get coins to spend

lib/flutter_libsparkmobile.dart

@@ -10,7 +10,8 @@ import 'package:flutter_libsparkmobile/src/models/spark_coin.dart';
 
 import 'src/flutter_libsparkmobile_bindings_generated.dart';
 
-const kSparkChain = 6;
+const kSparkChain = 0x6;
+const kSparkChange = 0x270F;
 const kSparkBaseDerivationPath = "m/44'/136'/0'/$kSparkChain/";
 const kSparkBaseDerivationPathTestnet = "m/44'/1'/0'/$kSparkChain/";
 
@@ -358,6 +359,110 @@ abstract final class LibSpark {
 
     return (serializedSpendPayload: message, fee: fee, outputScripts: scripts);
   }
+
+  static ({int changeToMint, List<LibSparkCoin> coins}) getCoinsToSpend({
+    required int sendAmount,
+    required int recipientsToSubtractFee,
+    required List<LibSparkCoin> coins,
+    required int privateRecipientsCount,
+    required int recipientsCount,
+  }) {
+    final coinsPtr = malloc.allocate<CCSparkMintMeta>(
+      sizeOf<CCSparkMintMeta>() * coins.length,
+    );
+
+    for (int i = 0; i < coins.length; i++) {
+      coinsPtr[i].height = coins[i].height!;
+      coinsPtr[i].id = coins[i].id!;
+      coinsPtr[i].isUsed = coins[i].isUsed! ? 1 : 0;
+      coinsPtr[i].txid = coins[i].txHash!.unsignedCharPointer();
+      coinsPtr[i].i = coins[i].diversifier!.toInt();
+      coinsPtr[i].d = coins[i].encryptedDiversifier!.unsignedCharPointer();
+      coinsPtr[i].dLength = coins[i].encryptedDiversifier!.length;
+      coinsPtr[i].k = coins[i].nonce!.unsignedCharPointer();
+      coinsPtr[i].kLength = coins[i].nonce!.length;
+      coinsPtr[i].memo = coins[i].memo!.toNativeUtf8().cast<Char>();
+      coinsPtr[i].memoLength = coins[i].memo!.length;
+      coinsPtr[i].serial_context =
+          coins[i].serialContext!.unsignedCharPointer();
+      coinsPtr[i].serial_contextLength = coins[i].serialContext!.length;
+      coinsPtr[i].type = coins[i].type.value;
+
+      final serCoin = base64Decode(coins[i].serializedCoin!);
+      coinsPtr[i].serializedCoin = serCoin.unsignedCharPointer();
+      coinsPtr[i].serializedCoinLength = serCoin.length;
+    }
+
+    final result = _bindings.getCoinsToSpend(
+      sendAmount,
+      coinsPtr,
+      coins.length,
+    );
+
+    for (int i = 0; i < coins.length; i++) {
+      malloc.free(coinsPtr[i].txid);
+      malloc.free(coinsPtr[i].d);
+      malloc.free(coinsPtr[i].k);
+      malloc.free(coinsPtr[i].memo);
+      malloc.free(coinsPtr[i].serial_context);
+      malloc.free(coinsPtr[i].serializedCoin);
+    }
+    malloc.free(coinsPtr);
+
+    final ({int changeToMint, List<LibSparkCoin> coins}) ret = (
+      changeToMint: result.ref.changeToMint,
+      coins: <LibSparkCoin>[],
+    );
+
+    for (int i = 0; i < result.ref.length; i++) {
+      final LibSparkCoinType coinType;
+      switch (result.ref.list[i].type) {
+        case 0:
+          coinType = LibSparkCoinType.mint;
+          break;
+        case 1:
+          coinType = LibSparkCoinType.mint;
+          break;
+        default:
+          throw Exception(
+            "Unknown coin type \"${result.ref.list[i].type}\" found.",
+          );
+      }
+
+      final coin = LibSparkCoin(
+        type: coinType,
+        id: result.ref.list[i].id,
+        height: result.ref.list[i].height,
+        isUsed: result.ref.list[i].isUsed > 0,
+        nonce: result.ref.list[i].k.toUint8List(result.ref.list[i].kLength),
+        value: BigInt.from(result.ref.list[i].v),
+        memo: result.ref.list[i].memo
+            .cast<Utf8>()
+            .toDartString(length: result.ref.list[i].memoLength),
+        txHash: result.ref.list[i].txid.toUint8List(32),
+        serialContext: result.ref.list[i].serial_context
+            .toUint8List(result.ref.list[i].serial_contextLength),
+        diversifier: BigInt.from(result.ref.list[i].i),
+        encryptedDiversifier:
+            result.ref.list[i].d.toUint8List(result.ref.list[i].dLength),
+        serializedCoin: base64Encode(result.ref.list[i].serializedCoin
+            .toUint8List(result.ref.list[i].serializedCoinLength)),
+      );
+
+      ret.coins.add(coin);
+
+      malloc.free(result.ref.list[i].txid);
+      malloc.free(result.ref.list[i].d);
+      malloc.free(result.ref.list[i].k);
+      malloc.free(result.ref.list[i].memo);
+      malloc.free(result.ref.list[i].serial_context);
+      malloc.free(result.ref.list[i].serializedCoin);
+    }
+
+    malloc.free(result);
+
+    return ret;
+  }
 }
 
