"""Authentication router.

``POST /api/auth/login``  — verify master password and issue a session.
``POST /api/auth/logout`` — revoke the current session.

The session token is returned both in the JSON body (for API-first
consumers) and as an ``HttpOnly`` cookie (for the browser SPA).
"""

from __future__ import annotations

import structlog
from fastapi import APIRouter, HTTPException, Request, Response, status

from app.dependencies import DbDep, SessionCacheDep, SessionRepoDep, SettingsDep
from app.models.auth import LoginRequest, LoginResponse, LogoutResponse
from app.services import auth_service
from app.utils.constants import SESSION_COOKIE_NAME

log: structlog.stdlib.BoundLogger = structlog.get_logger()

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


@router.post(
    "/login",
    response_model=LoginResponse,
    summary="Authenticate with the master password",
)
async def login(
    body: LoginRequest,
    response: Response,
    db: DbDep,
    settings: SettingsDep,
    session_repo: SessionRepoDep,
) -> LoginResponse:
    """Verify the master password and return a session token.

    On success the token is also set as an ``HttpOnly`` ``SameSite=Lax``
    cookie so the browser SPA benefits from automatic credential handling.

    Args:
        body: Login request validated by Pydantic.
        response: FastAPI response object used to set the cookie.
        db: Injected aiosqlite connection.
        settings: Application settings (used for session duration).

    Returns:
        :class:`~app.models.auth.LoginResponse` containing the token.

    Raises:
        HTTPException: 401 if the password is incorrect.
    """
    try:
        signed_token, expires_at = await auth_service.login(
            db,
            password=body.password,
            session_duration_minutes=settings.session_duration_minutes,
            session_secret=settings.session_secret,
            session_repo=session_repo,
        )
    except ValueError as exc:
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail=str(exc),
        ) from exc

    response.set_cookie(
        key=SESSION_COOKIE_NAME,
        value=signed_token,
        httponly=settings.session_cookie_httponly,
        samesite=settings.session_cookie_samesite,
        secure=settings.session_cookie_secure,
        max_age=settings.session_duration_minutes * 60,
    )
    return LoginResponse(token=signed_token, expires_at=expires_at)


@router.post(
    "/logout",
    response_model=LogoutResponse,
    summary="Revoke the current session",
)
async def logout(
    request: Request,
    response: Response,
    db: DbDep,
    settings: SettingsDep,
    session_cache: SessionCacheDep,
    session_repo: SessionRepoDep,
) -> LogoutResponse:
    """Invalidate the active session.

    The session token is read from the ``bangui_session`` cookie or the
    ``Authorization: Bearer`` header.  If no token is present the request
    is silently treated as a successful logout (idempotent).

    Args:
        request: FastAPI request (used to extract the token).
        response: FastAPI response (used to clear the cookie).
        db: Injected aiosqlite connection.
        settings: Application settings (used to unwrap signed tokens).

    Returns:
        :class:`~app.models.auth.LogoutResponse`.
    """
    token = _extract_token(request)
    if token:
        raw_token = await auth_service.logout(
            db,
            token,
            settings.session_secret,
            session_repo=session_repo,
        )
        if raw_token:
            session_cache.invalidate(raw_token)
            session_cache.invalidate(token)
    response.delete_cookie(key=SESSION_COOKIE_NAME)
    return LogoutResponse()


# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------


def _extract_token(request: Request) -> str | None:
    """Extract the session token from cookie or Authorization header.

    Args:
        request: The incoming FastAPI request.

    Returns:
        The token string, or ``None`` if absent.
    """
    token: str | None = request.cookies.get(SESSION_COOKIE_NAME)
    if token:
        return token
    auth_header: str = request.headers.get("Authorization", "")
    if auth_header.startswith("Bearer "):
        return auth_header[len("Bearer "):]
    return None
