import secrets

from fastapi import Depends, HTTPException, Request, status
from fastapi.security import HTTPBasic, HTTPBasicCredentials

from app.core.config import settings
from app.core.rate_limiter import (
    clear_failed_attempts,
    is_locked_out,
    record_failed_attempt,
)

security = HTTPBasic()

MAX_ATTEMPTS = 5
LOCKOUT_SECONDS = 900  # 15分钟


def _get_client_ip(request: Request) -> str:
    forwarded = request.headers.get("x-forwarded-for")
    if forwarded:
        return forwarded.split(",")[0].strip()
    if request.client and request.client.host:
        return request.client.host
    return "unknown"


async def admin_guard(
    request: Request,
    credentials: HTTPBasicCredentials = Depends(security),
):
    client_ip = _get_client_ip(request)
    lockout_key = f"admin_login:{client_ip}"

    # 检查是否被锁定
    remaining = await is_locked_out(lockout_key, MAX_ATTEMPTS, LOCKOUT_SECONDS)
    if remaining > 0:
        raise HTTPException(
            status_code=status.HTTP_429_TOO_MANY_REQUESTS,
            detail=f"登录尝试过多，请 {remaining} 秒后重试",
        )

    # 使用 secrets.compare_digest 防止时序攻击
    username_ok = secrets.compare_digest(
        credentials.username.encode(), settings.admin_username.encode()
    )
    password_ok = secrets.compare_digest(
        credentials.password.encode(), settings.admin_password.encode()
    )

    if not (username_ok and password_ok):
        await record_failed_attempt(lockout_key, MAX_ATTEMPTS, LOCKOUT_SECONDS)
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="用户名或密码错误",
        )

    # 登录成功，清除失败记录
    await clear_failed_attempts(lockout_key)
    return True