const GSM_BASIC = new Set(
  Array.from(
    `@£$¥èéùìòÇ\nØø\rÅåΔ_ΦΓΛΩΠΨΣΘΞÆæßÉ !"#¤%&'()*+,-./0123456789:;<=>?¡ABCDEFGHIJKLMNOPQRSTUVWXYZÄÖÑܧ¿abcdefghijklmnopqrstuvwxyzäöñüà`
  )
)
const GSM_EXTENDED = new Set(['\f', '^', '{', '}', '\\', '[', '~', ']', '|', '€'])

export interface SmsSegmentCount {
  chars: number
  segments: number
  unicode: boolean
}

const isGsmText = (text: string) => Array.from(text).every((character) => GSM_BASIC.has(character) || GSM_EXTENDED.has(character))

export const countSmsSegments = (text: string): SmsSegmentCount => {
  const chars = Array.from(text).length

  if (chars === 0) return { chars: 0, segments: 0, unicode: false }

  const unicode = !isGsmText(text)

  if (!unicode) {
    return {
      chars,
      segments: chars <= 160 ? 1 : Math.ceil(chars / 153),
      unicode: false,
    }
  }

  return {
    chars,
    segments: chars <= 70 ? 1 : Math.ceil(chars / 67),
    unicode: true,
  }
}