import os


UPLOAD_PATH = '/mcp/upload-headhaul-document'


class HeadhaulSlotMemory:
    def __init__(self):
        self._by_session = {}
        self._by_token = {}

    def remember(self, session_id, token):
        session_id = str(session_id or '').strip()
        token = str(token or '').strip()
        if not session_id or not token:
            return
        previous = self._by_session.get(session_id)
        if previous:
            self._by_token.pop(previous, None)
        self._by_session[session_id] = token
        self._by_token[token] = session_id

    def token_for_session(self, session_id):
        return self._by_session.get(str(session_id or '').strip(), '')

    def session_for_token(self, token):
        return self._by_token.get(str(token or '').strip(), '')


def public_upload_url():
    base = str(os.environ.get('FMS_GATEWAY_PUBLIC_BASE') or '').strip().rstrip('/')
    if base:
        return base + UPLOAD_PATH
    return UPLOAD_PATH


def resource_list():
    return []


def read_resource(uri, upload_token='', upload_url=''):
    return None