--- /dev/null
+package match
+
+import (
+ "encoding/hex"
+ "math"
+
+ "github.com/vapor/application/mov/common"
+ "github.com/vapor/application/mov/contract"
+ "github.com/vapor/application/mov/database"
+ "github.com/vapor/consensus/segwit"
+ "github.com/vapor/errors"
+ vprMath "github.com/vapor/math"
+ "github.com/vapor/protocol/bc"
+ "github.com/vapor/protocol/bc/types"
+ "github.com/vapor/protocol/vm"
+ "github.com/vapor/protocol/vm/vmutil"
+)
+
+const maxFeeRate = 0.05
+
+type Engine struct {
+ orderTable *OrderTable
+ nodeProgram []byte
+}
+
+func NewEngine(movStore database.MovStore, nodeProgram []byte) *Engine {
+ return &Engine{orderTable: NewOrderTable(movStore), nodeProgram: nodeProgram}
+}
+
+func (e *Engine) HasMatchedTx(tradePairs ...*common.TradePair) bool {
+ if err := validateTradePairs(tradePairs); err != nil {
+ return false
+ }
+
+ orders := e.peekOrders(tradePairs)
+ if len(orders) == 0 {
+ return false
+ }
+
+ for i, order := range orders {
+ if canNotBeMatched(order, orders[getOppositeIndex(len(orders), i)]) {
+ return false
+ }
+ }
+ return true
+}
+
+// NextMatchedTx return the next matchable transaction by the specified trade pairs
+// the size of trade pairs at least 2, and the sequence of trade pairs can form a loop
+// for example, [assetA -> assetB, assetB -> assetC, assetC -> assetA]
+func (e *Engine) NextMatchedTx(tradePairs ...*common.TradePair) (*types.Tx, error) {
+ if err := validateTradePairs(tradePairs); err != nil {
+ return nil, err
+ }
+
+ orders := e.peekOrders(tradePairs)
+ if len(orders) == 0 {
+ return nil, errors.New("no order for the specified trade pair in the order table")
+ }
+
+ tx, err := e.buildMatchTx(orders)
+ if err != nil {
+ return nil, err
+ }
+
+ for _, tradePair := range tradePairs {
+ e.orderTable.PopOrder(tradePair)
+ }
+
+ if err := addPartialTradeOrder(tx, e.orderTable); err != nil {
+ return nil, err
+ }
+ return tx, nil
+}
+
+func (e *Engine) peekOrders(tradePairs []*common.TradePair) []*common.Order {
+ var orders []*common.Order
+ for _, tradePair := range tradePairs {
+ order := e.orderTable.PeekOrder(tradePair)
+ if order == nil {
+ return nil
+ }
+
+ orders = append(orders, order)
+ }
+ return orders
+}
+
+func validateTradePairs(tradePairs []*common.TradePair) error {
+ if len(tradePairs) < 2 {
+ return errors.New("size of trade pairs at least 2")
+ }
+
+ for i, tradePair := range tradePairs {
+ oppositeTradePair := tradePairs[getOppositeIndex(len(tradePairs), i)]
+ if *tradePair.ToAssetID != *oppositeTradePair.FromAssetID {
+ return errors.New("specified trade pairs is invalid")
+ }
+ }
+ return nil
+}
+
+func canNotBeMatched(order, oppositeOrder *common.Order) bool {
+ rate := 1 / order.Rate
+ return rate < oppositeOrder.Rate
+}
+
+func (e *Engine) buildMatchTx(orders []*common.Order) (*types.Tx, error) {
+ txData := &types.TxData{Version: 1}
+ for i, order := range orders {
+ input := types.NewSpendInput(nil, *order.Utxo.SourceID, *order.FromAssetID, order.Utxo.Amount, order.Utxo.SourcePos, order.Utxo.ControlProgram)
+ txData.Inputs = append(txData.Inputs, input)
+
+ oppositeOrder := orders[getOppositeIndex(len(orders), i)]
+ if err := addMatchTxOutput(txData, input, order, oppositeOrder.Utxo.Amount); err != nil {
+ return nil, err
+ }
+ }
+
+ if err := e.addMatchTxFeeOutput(txData); err != nil {
+ return nil, err
+ }
+
+ byteData, err := txData.MarshalText()
+ if err != nil {
+ return nil, err
+ }
+
+ txData.SerializedSize = uint64(len(byteData))
+ return types.NewTx(*txData), nil
+}
+
+func addMatchTxOutput(txData *types.TxData, txInput *types.TxInput, order *common.Order, oppositeAmount uint64) error {
+ contractArgs, err := segwit.DecodeP2WMCProgram(order.Utxo.ControlProgram)
+ if err != nil {
+ return err
+ }
+
+ requestAmount := calcRequestAmount(order.Utxo.Amount, contractArgs)
+ receiveAmount := vprMath.MinUint64(requestAmount, oppositeAmount)
+ shouldPayAmount := CalcShouldPayAmount(receiveAmount, contractArgs)
+ isPartialTrade := order.Utxo.Amount > shouldPayAmount
+
+ setMatchTxArguments(txInput, isPartialTrade, len(txData.Outputs), receiveAmount)
+ txData.Outputs = append(txData.Outputs, types.NewIntraChainOutput(*order.ToAssetID, receiveAmount, contractArgs.SellerProgram))
+ if isPartialTrade {
+ txData.Outputs = append(txData.Outputs, types.NewIntraChainOutput(*order.FromAssetID, order.Utxo.Amount-shouldPayAmount, order.Utxo.ControlProgram))
+ }
+ return nil
