app.py

import streamlit as st
import requests
import json
import web3

# Global Variables
radio_options = ["Comedy", "Drama", "Documentary"]

# Auxiliary function to disable buttons
def button_disable():
    st.session_state["disabled"] = True


# Changing the App title
st.set_page_config(page_title="IPFS-Based Survey",)

# Page title
st.title('Sample Survey')

# The following code centralizes all the buttons
st.markdown("<style>.row-widget.stButton {text-align: center;}</style>", unsafe_allow_html=True)

# Initialize state
if "current_page" not in st.session_state:
    st.session_state["current_page"] = 1
    st.session_state["Q1"] = ""
    st.session_state["Q2"] = None
    st.session_state["Q3"] = False
    st.session_state["disabled"] = False


# Page 1
if st.session_state["current_page"]  == 1:

    st.header('Please start by watching the video below', divider = 'gray')

    video_file = open('./media/sample-5s.mp4', 'rb')
    video_bytes = video_file.read()

    st.video(video_bytes)
   
    if  st.button('Next'):
       st.session_state["current_page"] += 1
       st.rerun()


# Page 2
elif st.session_state["current_page"]  == 2:

    st.session_state["Q1"] = st.text_area(r"$\textsf{\Large Q1: What is the meaning of life?}$",
                                           value = st.session_state["Q1"])

    st.markdown("# <br>", unsafe_allow_html=True)
       
    option_selected = st.radio(r"$\textsf{\Large Q2: What's your favorite movie genre?}$",
                                radio_options,
                                index = st.session_state["Q2"])
    for i, x in enumerate(radio_options):
        if x == option_selected:
            st.session_state["Q2"] = i
            break
    

    st.markdown("# <br>", unsafe_allow_html=True)

    col1, col2 = st.columns(2)
    with col1:
        if st.button('Back'):
            st.session_state["current_page"] -= 1
            st.rerun()

    with col2:
        if st.button('Next'):
            st.session_state["current_page"] += 1
            st.rerun()


# Page 3
elif st.session_state["current_page"]  == 3:
   
    st.session_state["Q3"] = st.checkbox('Check if you like this survey', 
                                         value = st.session_state["Q3"], 
                                         disabled = st.session_state["disabled"])

    st.markdown("# <br>", unsafe_allow_html=True)

    col1, col2 = st.columns(2)
    with col1:
        button1 = st.button('Back', disabled = st.session_state["disabled"])
        if button1:
            st.session_state["current_page"] -= 1
            st.rerun()

    with col2:
        button2 = st.button('Submit Responses', 
                            disabled = st.session_state["disabled"],
                            on_click = button_disable)
            
    st.markdown("# <br>", unsafe_allow_html=True)
    if st.session_state["disabled"]:     
        with st.spinner(r"$\textsf{\normalsize Storing data on IPFS and Ethereum. This operation might take a few minutes. Please wait!}$"):
                try:
                    response = {'file': json.dumps({"Q1":st.session_state["Q1"],
                                                    "Q2":radio_options[st.session_state["Q2"]],
                                                    "Q3":st.session_state["Q3"]
                                        })
                            }   
                    
                    response = requests.post('https://ipfs.infura.io:5001/api/v0/add', 
                                            files=response, 
                                            auth=(st.secrets["username"], st.secrets["password"]))
                    
                    IPFS_hash = response.json()["Hash"]
                    print(IPFS_hash)
                

                    # Connect to the Ethereum blockchain
                    w3 = web3.Web3(web3.HTTPProvider(st.secrets["infura"]))

                    # Get the contract address
                    caller = "0xbdB61Ada027eF27ef0709D3848Db1Dd13c96F970"
                    
                    ABI = '[ { "anonymous": false, "inputs": [ { "indexed": false, "internalType": "string", "name": "data", "type": "string" } ], "name": "Store", "type": "event" }, { "inputs": [ { "internalType": "string", "name": "_IPFSHash", "type": "string" } ], "name": "storeHash", "outputs": [], "stateMutability": "nonpayable", "type": "function" } ]'

                    # Create a contract instance. Address is equal to the address of the smart contract
                    contract = w3.eth.contract(address= "0x1e14B06209ACD932EF7731632999Cf4aE1b86e5c", abi=ABI)

                    # Call your function: 11155111 is Sepolia's id
                    call_function = contract.functions.storeHash(IPFS_hash).build_transaction({"chainId": 11155111, 
                                                                                            "from": caller,
                                                                                            "nonce": w3.eth.get_transaction_count(caller)}) # Initialize address nonce
    

                    # Sign transaction
                    signed_tx = w3.eth.account.sign_transaction(call_function, private_key=st.secrets["pk"])

                    # Send transaction
                    send_tx = w3.eth.send_raw_transaction(signed_tx.rawTransaction)

                    # Wait for transaction receipt
                    tx_receipt = w3.eth.wait_for_transaction_receipt(send_tx)

                    print(tx_receipt)

                    st.success('Data successfully stored. Thank you for taking the survey!', icon="✅")
                    st.info(f'The IPFS hash is: {IPFS_hash}', icon="ℹ️")
                    st.info(f'The Ethereum hash is: {tx_receipt.logs[0].transactionHash.hex()}', icon="ℹ️")
                
                except Exception as e:
                    print(e)
                    st.error(f'An error ocurred. Here is the error message: {e}', icon="🚨")