app.py

import streamlit as st
import hashlib

# Helper function to hash passwords
def hash_password(password):
    return hashlib.sha256(str.encode(password)).hexdigest()

# Initialize session state for login and signup data
if 'logged_in' not in st.session_state:
    st.session_state['logged_in'] = False
if 'users' not in st.session_state:
    st.session_state['users'] = {}

# Function to handle login
def handle_login(username, password):
    if username in st.session_state['users']:
        hashed_password = hash_password(password)
        if st.session_state['users'][username] == hashed_password:
            st.session_state['logged_in'] = True
            st.session_state['username'] = username
            st.success(f"Successfully logged in as {username}")
            st.rerun()  # Redirect to the main page
        else:
            st.error("Incorrect password")
    else:
        st.error("Username does not exist")

# Function to handle logout
def handle_logout():
    st.session_state['logged_in'] = False
    st.session_state['username'] = None
    st.rerun()  # Rerun to show the login page

# Signup functionality
def handle_signup(username, password, confirm_password):
    if username in st.session_state['users']:
        st.error("Username already exists! Please choose another.")
    elif password != confirm_password:
        st.error("Passwords do not match!")
    else:
        st.session_state['users'][username] = hash_password(password)
        st.success(f"User {username} successfully signed up! You can now log in.")

def main_page():
    st.title("Main Page")
    st.write(f"Welcome, {st.session_state['username']}!")

    # Create multiple tabs for different functionalities
    tab1, tab2, tab3 = st.tabs(["Predict and Save in Blockchain", "Retrieve from Blockchain", "Logout"])

   # Tab 1: Predict and Save in Blockchain
    with tab1:
        st.header("Predict and Save in Blockchain")

        # Multiple input fields for crop data
        nitrogen = st.number_input("Nitrogen (N) content in soil (mg/kg)", min_value=0, step=1)
        phosphorus = st.number_input("Phosphorus (P) content in soil (mg/kg)", min_value=0, step=1)
        potassium = st.number_input("Potassium (K) content in soil (mg/kg)", min_value=0, step=1)
        soil_type = st.selectbox("Select Soil Type", ["Clay", "Loamy", "Sandy", "Silt"])
        temperature = st.number_input("Temperature (°C)", min_value=-50.0, max_value=60.0, step=0.1)
        rainfall = st.number_input("Rainfall (mm)", min_value=0.0, step=0.1)
        humidity = st.number_input("Humidity (%)", min_value=0, max_value=100, step=1)
        pH = st.number_input("Soil pH", min_value=0.0, max_value=14.0, step=0.1)

        # Button to make predictions and save to blockchain
        if st.button("Predict and Save"):
            # Check if all required fields are filled
            if nitrogen and phosphorus and potassium and temperature and rainfall and humidity and pH:
                # Placeholder for prediction logic (can use a machine learning model here)
                prediction_result = f"Best crop based on N: {nitrogen}, P: {phosphorus}, K: {potassium}, Soil Type: {soil_type}, Temp: {temperature}, Rainfall: {rainfall}, Humidity: {humidity}, pH: {pH}"
                
                # Display the prediction
                st.success(prediction_result)
                
                # Save the prediction result to the blockchain (replace with actual blockchain logic)
                st.session_state['blockchain'].add_block(prediction_result)
                st.success("Prediction saved in the blockchain!")
            else:
                st.error("Please fill out all the fields!")


    # Tab 2: Retrieve from Blockchain
    with tab2:
        st.header("Retrieve Data from Blockchain")
        if st.button("Retrieve Blockchain Data"):
            # Assuming blockchain retrieval logic here
            st.success("Blockchain data retrieved!")
            # Display blockchain data (assuming JSON format for simplicity)
            st.json({"block_1": "Sample Data", "block_2": "More Data"})  # Example data

    # Tab 3: Logout
    with tab3:
        st.header("Logout")
        if st.button("Logout"):
            handle_logout()

# Define a simple logout function
def handle_logout():
    st.session_state['logged_in'] = False
    st.rerun()  # Rerun to show the login page again


# Login/signup interface
def login_page():
    st.title("Crop Recomendation")

    # Tabs for login and signup
    tab1, tab2 = st.tabs(["Login", "Signup"])

    # Login Tab
    with tab1:
        st.header("Login")
        login_username = st.text_input("Username", key="login_username")
        login_password = st.text_input("Password", type="password", key="login_password")
        
        if st.button("Login"):
            handle_login(login_username, login_password)

    # Signup Tab
    with tab2:
        st.header("Signup")
        signup_username = st.text_input("Create Username", key="signup_username")
        signup_password = st.text_input("Create Password", type="password", key="signup_password")
        signup_confirm_password = st.text_input("Confirm Password", type="password", key="signup_confirm_password")
        
        if st.button("Signup"):
            handle_signup(signup_username, signup_password, signup_confirm_password)

# Conditional display based on login state
if st.session_state['logged_in']:
    main_page()  # Show main page with logout
else:
    login_page()  # Show login/signup page