 extension on Pointer<UnsignedChar> {

lib/src/flutter_libsparkmobile_bindings_generated.dart

@@ -188,6 +188,26 @@ class FlutterLibsparkmobileBindings {
               int,
               ffi.Pointer<CCoverSetData>,
               int)>();
+
+  ffi.Pointer<SelectedSparkSpendCoins> getCoinsToSpend(
+    int spendAmount,
+    ffi.Pointer<CCSparkMintMeta> coins,
+    int coinLength,
+  ) {
+    return _getCoinsToSpend(
+      spendAmount,
+      coins,
+      coinLength,
+    );
+  }
+
+  late final _getCoinsToSpendPtr = _lookup<
+      ffi.NativeFunction<
+          ffi.Pointer<SelectedSparkSpendCoins> Function(ffi.Int64,
+              ffi.Pointer<CCSparkMintMeta>, ffi.Int)>>('getCoinsToSpend');
+  late final _getCoinsToSpend = _getCoinsToSpendPtr.asFunction<
+      ffi.Pointer<SelectedSparkSpendCoins> Function(
+          int, ffi.Pointer<CCSparkMintMeta>, int)>();
 }
 
 /// FFI-friendly wrapper for a spark::Coin.
@@ -330,6 +350,70 @@ final class CCDataStream extends ffi.Struct {
   external int length;
 }
 
+/// FFI-friendly wrapper for a spark::CSparkMintMeta.
+///
+/// CSparkMintMeta: https://github.com/firoorg/sparkmobile/blob/8bf17cd3deba6c3b0d10e89282e02936d7e71cdd/src/primitives.h#L9
+final class CCSparkMintMeta extends ffi.Struct {
+  @ffi.Int()
+  external int height;
+
+  @ffi.Int()
+  external int id;
+
+  @ffi.Int()
+  external int isUsed;
+
+  external ffi.Pointer<ffi.UnsignedChar> txid;
+
+  /// Diversifier.
+  @ffi.Uint64()
+  external int i;
+
+  /// Encrypted diversifier.
+  external ffi.Pointer<ffi.UnsignedChar> d;
+
+  @ffi.Int()
+  external int dLength;
+
+  /// Value.
+  @ffi.Uint64()
+  external int v;
+
+  /// Nonce.
+  external ffi.Pointer<ffi.UnsignedChar> k;
+
+  @ffi.Int()
+  external int kLength;
+
+  external ffi.Pointer<ffi.Char> memo;
+
+  @ffi.Int()
+  external int memoLength;
+
+  external ffi.Pointer<ffi.UnsignedChar> serial_context;
+
+  @ffi.Int()
+  external int serial_contextLength;
+
+  @ffi.Char()
+  external int type;
+
+  external ffi.Pointer<ffi.UnsignedChar> serializedCoin;
+
+  @ffi.Int()
+  external int serializedCoinLength;
+}
+
+final class SelectedSparkSpendCoins extends ffi.Struct {
+  external ffi.Pointer<CCSparkMintMeta> list;
+
+  @ffi.Int()
+  external int length;
+
+  @ffi.Int64()
+  external int changeToMint;
+}
+
 /// FFI-friendly wrapper for a spark::CoverSetData.
 ///
 /// CoverSetData: https://github.com/firoorg/sparkmobile/blob/8bf17cd3deba6c3b0d10e89282e02936d7e71cdd/src/spend_transaction.h#L28

lib/src/models/spark_coin.dart

@@ -11,6 +11,11 @@ enum LibSparkCoinType {
 class LibSparkCoin {
   final LibSparkCoinType type;
 
+  final int? id;
+  final int? height;
+
+  final bool? isUsed;
+
   final Uint8List? nonce;
 
   final String? address;
@@ -18,6 +23,9 @@ class LibSparkCoin {
   final BigInt? value;
 
   final String? memo;
+
+  final Uint8List? txHash;
+
   final Uint8List? serialContext;
 
   final BigInt? diversifier;
@@ -28,45 +36,62 @@ class LibSparkCoin {
 
   final String? lTagHash;
 
