from __future__ import annotations

from datetime import UTC, datetime

from fastapi import APIRouter, Depends, Request, Response, status
from sqlalchemy.orm import Session

from app.core.config import get_settings
from app.core.errors import AppError
from app.db.session import get_db
from app.schemas.auth import AuthLoginRequest, AuthSession, AuthSessionEnvelope
from app.services.auth_service import AuthPrincipal, AuthService
from app.services.demo_workflow_service import DemoWorkflowService


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


def _session_from_principal(principal: AuthPrincipal, *, guest_access_enabled: bool) -> AuthSession:
    return AuthSession(
        authentication_required=True,
        authenticated=True,
        username=principal.username,
        expires_at=datetime.fromtimestamp(principal.expires_at, tz=UTC),
        role=principal.role,
        guest_access_enabled=guest_access_enabled,
        guest_project_id=principal.project_id,
    )


def _session_payload(request: Request) -> AuthSession:
    settings = get_settings()
    guest_access_enabled = settings.auth_enabled and settings.guest_access_enabled
    if not settings.auth_enabled:
        return AuthSession(
            authentication_required=False,
            authenticated=True,
            guest_access_enabled=False,
        )
    principal = AuthService.verify_session_token(request.cookies.get(COOKIE_NAME), settings)
    if principal is None:
        return AuthSession(
            authentication_required=True,
            authenticated=False,
            guest_access_enabled=guest_access_enabled,
        )
    return _session_from_principal(
        principal,
        guest_access_enabled=guest_access_enabled,
    )


def _set_session_cookie(
    *,
    request: Request,
    response: Response,
    token: str,
    max_age: int,
) -> None:
    forwarded_proto = request.headers.get("x-forwarded-proto", "").split(",", 1)[0].strip().lower()
    response.set_cookie(
        key=COOKIE_NAME,
        value=token,
        max_age=max_age,
        httponly=True,
        secure=forwarded_proto == "https" or request.url.scheme == "https",
        samesite="strict",
        path="/",
    )


@router.get("/session", response_model=AuthSessionEnvelope)
def session(request: Request) -> AuthSessionEnvelope:
    return AuthSessionEnvelope(data=_session_payload(request))


@router.post("/login", response_model=AuthSessionEnvelope)
def login(payload: AuthLoginRequest, request: Request, response: Response) -> AuthSessionEnvelope:
    settings = get_settings()
    if not settings.auth_enabled:
        raise AppError(
            code="AUTHENTICATION_DISABLED",
            message="Operator authentication is not enabled on this runtime",
            status_code=status.HTTP_409_CONFLICT,
        )
    client_host = request.client.host if request.client else "unknown"
    throttle_key = f"{client_host}:{payload.username.casefold()}"
    retry_after = AuthService.retry_after_seconds(throttle_key)
    if retry_after:
        raise AppError(
            code="LOGIN_RATE_LIMITED",
            message="Te veel mislukte aanmeldpogingen. Probeer later opnieuw.",
            details={"retry_after_seconds": retry_after},
            status_code=status.HTTP_429_TOO_MANY_REQUESTS,
        )
    if not AuthService.credentials_match(payload.username, payload.password, settings):
        AuthService.record_failure(throttle_key)
        raise AppError(
            code="INVALID_CREDENTIALS",
            message="Gebruikersnaam of wachtwoord is onjuist.",
            status_code=status.HTTP_401_UNAUTHORIZED,
        )
    AuthService.clear_failures(throttle_key)
    token = AuthService.create_session_token(payload.username, settings)
    principal = AuthService.verify_session_token(token, settings)
    if principal is None:  # pragma: no cover - defensive invariant
        raise AppError(
            code="SESSION_CREATION_FAILED",
            message="De beveiligde sessie kon niet worden aangemaakt.",
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
        )
    _set_session_cookie(
        request=request,
        response=response,
        token=token,
        max_age=settings.auth_session_ttl_seconds,
    )
    return AuthSessionEnvelope(
        data=_session_from_principal(
            principal,
            guest_access_enabled=settings.guest_access_enabled,
        )
    )


@router.post("/guest", response_model=AuthSessionEnvelope)
def guest_login(
    request: Request,
    response: Response,
    db: Session = Depends(get_db),
) -> AuthSessionEnvelope:
    settings = get_settings()
    if not settings.auth_enabled or not settings.guest_access_enabled:
        raise AppError(
            code="GUEST_ACCESS_DISABLED",
            message="Gasttoegang is niet ingeschakeld op deze GeoIntel-installatie.",
            status_code=status.HTTP_403_FORBIDDEN,
        )

    demo = DemoWorkflowService.seed(db)
    token = AuthService.create_session_token(
        settings.guest_display_name,
        settings,
        role="guest",
        project_id=demo.project_id,
        ttl_seconds=settings.guest_session_ttl_seconds,
    )
    principal = AuthService.verify_session_token(token, settings)
    if principal is None:  # pragma: no cover - defensive invariant
        raise AppError(
            code="SESSION_CREATION_FAILED",
            message="De tijdelijke gastensessie kon niet worden aangemaakt.",
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
        )
    _set_session_cookie(
        request=request,
        response=response,
        token=token,
        max_age=settings.guest_session_ttl_seconds,
    )
    return AuthSessionEnvelope(
        data=_session_from_principal(
            principal,
            guest_access_enabled=True,
        )
    )


@router.post("/logout", response_model=AuthSessionEnvelope)
def logout(response: Response) -> AuthSessionEnvelope:
    settings = get_settings()
    response.delete_cookie(key=COOKIE_NAME, path="/", httponly=True, samesite="strict")
    return AuthSessionEnvelope(
        data=AuthSession(
            authentication_required=settings.auth_enabled,
            authenticated=not settings.auth_enabled,
            guest_access_enabled=settings.auth_enabled and settings.guest_access_enabled,
        )
    )