| import os | |
| import uuid | |
| import google.generativeai as genai | |
| from langgraph.graph import START, MessagesState, StateGraph | |
| from langgraph.checkpoint.memory import MemorySaver | |
| from langchain_core.messages import HumanMessage, AIMessage | |
| from langchain_core.prompts.chat import (ChatPromptTemplate, SystemMessagePromptTemplate, MessagesPlaceholder, HumanMessagePromptTemplate,) | |
| from langchain_google_genai import ChatGoogleGenerativeAI | |
| import gradio as gr | |
| import time | |
| import json | |
| import logging | |
| from dotenv import load_dotenv | |
| logging.basicConfig(level=logging.INFO, format="%(asctime)s - %(levelname)s - %(message)s") | |
| logger = logging.getLogger(__name__) | |
| load_dotenv() | |
| GEMINI_API_KEY = os.getenv("GEMINI_API_KEY") | |
| if not GEMINI_API_KEY: | |
| raise ValueError("Missing GEMINI_API_KEY") | |
| genai.configure(api_key=GEMINI_API_KEY) | |
| HISTORY_FILE = "chat_history.json" | |
| def load_all_sessions(): | |
| if os.path.exists(HISTORY_FILE): | |
| with open(HISTORY_FILE, "r", encoding="utf-8") as f: | |
| return json.load(f) | |
| return {} | |
| def save_all_sessions(sessions): | |
| with open(HISTORY_FILE, "w", encoding="utf-8") as f: | |
| json.dump(sessions, f, indent=2) | |
| class GeminiChatbot: | |
| def __init__(self): | |
| self.setup_model() | |
| def setup_model(self): | |
| system_template = """ | |
| You are a helpful, respectful and honest assistant. Always answer as helpfully as possible, while being safe. | |
| Your answers should be informative, engaging, and accurate. If a question doesn't make any sense, or isn't factually coherent, explain why instead of answering something not correct. | |
| If you don't know the answer to a question, please don't share false information. | |
| """ | |
| self.prompt = ChatPromptTemplate.from_messages([ | |
| SystemMessagePromptTemplate.from_template(system_template), | |
| MessagesPlaceholder(variable_name="chat_history"), | |
| HumanMessagePromptTemplate.from_template("{input}") | |
| ]) | |
| self.model = ChatGoogleGenerativeAI( | |
| model="gemini-2.0-flash", | |
| temperature=0.7, | |
| top_p=0.95, | |
| google_api_key=GEMINI_API_KEY, | |
| convert_system_message_to_human=True | |
| ) | |
| def call_model(state: MessagesState): | |
| chat_history = state["messages"][:-1] | |
| user_input = state["messages"][-1].content | |
| formatted_messages = self.prompt.format_messages( | |
| chat_history=chat_history, | |
| input=user_input | |
| ) | |
| response = self.model.invoke(formatted_messages) | |
| return {"messages": response} | |
| workflow = StateGraph(state_schema=MessagesState) | |
| workflow.add_node("model", call_model) | |
| workflow.add_edge(START, "model") | |
| self.memory = MemorySaver() | |
| self.app = workflow.compile(checkpointer=self.memory) | |
| def get_response(self, user_message, history, thread_id): | |
| try: | |
| langchain_history = [] | |
| for user, bot in history: | |
| langchain_history.append(HumanMessage(content=user)) | |
| langchain_history.append(AIMessage(content=bot)) | |
| input_message = HumanMessage(content=user_message) | |
| full_history = langchain_history + [input_message] | |
| full_response = "" | |
| config = {"configurable": {"thread_id": thread_id}} | |
| response = self.app.invoke({"messages": full_history}, config) | |
| complete_response = response["messages"][-1].content | |
| for char in complete_response: | |
| full_response += char | |
| yield full_response | |
| time.sleep(0.01) | |
| except Exception as e: | |
| logger.error(f"LangGraph Error: {e}") | |
| yield f"Error: {type(e).__name__} — {str(e)}" | |
| chatbot = GeminiChatbot() | |
| sessions = load_all_sessions() | |
| def launch_interface(): | |
| with gr.Blocks( | |
| theme=gr.themes.Base(), | |
| css=""" | |
| body { | |
