timelimit-server/src/util/bitmask.ts

/*
 * server component for the TimeLimit App
 * Copyright (C) 2019 - 2022 Jonas Lochmann
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, version 3 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

import { range, split } from 'lodash'

export const serializedBitmaskRegex = /^(\d*,\d*(,\d*,\d*)*)?$/

export const validateBitmask = (bitmask: string, maxLength: number) => {
  if (!serializedBitmaskRegex.test(bitmask)) {
    throw new BitmapValidationException('bitmask does not match regex')
  }

  if (bitmask === '') {
    return
  }

  const splitpoints = split(bitmask, ',').map((item) => parseInt(item, 10))

  if (splitpoints.findIndex((item) => !Number.isSafeInteger(item)) !== -1) {
    throw new BitmapValidationException('bitmask contains non-safe integers')
  }

  if (splitpoints.findIndex((item) => item < 0) !== -1) {
    throw new BitmapValidationException('bitmask contains negative integers')
  }

  if (splitpoints.findIndex((item) => item > maxLength) !== -1) {
    throw new BitmapValidationException('bitmask contains integers bigger than maxSize')
  }

  let previousValue = -1

  splitpoints.forEach((item) => {
    if (item <= previousValue) {
      throw new BitmapValidationException('bitmask numbers are not strictly sorted')
    }

    previousValue = item
  })
}

export const validateAndParseBitmask = (bitmask: string, maxLength: number) => {
  validateBitmask(bitmask, maxLength)

  const result = range(0, maxLength).map(() => false)

  const splitpoints = split(bitmask, ',').map((item) => parseInt(item, 10))

  let i = 0
  while (i < splitpoints.length) {
    const start = splitpoints[i++]
    const end = splitpoints[i++]

    for (let j = start; j < end; j++) {
      result[j] = true
    }
  }

  return result
}

export class BitmapValidationException extends Error {}