WIP mint serial context serialization

lib/flutter_libsparkmobile.dart

@@ -160,6 +160,28 @@ abstract final class LibSpark {
     return ret;
   }
 
+  static Uint8List serializeMintContext({required List<(String, int)> inputs}) {
+    final inputsPtr =
+        malloc.allocate<DartInputData>(sizeOf<DartInputData>() * inputs.length);
+
+    for (int i = 0; i < inputs.length; i++) {
+      final hash =
+          Uint8List.fromList(inputs[i].$1.to32BytesFromHex().reversed.toList());
+
+      inputsPtr[i].txHashLength = hash.length;
+      inputsPtr[i].txHash = hash.unsignedCharPointer();
+      inputsPtr[i].vout = inputs[i].$2;
+    }
+
+    final result = _bindings.serializeMintContext(inputsPtr, inputs.length);
+
+    final serialized = result.ref.context.toUint8List(result.ref.contextLength);
+
+    // TODO frees
+
+    return serialized;
+  }
+
   ///
   /// Create spark mint recipients
   ///

lib/src/flutter_libsparkmobile_bindings_generated.dart

@@ -229,6 +229,24 @@ class FlutterLibsparkmobileBindings {
   late final _selectSparkCoins = _selectSparkCoinsPtr.asFunction<
       ffi.Pointer<SelectSparkCoinsResult> Function(
           int, int, ffi.Pointer<CCSparkMintMeta>, int, int)>();
+
+  ffi.Pointer<SerializedMintContextResult> serializeMintContext(
+    ffi.Pointer<DartInputData> inputs,
+    int inputsLength,
+  ) {
+    return _serializeMintContext(
+      inputs,
+      inputsLength,
+    );
+  }
+
+  late final _serializeMintContextPtr = _lookup<
+      ffi.NativeFunction<
+          ffi.Pointer<SerializedMintContextResult> Function(
+              ffi.Pointer<DartInputData>, ffi.Int)>>('serializeMintContext');
+  late final _serializeMintContext = _serializeMintContextPtr.asFunction<
+      ffi.Pointer<SerializedMintContextResult> Function(
+          ffi.Pointer<DartInputData>, int)>();
 }
 
 /// FFI-friendly wrapper for a spark::Coin.
@@ -539,3 +557,20 @@ final class SparkSpendTransactionResult extends ffi.Struct {
   @ffi.Int()
   external int isError;
 }
+
+final class DartInputData extends ffi.Struct {
+  external ffi.Pointer<ffi.UnsignedChar> txHash;
+
+  @ffi.Int()
+  external int txHashLength;
+
+  @ffi.Int()
+  external int vout;
+}
+
+final class SerializedMintContextResult extends ffi.Struct {
+  external ffi.Pointer<ffi.UnsignedChar> context;
+
+  @ffi.Int()
+  external int contextLength;
+}