| background-color: black; | |
| } | |
| .gr-block.gr-textbox textarea { | |
| background-color: #2f2f2f; | |
| color: white; | |
| } | |
| .gr-chatbot { | |
| background-color: #2f2f2f; | |
| color: white; | |
| } | |
| .gr-button, .gr-dropdown { | |
| margin: 5px auto; | |
| display: block; | |
| width: 50%; | |
| } | |
| .gr-markdown h2 { | |
| text-align: center; | |
| color: white; | |
| } | |
| """ | |
| ) as demo: | |
| demo.title = "LangChain Powered ChatBot" | |
| gr.Markdown("## LangChain Powered ChatBot") | |
| current_thread_id = gr.State() | |
| session_names = gr.State() | |
| history = gr.State([]) | |
| if not sessions: | |
| new_id = str(uuid.uuid4()) | |
| sessions[new_id] = [] | |
| save_all_sessions(sessions) | |
| current_thread_id.value = new_id | |
| session_names.value = [f"NEW: {new_id}"] | |
| else: | |
| current_thread_id.value = next(iter(sessions.keys())) | |
| session_names.value = [f"PREVIOUS: {k}" for k in sessions.keys()] | |
| def get_dropdown_choices(): | |
| choices = [] | |
| for session_id in sessions: | |
| if sessions[session_id]: | |
| choices.append(f"PREVIOUS: {session_id}") | |
| choices.append(f"NEW: {current_thread_id.value}") | |
| return choices | |
| with gr.Column(): | |
| new_chat_btn = gr.Button("New Chat", variant="primary") | |
| session_selector = gr.Dropdown( | |
| label="Chats", | |
| choices=get_dropdown_choices(), | |
| value=f"NEW: {current_thread_id.value}", | |
| interactive=True | |
| ) | |
| chatbot_ui = gr.Chatbot(label="Conversation", height=320) | |
| with gr.Row(): | |
| msg = gr.Textbox(placeholder="Ask a question...", container=False, scale=9) | |
| send = gr.Button("Send", variant="primary", scale=1) | |
| clear = gr.Button("Clear Current Chat") | |
| def start_new_chat(): | |
| new_id = str(uuid.uuid4()) | |
| sessions[new_id] = [] | |
| save_all_sessions(sessions) | |
| display_name = f"NEW: {new_id}" | |
| updated_choices = [f"PREVIOUS: {k}" for k in sessions if sessions[k]] + [display_name] | |
| return ( | |
| new_id, | |
| [], | |
| gr.update(choices=updated_choices, value=display_name), | |
| display_name | |
| ) | |
| def switch_chat(selected_display_id): | |
| if not selected_display_id: | |
| return current_thread_id.value, [], "" | |
| true_id = selected_display_id.split(": ", 1)[-1] | |
| chat_history = sessions.get(true_id, []) | |
| return true_id, chat_history, selected_display_id | |
| def respond(message, history, thread_id): | |
| if not message.strip(): | |
| yield history | |
| return | |
| history.append((message, "")) | |
| yield history | |
| full_response = "" | |
| for chunk in chatbot.get_response(message, history[:-1], thread_id): | |
| full_response = chunk | |
| history[-1] = (message, full_response) | |
| yield history | |
| sessions[thread_id] = history | |
| save_all_sessions(sessions) | |
| def clear_current(thread_id): | |
| sessions[thread_id] = [] | |
| save_all_sessions(sessions) | |
| return [] | |
| new_chat_btn.click( | |
| start_new_chat, | |
| outputs=[current_thread_id, chatbot_ui, session_selector, session_selector] | |
| ) | |
| session_selector.change( | |
| switch_chat, | |
| inputs=session_selector, | |
| outputs=[current_thread_id, chatbot_ui, session_selector] | |
| ) | |
| send.click( | |
| respond, | |
| inputs=[msg, chatbot_ui, current_thread_id], | |
| outputs=[chatbot_ui] | |
| ).then( | |
| lambda: "", None, msg | |
| ) | |
| msg.submit( | |
| respond, | |
| inputs=[msg, chatbot_ui, current_thread_id], | |
| outputs=[chatbot_ui] | |
| ).then( | |
| lambda: "", None, msg | |
| ) | |
| clear.click( | |
| clear_current, | |
| inputs=[current_thread_id], | |
| outputs=[chatbot_ui] | |
| ) | |
| return demo | |
| if __name__ == "__main__": | |
| try: | |
| demo = launch_interface() | |
| demo.launch(share=True) | |
| except Exception as e: | |
| logger.critical(f"App failed: {e}") | |