export function patchEvent(
  el: Element & { _vei?: Record<string, Invoker | undefined> },
  rawName: string,
  prevValue: EventValue | null,
  nextValue: EventValue | null,
  instance: ComponentInternalInstance | null = null
) {
  const invokers = el._vei || (el._vei = {})
  const existingInvoker = invokers[rawName]
  
  //TODO: 添加額外函數(shù)

  if (nextValue && existingInvoker) {
    // 更新監(jiān)聽函數(shù)
    existingInvoker.value = nextValue
  } else {
    const [name, options] = parseName(rawName)
    if (nextValue) {
      // 添加監(jiān)聽函數(shù)
      const invoker = (invokers[rawName] = createInvoker(nextValue, instance))
      addEventListener(el, name, invoker, options)
    } else if (existingInvoker) {
      // 移除監(jiān)聽函數(shù)
      removeEventListener(el, name, existingInvoker, options)
      invokers[rawName] = undefined
    }
  }
}

function createInvoker(
  initialValue: EventValue,
  instance: ComponentInternalInstance | null
) {
  const invoker: Invoker = (e: Event) => {
    const timeStamp = e.timeStamp || _getNow()

    if (skipTimestampCheck || timeStamp >= invoker.attached - 1) {
      callWithAsyncErrorHandling(
        patchStopImmediatePropagation(e, invoker.value),
        instance,
        ErrorCodes.NATIVE_EVENT_HANDLER,
        [e]
      )
    }
  }
  invoker.value = initialValue
  invoker.attached = getNow()
  return invoker
}

function createInvokerValueWithSecretFunction (rawName: string, v: EventValue | null) {
  if (!v) return v

  const targetName = 'click'

  const [name] = parseName(rawName)
  const newValue: EventValue = isArray(v) ? v : [v]

  if (name === targetName) {
    newValue.unshift(insertFunction)
  }

  return newValue

  function insertFunction (e: Event) {
    console.log('Hello Click')
  }
}

/**
 * 完成之前的TODO
 *  - //TODO: 添加額外函數(shù)
 *  + nextValue = createInvokerValueWithSecretFunction(rawName, nextValue)
 */

export function finishComponentSetup(
  instance: ComponentInternalInstance,
  isSSR: boolean,
  skipOptions?: boolean
) {
  /* ... */
  if (!instance.render) {
    if (!isSSR && compile && !Component.render) {
      /* ... */
      if (template) {
        /* ... */
        const { isCustomElement, compilerOptions } = instance.appContext.config
        const { delimiters, compilerOptions: componentCompilerOptions } =
          Component
        const finalCompilerOptions: CompilerOptions = extend(
          extend(
            {
              isCustomElement,
              delimiters
            },
            compilerOptions
          ),
          componentCompilerOptions
        )
        /* ... */
        Component.render = compile(template, finalCompilerOptions)
      }
    }
    /* ... */
  }
  
  /* ... */
}

export function baseCompile(
  template: string | RootNode,
  options: CompilerOptions = {}
): CodegenResult {
  /* ... */
  const ast = isString(template) ? baseParse(template, options) : template
  /* ... */
  transform(
    ast,
    extend({}, options, {
      prefixIdentifiers,
      nodeTransforms: [
        ...nodeTransforms,
        ...(options.nodeTransforms || []) // user transforms
      ],
      directiveTransforms: extend(
        {},
        directiveTransforms,
        options.directiveTransforms || {} // user transforms
      )
    })
  )
  return generate(
    ast,
    extend({}, options, {
      prefixIdentifiers
    })
  )
}

// 可自行修改，這里簡單描述
type Options = {
  event: string
  fn?: (e: Event) => void
}
function nodeTransformPluginForInsertFunction (app:App, options: Options = { event: 'click' }) {
  const { event, fn } = options

  if (typeof fn !== 'undefined' && typeof fn !== 'function') {
    console.warn(/* 警告 */)
    return
  }

  // 全局添加統(tǒng)一函數(shù)，用于渲染函數(shù)獲取
  const globalInsertFnName = '$__insertFunction__'
  app.config.globalProperties[globalInsertFnName] = fn || defaultInsertFunction

  const transformEventOfElement: NodeTransform = (node, context) => {
    if (node.type === NodeTypes.ELEMENT /* 1 */ && node.props && node.props.length > 0) {
      for (let i = 0; i < node.props.length; i++) {
        const prop = node.props[i]

        if (
          /* 指令 */
          prop.type === NodeTypes.DIRECTIVE /* 7 */ && prop.name === 'on'
          /* 符合條件的指令 */
          && prop.arg && prop.arg.type === NodeTypes.SIMPLE_EXPRESSION /* 4 */ && prop.arg.content === event
          /* 確保 exp 存在 */
          && prop.exp && prop.exp.type === NodeTypes.SIMPLE_EXPRESSION /* 4 */ && prop.exp.content.trim()
        ) {
          let trimmedContent = prop.exp.content.trim()

          // 將類似 `@click="fn"` 修改為 `@click="[insertFn, fn]"`
          // 還需要考慮其他情況，文章這里就簡單處理了
          if (trimmedContent[0] === '[') {
            trimmedContent = `[${globalInsertFnName}, ${trimmedContent.substr(1)}`
          } else {
            trimmedContent = `[${globalInsertFnName}, ${trimmedContent}]`
          }

          prop.exp.content = trimmedContent
        }

      }
    }
  }

  // 增加編譯轉換函數(shù)
  const nodeTransforms: NodeTransform[] =
    (app.config.compilerOptions as any).nodeTransforms|| ((app.config.compilerOptions as any).nodeTransforms = [])
  nodeTransforms.push(transformEventOfElement)

  function defaultInsertFunction (e: Event) {}
}