import streamlit as st
import json

def load_contacts():
    """Load contacts from a JSON file."""
    try:
        with open("contacts.json", "r") as f:
            return json.load(f)
    except FileNotFoundError:
        return {}

def save_contacts(contacts):
    """Save contacts to a JSON file."""
    with open("contacts.json", "w") as f:
        json.dump(contacts, f)

# Load existing contacts
contacts = load_contacts()

# Streamlit app configuration
st.set_page_config(page_title="Chat App", layout="wide")

st.title("Chat App")

# Sidebar: Add Contact Section
st.sidebar.header("Add a New Contact")
with st.sidebar.form("add_contact_form"):
    contact_name = st.text_input("Contact Name")
    contact_number = st.text_input("Phone Number")
    submit_contact = st.form_submit_button("Add Contact")

    if submit_contact:
        if contact_name and contact_number:
            contacts[contact_name] = {"number": contact_number, "messages": []}
            save_contacts(contacts)
            st.sidebar.success(f"Contact '{contact_name}' added successfully!")
        else:
            st.sidebar.error("Please provide both name and number.")

# Main Section: Chat Functionality
st.header("Chat with Your Contacts")

selected_contact = st.selectbox(
    "Select a contact to chat with", options=["Select"] + list(contacts.keys())
)

if selected_contact != "Select":
    contact_data = contacts[selected_contact]

    st.subheader(f"Chat with {selected_contact}")

    # Display chat history
    chat_history = st.empty()
    if contact_data["messages"]:
        chat_history.write("\n".join(contact_data["messages"]))

    # Input message section
    with st.form("send_message_form"):
        message = st.text_input("Type your message")
        send_message = st.form_submit_button("Send")

        if send_message:
            if message.strip():
                contact_data["messages"].append(f"You: {message}")
                save_contacts(contacts)
                chat_history.write("\n".join(contact_data["messages"]))
            else:
                st.error("Message cannot be empty.")

# Footer
st.sidebar.markdown("---")
st.sidebar.markdown("### Instructions")
st.sidebar.markdown(
    "1. Use the sidebar to add new contacts.\n"
    "2. Select a contact from the dropdown to start chatting.\n"
    "3. Your chat history is saved locally."
)