feat: add streaming and error handling to proxy route

Introduced streaming support in the proxy route to handle large data transfers more efficiently without loading everything into memory at once. Added error handling for HTTP errors and content-type detection failures to provide more robust and user-friendly responses. Updated import statements to reflect new dependencies.

app.py

@@ -1,22 +1,50 @@
-from flask import Flask, redirect, 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://cdn.jsdelivr.net/{url}'
+    jsdelivr_url = f"https://cdn.jsdelivr.net/{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()