Update app.py

app.py

@@ -1,3 +1,4 @@
+import threading, time
 from flask import Flask, render_template, request, jsonify, Response
 import requests
 from bs4 import BeautifulSoup
@@ -11,6 +12,10 @@ app.config['CACHE_TYPE'] = 'SimpleCache'
 app.config['CACHE_DEFAULT_TIMEOUT'] = 300  # Cache responses for 5 minutes
 cache = Cache(app)
 
+# Global variables for pre-fetched image data
+cached_image = None
+cached_mimetype = None
+
 # Internal mapping of crops to pests (for the form)
 CROP_TO_PESTS = {
     "Sorgum": ["FallArmyWorm"],
@@ -103,8 +108,8 @@ def index():
         # Build the external image URL (using HTTP)
         base_url = f"http://www.icar-crida.res.in:8080/naip/gisimages/{crop}/{year}/{pest}_"
         external_image_url = f"{base_url}{param}{week}.jpg"
-        # Build our proxy URL to avoid direct linking
-        image_url = f"/proxy-image?url={external_image_url}"
+        # Build our proxy URL so that the image is served via our app
+        image_url = f"/fast-proxy?url={external_image_url}"
 
     return render_template('index.html',
                            crops=list(CROP_TO_PESTS.keys()),
@@ -118,7 +123,6 @@ def index():
                            selected_param=param,
                            image_url=image_url)
 
-# Cache this route based on its query string.
 @app.route('/fetch_weeks')
 @cache.cached(timeout=300, query_string=True)
 def fetch_weeks():
@@ -149,19 +153,48 @@ def fetch_weeks():
         weeks = [str(i) for i in range(1, 53)]
     return jsonify({"weeks": weeks})
 
-# Cache the fetched image for a short duration to avoid repeated external calls.
-@app.route('/proxy-image')
-@cache.cached(timeout=300, query_string=True)
-def proxy_image():
+# This endpoint now uses a background-prefetched image.
+@app.route('/fast-proxy')
+def fast_proxy():
+    global cached_image, cached_mimetype
+    # If the "url" parameter doesn't match our cached URL, you might consider triggering a prefetch update.
     external_url = request.args.get('url')
-    if not external_url:
-        return "Missing URL", 400
-
-    try:
-        resp = requests.get(external_url, timeout=10)
-        return Response(resp.content, mimetype=resp.headers.get('Content-Type', 'image/jpeg'))
-    except Exception as e:
-        return str(e), 500
+    if cached_image and external_url == prefetch_image.cached_url:
+        return Response(cached_image, mimetype=cached_mimetype)
+    else:
+        # If no pre-fetched image is available, fall back to a direct fetch.
+        try:
+            resp = requests.get(external_url, timeout=10)
+            return Response(resp.content, mimetype=resp.headers.get('Content-Type', 'image/jpeg'))
+        except Exception as e:
+            return str(e), 500
+
+# Background prefetching – we also store the URL that was prefetched.
+def prefetch_image_task():
+    global cached_image, cached_mimetype
+    # For demonstration, we prefetch one specific image.
+    # In a more dynamic scenario, you could maintain a dict of URL -> image data.
+    while True:
+        # Here, update the URL as needed. For example, if you have default parameters:
+        url = "http://www.icar-crida.res.in:8080/naip/gisimages/7/2024-25/74_Maxt1.jpg"
+        try:
+            response = requests.get(url, timeout=10)
+            if response.status_code == 200:
+                cached_image = response.content
+                cached_mimetype = response.headers.get('Content-Type', 'image/jpeg')
+                prefetch_image_task.cached_url = url
+                print("Prefetched image from", url)
+            else:
+                print("Failed to prefetch, status code:", response.status_code)
+        except Exception as ex:
+            print("Prefetch error:", ex)
+        time.sleep(300)  # Update every 5 minutes
+
+# Initialize cached_url attribute for our task function.
+prefetch_image_task.cached_url = ""
+
+# Start the background prefetch thread
+threading.Thread(target=prefetch_image_task, daemon=True).start()
 
 if __name__ == '__main__':
     app.run(debug=True)