solidityPack.ts

// solidityPack
// Extracted from https://github.com/ethereumjs/ethereumjs-util with TypeScript typings
// Original Copyright (c) 2015 Martin Becze
// LICENSE: MPL 2.0 - https://raw.githubusercontent.com/ethereumjs/ethereumjs-util/master/LICENSE

import {
  hexToBuffer,
  hexToEvenLengthHex,
  isHex,
  keccak256,
  numberToHex,
  setLengthLeft,
  setLengthRight,
  strip0x
} from './util'

import BN from 'bn.js'


export function solidityPack (types: string[], values: any[]): Buffer {
  if (types.length !== values.length) {
    throw new Error('Number of types are not matching the values')
  }

  let size: number
  let num: BN
  const ret: Buffer[] = []

  for (let i = 0; i < types.length; i++) {
    const type = elementaryName(types[i])
    const value = values[i]

    if (type === 'bytes') {
      ret.push(toBuffer(value))
    } else if (type === 'string') {
      ret.push(Buffer.from(value, 'utf8'))
    } else if (type === 'bool') {
      ret.push(Buffer.from(value ? '01' : '00', 'hex'))
    } else if (type === 'address') {
      ret.push(setLengthLeft(toBuffer(value), 20))
    } else if (type.startsWith('bytes')) {
      size = parseTypeN(type)
      if (size < 1 || size > 32) {
        throw new Error('Invalid bytes<N> width: ' + size)
      }

      ret.push(setLengthRight(toBuffer(value), size))
    } else if (type.startsWith('uint')) {
      size = parseTypeN(type)
      if (size % 8 || size < 8 || size > 256) {
        throw new Error('Invalid uint<N> width: ' + size)
      }

      num = parseNumber(value)
      if (num.bitLength() > size) {
        throw new Error(
          'Supplied uint exceeds width: ' + size + ' vs ' + num.bitLength()
        )
      }

      ret.push(num.toArrayLike(Buffer, 'be', size / 8))
    } else if (type.startsWith('int')) {
      size = parseTypeN(type)
      if (size % 8 || size < 8 || size > 256) {
        throw new Error('Invalid int<N> width: ' + size)
      }

      num = parseNumber(value)
      if (num.bitLength() > size) {
        throw new Error(
          'Supplied int exceeds width: ' + size + ' vs ' + num.bitLength()
        )
      }

      ret.push(num.toTwos(size).toArrayLike(Buffer, 'be', size / 8))
    } else {
      // FIXME: support all other types
      throw new Error('Unsupported or invalid type: ' + type)
    }
  }

  return Buffer.concat(ret)
}

export function soliditySHA3 (types: string[], values: any[]): Buffer {
  return keccak256(solidityPack(types, values))
}

function elementaryName (name: string): string {
  if (name.startsWith('int[')) {
    return 'int256' + name.slice(3)
  } else if (name === 'int') {
    return 'int256'
  } else if (name.startsWith('uint[')) {
    return 'uint256' + name.slice(4)
  } else if (name === 'uint') {
    return 'uint256'
  } else if (name.startsWith('fixed[')) {
    return 'fixed128x128' + name.slice(5)
  } else if (name === 'fixed') {
    return 'fixed128x128'
  } else if (name.startsWith('ufixed[')) {
    return 'ufixed128x128' + name.slice(6)
  } else if (name === 'ufixed') {
    return 'ufixed128x128'
  }
  return name
}

// Parse N from type<N>
function parseTypeN (type: string): number {
  const match = /^\D+(\d+)$/.exec(type)
  return match ? parseInt(match[1], 10) : 0
}

function parseNumber (arg: string | number | BN): BN {
  const type = typeof arg
  if (type === 'string') {
    const str = arg as string
    if (str.match(/^0x/i)) {
      return new BN(strip0x(str), 16)
    } else {
      return new BN(arg, 10)
    }
  } else if (type === 'number') {
    return new BN(arg)
  } else if (BN.isBN(arg)) {
    return arg as BN
  } else {
    throw new Error('Argument is not a number')
  }
}

function toBuffer (
  value: string | number[] | number | Buffer | BN | null | undefined
): Buffer {
  if (Buffer.isBuffer(value)) {
    return value
  } else if (value == null) {
    return Buffer.alloc(0)
  } else if (typeof value === 'string') {
    if (isHex(value)) {
      return hexToBuffer(value)
    } else {
      return Buffer.from(value)
    }
  } else if (typeof value === 'number') {
    return hexToBuffer(hexToEvenLengthHex(numberToHex(value)))
  } else if (Array.isArray(value)) {
    return Buffer.from(value)
  } else if (BN.isBN(value)) {
    return Buffer.from(value.toArray())
  } else {
    throw new Error('invalid type')
  }
}