Implement XdrCodec for TransactionMeta

crates/core/src/xdr/codec.rs

@@ -1,10 +1,34 @@
-//! XDR codec — thin wrapper over `stellar-xdr` with convenience methods.
+//! XDR codec - thin wrapper over `stellar-xdr` with convenience methods.
 //!
 //! Handles serialization/deserialization of transaction envelopes, results,
 //! ledger entries, SCVal, and SCSpecEntry types.
 
 use crate::types::error::{ PrismError, PrismResult };
 use base64::{ engine::general_purpose::STANDARD, Engine as _ };
+use stellar_xdr::curr::{ Limits, ReadXdr, TransactionMeta, WriteXdr };
+
+/// Convenience trait for working with base64-encoded Stellar XDR values.
+pub trait XdrCodec: Sized {
+    /// Deserialize a base64-encoded XDR payload into the target type.
+    fn from_xdr_base64(xdr_base64: &str) -> PrismResult<Self>;
+
+    /// Serialize the value to a base64-encoded XDR payload.
+    fn to_xdr_base64(&self) -> PrismResult<String>;
+}
+
+impl XdrCodec for TransactionMeta {
+    fn from_xdr_base64(xdr_base64: &str) -> PrismResult<Self> {
+        TransactionMeta::from_xdr_base64(xdr_base64, Limits::none()).map_err(|e|
+            PrismError::XdrError(format!("Failed to decode TransactionMeta XDR: {e}"))
+        )
+    }
+
+    fn to_xdr_base64(&self) -> PrismResult<String> {
+        WriteXdr::to_xdr_base64(self, Limits::none()).map_err(|e|
+            PrismError::XdrError(format!("Failed to encode TransactionMeta XDR: {e}"))
+        )
+    }
+}
 
 /// Decode a base64-encoded XDR transaction result.
 ///
@@ -14,9 +38,6 @@ use base64::{ engine::general_purpose::STANDARD, Engine as _ };
 /// # Returns
 /// The raw decoded bytes, ready for further parsing.
 pub fn decode_xdr_base64(xdr_base64: &str) -> PrismResult<Vec<u8>> {
-    // TODO: Implement full XDR decoding pipeline
-    let bytes = base64_decode(xdr_base64)
-        .map_err(|e| PrismError::XdrError(format!("Base64 decode failed: {e}")))?;
     let bytes = base64_decode(xdr_base64).map_err(|e|
         PrismError::XdrError(format!("Base64 decode failed: {e}"))
     )?;
@@ -67,6 +88,8 @@ fn hex_decode(input: &str) -> Result<Vec<u8>, String> {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use std::convert::TryInto;
+    use stellar_xdr::curr::{ LedgerEntryChanges, OperationMeta };
 
     #[test]
     fn test_decode_tx_hash_valid() {
@@ -92,4 +115,35 @@ mod tests {
         let result = decode_xdr_base64("!!!");
         assert!(result.is_err());
     }
+
+    #[test]
+    fn test_transaction_meta_xdr_codec_roundtrip() {
+        let meta = TransactionMeta::V0(
+            Vec::<OperationMeta>::new()
+                .try_into()
+                .expect("empty operation list should fit in XDR VecM"),
+        );
+
+        let encoded = XdrCodec::to_xdr_base64(&meta).expect("encode transaction meta");
+        let decoded = TransactionMeta::from_xdr_base64(&encoded).expect("decode transaction meta");
+
+        assert_eq!(decoded, meta);
+    }
+
+    #[test]
+    fn test_transaction_meta_xdr_codec_decodes_v1() {
+        let meta = TransactionMeta::V1(stellar_xdr::curr::TransactionMetaV1 {
+            tx_changes: LedgerEntryChanges::try_from(vec![])
+                .expect("empty ledger entry changes should fit"),
+            operations: Vec::<OperationMeta>::new()
+                .try_into()
+                .expect("empty operation list should fit"),
+        });
+
+        let encoded = XdrCodec::to_xdr_base64(&meta).expect("encode transaction meta");
+        let decoded = <TransactionMeta as XdrCodec>::from_xdr_base64(&encoded)
+            .expect("decode transaction meta");
+
+        assert_eq!(decoded, meta);
+    }
 }