Add /estimate_coin_sell_all endpoint

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## 0.18.0
 
+IMPROVEMENT
+
+- [api] Add `/estimate_coin_sell_all` endpoint
+
 BUG FIXES
 
 - [p2p] Make new addressbook file for each testnet

api/api.go

@@ -45,6 +45,7 @@ var Routes = map[string]*rpcserver.RPCFunc{
 	"net_info":               rpcserver.NewRPCFunc(NetInfo, ""),
 	"coin_info":              rpcserver.NewRPCFunc(CoinInfo, "symbol,height"),
 	"estimate_coin_sell":     rpcserver.NewRPCFunc(EstimateCoinSell, "coin_to_sell,coin_to_buy,value_to_sell,height"),
+	"estimate_coin_sell_all": rpcserver.NewRPCFunc(EstimateCoinSellAll, "coin_to_sell,coin_to_buy,value_to_sell,gas_price,height"),
 	"estimate_coin_buy":      rpcserver.NewRPCFunc(EstimateCoinBuy, "coin_to_sell,coin_to_buy,value_to_buy,height"),
 	"estimate_tx_commission": rpcserver.NewRPCFunc(EstimateTxCommission, "tx,height"),
 	"unconfirmed_txs":        rpcserver.NewRPCFunc(UnconfirmedTxs, "limit"),

api/estimate_coin_sell_all.go

@@ -0,0 +1,83 @@
+package api
+
+import (
+	"github.com/MinterTeam/minter-go-node/core/commissions"
+	"github.com/MinterTeam/minter-go-node/core/transaction"
+	"github.com/MinterTeam/minter-go-node/core/types"
+	"github.com/MinterTeam/minter-go-node/formula"
+	"github.com/MinterTeam/minter-go-node/rpc/lib/types"
+	"math/big"
+)
+
+type EstimateCoinSellAllResponse struct {
+	WillGet *big.Int `json:"will_get"`
+}
+
+func EstimateCoinSellAll(
+	coinToSellString string, coinToBuyString string, valueToSell *big.Int, gasPrice uint64, height int) (*EstimateCoinSellAllResponse,
+	error) {
+	cState, err := GetStateForHeight(height)
+	if err != nil {
+		return nil, err
+	}
+
+	if gasPrice < 1 {
+		gasPrice = 1
+	}
+
+	coinToSell := types.StrToCoinSymbol(coinToSellString)
+	coinToBuy := types.StrToCoinSymbol(coinToBuyString)
+
+	var result *big.Int
+
+	if coinToSell == coinToBuy {
+		return nil, rpctypes.RPCError{Code: 400, Message: "\"From\" coin equals to \"to\" coin"}
+	}
+
+	if !cState.CoinExists(coinToSell) {
+		return nil, rpctypes.RPCError{Code: 404, Message: "Coin to sell not exists"}
+	}
+
+	if !cState.CoinExists(coinToBuy) {
+		return nil, rpctypes.RPCError{Code: 404, Message: "Coin to buy not exists"}
+	}
+
+	commissionInBaseCoin := big.NewInt(commissions.ConvertTx)
+	commissionInBaseCoin.Mul(commissionInBaseCoin, transaction.CommissionMultiplier)
+	commission := big.NewInt(0).Set(commissionInBaseCoin)
+
+	switch {
+	case coinToSell == types.GetBaseCoin():
+		coin := cState.GetStateCoin(coinToBuy).Data()
+
+		valueToSell.Sub(valueToSell, commission)
+		if valueToSell.Cmp(big.NewInt(0)) != 1 {
+			return nil, rpctypes.RPCError{Code: 400, Message: "Not enough coins to pay commission"}
+		}
+
+		result = formula.CalculatePurchaseReturn(coin.Volume, coin.ReserveBalance, coin.Crr, valueToSell)
+	case coinToBuy == types.GetBaseCoin():
+		coin := cState.GetStateCoin(coinToSell).Data()
+		result = formula.CalculateSaleReturn(coin.Volume, coin.ReserveBalance, coin.Crr, valueToSell)
+
+		result.Sub(result, commission)
+		if result.Cmp(big.NewInt(0)) != 1 {
+			return nil, rpctypes.RPCError{Code: 400, Message: "Not enough coins to pay commission"}
+		}
+	default:
+		coinFrom := cState.GetStateCoin(coinToSell).Data()
+		coinTo := cState.GetStateCoin(coinToBuy).Data()
+		basecoinValue := formula.CalculateSaleReturn(coinFrom.Volume, coinFrom.ReserveBalance, coinFrom.Crr, valueToSell)
+
+		basecoinValue.Sub(basecoinValue, commission)
+		if basecoinValue.Cmp(big.NewInt(0)) != 1 {
+			return nil, rpctypes.RPCError{Code: 400, Message: "Not enough coins to pay commission"}
+		}
+
+		result = formula.CalculatePurchaseReturn(coinTo.Volume, coinTo.ReserveBalance, coinTo.Crr, basecoinValue)
+	}
+
+	return &EstimateCoinSellAllResponse{
+		WillGet: result,
+	}, nil
+}