fix buyback issues

 - take 1 reward token in addition to buyback nft
 - set correct creation height

core/src/box_kind/buyback_box.rs

@@ -1,7 +1,9 @@
 use std::vec;
 
+use crate::oracle_types::BlockHeight;
 use ergo_lib::ergotree_ir::chain::ergo_box::ErgoBox;
 use ergo_lib::ergotree_ir::chain::ergo_box::ErgoBoxCandidate;
+use ergo_lib::ergotree_ir::chain::token::Token;
 use thiserror::Error;
 
 use crate::spec_token::RewardTokenId;
@@ -42,24 +44,32 @@ impl BuybackBoxWrapper {
             })
     }
 
-    pub fn new_without_reward_token(&self) -> ErgoBoxCandidate {
-        // take only buyback nft
-        let tokens = vec![self
-            .ergo_box
-            .tokens
-            .as_ref()
-            .unwrap()
-            .get(0)
-            .unwrap()
-            .clone()]
+    pub fn new_with_one_reward_token(&self, creation_height: BlockHeight) -> ErgoBoxCandidate {
+        let single_reward_token = Token {
+            token_id: self.reward_token_id.token_id(),
+            amount: 1.try_into().unwrap(),
+        };
+
+        // take buyback nft and at least one reward token
+        let tokens = vec![
+            self.ergo_box
+                .tokens
+                .as_ref()
+                .unwrap()
+                .get(0)
+                .unwrap()
+                .clone(),
+            single_reward_token,
+        ]
         .try_into()
         .unwrap();
+
         ErgoBoxCandidate {
             value: self.ergo_box.value,
             ergo_tree: self.ergo_box.ergo_tree.clone(),
             tokens: Some(tokens),
             additional_registers: self.ergo_box.additional_registers.clone(),
-            creation_height: self.ergo_box.creation_height,
+            creation_height: creation_height.0,
         }
     }
 }

core/src/pool_commands/refresh.rs

@@ -160,9 +160,13 @@ pub fn build_refresh_action(
                 height,
                 rate,
                 reward_decrement,
-                Some(buyback_reward_token.amount),
+                Some(
+                    (buyback_reward_token.amount.as_u64() - 1)
+                        .try_into()
+                        .unwrap(),
+                ),
             )?;
-            let out_buyback_box = buyback_box.new_without_reward_token();
+            let out_buyback_box = buyback_box.new_with_one_reward_token(height);
             output_candidates.remove(0);
             output_candidates.insert(0, out_pool_box_w_buyback_rewards);
             // should be at index 2 (checked in the contract of the buyback input box)
@@ -694,8 +698,8 @@ mod tests {
                 .as_ref()
                 .unwrap()
                 .len(),
-            1,
-            "only one token should be in output buyback box"
+            2,
+            "only two tokens should be in output buyback box"
         );
         assert_eq!(
             action_with_buyback
@@ -710,8 +714,25 @@ mod tests {
                 .unwrap()
                 .token_id,
             buyback_token_id,
-            "only buyback nft should be in output buyback box"
+            "buyback nft should be in output buyback box"
         );
+        assert_eq!(
+            action_with_buyback
+                .tx
+                .output_candidates
+                .get(2)
+                .unwrap()
+                .tokens
+                .as_ref()
+                .unwrap()
+                .get(1)
+                .unwrap()
+                .amount
+                .as_u64(),
+            &1,
+            "one reward token should be in output buyback box"
+        );
+
         assert_eq!(
             action_with_buyback
                 .tx
@@ -725,7 +746,7 @@ mod tests {
                 .unwrap()
                 .amount
                 .as_u64(),
-            &190,
+            &189,
             "reward tokens should be added to the pool box"
         )
     }