+  final String? serializedCoin;
+
   LibSparkCoin({
     required this.type,
+    this.id,
+    this.height,
+    this.isUsed,
     this.nonce,
     this.address,
     this.value,
     this.memo,
+    this.txHash,
     this.serialContext,
     this.diversifier,
     this.encryptedDiversifier,
     this.serial,
     this.tag,
     this.lTagHash,
+    this.serializedCoin,
   });
 
   LibSparkCoin copyWith({
     LibSparkCoinType? type,
+    int? id,
+    int? height,
+    bool? isUsed,
     Uint8List? nonce,
     String? address,
     BigInt? value,
     String? memo,
+    Uint8List? txHash,
     Uint8List? serialContext,
     BigInt? diversifier,
     Uint8List? encryptedDiversifier,
     Uint8List? serial,
     Uint8List? tag,
     String? lTagHash,
+    String? serializedCoin,
   }) {
     return LibSparkCoin(
       type: type ?? this.type,
+      id: id ?? this.id,
+      height: height ?? this.height,
+      isUsed: isUsed ?? this.isUsed,
       nonce: nonce ?? this.nonce,
       address: address ?? this.address,
       value: value ?? this.value,
       memo: memo ?? this.memo,
+      txHash: txHash ?? this.txHash,
       serialContext: serialContext ?? this.serialContext,
       diversifier: diversifier ?? this.diversifier,
       encryptedDiversifier: encryptedDiversifier ?? this.encryptedDiversifier,
       serial: serial ?? this.serial,
       tag: tag ?? this.tag,
       lTagHash: lTagHash ?? this.lTagHash,
+      serializedCoin: serializedCoin ?? this.serializedCoin,
     );
   }
 
@@ -74,16 +99,21 @@ class LibSparkCoin {
   String toString() {
     return 'LibSparkCoin('
         ', type: $type'
+        ', id: $id'
+        ', height: $height'
+        ', isUsed: $isUsed'
         ', k: $nonce'
         ', address: $address'
         ', value: $value'
         ', memo: $memo'
+        ', txHash: $txHash'
         ', serialContext: $serialContext'
         ', diversifier: $diversifier'
         ', encryptedDiversifier: $encryptedDiversifier'
         ', serial: $serial'
         ', tag: $tag'
         ', lTagHash: $lTagHash'
+        ', serializedCoin: $serializedCoin'
         ')';
   }
 }

src/flutter_libsparkmobile.cpp

@@ -291,3 +291,78 @@ SparkSpendTransactionResult* cCreateSparkSpendTransaction(
         return result;
     }
 }
+
+
+FFI_PLUGIN_EXPORT
+SelectedSparkSpendCoins* getCoinsToSpend(int64_t spendAmount, CCSparkMintMeta* coins, int coinsLength) {
+    std::vector<CSparkMintMeta> coinsToSpend_out;
+    int64_t change;
+
+    std::list<CSparkMintMeta> _coins;
+
+    for (int i = 0; i < coinsLength; i++) {
+        CSparkMintMeta meta;
+        meta.nHeight = coins[i].height;
+        meta.nId = coins[i].id;
+        meta.isUsed = coins[i].isUsed > 0;
+        meta.txid = uint256S(coins[i].txid);
+        meta.i = coins[i].i;
+        meta.d = std::vector<unsigned char>(coins[i].d, coins[i].d + coins[i].dLength);
+        meta.v = coins[i].v;
+        meta.k = Scalar(coins[i].k);
+        meta.memo = std::string(coins[i].memo, coins[i].memoLength);
+        meta.serial_context = std::vector<unsigned char>(coins[i].serial_context, coins[i].serial_context + coins[i].serial_contextLength);
+        meta.type = coins[i].type;
+        meta.coin = deserializeCoin(coins[i].serializedCoin, coins[i].serializedCoinLength);
+
+        _coins.push_back(meta);
+    }
+
+    GetCoinsToSpend(spendAmount, coinsToSpend_out, _coins, change);
+
+    SelectedSparkSpendCoins* result = (SelectedSparkSpendCoins*)malloc(sizeof(SelectedSparkSpendCoins));
+    result->changeToMint = change;
+    result->length = coinsToSpend_out.size();
+    result->list = (CCSparkMintMeta*)malloc(sizeof(CCSparkMintMeta) * result->length);
+
+    for (int i = 0; i < coinsToSpend_out.size(); i++) {
+        result->list[i].height = coinsToSpend_out[i].nHeight;
+
+        result->list[i].id = coinsToSpend_out[i].nId;
+
+        result->list[i].isUsed = coinsToSpend_out[i].isUsed;
+
+        result->list[i].txid = (const char*)malloc(sizeof(const char*) * coinsToSpend_out[i].txid.size());
+        memcpy(result->list[i].txid, coinsToSpend_out[i].txid.begin(), sizeof(const char*) * coinsToSpend_out[i].txid.size());
+
+        result->list[i].i = coinsToSpend_out[i].i;
+
+        result->list[i].dLength = coinsToSpend_out[i].d.size();
+        result->list[i].d = (const unsigned char*)malloc(sizeof(const unsigned char) * coinsToSpend_out[i].d.size());
+        memcpy(result->list[i].d, coinsToSpend_out[i].d.begin(), sizeof(const unsigned char*) * coinsToSpend_out[i].d.size());
+
+        result->list[i].v = coinsToSpend_out[i].v;
+
+        result->list[i].kLength = coinsToSpend_out[i].k.s;
+        result->list[i].k = (const unsigned char*)malloc(sizeof(const unsigned char) * coinsToSpend_out[i].k.size());
+        memcpy(result->list[i].k, coinsToSpend_out[i].k.begin(), sizeof(const unsigned char*) * coinsToSpend_out[i].k.size());
+
+        result->list[i].memo = (const char*)malloc(sizeof(const char) * coinsToSpend_out[i].memo.size());
+        memcpy(result->list[i].memo, coinsToSpend_out[i].memo.begin(), sizeof(const char*) * coinsToSpend_out[i].memo.size());
+        result->list[i].memoLength = coinsToSpend_out[i].memo.size();
+
+        result->list[i].serial_context = (unsigned char*)malloc(sizeof(unsigned char) * coinsToSpend_out[i].serial_context.size());
+        memcpy(result->list[i].serial_context, coinsToSpend_out[i].serial_context.begin(), sizeof(unsigned char*) * coinsToSpend_out[i].serial_context.size());
+        result->list[i].serial_contextLength = coinsToSpend_out[i].serial_context.size();
+
+        CDataStream coinStream(SER_NETWORK, PROTOCOL_VERSION);
+        coinStream << coinsToSpend_out[i].coin;
+        result->list[i].serializedCoinLength = coinStream.size();
+        result->list[i].serializedCoin = (unsigned char*)malloc(sizeof(unsigned char) * coinStream.size());
+        memcpy(result->list[i].serializedCoin, coinStream.data(), coinStream.size());
+
+        result->list[i].type = coinsToSpend_out[i].type;
+    }
+
+    return result;
+}

