// directives/vT.js
import { watch } from 'vue'
import { lang } from '@/composables/config'

const TEXT_NODE_CLASS = 'v-t-node'

/**
 * 解析绑定值
 * 支持：'key' 或 ['key', param]
 */
const parseBinding = (val) => {
  if (Array.isArray(val)) {
    const [key, ...rest] = val
    if (rest.length === 0) return { key, param: undefined }
    if (rest.length === 1) return { key, param: rest[0] }
    return { key, param: rest }
  }
  return { key: val, param: undefined }
}

const isFormField = (el) => {
  const tag = el?.tagName?.toUpperCase?.() || ''
  return tag === 'INPUT' || tag === 'TEXTAREA'
}

/**
 * 在宿主内创建独立文本节点，避免直接改 button/view 的 textContent
 * 导致 Vue patch 时清空子树、click 等事件失效
 */
const ensureTextNode = (el) => {
  if (isFormField(el)) return el

  if (el._vTTextEl?.parentNode === el) {
    return el._vTTextEl
  }

  if (typeof document === 'undefined') {
    return el
  }

  const node = document.createElement('span')
  node.className = TEXT_NODE_CLASS
  node.setAttribute('data-v-t', '')
  node.style.pointerEvents = 'none'
  el.appendChild(node)
  el._vTTextEl = node
  return node
}

const updateElementText = (el, text) => {
  if (!el) return
  const target = ensureTextNode(el)

  if (isFormField(target)) {
    target.value = text
    return
  }

  if ('textContent' in target) {
    target.textContent = text
  } else if ('innerText' in target) {
    target.innerText = text
  }
}

const getI18n = () => {
  return typeof globalThis !== 'undefined' && globalThis.__i18n ? globalThis.__i18n : null
}

const bindingSignature = (val) => {
  if (Array.isArray(val)) return JSON.stringify(val)
  return String(val ?? '')
}

export default {
  mounted(el, binding) {
    const setState = (val) => {
      const { key, param } = parseBinding(val)
      el._vTKey = key
      el._vTParam = param
      el._vTBindingSig = bindingSignature(val)
    }

    const update = () => {
      const i18n = getI18n()
      const key = el._vTKey
      const param = el._vTParam

      if (!key) {
        updateElementText(el, '')
        return
      }

      let text = ''
      if (i18n) {
        const translated = i18n.global.t(key, param)
        text = translated === key ? '' : translated
      }

      updateElementText(el, text)
    }

    setState(binding.value)
    update()

    el._vTSetState = setState
    el._vTUpdate = update

    el._vTStopWatch = watch(
      () => lang.value,
      () => {
        const i18n = getI18n()
        if (i18n?.global?.locale?.value !== undefined) {
          i18n.global.locale.value = lang.value
        }
        update()
      },
      { immediate: false, flush: 'sync' }
    )
  },

  updated(el, binding) {
    const sig = bindingSignature(binding.value)
    if (sig === el._vTBindingSig) return

    if (el._vTSetState) el._vTSetState(binding.value)
    if (el._vTUpdate) el._vTUpdate()
  },

  unmounted(el) {
    if (el._vTStopWatch) {
      el._vTStopWatch()
      delete el._vTStopWatch
    }
    if (el._vTTextEl?.parentNode === el) {
      el.removeChild(el._vTTextEl)
    }
    delete el._vTTextEl
    delete el._vTUpdate
    delete el._vTSetState
    delete el._vTKey
    delete el._vTParam
    delete el._vTBindingSig
  },
}