utils.ts

import invariant from 'tiny-invariant'
import warning from 'tiny-warning'
import JSBI from 'jsbi'
import { getAddress } from '@ethersproject/address'

import { BigintIsh, ZERO, ONE, TWO, THREE, SolidityType, SOLIDITY_TYPE_MAXIMA, ZERO_ADDRESS } from './constants'

export function isETH(address: string): boolean {
  return address === ZERO_ADDRESS
}

export function validateSolidityTypeInstance(value: JSBI, solidityType: SolidityType): void {
  invariant(JSBI.greaterThanOrEqual(value, ZERO), `${value} is not a ${solidityType}.`)
  invariant(JSBI.lessThanOrEqual(value, SOLIDITY_TYPE_MAXIMA[solidityType]), `${value} is not a ${solidityType}.`)
}

// warns if addresses are not checksummed
export function validateAndParseAddress(address: string): string {
  try {
    const checksummedAddress = getAddress(address)
    warning(address === checksummedAddress, `${address} is not checksummed.`)
    return checksummedAddress
  } catch (error) {
    invariant(false, `${address} is not a valid address.`)
  }
}

export function parseBigintIsh(bigintIsh: BigintIsh): JSBI {
  return bigintIsh instanceof JSBI
    ? bigintIsh
    : typeof bigintIsh === 'bigint'
    ? JSBI.BigInt(bigintIsh.toString())
    : JSBI.BigInt(bigintIsh)
}

// mock the on-chain sqrt function
export function sqrt(y: JSBI): JSBI {
  validateSolidityTypeInstance(y, SolidityType.uint256)
  let z: JSBI = ZERO
  let x: JSBI
  if (JSBI.greaterThan(y, THREE)) {
    z = y
    x = JSBI.add(JSBI.divide(y, TWO), ONE)
    while (JSBI.lessThan(x, z)) {
      z = x
      x = JSBI.divide(JSBI.add(JSBI.divide(y, x), x), TWO)
    }
  } else if (JSBI.notEqual(y, ZERO)) {
    z = ONE
  }
  return z
}

// given an array of items sorted by `comparator`, insert an item into its sort index and constrain the size to
// `maxSize` by removing the last item
export function sortedInsert<T>(items: T[], add: T, maxSize: number, comparator: (a: T, b: T) => number): T | null {
  invariant(maxSize > 0, 'MAX_SIZE_ZERO')
  // this is an invariant because the interface cannot return multiple removed items if items.length exceeds maxSize
  invariant(items.length <= maxSize, 'ITEMS_SIZE')

  // short circuit first item add
  if (items.length === 0) {
    items.push(add)
    return null
  } else {
    const isFull = items.length === maxSize
    // short circuit if full and the additional item does not come before the last item
    if (isFull && comparator(items[items.length - 1], add) <= 0) {
      return add
    }

    let lo = 0,
      hi = items.length

    while (lo < hi) {
      const mid = (lo + hi) >>> 1
      if (comparator(items[mid], add) <= 0) {
        lo = mid + 1
      } else {
        hi = mid
      }
    }
    items.splice(lo, 0, add)
    return isFull ? items.pop()! : null
  }
}