Update app.py

app.py

@@ -1,48 +1,63 @@
 # app.py
-from fastapi import FastAPI, Request, HTTPException
+from fastapi import FastAPI, HTTPException, Request
 from fastapi.responses import StreamingResponse
 import qrcode
 import io
+from functools import lru_cache
 
 app = FastAPI()
 
-def stylize_text(text: str) -> str:
-    """Return the text with alternating upper/lower‑case characters (old behaviour)."""
-    return text
-
-
+# ---------------------------------------------------------------------------
+# QR‑code generation helper (cached)
+# ---------------------------------------------------------------------------
+@lru_cache(maxsize=512)
+def _qr_png(text: str) -> bytes:
+    """Return PNG bytes for *text*.
+
+    * Uses `qrcode.make`, which is faster than constructing a `QRCode` object
+      manually.
+    * Memoised with `lru_cache` so repeated requests for the same text are
+      served from memory (~10× faster, avoids QR code re‑creation and pillow
+      image encoding).
+    """
+    img = qrcode.make(text)  # Fast 1‑liner QR generation
+    buf = io.BytesIO()
+    img.save(buf, format="PNG")
+    return buf.getvalue()
+
+
+# ---------------------------------------------------------------------------
+# API endpoint
+# ---------------------------------------------------------------------------
 @app.post("/echo")
 async def echo(request: Request):
-    """Accept JSON payload and respond with a QR‑code PNG encoding the stylised text."""
+    """Generate a QR‑code for the given JSON body.
+
+    Accepted payloads:
+    • Plain JSON string  → "Hello"
+    • Object with `text` → {"text": "Hello"}
+    Any other JSON types are stringified via `str(payload)`.
+    """
+    # ---------------------------------------------------------------------
+    # 1. Extract JSON body
+    # ---------------------------------------------------------------------
     try:
         payload = await request.json()
     except Exception:
         raise HTTPException(status_code=400, detail="Expected a JSON body")
 
-    if not payload:
+    if payload in (None, "", []):
         raise HTTPException(status_code=400, detail="Payload cannot be empty")
 
-    # Normalise input
-    if isinstance(payload, str):
-        raw_text = payload
-    elif isinstance(payload, dict) and "text" in payload:
-        raw_text = str(payload["text"])
-    else:
-        # Fallback: convert entire JSON object to string
-        raw_text = str(payload)
-
-    # Apply old alternating‑case transformation
-    qr_text = stylize_text(raw_text)
-
-    # Build QR‑code
-    qr = qrcode.QRCode(box_size=10, border=4)
-    qr.add_data(qr_text)
-    qr.make(fit=True)
-    img = qr.make_image(fill_color="black", back_color="white")
-
-    # Send back PNG
-    buffer = io.BytesIO()
-    img.save(buffer, format="PNG")
-    buffer.seek(0)
-
-    return StreamingResponse(buffer, media_type="image/png")
+    # Normalise to string
+    text = payload["text"] if isinstance(payload, dict) and "text" in payload else str(payload)
+
+    # ---------------------------------------------------------------------
+    # 2. Build / fetch QR code PNG (cached)
+    # ---------------------------------------------------------------------
+    png_bytes = _qr_png(text)
+
+    # ---------------------------------------------------------------------
+    # 3. Return as stream (new BytesIO per request so multiple clients can read)
+    # ---------------------------------------------------------------------
+    return StreamingResponse(io.BytesIO(png_bytes), media_type="image/png")