improved the file part handling

app.py

@@ -29,36 +29,41 @@ def download_pdf():
         st.error(f"Failed to download PDF from Hugging Face Hub: {e}")
         st.stop()  # Stop if the download fails
 
-# Initialize session state for the uploaded PDF and its path
+# Initialize conversation history in Streamlit session state
+if "conversation_history" not in st.session_state:
+    st.session_state.conversation_history = []
+if "uploaded_file_part" not in st.session_state:  # Store the file *part*
+    st.session_state.uploaded_file_part = None
 if "uploaded_pdf_path" not in st.session_state:
     st.session_state.uploaded_pdf_path = download_pdf() 
-if "conversation_history" not in st.session_state:
-    st.session_state.conversation_history = []  # Store the conversation history
+
+
 
 def multimodal_prompt(pdf_path, text_prompt):
     """
-    Sends a multimodal prompt (PDF + text) to Gemini for the *first* message.
-
+    Sends a multimodal prompt to Gemini, handling file uploads efficiently.
     Args:
         pdf_path: The path to the PDF file.
         text_prompt: The text prompt for the model.
-
     Returns:
         The model's response as a string, or an error message.
     """
-
     try:
-        pdf_part = genai.upload_file(pdf_path, mime_type="application/pdf")
-
-        prompt = [
-            text_prompt,
-            pdf_part
-        ]
+        if st.session_state.uploaded_file_part is None:  # First time, upload
+            pdf_part = genai.upload_file(pdf_path, mime_type="application/pdf")
+            st.session_state.uploaded_file_part = pdf_part
+            prompt = [text_prompt, pdf_part] # First turn includes the actual file
+        else: # Subsequent turns, reference the file
+            
+            prompt = [text_prompt, st.session_state.uploaded_file_part] # Subsequent turns include the file reference
 
         response = chat.send_message(prompt)
-        st.session_state.conversation_history.append({"role": "user", "content": text_prompt, "has_pdf": True}) # Add to history
-        st.session_state.conversation_history.append({"role": "assistant", "content": response.text}) # Add to history
+
+        # Update conversation history
+        st.session_state.conversation_history.append({"role": "user", "content": text_prompt, "has_pdf": True})
+        st.session_state.conversation_history.append({"role": "assistant", "content": response.text})
         return response.text
+
     except Exception as e:
         return f"An error occurred: {e}"