feat(proxy): improve streaming and error handling

Enhanced proxy endpoint by adding streaming support to handle large files efficiently. Introduced error handling for various HTTP errors and Internal Server errors to provide more robust feedback. Updated content disposition to handle attachment downloads properly.

app.py

@@ -1,22 +1,50 @@
-from flask import Flask, render_template, request
+from flask import Flask, render_template, request, Response, abort
+from werkzeug.exceptions import InternalServerError
 
 from urllib.request import urlopen
+from urllib.error import HTTPError
+from urllib.parse import unquote
 
 app = Flask(__name__)
 
-@app.route('/')
+
+@app.route("/")
 def home():
     domain = request.url_root
-    return render_template('index.html', domain=domain)
+    return render_template("index.html", domain=domain)
 
-@app.route('/<path:url>')
+
+@app.route("/<path:url>")
 def proxy(url):
-    jsdelivr_url = f'https://cdnjs.cloudflare.com/{url}'
+    jsdelivr_url = f"https://cdnjs.cloudflare.com/{url}"
 
-    response = urlopen(jsdelivr_url)
-    content = response.read()
+    def generate():
+        # Subfunction to allow streaming the data instead of
+        # downloading all of it at once
+        try:
+            with urlopen(unquote(url)) as data:
+                while True:
+                    chunk = data.read(1024 * 1024)
+                    if not chunk:
+                        break
+                    yield chunk
+        except HTTPError as e:
+            abort(e.code)
 
-    return content
+    try:
+        with urlopen(unquote(jsdelivr_url)) as data:
+            content_type = data.headers["content-type"]
+    except HTTPError as e:
+        abort(e.code)
+    except KeyError:
+        raise InternalServerError()
 
-if __name__ == '__main__':
-    app.run()
+    headers = dict()
+    filename = url.split("/")[-1]
+    headers["Content-Disposition"] = f'attachment; filename="{filename}"'
+
+    return Response(generate(), content_type=content_type, headers=headers)
+
+
+if __name__ == "__main__":
+    app.run()