export function addLinkCardIfNecessary({
  uri,
  newText,
  cursorLocation,
  mayBePaste,
  onNewLink,
  prevAddedLinks,
}: {
  uri: string
  newText: string
  cursorLocation: number
  mayBePaste: boolean
  onNewLink: (uri: string) => void
  prevAddedLinks: Set<string>
}) {
  // It would be cool if we could just use facet.index.byteEnd, but you know... *upside down smiley*
  const lastCharacterPosition = findIndexInText(uri, newText) + uri.length

  // If the text being added is not from a paste, then we should only check if the cursor is one
  // position ahead of the last character. However, if it is a paste we need to check both if it's
  // the same position _or_ one position ahead. That is because iOS will add a space after a paste if
  // pasting into the middle of a sentence!
  const cursorLocationIsOkay =
    cursorLocation === lastCharacterPosition + 1 || mayBePaste

  // Checking previouslyAddedLinks keeps a card from getting added over and over i.e.
  // Link card added -> Remove link card -> Press back space -> Press space -> Link card added -> and so on

  // We use the isValidUrl regex below because we don't want to add embeds only if the url is valid, i.e.
  // http://facebook is a valid url, but that doesn't mean we want to embed it. We should only embed if
  // the url is a valid url _and_ domain. new URL() won't work for this check.
  const shouldCheck =
    cursorLocationIsOkay && !prevAddedLinks.has(uri) && isValidUrlAndDomain(uri)

  if (shouldCheck) {
    onNewLink(uri)
    prevAddedLinks.add(uri)
  }
}

// https://stackoverflow.com/questions/8667070/javascript-regular-expression-to-validate-url
// question credit Muhammad Imran Tariq https://stackoverflow.com/users/420613/muhammad-imran-tariq
// answer credit Christian David https://stackoverflow.com/users/967956/christian-david
function isValidUrlAndDomain(value: string) {
  return /^(?:(?:(?:https?|ftp):)?\/\/)(?:\S+(?::\S*)?@)?(?:(?!(?:10|127)(?:\.\d{1,3}){3})(?!(?:169\.254|192\.168)(?:\.\d{1,3}){2})(?!172\.(?:1[6-9]|2\d|3[0-1])(?:\.\d{1,3}){2})(?:[1-9]\d?|1\d\d|2[01]\d|22[0-3])(?:\.(?:1?\d{1,2}|2[0-4]\d|25[0-5])){2}(?:\.(?:[1-9]\d?|1\d\d|2[0-4]\d|25[0-4]))|(?:(?:[a-z\u00a1-\uffff0-9]-*)*[a-z\u00a1-\uffff0-9]+)(?:\.(?:[a-z\u00a1-\uffff0-9]-*)*[a-z\u00a1-\uffff0-9]+)*(?:\.(?:[a-z\u00a1-\uffff]{2,})))(?::\d{2,5})?(?:[/?#]\S*)?$/i.test(
    value,
  )
}

export function findIndexInText(term: string, text: string) {
  // This should find patterns like:
  // HELLO SENTENCE http://google.com/ HELLO
  // HELLO SENTENCE http://google.com HELLO
  // http://google.com/ HELLO.
  // http://google.com/.
  const pattern = new RegExp(`\\b(${term})(?![/w])`, 'i')
  const match = pattern.exec(text)
  return match ? match.index : -1
}