src/flutter_libsparkmobile.h

@@ -75,4 +75,11 @@ struct SparkSpendTransactionResult* cCreateSparkSpendTransaction(
         int cover_set_data_allLength
 );
 
+FFI_PLUGIN_EXPORT
+struct SelectedSparkSpendCoins* getCoinsToSpend(
+        int64_t spendAmount,
+        struct CCSparkMintMeta* coins,
+        int coinLength
+);
+
 #endif //ORG_FIRO_SPARK_DART_INTERFACE_H

src/structs.h

@@ -119,33 +119,32 @@ struct CCDataStream {
  *
  * CSparkMintMeta: https://github.com/firoorg/sparkmobile/blob/8bf17cd3deba6c3b0d10e89282e02936d7e71cdd/src/primitives.h#L9
  */
-//struct CCSparkMintMeta {
-//    uint64_t height;
-//    const char *id;
-//    int isUsed;
-//    const char *txid;
-//    uint64_t i; // Diversifier.
-//    const unsigned char *d; // Encrypted diversifier.
-//    int dLength;
-//    uint64_t v; // Value.
-//    const unsigned char *k; // Nonce.
-//    int kLength;
-//    const char *memo;
-//    int memoLength;
-//    unsigned char *serial_context;
-//    int serial_contextLength;
-//    char type;
-//    struct CCDataStream coin;
-//
-//    CCSparkMintMeta(uint64_t height, const char *id, int isUsed,
-//                    const char *txid, uint64_t i, const unsigned char *d,
-//                    int dLength, uint64_t v, const unsigned char *k,
-//                    int kLength, const char *memo, int memoLength,
-//                    unsigned char *serial_context, int serial_contextLength,
-//                    char type, const CCDataStream &coinData);
-//
-//    ~CCSparkMintMeta();
-//};
+struct CCSparkMintMeta {
+    int height;
+    int id;
+    int isUsed;
+    unsigned char *txid;
+    uint64_t i; // Diversifier.
+    const unsigned char *d; // Encrypted diversifier.
+    int dLength;
+    uint64_t v; // Value.
+    const unsigned char *k; // Nonce.
+    int kLength;
+    const char *memo;
+    int memoLength;
+    unsigned char *serial_context;
+    int serial_contextLength;
+    char type;
+    unsigned char* serializedCoin;
+    int serializedCoinLength;
+};
+
+struct SelectedSparkSpendCoins {
+    struct CCSparkMintMeta* list;
+    int length;
+
+    int64_t changeToMint;
+};
 
 /*
  * FFI-friendly wrapper for a spark::CoverSetData.