From d78bdde81fad8eaa034b6c20449c925d3800c627 Mon Sep 17 00:00:00 2001
From: elnosh <elnosh@pm.me>
Date: Thu, 20 Jun 2024 09:38:57 -0500
Subject: [PATCH] fix: make blinded messages in melt optional (#298)

---
 moksha-core/src/primitives.rs             |  2 +-
 moksha-mint/src/mint.rs                   | 54 ++++++++++++++---------
 moksha-mint/src/routes/default.rs         |  2 +-
 moksha-wallet/src/client/crossplatform.rs |  2 +-
 4 files changed, 37 insertions(+), 23 deletions(-)

diff --git a/moksha-core/src/primitives.rs b/moksha-core/src/primitives.rs
index ac953018..f9c6c1d8 100644
--- a/moksha-core/src/primitives.rs
+++ b/moksha-core/src/primitives.rs
@@ -201,7 +201,7 @@ impl From<Bolt11MeltQuote> for PostMeltQuoteBolt11Response {
 pub struct PostMeltBolt11Request {
     pub quote: String,
     pub inputs: Proofs,
-    pub outputs: Vec<BlindedMessage>,
+    pub outputs: Option<Vec<BlindedMessage>>,
 }
 
 #[derive(Deserialize, Serialize, Debug, Clone, ToSchema)]
diff --git a/moksha-mint/src/mint.rs b/moksha-mint/src/mint.rs
index 4540da4d..1c8673d9 100644
--- a/moksha-mint/src/mint.rs
+++ b/moksha-mint/src/mint.rs
@@ -182,7 +182,7 @@ where
         payment_request: String,
         fee_reserve: u64,
         proofs: &Proofs,
-        blinded_messages: &[BlindedMessage],
+        blinded_messages: Option<Vec<BlindedMessage>>,
         keyset: &MintKeyset,
     ) -> Result<(bool, String, Vec<BlindedSignature>), MokshaMintError> {
         let invoice = self
@@ -212,26 +212,33 @@ where
         let result = self.lightning.pay_invoice(payment_request).await?;
         self.db.add_used_proofs(tx, proofs).await?;
 
-        let change = if fee_reserve > 0 {
-            let return_fees = Amount(fee_reserve - result.total_fees).split();
-
-            if (return_fees.len()) > blinded_messages.len() {
-                // FIXME better handle case when there are more fees than blinded messages
+        let change = match blinded_messages {
+            Some(blinded_messages) => {
+                if fee_reserve > 0 {
+                    let return_fees = Amount(fee_reserve - result.total_fees).split();
+
+                    if (return_fees.len()) > blinded_messages.len() {
+                        // FIXME better handle case when there are more fees than blinded messages
+                        vec![]
+                    } else {
+                        let out: Vec<_> = blinded_messages[0..return_fees.len()]
+                            .iter()
+                            .zip(return_fees.into_iter())
+                            .map(|(message, fee)| BlindedMessage {
+                                amount: fee,
+                                ..message.clone()
+                            })
+                            .collect();
+
+                        self.create_blinded_signatures(&out, keyset)?
+                    }
+                } else {
+                    vec![]
+                }
+            }
+            None => {
                 vec![]
-            } else {
-                let out: Vec<_> = blinded_messages[0..return_fees.len()]
-                    .iter()
-                    .zip(return_fees.into_iter())
-                    .map(|(message, fee)| BlindedMessage {
-                        amount: fee,
-                        ..message.clone()
-                    })
-                    .collect();
-
-                self.create_blinded_signatures(&out, keyset)?
             }
-        } else {
-            vec![]
         };
         Ok((true, result.payment_hash, change))
     }
@@ -673,7 +680,14 @@ mod tests {
 
         let mut tx = mint.db.begin_tx().await?;
         let (paid, _payment_hash, change) = mint
-            .melt_bolt11(&mut tx, invoice, 4, &tokens.proofs(), &change, &mint.keyset)
+            .melt_bolt11(
+                &mut tx,
+                invoice,
+                4,
+                &tokens.proofs(),
+                Some(change),
+                &mint.keyset,
+            )
             .await?;
 
         assert!(paid);
diff --git a/moksha-mint/src/routes/default.rs b/moksha-mint/src/routes/default.rs
index d063a0c2..a8cc3036 100644
--- a/moksha-mint/src/routes/default.rs
+++ b/moksha-mint/src/routes/default.rs
@@ -257,7 +257,7 @@ pub async fn post_melt_bolt11(
             quote.payment_request.to_owned(),
             quote.fee_reserve,
             &melt_request.inputs,
-            &melt_request.outputs,
+            melt_request.outputs,
             &mint.keyset,
         )
         .await?;
diff --git a/moksha-wallet/src/client/crossplatform.rs b/moksha-wallet/src/client/crossplatform.rs
index fda03676..934a0e48 100644
--- a/moksha-wallet/src/client/crossplatform.rs
+++ b/moksha-wallet/src/client/crossplatform.rs
@@ -61,7 +61,7 @@ impl CashuClient for CrossPlatformHttpClient {
         let body = PostMeltBolt11Request {
             quote,
             inputs,
-            outputs,
+            outputs: Some(outputs),
         };
 
         self.do_post(&mint_url.join("v1/melt/bolt11")?, &body).await