Add create_transaction

src/silentpayments.rs

@@ -35,6 +35,63 @@ use crate::crypto::AnkSharedSecret;
 //     }
 // }
 
+pub fn create_transaction(sp_address: SilentPaymentAddress, sp_wallet: &SpWallet, fee_rate: Amount) -> Result<Transaction> {
+    let available_outpoints = sp_wallet.get_outputs().to_spendable_list();
+
+    // Here we need to add more heuristics about which outpoint we spend
+    // For now let's keep it simple
+
+    let mut inputs: HashMap<OutPoint, OwnedOutput> = HashMap::new();
+
+    let mut total_available = Amount::from_sat(0);
+    for (outpoint, output) in available_outpoints {
+        total_available += output.amount;
+        inputs.insert(outpoint, output);
+        if total_available > Amount::from_sat(1000) {
+            break;
+        }
+    }
+
+    if total_available < Amount::from_sat(1000) {
+        return Err(Error::msg("Not enough available funds"));
+    }
+
+    let recipient = Recipient {
+        address: sp_address.into(),
+        amount: Amount::from_sat(1000),
+        nb_outputs: 1,
+    };
+
+    let mut new_psbt = sp_wallet.get_client().create_new_psbt(
+        inputs,
+        vec![recipient],
+        None,
+    )?;
+
+    let change_addr = sp_wallet.get_client().sp_receiver.get_change_address();
+    SpClient::set_fees(&mut new_psbt, fee_rate, change_addr)?;
+
+    let partial_secret = sp_wallet
+        .get_client()
+        .get_partial_secret_from_psbt(&new_psbt)?;
+
+    // This wouldn't work with many recipients in the same transaction
+    // each address (or more precisely each scan public key) would have its own point
+    let shared_point = shared_secret_point(&sp_address.get_scan_key(), &partial_secret);
+
+    sp_wallet
+        .get_client()
+        .fill_sp_outputs(&mut new_psbt, partial_secret)?;
+    let mut aux_rand = [0u8; 32];
+    rand::thread_rng().fill(&mut aux_rand);
+    let mut signed = sp_wallet.get_client().sign_psbt(new_psbt, &aux_rand)?;
+    SpClient::finalize_psbt(&mut signed)?;
+
+    let final_tx = signed.extract_tx()?;
+
+    Ok(final_tx)
+}
+
 pub fn create_transaction_for_address_with_shared_secret(
     sp_address: SilentPaymentAddress,
     sp_wallet: &SpWallet,