/**
 * H5 上 uni.navigateBack 偶发既不成功也不进 fail；离开 OA web-view 时做兜底。
 * @param {{ fallbackUrl?: string, onStuck?: () => void }} [opts]
 */
export function isOaHostWebviewRoute(route) {
  const value = String(route || '')
  return (
    value.indexOf('oa/start/webview') !== -1 ||
    value.indexOf('oa/webview/') !== -1 ||
    value.indexOf('market/webview/') !== -1
  )
}

export function navigateBackFromOaHost(opts) {
  const onStuck = opts && opts.onStuck

  const pageRoute = (page) => {
    return String(
      (page && (page.route || (page.$page && page.$page.fullPath))) || ''
    )
  }

  const samePageStillOnTop = (start) => {
    try {
      const pages = getCurrentPages()
      const current = pages && pages[pages.length - 1]
      return (
        !!current &&
        pages.length === start.depth &&
        current === start.page &&
        pageRoute(current) === start.route &&
        isOaHostWebviewRoute(start.route)
      )
    } catch (_) {
      return false
    }
  }

  const resolveFallbackUrl = () => {
    const explicit = String((opts && opts.fallbackUrl) || '').trim()
    if (explicit) return explicit
    try {
      const pages = getCurrentPages()
      if (pages && pages.length >= 2) {
        const prev = pages[pages.length - 2]
        const route = prev && prev.route
        if (route) return '/' + String(route).replace(/^\//, '')
      }
    } catch (_) {
      /* ignore */
    }
    return '/pages/oa/start/index'
  }

  let fallbackStarted = false
  const fallback = () => {
    if (fallbackStarted) return
    fallbackStarted = true
    const fallbackUrl = resolveFallbackUrl()
    if (!fallbackUrl) {
      if (onStuck) onStuck()
      return
    }
    uni.redirectTo({
      url: fallbackUrl,
      fail: () => {
        uni.reLaunch({
          url: fallbackUrl,
          fail: () => {
            if (onStuck) onStuck()
          }
        })
      }
    })
  }

  try {
    const pages = getCurrentPages()
    if (pages && pages.length > 1) {
      const startPage = pages[pages.length - 1]
      const start = {
        page: startPage,
        route: pageRoute(startPage),
        depth: pages.length
      }
      uni.navigateBack({
        delta: 1,
        fail: () => fallback()
      })
      // H5：navigateBack 偶发静默失败
      setTimeout(() => {
        if (samePageStillOnTop(start)) fallback()
      }, 280)
      return
    }
  } catch (_) {
    /* fall through */
  }
  fallback()
}