Add app.py for a Streamlit-based chatbot

This commit introduces the app.py file, which implements a chatbot using the Streamlit framework and OpenAI API. The chatbot interface is designed to handle user inputs and generate responses through OpenAI's model. The implementation includes setup for API requests, response handling, and basic UI components for user interaction. This initial version sets up the foundational structure for further development and integration.

app.py

@@ -0,0 +1,33 @@
+from openai import OpenAI
+import streamlit as st
+
+st.title("ChatGPT-like clone")
+
+client = OpenAI(api_key=st.secrets["OPENAI_API_KEY"])
+
+if "openai_model" not in st.session_state:
+    st.session_state["openai_model"] = "gpt-3.5-turbo"
+
+if "messages" not in st.session_state:
+    st.session_state.messages = []
+
+for message in st.session_state.messages:
+    with st.chat_message(message["role"]):
+        st.markdown(message["content"])
+
+if prompt := st.chat_input("What is up?"):
+    st.session_state.messages.append({"role": "user", "content": prompt})
+    with st.chat_message("user"):
+        st.markdown(prompt)
+
+    with st.chat_message("assistant"):
+        stream = client.chat.completions.create(
+            model=st.session_state["openai_model"],
+            messages=[
+                {"role": m["role"], "content": m["content"]}
+                for m in st.session_state.messages
+            ],
+            stream=True,
+        )
+        response = st.write_stream(stream)
+    st.session_state.messages.append({"role": "assistant", "content": response})