sample: Add example program for melt

.github/workflows/ci.yml

@@ -54,6 +54,7 @@ jobs:
         build-args:
           [
             mint-token,
+            melt-token,
             p2pk,
             proof-selection,
             wallet

crates/cdk/Cargo.toml

@@ -68,6 +68,10 @@ getrandom = { version = "0.2", features = ["js"] }
 name = "mint-token"
 required-features = ["wallet"]
 
+[[example]]
+name = "melt-token"
+required-features = ["wallet"]
+
 [[example]]
 name = "p2pk"
 required-features = ["wallet"]

crates/cdk/examples/melt-token.rs

@@ -0,0 +1,90 @@
+use std::sync::Arc;
+
+use bitcoin::hashes::{sha256, Hash};
+use bitcoin::hex::prelude::FromHex;
+use bitcoin::secp256k1::Secp256k1;
+use cdk::amount::SplitTarget;
+use cdk::error::Error;
+use cdk::nuts::nut00::ProofsMethods;
+use cdk::nuts::{CurrencyUnit, MintQuoteState, NotificationPayload, SecretKey};
+use cdk::wallet::{Wallet, WalletSubscription};
+use cdk::Amount;
+use cdk_sqlite::wallet::memory;
+use lightning_invoice::{Currency, InvoiceBuilder, PaymentSecret};
+use rand::Rng;
+
+#[tokio::main]
+async fn main() -> Result<(), Error> {
+    // Initialize the memory store for the wallet
+    let localstore = memory::empty().await?;
+
+    // Generate a random seed for the wallet
+    let seed = rand::thread_rng().gen::<[u8; 32]>();
+
+    // Define the mint URL and currency unit
+    let mint_url = "https://testnut.cashu.space";
+    let unit = CurrencyUnit::Sat;
+    let amount = Amount::from(10);
+
+    // Create a new wallet
+    let wallet = Wallet::new(mint_url, unit, Arc::new(localstore), &seed, None)?;
+
+    // Request a mint quote from the wallet
+    let quote = wallet.mint_quote(amount, None).await?;
+    println!("Quote: {:#?}", quote);
+
+    // Subscribe to updates on the mint quote state
+    let mut subscription = wallet
+        .subscribe(WalletSubscription::Bolt11MintQuoteState(vec![quote
+            .id
+            .clone()]))
+        .await;
+
+    // Wait for the mint quote to be paid
+    while let Some(msg) = subscription.recv().await {
+        if let NotificationPayload::MintQuoteBolt11Response(response) = msg {
+            if response.state == MintQuoteState::Paid {
+                break;
+            }
+        }
+    }
+
+    // Mint the received amount
+    let proofs = wallet.mint(&quote.id, SplitTarget::default(), None).await?;
+    let receive_amount = proofs.total_amount()?;
+    println!("Received {} from mint {}", receive_amount, mint_url);
+
+    // Now melt what we have
+    // We need to prepare a lightning invoice
+    let private_key = SecretKey::from_slice(
+        &<[u8; 32]>::from_hex("e126f68f7eafcc8b74f54d269fe206be715000f94dac067d1c04a8ca3b2db734")
+            .unwrap(),
+    )
+    .unwrap();
+    let mut random_bytes = [1u8; 32];
+    rand::thread_rng().fill(&mut random_bytes);
+    let payment_hash = sha256::Hash::from_slice(&random_bytes).unwrap();
+    let payment_secret = PaymentSecret([42u8; 32]);
+    let invoice_to_be_paid = InvoiceBuilder::new(Currency::Bitcoin)
+        .amount_milli_satoshis(5 * 1000)
+        .description("Pay me".into())
+        .payment_hash(payment_hash)
+        .payment_secret(payment_secret)
+        .current_timestamp()
+        .min_final_cltv_expiry_delta(144)
+        .build_signed(|hash| Secp256k1::new().sign_ecdsa_recoverable(hash, &private_key))
+        .unwrap()
+        .to_string();
+    println!("Invoice to be paid: {}", invoice_to_be_paid);
+
+    let melt_quote = wallet.melt_quote(invoice_to_be_paid, None).await?;
+    println!(
+        "Melt quote: {} {} {:?}",
+        melt_quote.amount, melt_quote.state, melt_quote,
+    );
+
+    let melted = wallet.melt(&melt_quote.id).await?;
+    println!("Melted: {:?}", melted);
+
+    Ok(())
+}

justfile

@@ -93,6 +93,7 @@ fake-auth-mint-itest db openid_discovery:
 run-examples:
   cargo r --example p2pk
   cargo r --example mint-token
+  cargo r --example melt-token
   cargo r --example proof_selection
   cargo r --example wallet
 

misc/justfile.custom.just

@@ -22,6 +22,7 @@ check-wasm *ARGS="--target wasm32-unknown-unknown":
 run-examples:
   cargo r --example p2pk
   cargo r --example mint-token
+  cargo r --example melt-token
   cargo r --example proof_selection
   cargo r --example wallet