = _env_proxy_override()
    if override is False:
        return None
    if override is None and not _normalize_bool(config.get("enabled"), True):
        return None

    tunnel = str(config.get("tunnel") or "").strip()
    username = str(config.get("username") or "").strip()
    password = str(config.get("password") or "").strip()
    scheme = str(config.get("scheme") or "http").strip().lower()

    if not tunnel or not username or not password:
        print("[proxy] missing proxy credentials, proxy disabled")
        return None

    proxy = f"{scheme}://{username}:{password}@{tunnel}/"
    return {"http": proxy, "https": proxy}


def apply_proxy(session) -> Optional[Dict[str, str]]:
    """为 requests.Session 应用统一代理配置，返回最终代理字典或 None。"""
    report_proxy_status()
    proxies = get_proxies()
    session.trust_env = False
    if proxies:
        session.proxies.update(proxies)
    else:
        session.proxies.clear()
    return proxies


__all__ = ["get_proxies", "apply_proxy", "report_proxy_status"]


def is_proxy_enabled() -> bool:
    """
    判断当前进程是否启用了代理。

    优先遵循环境变量 PROXY_ENABLED；
    未设置时回退到 proxy_settings.json 的 enabled 配置。
    """
    config = _load_config()
    override = _env_proxy_override()
    if override is False:
        return False
    if override is True:
        return True
    return _normalize_bool(config.get("enabled"), True)


__all__ = ["get_proxies", "apply_proxy", "report_proxy_status", "is_proxy_enabled"]