# mcp/clinicaltrials.py

import httpx
from typing import List, Dict

BASE_V2 = "https://clinicaltrials.gov/api/v2/studies"
BASE_V1 = "https://clinicaltrials.gov/api/query/study_fields"

HEADERS = {
    "User-Agent": (
        "Mozilla/5.0 (Windows NT 10.0; Win64; x64) "
        "AppleWebKit/537.36 (KHTML, like Gecko) "
        "Chrome/124.0 Safari/537.36"
    )
}

async def fetch_trials_v2(term: str, limit: int = 10) -> List[Dict]:
    """Fetch clinical trials using v2 API."""
    params = {
        "query": term,
        "pageSize": limit,
        "fields": "nctId,briefTitle,phase,status,startDate,conditions,interventions"
    }
    async with httpx.AsyncClient(timeout=20, headers=HEADERS) as client:
        r = await client.get(BASE_V2, params=params)
        if r.status_code == 403:
            return []  # API blocked or IP rate-limited
        r.raise_for_status()
        js = r.json()
        # List of studies under ['studies']
        return js.get("studies", [])

async def fetch_trials_v1(term: str, limit: int = 10) -> List[Dict]:
    """Fallback: Fetch trials using legacy v1 API."""
    params = dict(
        expr=term,
        fields="NCTId,BriefTitle,Condition,InterventionName,Phase,OverallStatus,StartDate",
        max_rnk=limit,
        min_rnk=1,
        fmt="json",
    )
    async with httpx.AsyncClient(timeout=20, headers=HEADERS) as client:
        r = await client.get(BASE_V1, params=params)
        if r.status_code == 403:
            return []
        r.raise_for_status()
        js = r.json()
        return js.get("StudyFieldsResponse", {}).get("StudyFields", [])

async def search_trials(term: str, max_studies: int = 10) -> List[Dict]:
    """Unified entry point. Try V2, fallback to V1 if needed."""
    try:
        trials = await fetch_trials_v2(term, max_studies)
        if trials:
            return trials
    except Exception:
        pass
    try:
        trials = await fetch_trials_v1(term, max_studies)
        return trials
    except Exception:
        return []