pump-parser/swap_amounts.go

package pump_parser

import (
	"encoding/json"

	"github.com/gagliardetto/solana-go"
	"github.com/shopspring/decimal"
)

var maxSlippageBps = decimal.NewFromInt(10000)

type SwapMode uint8
type SwapAmountSide uint8
type SwapLimitType uint8

const (
	SwapModeUnknown SwapMode = iota
	SwapModeExactIn
	SwapModeExactOut
)

const (
	SwapAmountSideUnknown SwapAmountSide = iota
	SwapAmountSideBase
	SwapAmountSideQuote
)

const (
	SwapLimitTypeUnknown SwapLimitType = iota
	SwapLimitTypeMinOut
	SwapLimitTypeMaxIn
)

func (m SwapMode) String() string {
	switch m {
	case SwapModeExactIn:
		return "exact_in"
	case SwapModeExactOut:
		return "exact_out"
	default:
		return ""
	}
}

func (m SwapMode) MarshalJSON() ([]byte, error) {
	return json.Marshal(m.String())
}

func (s SwapAmountSide) String() string {
	switch s {
	case SwapAmountSideBase:
		return "base"
	case SwapAmountSideQuote:
		return "quote"
	default:
		return ""
	}
}

func (s SwapAmountSide) MarshalJSON() ([]byte, error) {
	return json.Marshal(s.String())
}

func (t SwapLimitType) String() string {
	switch t {
	case SwapLimitTypeMinOut:
		return "min_out"
	case SwapLimitTypeMaxIn:
		return "max_in"
	default:
		return ""
	}
}

func (t SwapLimitType) MarshalJSON() ([]byte, error) {
	return json.Marshal(t.String())
}

func swapAmountForSide(baseAmount, quoteAmount decimal.Decimal, side SwapAmountSide) decimal.Decimal {
	switch side {
	case SwapAmountSideBase:
		return baseAmount
	case SwapAmountSideQuote:
		return quoteAmount
	default:
		return decimal.Zero
	}
}

func swapMintForSide(baseMint, quoteMint solana.PublicKey, side SwapAmountSide) solana.PublicKey {
	switch side {
	case SwapAmountSideBase:
		return baseMint
	case SwapAmountSideQuote:
		return quoteMint
	default:
		return solana.PublicKey{}
	}
}

func oppositeSwapAmountSide(side SwapAmountSide) SwapAmountSide {
	switch side {
	case SwapAmountSideBase:
		return SwapAmountSideQuote
	case SwapAmountSideQuote:
		return SwapAmountSideBase
	default:
		return SwapAmountSideUnknown
	}
}

func fixedSwapAmountSide(event string, swapMode SwapMode) SwapAmountSide {
	switch swapMode {
	case SwapModeExactIn:
		switch event {
		case TxEventBuy:
			return SwapAmountSideQuote
		case TxEventSell:
			return SwapAmountSideBase
		}
	case SwapModeExactOut:
		switch event {
		case TxEventBuy:
			return SwapAmountSideBase
		case TxEventSell:
			return SwapAmountSideQuote
		}
	}
	return SwapAmountSideUnknown
}

func limitSwapAmountType(swapMode SwapMode) SwapLimitType {
	switch swapMode {
	case SwapModeExactIn:
		return SwapLimitTypeMinOut
	case SwapModeExactOut:
		return SwapLimitTypeMaxIn
	default:
		return SwapLimitTypeUnknown
	}
}

func calculateLimitSlippageBps(limitType SwapLimitType, limitAmount, actualAmount decimal.Decimal) decimal.Decimal {
	switch limitType {
	case SwapLimitTypeMinOut:
		if !actualAmount.IsPositive() {
			if !limitAmount.IsPositive() {
				return maxSlippageBps
			}
			return maxSlippageBps.Neg()
		}
		if !limitAmount.IsPositive() {
			return maxSlippageBps
		}
		return actualAmount.Sub(limitAmount).Mul(maxSlippageBps).Div(actualAmount)
	case SwapLimitTypeMaxIn:
		if !limitAmount.IsPositive() {
			if !actualAmount.IsPositive() {
				return maxSlippageBps
			}
			return maxSlippageBps.Neg()
		}
		return limitAmount.Sub(actualAmount).Mul(maxSlippageBps).Div(limitAmount)
	default:
		return decimal.Zero
	}
}

func (s *Swap) SetSwapAmountInfoDetailed(
	swapMode SwapMode,
	fixedAmount decimal.Decimal,
	fixedSide SwapAmountSide,
	fixedMint solana.PublicKey,
	limitType SwapLimitType,
	limitAmount decimal.Decimal,
	limitSide SwapAmountSide,
	limitMint solana.PublicKey,
	actualLimitAmount decimal.Decimal,
) {
	s.SwapMode = swapMode
	s.FixedAmount = fixedAmount
	s.FixedAmountSide = fixedSide
	s.FixedMint = fixedMint
	s.LimitAmountType = limitType
	s.LimitAmount = limitAmount
	s.LimitAmountSide = limitSide
	s.LimitMint = limitMint
	s.ActualLimitAmount = actualLimitAmount
	s.ActualLimitAmountSide = limitSide
	s.SlippageBps = calculateLimitSlippageBps(limitType, limitAmount, actualLimitAmount)
}

func (s *Swap) SetSwapAmountInfo(swapMode SwapMode, fixedAmount, limitAmount decimal.Decimal) {
	fixedSide := fixedSwapAmountSide(s.Event, swapMode)
	if fixedSide == SwapAmountSideUnknown {
		return
	}

	limitType := limitSwapAmountType(swapMode)
	limitSide := oppositeSwapAmountSide(fixedSide)
	actualLimitAmount := swapAmountForSide(s.BaseAmount, s.QuoteAmount, limitSide)
	s.SetSwapAmountInfoDetailed(
		swapMode,
		fixedAmount,
		fixedSide,
		swapMintForSide(s.BaseMint, s.QuoteMint, fixedSide),
		limitType,
		limitAmount,
		limitSide,
		swapMintForSide(s.BaseMint, s.QuoteMint, limitSide),
		actualLimitAmount,
	)
}