import hashlib
import os
import secrets
from datetime import timedelta
from typing import Any

import jwt
from argon2 import PasswordHasher
from argon2.exceptions import InvalidHash, VerificationError, VerifyMismatchError

from yuxi.utils.datetime_utils import utc_now

JWT_ALGORITHM = "HS256"
JWT_EXPIRATION = 7 * 24 * 60 * 60
JWT_AUDIENCE = "yuxi-know-api"
PUBLIC_DEFAULT_JWT_SECRET_KEY = "yuxi_know_secure_key"
PASSWORD_HASHER = PasswordHasher()


def _is_production_env() -> bool:
    return os.environ.get("YUXI_ENV", "development").strip().lower() in {"prod", "production"}


def _get_or_create_dev_env(name: str, value_factory) -> str:
    value = os.environ.get(name, "").strip()
    if value:
        return value
    if _is_production_env():
        raise ValueError(f"{name} 未配置，请在生产环境的 .env.prod 中设置持久化随机值")

    value = value_factory()
    os.environ[name] = value
    print(f"{name} 未配置，开发环境已自动生成临时随机值，服务重启后会重新生成。")
    return value


def _get_jwt_secret_key() -> str:
    secret_key = _get_or_create_dev_env("JWT_SECRET_KEY", lambda: secrets.token_hex(32))
    if _is_production_env() and secret_key == PUBLIC_DEFAULT_JWT_SECRET_KEY:
        raise ValueError("JWT_SECRET_KEY 不能使用公开默认密钥，请重新生成随机强密钥")
    return secret_key


def _get_jwt_issuer() -> str:
    instance_id = _get_or_create_dev_env("YUXI_INSTANCE_ID", lambda: f"instance-{secrets.token_hex(8)}")
    return f"yuxi-know:{instance_id}"


class AuthUtils:
    @staticmethod
    def generate_api_key() -> tuple[str, str, str]:
        random_part = secrets.token_hex(24)
        full_key = f"yxkey_{random_part}"
        key_hash = hashlib.sha256(full_key.encode()).hexdigest()
        key_prefix = full_key[:12]
        return full_key, key_hash, key_prefix

    @staticmethod
    def hash_password(password: str) -> str:
        return PASSWORD_HASHER.hash(password)

    @staticmethod
    def verify_password(stored_password: str, provided_password: str) -> bool:
        if not stored_password.startswith("$argon2"):
            return False
        try:
            return PASSWORD_HASHER.verify(stored_password, provided_password)
        except (InvalidHash, VerifyMismatchError, VerificationError):
            return False

    @staticmethod
    def create_access_token(data: dict[str, Any], expires_delta: timedelta | None = None) -> str:
        to_encode = data.copy()
        expire = utc_now() + (expires_delta or timedelta(seconds=JWT_EXPIRATION))
        to_encode.update({"exp": expire, "iss": _get_jwt_issuer(), "aud": JWT_AUDIENCE})
        return jwt.encode(to_encode, _get_jwt_secret_key(), algorithm=JWT_ALGORITHM)

    @staticmethod
    def decode_token(token: str) -> dict[str, Any] | None:
        try:
            return jwt.decode(
                token,
                _get_jwt_secret_key(),
                algorithms=[JWT_ALGORITHM],
                issuer=_get_jwt_issuer(),
                audience=JWT_AUDIENCE,
                options={"require": ["exp", "sub", "iss", "aud"]},
            )
        except (jwt.PyJWTError, ValueError):
            return None

    @staticmethod
    def verify_access_token(token: str) -> dict[str, Any]:
        try:
            return jwt.decode(
                token,
                _get_jwt_secret_key(),
                algorithms=[JWT_ALGORITHM],
                issuer=_get_jwt_issuer(),
                audience=JWT_AUDIENCE,
                options={"require": ["exp", "sub", "iss", "aud"]},
            )
        except jwt.ExpiredSignatureError:
            raise ValueError("令牌已过期")
        except jwt.InvalidTokenError:
            raise ValueError("无效的令牌")