"""인증 API — 로그인, 토큰 갱신, TOTP 검증

access token: 응답 body (프론트에서 메모리 보관)
refresh token: HttpOnly cookie (XSS 방어)
"""

from datetime import datetime, timezone
from typing import Annotated

from fastapi import APIRouter, Cookie, Depends, HTTPException, Request, Response, status
from pydantic import BaseModel
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from core.auth import (
    REFRESH_TOKEN_EXPIRE_DAYS,
    create_access_token,
    create_refresh_token,
    decode_token,
    get_current_user,
    hash_password,
    verify_password,
    verify_totp,
)
from core.database import get_session
from models.user import User

router = APIRouter()


# ─── 요청/응답 스키마 ───


class LoginRequest(BaseModel):
    username: str
    password: str
    totp_code: str | None = None


class AccessTokenResponse(BaseModel):
    access_token: str
    token_type: str = "bearer"


class ChangePasswordRequest(BaseModel):
    current_password: str
    new_password: str


class UserResponse(BaseModel):
    id: int
    username: str
    is_active: bool
    totp_enabled: bool
    last_login_at: datetime | None

    class Config:
        from_attributes = True


# ─── 헬퍼 ───

def _set_refresh_cookie(response: Response, token: str):
    """refresh token을 HttpOnly cookie로 설정"""
    response.set_cookie(
        key="refresh_token",
        value=token,
        httponly=True,
        secure=True,
        samesite="strict",
        max_age=REFRESH_TOKEN_EXPIRE_DAYS * 86400,
        path="/api/auth",
    )


# ─── 엔드포인트 ───


@router.post("/login", response_model=AccessTokenResponse)
async def login(
    body: LoginRequest,
    response: Response,
    session: Annotated[AsyncSession, Depends(get_session)],
):
    """로그인 → access token(body) + refresh token(cookie)"""
    result = await session.execute(
        select(User).where(User.username == body.username)
    )
    user = result.scalar_one_or_none()

    if not user or not verify_password(body.password, user.password_hash):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="아이디 또는 비밀번호가 올바르지 않습니다",
        )

    if not user.is_active:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="비활성화된 계정입니다",
        )

    # TOTP 검증 (설정된 경우)
    if user.totp_secret:
        if not body.totp_code:
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="TOTP 코드가 필요합니다",
            )
        if not verify_totp(body.totp_code, user.totp_secret):
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="TOTP 코드가 올바르지 않습니다",
            )

    # 마지막 로그인 시간 업데이트
    user.last_login_at = datetime.now(timezone.utc)
    await session.commit()

    # refresh token → HttpOnly cookie
    _set_refresh_cookie(response, create_refresh_token(user.username))

    return AccessTokenResponse(
        access_token=create_access_token(user.username),
    )


@router.post("/refresh", response_model=AccessTokenResponse)
async def refresh_token(
    response: Response,
    session: Annotated[AsyncSession, Depends(get_session)],
    refresh_token: str | None = Cookie(None),
):
    """cookie의 refresh token으로 새 토큰 쌍 발급"""
    if not refresh_token:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="리프레시 토큰이 없습니다",
        )

    payload = decode_token(refresh_token)
    if not payload or payload.get("type") != "refresh":
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="유효하지 않은 리프레시 토큰",
        )

    username = payload.get("sub")
    result = await session.execute(
        select(User).where(User.username == username, User.is_active.is_(True))
    )
    user = result.scalar_one_or_none()
    if not user:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="유저를 찾을 수 없음",
        )

    # 새 refresh token → cookie
    _set_refresh_cookie(response, create_refresh_token(user.username))

    return AccessTokenResponse(
        access_token=create_access_token(user.username),
    )


@router.post("/logout")
async def logout(response: Response):
    """로그아웃 — refresh cookie 삭제"""
    response.delete_cookie("refresh_token", path="/api/auth")
    return {"message": "로그아웃 완료"}


@router.get("/me", response_model=UserResponse)
async def get_me(user: Annotated[User, Depends(get_current_user)]):
    """현재 로그인한 유저 정보"""
    return UserResponse(
        id=user.id,
        username=user.username,
        is_active=user.is_active,
        totp_enabled=bool(user.totp_secret),
        last_login_at=user.last_login_at,
    )


@router.post("/change-password")
async def change_password(
    body: ChangePasswordRequest,
    user: Annotated[User, Depends(get_current_user)],
    session: Annotated[AsyncSession, Depends(get_session)],
):
    """비밀번호 변경"""
    if not verify_password(body.current_password, user.password_hash):
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="현재 비밀번호가 올바르지 않습니다",
        )

    user.password_hash = hash_password(body.new_password)
    await session.commit()
    return {"message": "비밀번호가 변경되었습니다"}