miniscript with bdk example

miniscript2.rs

use std::str::FromStr;
use bitcoin::Address;
use bitcoin::util::psbt::PartiallySignedTransaction;
use bitcoin::consensus::{encode::serialize};
use anyhow::{Result};
use bdk::{Wallet, database::MemoryDatabase};
use bdk::wallet::{coin_selection::DefaultCoinSelectionAlgorithm};
use bdk::blockchain::{electrum, noop_progress};
use bdk::electrum_client::Client;
use bdk::KeychainKind;
use bdk::SignOptions;
use std::collections::BTreeMap;

fn main() {
    let descriptor = "wsh(or_d(pk([dc342821/87h/1h/0h]tprv8ZgxMBicQKsPedzjvU2gY32Vwbqbsn5tDjgGuNVPvFrJ8p8FzidHcrTMusCpbEVUPEqfJaS9fAnNLwoGsKhH13QzygmHLGR4PAzauA3Z1Ly/0/*),and_v(v:pk([a7bc5042/87h/1h/0h]tprv8ZgxMBicQKsPeGtmpVwHZdvzjYDiP27st4auCCVk3WG8KeS4PqUNxqns5S2gyaRtRGZmYmMY3GD3kgNk47HAueLFKA9NN963B3cLk6MN4qF/0/*),older(25920))))";
    // let change_descriptor = "wsh(or_d(pk([dc342821/87h/1h/0h]tprv8ZgxMBicQKsPedzjvU2gY32Vwbqbsn5tDjgGuNVPvFrJ8p8FzidHcrTMusCpbEVUPEqfJaS9fAnNLwoGsKhH13QzygmHLGR4PAzauA3Z1Ly/1/*),and_v(v:pk([a7bc5042/87h/1h/0h]tprv8ZgxMBicQKsPeGtmpVwHZdvzjYDiP27st4auCCVk3WG8KeS4PqUNxqns5S2gyaRtRGZmYmMY3GD3kgNk47HAueLFKA9NN963B3cLk6MN4qF/1/*),older(25920))))";
    let destination = "tb1qk3ux994n9fcstcegjkfy8zden8zxtwhqjkwvt2";
    let amount = 5000;
    let response = execute(&descriptor, &destination, amount);
    println!("{:?}", response);
}

fn execute(descriptor: &str, destination: &str, amount: u64) -> Result<()> {
    // building the psbt
    let wallet = create_wallet(&descriptor, None)?;
    // let x = wallet.policies(KeychainKind::External).unwrap();
    // println!("{:?}", x); I got the id (qch8dkye) from here
    let mut path = BTreeMap::new();
    path.insert("qch8dkye".to_string(), vec![0]);
    // We parse the address and convert it to a script pubkey
    let dest_script = Address::from_str(destination)?.script_pubkey();

    // Create a transaction builder TxBuilder
    let mut tx_builder = wallet
    .build_tx()
    .coin_selection(DefaultCoinSelectionAlgorithm::default());
    // println!("{:?}", tx_builder);

    // Add our script and the amount in sats to send
    tx_builder
        .add_recipient(dest_script, amount)
        .policy_path(path, KeychainKind::External);

    // "Finish" the builder which returns a tuple:
    // A `PartiallySignedTransaction` which serializes as a psbt
    // And `TransactionDetails` which has helpful info about the transaction we just built
    let (psbt, details) = tx_builder.finish()?;
    println!("{:#?}", details);
    println!("================ PSBT ================");
    println!("{}", base64::encode(&serialize(&psbt)));
    println!("================ PSBT ================");

    // here we broadcast

    let mut psbt: PartiallySignedTransaction = psbt;

    // Default options for finalizing the transaction
    let sign_options = SignOptions::default();

    wallet.finalize_psbt(&mut psbt, sign_options)?;

    // Get the transaction out of the PSBT so we can broadcast it
    let tx = psbt.extract_tx();

    // Broadcast the transaction using our chosen backend, returning a `Txid` or an error
    let txid = wallet.broadcast(tx)?;

    println!("{:#?}", txid);

    Ok(())
}

fn create_wallet(
    desc_string: &str,
    change_desc: Option<&str>,
) -> Result<Wallet<electrum::ElectrumBlockchain, MemoryDatabase>> {
    // Create a SSL-encrypted Electrum client
    let client = Client::new("ssl://electrum.blockstream.info:60002")?;

    // Create a BDK wallet
    let wallet = Wallet::new(
        // Our wallet descriptor
        desc_string,
        // Descriptor used for generating change addresses
        change_desc,
        // Which network we'll using. If you change this to `Bitcoin` things get real.
        bitcoin::Network::Testnet,
        // In-memory ephemeral database. There's also a default key value storage provided by BDK if you want persistence.
        MemoryDatabase::default(),
        // This wrapper implements the blockchain traits BDK needs for this specific client type
        electrum::ElectrumBlockchain::from(client),
    )?;

    println!("Syncing...");

    // Important! We have to sync our wallet with the blockchain.
    // Because our wallet is ephemeral we need to do this on each run, so I put it in `create_wallet` for convenience.
    wallet.sync(noop_progress(), None)?;

    Ok(wallet)
}