BalloonWallet

use std::fs::{File, OpenOptions};
use std::io::{Write, BufReader, BufRead};
use rand::rngs::OsRng;
use rand::RngCore;
use sha2::{Sha256, Digest};
use bip39::{Mnemonic, Language, Seed};
use bip39::Entropy;

const WALLET_FILE: &str = "wallet.txt";

fn main() {
    // Check if a wallet already exists
    if let Ok(file) = File::open(WALLET_FILE) {
        let reader = BufReader::new(file);
        let lines: Vec<String> = reader.lines().map(|l| l.unwrap()).collect();

        if lines.len() == 2 {
            println!("Wallet already exists with address: {}", &lines[0]);
            return;
        }
    }

    // Generate a new wallet
    let mut entropy = [0; 32];
    OsRng.fill_bytes(&mut entropy);

    let mnemonic = Mnemonic::from_entropy(&Entropy::Raw(&entropy), Language::English)
        .expect("Could not generate mnemonic phrase");

    let seed = Seed::new(&mnemonic, "");

    let mut address = [0; 32];
    let mut hasher = Sha256::new();
    hasher.update(&seed.as_bytes()[..32]);
    let private_key = hasher.finalize();
    hasher.update(&private_key);
    hasher.update(&address);
    address.copy_from_slice(&hasher.finalize());

    let mut writer = OpenOptions::new().write(true).create(true).open(WALLET_FILE).unwrap();
    writer.write_all(&mnemonic.to_string().as_bytes()).unwrap();
    writer.write_all(b"\n").unwrap();
    writer.write_all(&address).unwrap();
    writer.write_all(b"\n").unwrap();
    writer.write_all(&private_key).unwrap();
    writer.write_all(b"\n").unwrap();

    println!("New wallet generated with address: {}", hex::encode(address));
    println!("Mnemonic phrase: {}", mnemonic.to_string());
}