src/api/v1/auth.py

import logging
from typing import Annotated
from urllib.parse import urlencode

import httpx
from fastapi import APIRouter, Depends, Query
from fastapi.responses import RedirectResponse

from src.api.dependencies import CurrentUserDep, DbSessionDep
from src.models.auth import (
    CurrentUserResponse,
    LoginRequest,
    LogoutRequest,
    RefreshTokenRequest,
    RegisterRequest,
    TokenResponse,
)
from src.services.auth import AuthService, AuthServiceError
from src.services.security import (
    SecurityError,
    build_google_authorization_url,
    create_oauth_state,
    exchange_google_code,
    verify_google_id_token,
    verify_oauth_state,
)

logger = logging.getLogger(__name__)

router = APIRouter(prefix="/auth", tags=["auth"])


def get_auth_service(db: DbSessionDep) -> AuthService:
    return AuthService(db)


AuthServiceDep = Annotated[AuthService, Depends(get_auth_service)]


def build_frontend_auth_redirect(callback_url: str, token_response: TokenResponse) -> str:
    fragment = urlencode(
        {
            "access_token": token_response.access_token,
            "refresh_token": token_response.refresh_token,
            "token_type": token_response.token_type,
            "access_token_expires_in": token_response.access_token_expires_in,
        }
    )
    separator = "&" if "#" in callback_url else "#"
    return f"{callback_url}{separator}{fragment}"


@router.post("/register")
def register(payload: RegisterRequest, auth_service: AuthServiceDep) -> TokenResponse:
    return auth_service.register(
        email=payload.email,
        password=payload.password,
        full_name=payload.full_name,
    )


@router.post("/login")
def login(payload: LoginRequest, auth_service: AuthServiceDep) -> TokenResponse:
    return auth_service.login(email=payload.email, password=payload.password)


@router.post("/refresh")
def refresh(payload: RefreshTokenRequest, auth_service: AuthServiceDep) -> TokenResponse:
    return auth_service.refresh(payload.refresh_token)


@router.post("/logout")
def logout(payload: LogoutRequest, auth_service: AuthServiceDep) -> dict[str, str]:
    auth_service.logout(payload.refresh_token)
    return {"status": "ok"}


@router.get("/me")
def me(current_user: CurrentUserDep, auth_service: AuthServiceDep) -> CurrentUserResponse:
    return auth_service.current_user_response(current_user)


@router.get("/google/login")
def google_login(auth_service: AuthServiceDep) -> RedirectResponse:
    settings = auth_service.settings
    if not settings.google_client_id or not settings.google_client_secret:
        raise AuthServiceError(503, "auth_unavailable", "Google OAuth is not configured.")
    state = create_oauth_state(settings)
    return RedirectResponse(build_google_authorization_url(settings, state))


@router.get("/google/callback")
async def google_callback(
    code: Annotated[str, Query(min_length=1)],
    state: Annotated[str, Query(min_length=1)],
    auth_service: AuthServiceDep,
) -> RedirectResponse:
    settings = auth_service.settings
    try:
        verify_oauth_state(state, settings)
        token_payload = await exchange_google_code(code, settings)
        claims = verify_google_id_token(str(token_payload.get("id_token") or ""), settings)
    except httpx.HTTPStatusError as exc:
        try:
            google_error = exc.response.json()
        except ValueError:
            google_error = {"body": exc.response.text[:500]}

        logger.exception(
            "Google OAuth token exchange failed: status=%s error=%s redirect_uri=%s client_id_suffix=%s",
            exc.response.status_code,
            google_error,
            settings.google_redirect_uri,
            settings.google_client_id[-12:],
        )
        raise AuthServiceError(401, "unauthorized", "Google OAuth failed.") from exc

    except (SecurityError, ValueError, httpx.HTTPError) as exc:
        logger.exception(
            "Google OAuth failed after callback: error_type=%s message=%s redirect_uri=%s client_id_suffix=%s",
            type(exc).__name__,
            str(exc),
            settings.google_redirect_uri,
            settings.google_client_id[-12:],
        )
        raise AuthServiceError(401, "unauthorized", "Google OAuth failed.") from exc
    token_response = auth_service.upsert_google_user(claims)
    # MVP/dev handoff: URL fragments are not sent to the backend in follow-up
    # requests. A future production flow should prefer HttpOnly cookies.
    return RedirectResponse(
        build_frontend_auth_redirect(
            settings.frontend_auth_callback_url,
            token_response,
        )
    )