import { nextTick, ref } from 'vue'
import { isKorean } from '@element-plus/utils'

interface UseCompositionOptions {
  afterComposition: (event: CompositionEvent) => void
  emit?: ((event: 'compositionstart', evt: CompositionEvent) => void) &
    ((event: 'compositionupdate', evt: CompositionEvent) => void) &
    ((event: 'compositionend', evt: CompositionEvent) => void)
}

export function useComposition({
  afterComposition,
  emit,
}: UseCompositionOptions) {
  const isComposing = ref(false)

  const handleCompositionStart = (event: CompositionEvent) => {
    emit?.('compositionstart', event)
    isComposing.value = true
  }

  const handleCompositionUpdate = (event: CompositionEvent) => {
    emit?.('compositionupdate', event)
    const text = (event.target as HTMLInputElement)?.value
    const lastCharacter = text[text.length - 1] || ''
    isComposing.value = !isKorean(lastCharacter)
  }

  const handleCompositionEnd = (event: CompositionEvent) => {
    emit?.('compositionend', event)
    if (isComposing.value) {
      isComposing.value = false
      nextTick(() => afterComposition(event))
    }
  }

  const handleComposition = (event: CompositionEvent) => {
    event.type === 'compositionend'
      ? handleCompositionEnd(event)
      : handleCompositionUpdate(event)
  }

  return {
    isComposing,
    handleComposition,
    handleCompositionStart,
    handleCompositionUpdate,
    handleCompositionEnd,
  }
}