index.js

'use strict'

const sumDigits = require('@pelevesque/sum-digits')

const isObjectEmpty = (obj) => Object.entries(obj).length === 0

module.exports = (str, prohibitedSubstrings,
  {
    substringsToDigits = null,
    sumPlainDigits = true,
    allowLastSubstringToBleed = false
  } = {}
) => {
  if (isObjectEmpty(prohibitedSubstrings) || str === '') return false
  let hasProhibitedSubstring = false
  for (let i = 0, len = str.length; i < len; i++) {
    const sum = sumDigits(str.substr(0, i + 1), {
      substringsToDigits: substringsToDigits,
      sumPlainDigits: sumPlainDigits
    })
    if (Object.prototype.hasOwnProperty.call(prohibitedSubstrings, sum)) {
      let substrings = prohibitedSubstrings[sum]
      if (!Array.isArray(substrings)) substrings = [substrings]
      for (let j = 0, len = substrings.length; j < len; j++) {
        let substring = substrings[j]
        if (allowLastSubstringToBleed) {
          const substringMaxLength = str.length - i - 1
          if (substring.length > substringMaxLength) {
            substring = substring.substr(0, substringMaxLength)
          }
        }
        const target = str.substr(i + 1, substring.length)
        if (substring.localeCompare(target) === 0) {
          hasProhibitedSubstring = true
          break
        }
      }
      if (hasProhibitedSubstring) {
        break
      }
    }
  }
  return hasProhibitedSubstring
}