stringUtils.ts

// Assuming input string is following the HTTP Cookie format defined in
// https://www.ietf.org/rfc/rfc2616.txt and https://www.ietf.org/rfc/rfc6265.txt, we don't need to
// be too strict with this regex.
const COMMA_SEPARATED_KEY_VALUE = /(\S+?)\s*=\s*(.*?)(?:;|$)/g

/**
 * Returns the value of the key with the given name
 * If there are multiple values with the same key, returns the first one
 */
export function findCommaSeparatedValue(rawString: string, name: string): string | undefined {
  COMMA_SEPARATED_KEY_VALUE.lastIndex = 0
  while (true) {
    const match = COMMA_SEPARATED_KEY_VALUE.exec(rawString)
    if (match) {
      if (match[1] === name) {
        return match[2]
      }
    } else {
      break
    }
  }
}

/**
 * Returns a map of all the values with the given key
 * If there are multiple values with the same key, returns all the values
 */
export function findAllCommaSeparatedValues(rawString: string): Map<string, string[]> {
  const result = new Map<string, string[]>()
  COMMA_SEPARATED_KEY_VALUE.lastIndex = 0
  while (true) {
    const match = COMMA_SEPARATED_KEY_VALUE.exec(rawString)
    if (match) {
      const key = match[1]
      const value = match[2]
      if (result.has(key)) {
        result.get(key)!.push(value)
      } else {
        result.set(key, [value])
      }
    } else {
      break
    }
  }
  return result
}

/**
 * Returns a map of the values with the given key
 * ⚠️ If there are multiple values with the same key, returns the LAST one
 *
 * @deprecated use `findAllCommaSeparatedValues()` instead
 */
export function findCommaSeparatedValues(rawString: string): Map<string, string> {
  const result = new Map<string, string>()
  COMMA_SEPARATED_KEY_VALUE.lastIndex = 0
  while (true) {
    const match = COMMA_SEPARATED_KEY_VALUE.exec(rawString)
    if (match) {
      result.set(match[1], match[2])
    } else {
      break
    }
  }
  return result
}

export function safeTruncate(candidate: string, length: number, suffix = '') {
  const lastChar = candidate.charCodeAt(length - 1)
  const isLastCharSurrogatePair = lastChar >= 0xd800 && lastChar <= 0xdbff
  const correctedLength = isLastCharSurrogatePair ? length + 1 : length

  if (candidate.length <= correctedLength) {
    return candidate
  }

  return `${candidate.slice(0, correctedLength)}${suffix}`
}