Fix Add transfer_stream function to reassign recipient

contracts/streaming/src/lib.rs

@@ -84,6 +84,10 @@ pub struct CancelEvent {
 }
 
 #[soroban_sdk::contractevent]
+pub struct StreamTransferEvent {
+    pub stream_id: u64,
+    pub old_recipient: Address,
+    pub new_recipient: Address,
 pub struct TopUpEvent {
     pub stream_id: u64,
     pub additional_amount: i128,
@@ -178,6 +182,23 @@ impl StreamingContract {
         id
     }
 
+     // ── Write: Transfer ────────────────────────────────────────────────────────
+
+    /// Transfer a token stream right to a new address
+    pub fn transfer_stream(env: Env, stream_id: u64, new_recipient: Address) {
+        let mut stream = Self::load_stream(&env, stream_id);
+        stream.recipient.require_auth();
+        let old_recipient = stream.recipient;
+        if stream.cancelled {
+            panic!("cannot transfer a cancelled stream");
+        }
+        if new_recipient == old_recipient {
+            panic!("new_recipient must differ from current recipient");
+        }
+
+        stream.recipient = new_recipient.clone();
+
+        // ── Persist stream ───────────────────────────────────────────────────
     /// Top up an existing stream with additional funds.
     ///
     /// Increases `deposited_amount` and recalculates `amount_per_second` over
@@ -250,6 +271,11 @@ impl StreamingContract {
             .persistent()
             .set(&DataKey::Stream(stream_id), &stream);
 
+        Self::remove_from_index(&env, DataKey::ReceivedBy(old_recipient.clone()), stream_id);
+        Self::push_to_index(&env, DataKey::ReceivedBy(new_recipient.clone()), stream_id);
+
+        StreamTransferEvent { stream_id, old_recipient, new_recipient }
+            .publish(&env);
         Self::extend_stream_ttl(&env, stream_id);
 
         // ── Emit event ───────────────────────────────────────────────────────
@@ -505,6 +531,22 @@ impl StreamingContract {
         );
     }
 
+    /// Append a stream ID to an address index list.
+    fn remove_from_index(env: &Env, key: DataKey, id: u64) {
+        let mut indexes: Vec<u64> = env
+            .storage()
+            .persistent()
+            .get(&key)
+            .unwrap_or(Vec::new(env));
+
+        let position = indexes.iter().position(|id| id == id);
+        if let Some(i) = position {
+            indexes.remove(i as u32);
+        }
+
+        env.storage().persistent().set(&key, &indexes);
+    }
+
     /// Extend the TTL of a stream entry (~30 days).
     fn extend_stream_ttl(env: &Env, id: u64) {
         env.storage().persistent().extend_ttl(

contracts/streaming/src/test.rs

@@ -4,9 +4,7 @@ extern crate std;
 
 use super::*;
 use soroban_sdk::{
-    testutils::{Address as _, Ledger},
-    token::{Client as TokenClient, StellarAssetClient},
-    Address, Env,
+    Address, Env, log, testutils::{Address as _, Ledger}, token::{Client as TokenClient, StellarAssetClient}, vec
 };
 
 // ─── Test helpers ─────────────────────────────────────────────────────────────
@@ -402,6 +400,12 @@ fn test_incrementing_ids() {
     }
 }
 
+#[test]
+fn test_transfer_stream() {
+    let t = TestEnv::setup();
+    let now = 1_000_000u64;
+    t.set_time(now);
+
 // ─── top up ───────────────────────────────────────────────────────────────────
 
 #[test]
@@ -413,6 +417,45 @@ fn test_top_up_increases_deposited_amount() {
     let params = t.default_params(now);
     let total = params.total_amount;
 
+    // Approve contract to pull funds.
+    t.token().approve(&t.sender, &t.contract_id, &total, &(t.env.ledger().sequence() + 500));
+
+    let stream_id = client.create_stream(&t.sender, &params);
+
+    assert_eq!(stream_id, 1);
+
+    let stream = client.get_stream(&stream_id);
+    assert_eq!(stream.sender, t.sender);
+    assert_eq!(stream.recipient, t.recipient);
+    assert_eq!(stream.deposited_amount, total);
+    assert_eq!(stream.withdrawn_amount, 0);
+    assert!(!stream.cancelled);
+
+    let new_recipient = Address::generate(&t.env);
+    client.transfer_stream(&stream_id, &new_recipient);
+
+    let stream = client.get_stream(&stream_id);
+    assert_eq!(stream.sender, t.sender);
+    assert_eq!(stream.recipient, new_recipient);
+    assert_eq!(stream.deposited_amount, total);
+    assert_eq!(stream.withdrawn_amount, 0);
+    assert!(!stream.cancelled);
+
+    let old_id = client.get_received_streams(&t.recipient);
+    assert_eq!(old_id, Vec::new(&t.env));
+
+    let new_id = client.get_received_streams(&new_recipient);
+    assert_eq!(new_id, vec![&t.env, 1]);
+
+}
+
+#[should_panic(expected = "cannot transfer a cancelled stream")]
+#[test]
+fn test_transfer_stream_panic() {
+    let t = TestEnv::setup();
+    let now = 1_000_000u64;
+    t.set_time(now);
+
     t.token().approve(&t.sender, &t.contract_id, &total, &(t.env.ledger().sequence() + 500));
     let stream_id = client.create_stream(&t.sender, &params);
 
@@ -458,6 +501,25 @@ fn test_top_up_mid_stream_recalculates_rate() {
     let params = t.default_params(now);
     let total = params.total_amount;
 
+    // Approve contract to pull funds.
+    t.token().approve(&t.sender, &t.contract_id, &total, &(t.env.ledger().sequence() + 500));
+
+    let stream_id = client.create_stream(&t.sender, &params);
+
+    assert_eq!(stream_id, 1);
+
+    let stream = client.get_stream(&stream_id);
+    assert_eq!(stream.sender, t.sender);
+    assert_eq!(stream.recipient, t.recipient);
+    assert_eq!(stream.deposited_amount, total);
+    assert_eq!(stream.withdrawn_amount, 0);
+    assert!(!stream.cancelled);
+
+    client.cancel(&stream_id);
+
+    let new_recipient = Address::generate(&t.env);
+    client.transfer_stream(&stream_id, &new_recipient);
+}
     t.token().approve(&t.sender, &t.contract_id, &total, &(t.env.ledger().sequence() + 500));
     let stream_id = client.create_stream(&t.sender, &params);