From 896a6d613c0dc431cd489b2a4febf8d39e741c55 Mon Sep 17 00:00:00 2001
From: DanGould <d@ngould.dev>
Date: Fri, 7 Jul 2023 13:15:37 -0400
Subject: [PATCH] Draft send payjoin

---
 mutiny-core/Cargo.toml         |  1 +
 mutiny-core/src/nodemanager.rs | 17 +++++++++++
 mutiny-core/src/onchain.rs     | 53 ++++++++++++++++++++++++++++++++++
 3 files changed, 71 insertions(+)

diff --git a/mutiny-core/Cargo.toml b/mutiny-core/Cargo.toml
index 59a1042d0..0e0066de8 100644
--- a/mutiny-core/Cargo.toml
+++ b/mutiny-core/Cargo.toml
@@ -39,6 +39,7 @@ nostr-sdk = { version = "0.22.0-bitcoin-v0.29", default-features = false }
 cbc = { version = "0.1", features = ["alloc"] }
 aes = { version = "0.8" }
 jwt-compact = { version = "0.8.0-beta.1", features = ["es256k"] }
+payjoin = { version = "0.8.1", features = ["send"] }
 
 base64 = "0.13.0"
 pbkdf2 = "0.11"
diff --git a/mutiny-core/src/nodemanager.rs b/mutiny-core/src/nodemanager.rs
index e88755e24..295661747 100644
--- a/mutiny-core/src/nodemanager.rs
+++ b/mutiny-core/src/nodemanager.rs
@@ -978,6 +978,23 @@ impl<S: MutinyStorage> NodeManager<S> {
         })
     }
 
+    pub async fn send_payjoin(
+        &self,
+        send_to: Address,
+        amount: u64,
+        labels: Vec<String>,
+        fee_rate: Option<f32>, // Why not FeeRate?
+        pj: String,
+    ) -> Result<Txid, MutinyError> {
+        if !send_to.is_valid_for_network(self.network) {
+            return Err(MutinyError::IncorrectNetwork(send_to.network));
+        }
+
+        self.wallet
+            .send_payjoin(send_to, amount, labels, fee_rate, pj)
+            .await
+    }
+
     /// Sends an on-chain transaction to the given address.
     /// The amount is in satoshis and the fee rate is in sat/vbyte.
     ///
diff --git a/mutiny-core/src/onchain.rs b/mutiny-core/src/onchain.rs
index eab337b51..61f0196c8 100644
--- a/mutiny-core/src/onchain.rs
+++ b/mutiny-core/src/onchain.rs
@@ -1,4 +1,5 @@
 use anyhow::anyhow;
+use payjoin::{UriExt, PjUriExt};
 use std::collections::HashSet;
 use std::str::FromStr;
 use std::sync::atomic::{AtomicBool, Ordering};
@@ -404,6 +405,58 @@ impl<S: MutinyStorage> OnChainWallet<S> {
         Ok(txid)
     }
 
+    pub async fn send_payjoin(
+        &self,
+        uri: String,
+        amount: u64,
+        labels: Vec<String>,
+        fee_rate: Option<f32>,
+    ) -> Result<Txid, MutinyError> {
+        let uri = payjoin::Uri::try_from(uri)
+            .expect("Invalid payjoin URI")
+            .require_network(self.network)
+            .expect("Payjoin network mismatch")
+            .check_pj_supported()
+            .expect("Payjoin not supported");
+
+        let amount = uri.amount().unwrap_or(amount);
+
+        // is this finalized?
+        let original_psbt = self.create_signed_psbt(uri.address, amount, Some(fee_rate))?;
+
+        let pj_params = payjoin::send::Configuration::min_fee_rate_sat_per_vb(self, fee_rate);
+        let (req, ctx) = uri.create_pj_request(psbt, pj_params).expect("Could not create Payjoin request");
+
+        let client = reqwest::ClientBuilder::new()
+            .build()
+            .expect("Could not build HTTP client");
+
+        let &mut res = client
+            .post(req.url)
+            .body(req.body)
+            .header("Content-Type", "text/plain")
+            .send()
+            .await
+            .expect("Payjoin request failed")
+            .text()
+            .await
+            .expect("Could not read Payjoin response");
+
+        let mut proposal_psbt = ctx.process_response(res).expect("Could not process Payjoin response");
+
+        // TODO add original psbt input map data in place so BDK knows which scripts to sign,
+        // proposal_psbt only contains the sender input outpoints, not scripts, which BDK
+        // does not look up
+
+        // sign and finalize payjoin
+        let payjoin = self.wallet.read().unwrap().sign(&mut psbt, SignOptions::default())?.extract_tx();
+        let txid = payjoin.txid();
+
+        self.broadcast_transaction(payjoin.clone()).await?;
+        log_debug!(self.logger, "Payjoin broadcast! TXID: {txid}");
+        Ok(txid)
+    }
+
     pub fn create_sweep_psbt(
         &self,
         spk: Script,