fix: standardize memo type handling in Stellar transactions

- Updated tests and implementation to use the new MemoType type for memoType fields in Stellar transactions.
- Replaced string comparisons with MemoType constants to ensure consistency and type safety across the codebase.
- Adjusted related tests to reflect the changes in memoType assertions.

Author: vietddude

internal/indexer/stellar.go

@@ -428,11 +428,11 @@ func (s *StellarIndexer) convertPayment(
 
 	fee := decimal.Zero
 	memo := ""
-	memoType := ""
+	var memoType types.MemoType
 	if txDetail != nil {
 		fee = stroopsToXLM(strings.TrimSpace(txDetail.FeeCharged))
 		memo = strings.TrimSpace(txDetail.Memo)
-		memoType = strings.TrimSpace(txDetail.MemoType)
+		memoType = types.MemoType(strings.TrimSpace(txDetail.MemoType))
 	}
 
 	tx := types.Transaction{
@@ -700,7 +700,7 @@ func (s *StellarIndexer) newOperationTransaction(
 			tx.Memo = memo
 		}
 		if memoType := strings.TrimSpace(txDetail.MemoType); memoType != "" {
-			tx.MemoType = memoType
+			tx.MemoType = types.MemoType(memoType)
 		}
 	}
 	return tx

internal/indexer/stellar_test.go

@@ -374,7 +374,7 @@ func TestStellarGetBlock_ParsesNativeAndIssuedPaymentsWithMemo(t *testing.T) {
 	memo := nativeTx.Memo
 	assert.Equal(t, "memo-1", memo)
 	memoType := nativeTx.MemoType
-	assert.Equal(t, "text", memoType)
+	assert.Equal(t, types.MemoTypeText, memoType)
 	assert.Equal(t, "0.00001", nativeTx.TxFee.String())
 
 	tokenTx := block.Transactions[1]
@@ -1094,7 +1094,7 @@ func TestStellarMainnetFetchAndParseTransactions(t *testing.T) {
 				require.NotNil(t, payment)
 				assert.Equal(t, formatStellarAsset(payment.AssetIssuer, payment.AssetCode), tx.AssetAddress)
 				assert.Equal(t, "pspb:4441859", tx.Memo)
-				assert.Equal(t, "text", tx.MemoType)
+				assert.Equal(t, types.MemoTypeText, tx.MemoType)
 			},
 		},
 		{
@@ -1348,6 +1348,6 @@ func TestStellarMainnetBatchPaymentProducesMultipleTransactions(t *testing.T) {
 	for _, tx := range converted {
 		assert.Equal(t, batchTxHash, tx.TxHash)
 		assert.Equal(t, "pspb:4441859", tx.Memo)
-		assert.Equal(t, "text", tx.MemoType)
+		assert.Equal(t, types.MemoTypeText, tx.MemoType)
 	}
 }

internal/worker/base_test.go

@@ -196,7 +196,7 @@ func TestBaseWorkerEmitBlock_AppliesNativeOutgoingOverrides(t *testing.T) {
 				Amount:        "5.0000000",
 				Type:          constant.TxTypeTokenTransfer,
 				AssetAddress:  "GISSUER:USDC",
-				MemoType:      "text",
+				MemoType:      types.MemoTypeText,
 				Metadata: map[string]any{
 					testSourceTypeKey:         string(constant.TxTypeNativeTransfer),
 					testSourceAmountKey:       "7.5000000",
@@ -217,7 +217,7 @@ func TestBaseWorkerEmitBlock_AppliesNativeOutgoingOverrides(t *testing.T) {
 	if outTx.Type != constant.TxTypeNativeTransfer || outTx.Amount != "7.5000000" || outTx.AssetAddress != "" {
 		t.Fatalf("outgoing native override should clear receiver-side asset, got type=%s amount=%s asset=%s", outTx.Type, outTx.Amount, outTx.AssetAddress)
 	}
-	if outTx.MemoType != "text" {
+	if outTx.MemoType != types.MemoTypeText {
 		t.Fatalf("outgoing tx should preserve unrelated metadata")
 	}
 	if outTx.GetMetadataString(testSourceTypeKey) != "" || outTx.GetMetadataString(testSourceAmountKey) != "" || outTx.GetMetadataString(testSourceAssetKey) != "" {

pkg/common/types/types.go

@@ -11,6 +11,26 @@ import (
 	"github.com/shopspring/decimal"
 )
 
+// MemoType represents a chain-specific memo type.
+//
+// For Stellar this maps to the underlying XDR memo type:
+// - "none"   -> MEMO_NONE
+// - "text"   -> MEMO_TEXT
+// - "id"     -> MEMO_ID
+// - "hash"   -> MEMO_HASH
+// - "return" -> MEMO_RETURN (32-byte refund hash)
+//
+// Other chains may reuse these values or leave MemoType empty.
+type MemoType string
+
+const (
+	MemoTypeNone   MemoType = "none"
+	MemoTypeText   MemoType = "text"
+	MemoTypeID     MemoType = "id"
+	MemoTypeHash   MemoType = "hash"
+	MemoTypeReturn MemoType = "return"
+)
+
 type Block struct {
 	Number       uint64                 `json:"number"`
 	Hash         string                 `json:"hash"`
@@ -60,7 +80,7 @@ type Transaction struct {
 	Direction      string          `json:"direction"`     // "in" (deposit) or "out" (withdrawal)
 	DestinationTag string          `json:"destinationTag,omitempty"`
 	Memo           string          `json:"memo,omitempty"`
-	MemoType       string          `json:"memoType,omitempty"`
+	MemoType       MemoType        `json:"memoType,omitempty"`
 	Metadata       map[string]any  `json:"metadata,omitempty"`
 }
 
@@ -192,7 +212,7 @@ func (t Transaction) Hash() string {
 			builder.WriteByte('|')
 			builder.WriteString(memo)
 		}
-		if memoType := strings.TrimSpace(t.MemoType); memoType != "" {
+		if memoType := strings.TrimSpace(string(t.MemoType)); memoType != "" {
 			builder.WriteByte('|')
 			builder.WriteString(memoType)
 		}

pkg/common/types/types_test.go

@@ -28,7 +28,7 @@ func TestTransactionBinaryRoundTripPreservesRoutingFields(t *testing.T) {
 	}
 	tx.DestinationTag = "12345"
 	tx.Memo = "invoice-42"
-	tx.MemoType = "text"
+	tx.MemoType = MemoTypeText
 	tx.SetMetadata("custom_routing_note", "internal")
 
 	data, err := tx.MarshalBinary()
@@ -38,7 +38,7 @@ func TestTransactionBinaryRoundTripPreservesRoutingFields(t *testing.T) {
 	require.NoError(t, decoded.UnmarshalBinary(data))
 	require.Equal(t, "12345", decoded.DestinationTag)
 	require.Equal(t, "invoice-42", decoded.Memo)
-	require.Equal(t, "text", decoded.MemoType)
+	require.Equal(t, MemoTypeText, decoded.MemoType)
 	require.Equal(t, "internal", decoded.GetMetadataString("custom_routing_note"))
 }
 
@@ -59,7 +59,7 @@ func TestTransactionHashIncludesRoutingFields(t *testing.T) {
 
 	withMemo := base
 	withMemo.Memo = "memo"
-	withMemo.MemoType = "text"
+	withMemo.MemoType = MemoTypeText
 
 	require.NotEqual(t, base.Hash(), withTag.Hash())
 	require.NotEqual(t, base.Hash(), withMemo.Hash())