chunkRes.ts

/**
 * 微信http流式响应处理
 * ```
 * // Example:
 * const chunkRes = ChunkRes()
 * // can`t use ref() to save task; it will lost task info
 * const task = wx.request({
 *  //...other params
 *  enableChunked: true,
 *  success: (res) => {
 *    const lastResTexts:string[] | undefined = chunkRes.onComplateReturn()
 *    // dosomething
 *   }
 * })
 * task.onChunkReceived(res => {
 *   const resTexts:string[] | undefined = chunkRes.onChunkReceivedReturn(res)
 *   // dosomething
 * })
 * ```
 * @returns
 */
export const ChunkRes = () => {
  /**
   * 分段返回开始
   */
  const CHUNK_START = 'data:'
  /**
   * 分段返回中断
   */
  const SPLIT_WORD = '\ndata:'
  /**
   * 保存返回文本
   */
  let lastText = ''
  /**
   * 保存解码异常的数据
   */
  let lastData = new Uint8Array()
  /**
   * 返回数据转文本
   * @param res
   * @returns
   */
  const getChunkText = (data: any) => {
    // let data = res.data;
    // console.log('getSeeResData:', data)
    // 兼容处理,真机返回的的是 ArrayBuffer
    if (data instanceof ArrayBuffer) {
      data = new Uint8Array(data)
    }
    let text = data
    // Uint8Array转码
    if (typeof data != 'string') {
      // 兼容处理  微信小程序不支持TextEncoder/TextDecoder
      try {
        console.log('lastData', lastData)
        text = decodeURIComponent(escape(String.fromCharCode(...lastData, ...data)))
        lastData = new Uint8Array()
      } catch (error) {
        text = ''
        console.log('解码异常', data)
        // Uint8Array 拼接
        let swap = new Uint8Array(lastData.length + data.length)
        swap.set(lastData, 0)
        swap.set(data, lastData.length)
        // lastData = lastData.concat(data)
        lastData = swap
      }
    }
    return text
  }

  /**
   * 判断是否被拆分
   * @param text
   * @returns
   */
  const isStartString = (text: string) => {
    return text.substring(0, 5) == CHUNK_START
  }

  /**
   * 对被合并的多段请求拆分
   * @param text
   */
  const splitText = (text: string) => {
    return text
      .replaceAll(`\n\n${SPLIT_WORD}`, `\n${SPLIT_WORD}`)
      .replaceAll(`\n${SPLIT_WORD}`, `${SPLIT_WORD}`)
      .split(SPLIT_WORD)
      .filter((str) => !!str)
  }

  /**
   * 返回数据集
   * @param res
   * @param onSuccess
   */
  const onChunkReceived = (res: any, onSuccess: (value: string[]) => void) => {
    let text = getChunkText(res)
    console.log('onChunkReceived', text)
    if (isStartString(text) && lastText) {
      console.log('onSuccess', lastText)
      onSuccess(splitText(removeStartText(lastText)))
      // 存储本次的数据
      lastText = text
    } else {
      lastText = lastText + text
    }
  }

  /**
   * 返回数据集(返回数据)
   * @param res
   * @param onSuccess
   */
  const onChunkReceivedReturn = function (res: any) {
    let text = getChunkText(res)
    console.log('onChunkReceived', text)
    if (isStartString(text) && lastText) {
      // console.log("onSuccess", lastText);
      // onSuccess();
      let swap = lastText
      // 存储本次的数据
      lastText = text
      return splitText(removeStartText(swap))
    } else {
      lastText = lastText + text
    }
  }

  /**
   * 删除文本的开始的 data:
   * @param text
   * @returns
   */
  const removeStartText = (text: string) => {
    if (text.substring(0, CHUNK_START.length) == CHUNK_START) {
      return text.substring(CHUNK_START.length)
    }
    return text
  }

  /**
   * 请求完成调用一下
   * @param onSuccess
   */
  const onComplate = (onSuccess: (value: string[]) => void) => {
    if (lastText) {
      onSuccess(splitText(removeStartText(lastText)))
      lastText = ''
    }
  }
  /**
   * 请求完成调用一下(返回数据)
   * @param onSuccess
   */
  const onComplateReturn = () => {
    if (lastText) {
      let swap = lastText
      lastText = ''
      return splitText(removeStartText(swap))
    }
  }

  return {
    getChunkText,
    onChunkReceived,
    onChunkReceivedReturn,
    onComplateReturn,
    onComplate
  }
}