import Vue from 'vue'
import Router from 'vue-router'

Vue.use(Router)

const KAIFAIN = 'kaifain'
const JISHUIN = 'jishuin'
const RE_IPV4 = /^(\d+.)+\d+$/

const getServerHostname = ({ req }) => {
  const { host, referer } = req.headers
  let hostname = host.split(':')[0]

  if (RE_IPV4.test(hostname)) {
    hostname = referer && new URL(referer).hostname
  }

  return hostname
}

const filterAndRemapRoutesByScope = (routes, scope) => {
  return [
    ...routes
    .filter(r => r.path.startsWith('/' + scope))
    .map(r => {
      const clone = { ...r }
      clone.path = r.path.replace('/' + scope, '') || '/'

      if (r.name) {
        clone.name = r.name + '_$'
      }

      return clone
    }),
    ...routes
  ]
}

export function createRouter(ssrContext, createDefaultRouter, routerOptions) {
  const options = routerOptions || createDefaultRouter(ssrContext).options
  const hostname = ssrContext ? getServerHostname(ssrContext) : location.host

  return new Router({
    ...options,
    routes: fixRoutes(options.routes, hostname),
  })
}

function fixRoutes(defaultRoutes, hostname) {
  if (hostname && hostname.includes(KAIFAIN)) return kaifainRoutes(defaultRoutes)
  if (hostname && hostname.includes(JISHUIN)) return jishuinRoutes(defaultRoutes)
  return defaultRoutes
}

function kaifainRoutes(defaultRoutes) {
  return filterAndRemapRoutesByScope(defaultRoutes, KAIFAIN)
}

function jishuinRoutes(defaultRoutes) {
  return filterAndRemapRoutesByScope(defaultRoutes, JISHUIN)
}