+}
+
+func (e *Engine) addMatchTxFeeOutput(txData *types.TxData) error {
+ feeAssetAmountMap, err := CalcFeeFromMatchedTx(txData)
+ if err != nil {
+ return err
+ }
+
+ for feeAssetID, amount := range feeAssetAmountMap {
+ var reminder int64 = 0
+ feeAmount := amount.payableFeeAmount
+ if amount.payableFeeAmount > amount.maxFeeAmount {
+ feeAmount = amount.maxFeeAmount
+ reminder = amount.payableFeeAmount - amount.maxFeeAmount
+ }
+ txData.Outputs = append(txData.Outputs, types.NewIntraChainOutput(feeAssetID, uint64(feeAmount), e.nodeProgram))
+
+ // There is the remaining amount after paying the handling fee, assign it evenly to participants in the transaction
+ averageAmount := reminder / int64(len(txData.Inputs))
+ if averageAmount == 0 {
+ averageAmount = 1
+ }
+ for i := 0; i < len(txData.Inputs) && reminder > 0; i++ {
+ contractArgs, err := segwit.DecodeP2WMCProgram(txData.Inputs[i].ControlProgram())
+ if err != nil {
+ return err
+ }
+
+ if i == len(txData.Inputs)-1 {
+ txData.Outputs = append(txData.Outputs, types.NewIntraChainOutput(feeAssetID, uint64(reminder), contractArgs.SellerProgram))
+ } else {
+ txData.Outputs = append(txData.Outputs, types.NewIntraChainOutput(feeAssetID, uint64(averageAmount), contractArgs.SellerProgram))
+ }
+ reminder -= averageAmount
+ }
+ }
+ return nil
+}
+
+func setMatchTxArguments(txInput *types.TxInput, isPartialTrade bool, position int, receiveAmounts uint64) {
+ var arguments [][]byte
+ if isPartialTrade {
+ arguments = [][]byte{vm.Int64Bytes(int64(receiveAmounts)), vm.Int64Bytes(int64(position)), vm.Int64Bytes(contract.PartialTradeClauseSelector)}
+ } else {
+ arguments = [][]byte{vm.Int64Bytes(int64(position)), vm.Int64Bytes(contract.FullTradeClauseSelector)}
+ }
+ txInput.SetArguments(arguments)
+}
+
+func addPartialTradeOrder(tx *types.Tx, orderTable *OrderTable) error {
+ for i, output := range tx.Outputs {
+ if !segwit.IsP2WMCScript(output.ControlProgram()) {
+ continue
+ }
+
+ order, err := common.NewOrderFromOutput(tx, i)
+ if err != nil {
+ return err
+ }
+
+ if err := orderTable.AddOrder(order); err != nil {
+ return err
+ }
+ }
+ return nil
+}
+
+func getOppositeIndex(size int, selfIdx int) int {
+ oppositeIdx := selfIdx + 1
+ if selfIdx >= size-1 {
+ oppositeIdx = 0
+ }
+ return oppositeIdx
+}
+
+type feeAmount struct {
+ maxFeeAmount int64
+ payableFeeAmount int64
+}
+
+func CalcFeeFromMatchedTx(txData *types.TxData) (map[bc.AssetID]*feeAmount, error) {
+ assetAmountMap := make(map[bc.AssetID]*feeAmount)
+ for _, input := range txData.Inputs {
+ assetAmountMap[input.AssetID()] = &feeAmount{}
+ }
+
+ receiveOutputMap := make(map[string]*types.TxOutput)
+ for _, output := range txData.Outputs {
+ // minus the amount of the re-order
+ if segwit.IsP2WMCScript(output.ControlProgram()) {
+ assetAmountMap[*output.AssetAmount().AssetId].payableFeeAmount -= int64(output.AssetAmount().Amount)
+ } else {
+ receiveOutputMap[hex.EncodeToString(output.ControlProgram())] = output
+ }
+ }
+
+ for _, input := range txData.Inputs {
+ contractArgs, err := segwit.DecodeP2WMCProgram(input.ControlProgram())
+ if err != nil {
+ return nil, err
+ }
+
+ assetAmountMap[input.AssetID()].payableFeeAmount += int64(input.AssetAmount().Amount)
+ receiveOutput, ok := receiveOutputMap[hex.EncodeToString(contractArgs.SellerProgram)]
+ if !ok {
+ return nil, errors.New("the input of matched tx has no receive output")
+ }
+
+ assetAmountMap[*receiveOutput.AssetAmount().AssetId].payableFeeAmount -= int64(receiveOutput.AssetAmount().Amount)
+ assetAmountMap[input.AssetID()].maxFeeAmount = CalcMaxFeeAmount(CalcShouldPayAmount(receiveOutput.AssetAmount().Amount, contractArgs))
+ }
+
+ for assetID, amount := range assetAmountMap {
+ if amount.payableFeeAmount == 0 {
+ delete(assetAmountMap, assetID)
+ }
+ }
+ return assetAmountMap, nil
+}
+
+func calcRequestAmount(fromAmount uint64, contractArg *vmutil.MagneticContractArgs) uint64 {
+ return uint64(int64(fromAmount) * contractArg.RatioNumerator / contractArg.RatioDenominator)
+}
+
+func CalcShouldPayAmount(receiveAmount uint64, contractArg *vmutil.MagneticContractArgs) uint64 {
+ return uint64(math.Ceil(float64(receiveAmount) * float64(contractArg.RatioDenominator) / float64(contractArg.RatioNumerator)))
+}
+
+func CalcMaxFeeAmount(shouldPayAmount uint64) int64 {
+ return int64(math.Ceil(float64(shouldPayAmount) * maxFeeRate))
+}
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