6 "github.com/bytom/vapor/application/mov/common"
7 "github.com/bytom/vapor/application/mov/contract"
8 "github.com/bytom/vapor/consensus/segwit"
9 "github.com/bytom/vapor/errors"
10 vprMath "github.com/bytom/vapor/math"
11 "github.com/bytom/vapor/protocol/bc"
12 "github.com/bytom/vapor/protocol/bc/types"
13 "github.com/bytom/vapor/protocol/vm"
16 // Engine is used to generate math transactions
19 feeStrategy FeeStrategy
23 type orderPosition struct {
28 // NewEngine return a new Engine
29 func NewEngine(orderBook *OrderBook, rewardProgram []byte) *Engine {
30 return &Engine{orderBook: orderBook, feeStrategy: NewDefaultFeeStrategy(), rewardProgram: rewardProgram}
33 // HasMatchedTx check does the input trade pair can generate a match deal
34 func (e *Engine) HasMatchedTx(tradePairs ...*common.TradePair) bool {
35 if err := validateTradePairs(tradePairs); err != nil {
39 orders := e.orderBook.PeekOrders(tradePairs)
44 return IsMatched(orders)
47 // NextMatchedTx return the next matchable transaction by the specified trade pairs
48 // the size of trade pairs at least 2, and the sequence of trade pairs can form a loop
49 // for example, [assetA -> assetB, assetB -> assetC, assetC -> assetA]
50 func (e *Engine) NextMatchedTx(tradePairs ...*common.TradePair) (*types.Tx, error) {
51 if !e.HasMatchedTx(tradePairs...) {
52 return nil, errors.New("the specified trade pairs can not be matched")
55 tx, partialOrderPositions, err := e.buildMatchTx(sortOrders(e.orderBook.PeekOrders(tradePairs)))
60 for _, tradePair := range tradePairs {
61 e.orderBook.PopOrder(tradePair)
64 if err := e.addReOrder(tx, partialOrderPositions); err != nil {
70 func addMatchTxFeeOutput(txData *types.TxData, fees []*bc.AssetAmount, rewardProgram []byte) {
71 for _, feeAmount := range fees {
72 txData.Outputs = append(txData.Outputs, types.NewIntraChainOutput(*feeAmount.AssetId, feeAmount.Amount, rewardProgram))
76 func (e *Engine) addReOrder(tx *types.Tx, partialOrderPositions []*orderPosition) error {
78 for i, output := range tx.Outputs {
79 if !segwit.IsP2WMCScript(output.ControlProgram()) || output.AssetAmount().Amount == 0 {
83 partialOrderPos := partialOrderPositions[index]
84 order, err := common.NewOrderFromOutput(tx, i, partialOrderPos.blockHeight, partialOrderPos.txIndex)
90 e.orderBook.AddOrder(order)
95 func addRefundOutput(txData *types.TxData, takerProgram []byte) {
96 refundAmount := map[bc.AssetID]uint64{}
97 for _, input := range txData.Inputs {
98 refundAmount[input.AssetID()] += input.Amount()
101 for _, output := range txData.Outputs {
102 assetAmount := output.AssetAmount()
103 refundAmount[*assetAmount.AssetId] -= assetAmount.Amount
106 for assetID, amount := range refundAmount {
108 txData.Outputs = append(txData.Outputs, types.NewIntraChainOutput(assetID, amount, takerProgram))
113 func (e *Engine) buildMatchTx(orders []*common.Order) (*types.Tx, []*orderPosition, error) {
114 txData := &types.TxData{Version: 1}
115 for _, order := range orders {
116 input := types.NewSpendInput(nil, *order.Utxo.SourceID, *order.FromAssetID, order.Utxo.Amount, order.Utxo.SourcePos, order.Utxo.ControlProgram)
117 txData.Inputs = append(txData.Inputs, input)
120 takerPos := takerPos(orders)
121 receivedAmounts, priceDiffs := CalcReceivedAmount(orders)
122 allocatedAssets := e.feeStrategy.Allocate(receivedAmounts, priceDiffs, takerPos)
124 partialOrderPositions, err := addMatchTxOutput(txData, orders, receivedAmounts, allocatedAssets)
129 addMatchTxFeeOutput(txData, allocatedAssets.Fees, e.rewardProgram)
130 addRefundOutput(txData, orders[takerPos].SellerProgram)
132 byteData, err := txData.MarshalText()
137 txData.SerializedSize = uint64(len(byteData))
138 return types.NewTx(*txData), partialOrderPositions, nil
141 func addMatchTxOutput(txData *types.TxData, orders []*common.Order, receivedAmounts []*bc.AssetAmount, allocatedAssets *AllocatedAssets) ([]*orderPosition, error) {
142 var partialOrderPositions []*orderPosition
143 for i, order := range orders {
144 receivedAmount := receivedAmounts[i].Amount
145 shouldPayAmount := calcShouldPayAmount(receivedAmount, order.RatioNumerator, order.RatioDenominator)
147 requestAmount := CalcRequestAmount(order.Utxo.Amount, order.RatioNumerator, order.RatioDenominator)
148 exchangeAmount := order.Utxo.Amount - shouldPayAmount
149 isPartialTrade := requestAmount > receivedAmount && CalcRequestAmount(exchangeAmount, order.RatioNumerator, order.RatioDenominator) >= 1
151 setMatchTxArguments(txData.Inputs[i], isPartialTrade, len(txData.Outputs), receivedAmount)
153 txData.Outputs = append(txData.Outputs, types.NewIntraChainOutput(*order.ToAssetID, allocatedAssets.Receives[i].Amount, order.SellerProgram))
