62 lines
1.8 KiB
TypeScript
62 lines
1.8 KiB
TypeScript
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import { utils } from 'ethers'
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import { FeeAmount } from './constants'
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const ADDR_SIZE = 20
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const FEE_SIZE = 3
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const OFFSET = ADDR_SIZE + FEE_SIZE
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const DATA_SIZE = OFFSET + ADDR_SIZE
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export function encodePath(path: string[], fees: FeeAmount[]): string {
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if (path.length != fees.length + 1) {
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throw new Error('path/fee lengths do not match')
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}
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let encoded = '0x'
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for (let i = 0; i < fees.length; i++) {
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// 20 byte encoding of the address
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encoded += path[i].slice(2)
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// 3 byte encoding of the fee
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encoded += fees[i].toString(16).padStart(2 * FEE_SIZE, '0')
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}
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// encode the final token
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encoded += path[path.length - 1].slice(2)
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return encoded.toLowerCase()
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}
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function decodeOne(tokenFeeToken: Buffer): [[string, string], number] {
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// reads the first 20 bytes for the token address
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const tokenABuf = tokenFeeToken.slice(0, ADDR_SIZE)
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const tokenA = utils.getAddress('0x' + tokenABuf.toString('hex'))
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// reads the next 2 bytes for the fee
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const feeBuf = tokenFeeToken.slice(ADDR_SIZE, OFFSET)
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const fee = feeBuf.readUIntBE(0, FEE_SIZE)
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// reads the next 20 bytes for the token address
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const tokenBBuf = tokenFeeToken.slice(OFFSET, DATA_SIZE)
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const tokenB = utils.getAddress('0x' + tokenBBuf.toString('hex'))
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return [[tokenA, tokenB], fee]
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}
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export function decodePath(path: string): [string[], number[]] {
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let data = Buffer.from(path.slice(2), 'hex')
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let tokens: string[] = []
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let fees: number[] = []
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let i = 0
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let finalToken: string = ''
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while (data.length >= DATA_SIZE) {
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const [[tokenA, tokenB], fee] = decodeOne(data)
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finalToken = tokenB
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tokens = [...tokens, tokenA]
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fees = [...fees, fee]
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data = data.slice((i + 1) * OFFSET)
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i += 1
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}
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tokens = [...tokens, finalToken]
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return [tokens, fees]
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}
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