Update mcp/drugbank.py

mcp/drugbank.py

@@ -1,28 +1,55 @@
-# mcp/drugbank.py
-"""
-Lightweight DrugBank Open-Data helper.
-Download the TSV once and keep in /data or load at runtime.
+#!/usr/bin/env python3
+"""MedGenesis – lightweight **DrugBank Open Data** TSV helper.
+
+* Loads the DrugBank TSV once into an in‑memory dict (lazy, cached).
+* Case‑insensitive lookup via `lookup_drug(name)`.
+* Raises actionable `FileNotFoundError` if the TSV is missing and
+  provides official download URL in the error message.
+* TSV expected at  `<repo_root>/mcp/data/drugbank_open_structured_drug_links.tsv`.
 """
+from __future__ import annotations
 
 import csv
+from functools import lru_cache
 from pathlib import Path
 from typing import Dict, Optional
 
-_DATA = Path(__file__).parent / "data" / "drugbank_open_structured_drug_links.tsv"
+_DATA = Path(__file__).with_suffix("").parent / "data" / "drugbank_open_structured_drug_links.tsv"
+_DOWNLOAD_URL = "https://go.drugbank.com/releases/latest#open-data"
+
+# ---------------------------------------------------------------------
+# Lazy index loader
+# ---------------------------------------------------------------------
 
+@lru_cache(maxsize=1)
 def _load_index() -> Dict[str, Dict]:
-    index = {}
     if not _DATA.exists():
-        raise FileNotFoundError("DrugBank TSV not found – download open data first.")
-    with _DATA.open() as f:
-        reader = csv.DictReader(f, delimiter="\t")
+        raise FileNotFoundError(
+            f"DrugBank TSV not found at {_DATA}. Download the open-data TSV from\n"
+            f"{_DOWNLOAD_URL} and place it in the same path."
+        )
+
+    index: Dict[str, Dict] = {}
+    with _DATA.open(newline="", encoding="utf-8") as fh:
+        reader = csv.DictReader(fh, delimiter="\t")
         for row in reader:
-            name = row["Name"].lower()
-            index[name] = row
+            # Primary key is lower‑cased `Name`; keep original row otherwise untouched.
+            index[row["Name"].lower()] = row
     return index
 
-_DRUG_INDEX = _load_index()
+# ---------------------------------------------------------------------
+# Public lookup
+# ---------------------------------------------------------------------
 
 def lookup_drug(name: str) -> Optional[Dict]:
-    """Return DrugBank row dict or None."""
-    return _DRUG_INDEX.get(name.lower())
+    """Return DrugBank row dict for *name* (case‑insensitive) or `None`."""
+    idx = _load_index()
+    return idx.get(name.lower())
+
+
+# ---------------------------------------------------------------------
+# CLI demo
+# ---------------------------------------------------------------------
+if __name__ == "__main__":
+    hit = lookup_drug("Temozolomide")
+    print(hit or "Drug not found – ensure TSV downloaded.")