# api_clients/umls_client.py
"""
Client for the NLM Unified Medical Language System (UMLS) API.
Handles the complex ticket-based authentication.
"""
import aiohttp
from lxml import html
from .config import UMLS_API_KEY, UMLS_AUTH_URL, UMLS_BASE_URL, REQUEST_HEADERS

class UMLSClient:
    def __init__(self, session: aiohttp.ClientSession):
        self.session = session
        self.service_ticket = None

    async def authenticate(self):
        """Gets a single-use service ticket for API requests."""
        if not UMLS_API_KEY:
            print("Warning: UMLS_API_KEY not found. UMLS features will be disabled.")
            return False
        params = {'apikey': UMLS_API_KEY}
        async with self.session.post(UMLS_AUTH_URL, data=params, headers=REQUEST_HEADERS) as resp:
            if resp.status == 201:
                response_text = await resp.text()
                self.service_ticket = html.fromstring(response_text).find('.//form').get('action')
                return True
            else:
                print(f"Error authenticating with UMLS: {resp.status}")
                return False

    async def get_cui_for_term(self, term: str):
        """Searches for a Concept Unique Identifier (CUI) for a given term."""
        if not await self.authenticate():
            return None

        query = {'string': term, 'ticket': self.service_ticket}
        url = f"{UMLS_BASE_URL}/search/current"
        
        async with self.session.get(url, params=query, headers=REQUEST_HEADERS) as resp:
            if resp.status == 200:
                data = await resp.json()
                results = data.get('result', {}).get('results', [])
                return results[0] if results else None
            else:
                print(f"Error searching UMLS for term '{term}': {resp.status}")
                return None