export class Updater {
  oldScript: string[];
  newScript: string[];
  dispatch: Record<string, any>;
  interVal: any;
  constructor(options) {
    this.oldScript = [];
    this.newScript = [];
    this.dispatch = {};
    this.interVal = null;
    this.init();
    this.timing(options.timer || 2000);
  }

  async init() {
    const html = await this.getHtml();
    this.oldScript = this.parserScript(html);
  }

  async getHtml() {
    const html = await fetch('/').then((res) => res.text());
    return html;
  }

  parserScript(html) {
    const reg = new RegExp(/<script(?:\s+[^>]*)?>(.*?)<\/script\s*>/gi);
    return html.match(reg);
  }

  on(key, fn) {
    (this.dispatch[key] || (this.dispatch[key] = [])).push(fn);
    return this;
  }

  compare(oldArr, newArr) {
    const base = oldArr.length;
    const arr = Array.from(new Set(oldArr.concat(newArr)));
    if (arr.length === base) {
      this.dispatch['no-update']?.forEach((fn) => {
        // 没有更新
        fn();
      });
    } else {
      this.dispatch['update']?.forEach((fn) => {
        // 有新版本更新
        fn();
      });
    }
  }

  // 开启定时查询
  timing(time) {
    this.interVal = setInterval(async () => {
      const newHtml = await this.getHtml();
      this.newScript = this.parserScript(newHtml);
      this.compare(this.oldScript, this.newScript);
    }, time);
  }

  // 关闭定时器
  closeInterVal() {
    if (this.interVal) {
      clearInterval(this.interVal);
      this.interVal = null;
    }
  }
}