import {
  ref,
  onMounted,
  getCurrentInstance
} from 'vue'

export function useSystemInfo() {
  const {
    proxy
  } = getCurrentInstance()
  const systemInfo = ref({})
  const validHeight = ref(0)
  const navHeight = ref(0)

  // 获取页面可用高度
  const getValidHeight = (info) => {
    const windowHeight = info.windowHeight
    // 在非tabbar页，ios端预留底部安全高度
    const safeBottom = info.osName === 'ios' && info.safeAreaInsets.bottom && info.uniPlatform !== 'web' && info
      .uniPlatform !== 'app' ? 20 : 0

    return windowHeight - safeBottom
  }


  // 获取导航栏高度
  const getNavHeight = (info) => {
    let navHeight = 0
    if (info.uniPlatform === 'mp-weixin') {
      const custom = uni.getMenuButtonBoundingClientRect();
      navHeight = custom.height + (custom.top - info.statusBarHeight) * 2;
    } else if (info.uniPlatform === 'mp-alipay') {
      navHeight = info.titleBarHeight
    } else if (info.uniPlatform === 'mp-baidu') {
      navHeight = info.navigationBarHeight
    }
    return navHeight
  }

  onMounted(() => {
    systemInfo.value = uni.getSystemInfoSync()
    validHeight.value = getValidHeight(systemInfo.value)
    navHeight.value = getNavHeight(systemInfo.value)
  })

  // 计算dom高度（需要在mounted生命周期后调用）
  const computedDomHeight = (selectors, selectType = 'select') => {
    return new Promise(async (resolve, reject) => {
      let context = uni.createSelectorQuery().in(proxy)
      if (systemInfo.value.uniPlatform === 'mp-alipay') {
        context = uni.createSelectorQuery();
      }

      let domHeight = 0;
      let domWidth = 0;
      let queriesCount = 0;
      let selectorQueries = [];

      // 如果selectors是字符串，则将其转换为单元素数组  
      if (typeof selectors === 'string') {
        selectors = [selectors];
      }
      if (!Array.isArray(selectors)) {
        console.error('selectors 必须是字符串或字符串数组')
        reject(false)
        return
      }

      // 长度为0
      if (!selectors.length) {
        resolve(0)
        return
      }

      // 添加到执行上下文
      for (let selectorStr of selectors) {
        context[selectType](selectorStr).boundingClientRect();
      }

      // 执行查询  
      context.exec(result => {
        // 累加高度
        result.forEach((cur) => {
          if (cur) {
            domHeight += cur.height;
            domWidth += cur.width;
          }
        });
        resolve({
          height: domHeight,
          width: domWidth,
          rect: result
        });
      });
    })
  }

  return {
    systemInfo,
    validHeight,
    navHeight,
    computedDomHeight
  }
}