"""Team JWT minting.

Team tokens are the ``typ=team`` variant described in §5.2 of
``docs/DAEDALUS_PALLAS_INTEGRATION_v1.md``: long-lived (10 years),
no per-request scope claims, revocable via ``Team.active`` and
``Team.active_jti``. They are signed with whichever
:class:`~mcp_server.models.MCPSigningKey` is currently
``MCPSigningKey.objects.current()`` — the same keyring the legacy
per-turn path uses.

Typical flow from the REST API:

    team = Team.objects.get(pk=...)
    team.rotate_jti()                # installs a fresh active_jti
    jwt_string = mint_team_jwt(team) # signs with current kid + new jti
"""

from __future__ import annotations

import logging
import time

import jwt as pyjwt

from .models import MCPSigningKey, Team

logger = logging.getLogger(__name__)


# Team JWT lifetime. 10 years in seconds — matches the "operator cannot
# tolerate a silent expiry-induced outage" rationale in §13.1.
_TEAM_TOKEN_LIFETIME_SECONDS = 10 * 365 * 24 * 60 * 60


class TeamJWTError(Exception):
    """Raised when a team JWT cannot be minted (e.g. no active signing key)."""


def mint_team_jwt(team: Team) -> str:
    """Mint a team JWT for ``team`` using the current active signing key.

    Requires:

    * An active :class:`MCPSigningKey` to exist (seed one via
      ``python manage.py seed_signing_key``).
    * ``team.active_jti`` to be set — callers should invoke
      :meth:`Team.rotate_jti` immediately before minting so each
      issuance ties to a fresh UUID, invalidating whatever token
      preceded it.

    The claim shape mirrors §5.2:

    * ``iss`` = ``"mnemosyne"``   — distinguishes from Daedalus per-turn.
    * ``aud`` = ``"mnemosyne"``   — informational; not enforced at verify.
    * ``typ`` = ``"team"``        — the single discriminator the middleware
                                    uses to pick the team branch.
    * ``sub`` = ``"team:<uuid>"`` — carries the team's primary key.
    * ``jti`` = ``str(active_jti)`` — validated against the DB on every
                                    request, so rotate → old token dies.
    """
    key = MCPSigningKey.objects.current()
    if key is None:
        raise TeamJWTError(
            "No active MCPSigningKey to sign the team JWT. "
            "Seed one via `python manage.py seed_signing_key`."
        )
    if team.active_jti is None:
        raise TeamJWTError(
            f"Team {team.id} has no active_jti; call rotate_jti() before mint."
        )

    try:
        secret = bytes.fromhex(key.secret_hex)
    except ValueError as exc:
        raise TeamJWTError(
            f"Stored secret for kid={key.kid!r} is not valid hex: {exc}"
        )

    now = int(time.time())
    payload = {
        "iss": "mnemosyne",
        "aud": "mnemosyne",
        "sub": f"team:{team.id}",
        "typ": "team",
        "iat": now,
        "exp": now + _TEAM_TOKEN_LIFETIME_SECONDS,
        "jti": str(team.active_jti),
    }
    token = pyjwt.encode(
        payload,
        secret,
        algorithm="HS256",
        headers={"kid": key.kid},
    )
    logger.info(
        "team_jwt_minted team_id=%s kid=%s jti=%s",
        team.id,
        key.kid,
        team.active_jti,
    )
    return token