"""Authentification.

Deux systèmes, selon le compte :
- **mot de passe** (`POST .../auth/login`) pour les comptes qui en ont un —
  la coordination ;
- **lien magique** (`.../auth/magic-link` puis `.../auth/verify`) pour les
  comptes sans mot de passe — référents et bénévoles.
"""

import logging
import uuid

from fastapi import APIRouter, BackgroundTasks, Depends, HTTPException, status
from sqlalchemy import func
from sqlmodel import Session, select

from app.api.schemas import (
    AccountRead,
    ChangePasswordRequest,
    LoginRequest,
    MagicLinkRequest,
    TokenResponse,
    VerifyRequest,
)
from app.auth.deps import get_current_account
from app.auth.magic_link import build_magic_link_url, issue_magic_link_token
from app.auth.passwords import MIN_LENGTH, hash_password, verify_password
from app.auth.rate_limit import login_limiter, magic_link_limiter
from app.auth.tokens import create_access_token, hash_token
from app.config import get_settings
from app.db import get_session
from app.email import edition_logo, render_magic_link, send
from app.models import Account, MagicLinkToken, local_now

router = APIRouter(tags=["auth"])
logger = logging.getLogger("app.auth")


def _account_by_email(
    session: Session, edition_id: uuid.UUID, email: str
) -> Account | None:
    return session.exec(
        select(Account)
        .where(Account.edition_id == edition_id)
        .where(func.lower(Account.email) == email.strip().lower())
    ).first()


def _issue(account: Account) -> TokenResponse:
    return TokenResponse(
        access_token=create_access_token(account),
        token_type="bearer",
        account=AccountRead.model_validate(account),
    )


def _invalid_credentials() -> HTTPException:
    return HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail={"code": "auth.invalid_credentials"},
    )


def _invalid_token() -> HTTPException:
    return HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail={"code": "auth.invalid_token"},
    )


# --------------------------------------------------------------------------- #
# Mot de passe (admins)                                                        #
# --------------------------------------------------------------------------- #
@router.post("/editions/{edition_id}/auth/login", response_model=TokenResponse)
def login(
    edition_id: uuid.UUID,
    payload: LoginRequest,
    session: Session = Depends(get_session),
) -> TokenResponse:
    login_limiter.hit(f"{edition_id}:{payload.email.strip().lower()}")
    account = _account_by_email(session, edition_id, payload.email)
    if (
        account is None
        or account.password_hash is None
        or not verify_password(payload.password, account.password_hash)
    ):
        # Cause réelle dans les logs seulement — la réponse reste la même
        # (pas de divulgation). Jamais l'email saisi.
        if account is None:
            reason = "aucun compte pour cet email"
        elif account.password_hash is None:
            reason = f"compte {account.id} sans mot de passe (lien magique)"
        else:
            reason = f"mot de passe incorrect pour le compte {account.id}"
        logger.info("Connexion refusée (édition %s) : %s", edition_id, reason)
        raise _invalid_credentials()
    logger.info("Connexion par mot de passe : compte %s (édition %s)", account.id, edition_id)
    return _issue(account)


@router.post(
    "/editions/{edition_id}/auth/change-password",
    status_code=status.HTTP_204_NO_CONTENT,
)
def change_password(
    edition_id: uuid.UUID,
    payload: ChangePasswordRequest,
    account: Account = Depends(get_current_account),
    session: Session = Depends(get_session),
) -> None:
    if account.edition_id != edition_id:
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail={"code": "error.forbidden"},
        )
    if account.password_hash is None or not verify_password(
        payload.current_password, account.password_hash
    ):
        raise _invalid_credentials()
    if len(payload.new_password) < MIN_LENGTH:
        raise HTTPException(
            status_code=422,
            detail={"code": "auth.password_too_short", "min": MIN_LENGTH},
        )
    account.password_hash = hash_password(payload.new_password)
    session.add(account)
    session.commit()


# --------------------------------------------------------------------------- #
# Lien magique (référents, bénévoles)                                          #
# --------------------------------------------------------------------------- #
@router.post(
    "/editions/{edition_id}/auth/magic-link",
    status_code=status.HTTP_202_ACCEPTED,
)
def request_magic_link(
    edition_id: uuid.UUID,
    payload: MagicLinkRequest,
    background: BackgroundTasks,
    session: Session = Depends(get_session),
) -> dict[str, str]:
    """Émet un lien magique si un compte **sans mot de passe** correspond.
    Réponse identique dans tous les cas (pas de divulgation). L'email part en
    tâche de fond (une erreur SMTP est journalisée, pas remontée)."""
    magic_link_limiter.hit(f"{edition_id}:{payload.email.strip().lower()}")
    account = _account_by_email(session, edition_id, payload.email)
    if account is None:
        logger.info(
            "Lien magique demandé sans compte correspondant (édition %s) — rien envoyé "
            "(un email sur une fiche bénévole ne crée pas d'accès)",
            edition_id,
        )
    elif account.password_hash is not None:
        logger.info(
            "Lien magique demandé pour le compte %s, qui a un mot de passe — rien envoyé",
            account.id,
        )
    if account is not None and account.password_hash is None:
        logger.info("Lien magique émis pour le compte %s (édition %s)", account.id, edition_id)
        settings = get_settings()
        raw = issue_magic_link_token(session, account)
        session.commit()
        subject, body = render_magic_link(
            link=build_magic_link_url(raw),
            minutes=settings.magic_link_ttl_minutes,
        )
        background.add_task(
            send, account.email, subject, body, logo=edition_logo(session, edition_id)
        )
        if not settings.email_enabled:
            # Aide au dev sans SMTP : le jeton (non nominatif) est journalisé.
            logger.info(
                "Lien magique (email désactivé) — compte=%s jeton=%s",
                account.id,
                raw,
            )
    return {"status": "accepted"}


@router.post("/editions/{edition_id}/auth/verify", response_model=TokenResponse)
def verify_magic_link(
    edition_id: uuid.UUID,
    payload: VerifyRequest,
    session: Session = Depends(get_session),
) -> TokenResponse:
    token = session.exec(
        select(MagicLinkToken).where(
            MagicLinkToken.token_hash == hash_token(payload.token.strip())
        )
    ).first()
    if (
        token is None
        or token.used_at is not None
        or token.expires_at < local_now()
    ):
        if token is None:
            reason = "jeton inconnu"
        elif token.used_at is not None:
            reason = f"jeton déjà utilisé (compte {token.account_id})"
        else:
            reason = f"jeton expiré (compte {token.account_id})"
        logger.info("Lien magique refusé (édition %s) : %s", edition_id, reason)
        raise _invalid_token()
    account = session.get(Account, token.account_id)
    if account is None or account.edition_id != edition_id:
        logger.info(
            "Lien magique refusé (édition %s) : compte %s absent ou d'une autre édition",
            edition_id,
            token.account_id,
        )
        raise _invalid_token()
    token.used_at = local_now()
    session.commit()
    session.refresh(account)
    logger.info("Connexion par lien magique : compte %s (édition %s)", account.id, edition_id)
    return _issue(account)


@router.get("/auth/me", response_model=AccountRead)
def read_me(account: Account = Depends(get_current_account)) -> Account:
    return account