155 txData.Outputs = append(txData.Outputs, types.NewIntraChainOutput(*order.FromAssetID, exchangeAmount, order.Utxo.ControlProgram))
156 partialOrderPositions = append(partialOrderPositions, &orderPosition{blockHeight: order.BlockHeight, txIndex: order.TxIndex})
159 return partialOrderPositions, nil
162 func calcOppositeIndex(size int, selfIdx int) int {
163 return (selfIdx + 1) % size
166 // CalcRequestAmount is from amount * numerator / ratioDenominator
167 func CalcRequestAmount(fromAmount uint64, ratioNumerator, ratioDenominator int64) uint64 {
168 res := big.NewInt(0).SetUint64(fromAmount)
169 res.Mul(res, big.NewInt(ratioNumerator)).Quo(res, big.NewInt(ratioDenominator))
176 func calcShouldPayAmount(receiveAmount uint64, ratioNumerator, ratioDenominator int64) uint64 {
177 res := big.NewInt(0).SetUint64(receiveAmount)
178 res.Mul(res, big.NewInt(ratioDenominator)).Quo(res, big.NewInt(ratioNumerator))
185 // CalcReceivedAmount return amount of assets received by each participant in the matching transaction and the price difference
186 func CalcReceivedAmount(orders []*common.Order) ([]*bc.AssetAmount, []*bc.AssetAmount) {
187 var receivedAmounts, priceDiffs, shouldPayAmounts []*bc.AssetAmount
188 for i, order := range orders {
189 requestAmount := CalcRequestAmount(order.Utxo.Amount, order.RatioNumerator, order.RatioDenominator)
190 oppositeOrder := orders[calcOppositeIndex(len(orders), i)]
191 receiveAmount := vprMath.MinUint64(oppositeOrder.Utxo.Amount, requestAmount)
192 shouldPayAmount := calcShouldPayAmount(receiveAmount, order.RatioNumerator, order.RatioDenominator)
193 receivedAmounts = append(receivedAmounts, &bc.AssetAmount{AssetId: order.ToAssetID, Amount: receiveAmount})
194 shouldPayAmounts = append(shouldPayAmounts, &bc.AssetAmount{AssetId: order.FromAssetID, Amount: shouldPayAmount})
197 for i, receivedAmount := range receivedAmounts {
198 oppositeShouldPayAmount := shouldPayAmounts[calcOppositeIndex(len(orders), i)]
199 priceDiffs = append(priceDiffs, &bc.AssetAmount{AssetId: oppositeShouldPayAmount.AssetId, Amount: 0})
200 if oppositeShouldPayAmount.Amount > receivedAmount.Amount {
201 priceDiffs[i].Amount = oppositeShouldPayAmount.Amount - receivedAmount.Amount
204 return receivedAmounts, priceDiffs
207 // IsMatched check does the orders can be exchange
208 func IsMatched(orders []*common.Order) bool {
209 sortedOrders := sortOrders(orders)
210 if len(sortedOrders) == 0 {
214 product := big.NewRat(1, 1)
215 for _, order := range orders {
216 product.Mul(product, big.NewRat(order.RatioNumerator, order.RatioDenominator))
218 one := big.NewRat(1, 1)
219 return product.Cmp(one) <= 0
222 func takerPos(orders []*common.Order) int {
223 for i, order := range orders {
224 if !isMaker(order, orders[calcOppositeIndex(len(orders), i)]) {
231 func isMaker(order, oppositeOrder *common.Order) bool {
232 if order.BlockHeight != oppositeOrder.BlockHeight {
233 return order.BlockHeight < oppositeOrder.BlockHeight
236 if order.TxIndex != oppositeOrder.TxIndex {
237 return order.TxIndex < oppositeOrder.TxIndex
240 return order.UTXOHash().String() < oppositeOrder.UTXOHash().String()
243 func setMatchTxArguments(txInput *types.TxInput, isPartialTrade bool, position int, receiveAmounts uint64) {
244 var arguments [][]byte
246 arguments = [][]byte{vm.Int64Bytes(int64(receiveAmounts)), vm.Int64Bytes(int64(position)), vm.Int64Bytes(contract.PartialTradeClauseSelector)}
248 arguments = [][]byte{vm.Int64Bytes(int64(position)), vm.Int64Bytes(contract.FullTradeClauseSelector)}
250 txInput.SetArguments(arguments)
253 func sortOrders(orders []*common.Order) []*common.Order {
254 if len(orders) == 0 {
258 orderMap := make(map[bc.AssetID]*common.Order)
259 firstOrder := orders[0]
260 for i := 1; i < len(orders); i++ {
261 orderMap[*orders[i].FromAssetID] = orders[i]
264 sortedOrders := []*common.Order{firstOrder}
265 for order := firstOrder; *order.ToAssetID != *firstOrder.FromAssetID; {
266 nextOrder, ok := orderMap[*order.ToAssetID]
271 sortedOrders = append(sortedOrders, nextOrder)
277 func validateTradePairs(tradePairs []*common.TradePair) error {
278 if len(tradePairs) < 2 {
279 return errors.New("size of trade pairs at least 2")
282 assetMap := make(map[string]bool)
283 for _, tradePair := range tradePairs {
284 assetMap[tradePair.FromAssetID.String()] = true
285 if *tradePair.FromAssetID == *tradePair.ToAssetID {
286 return errors.New("from asset id can't equal to asset id")
290 for _, tradePair := range tradePairs {
291 key := tradePair.ToAssetID.String()
292 if _, ok := assetMap[key]; !ok {
293 return errors.New("invalid trade pairs")
295 delete(assetMap, key)