const stack = [];
const originPushState = window.history.pushState;
window.history.pushState = function() {
  if(stack[stack.length - 1] === arguments[2]) {
    return;
  }
  stack.push(arguments[2])
  originPushState.call(history, ...arguments);
}

function createPopStateEvent(state, title) {
  return new PopStateEvent("popstate", {
    state: state,
    title: title
  });
}
window.history.pushState = function() {
  if(stack[stack.length - 1] === arguments[2]) {
    return;
  }
  stack.push(arguments[2])
  window.dispatchEvent(createPopStateEvent(...arguments));
  originPushState.call(history, ...arguments);
}

// src/history/hash.js
function pushHash (path) {
  if (supportsPushState) {
    pushState(getUrl(path))
  } else {
    window.location.hash = path
  }
}

const eventType = supportsPushState ? 'popstate' : 'hashchange'
window.addEventListener(
  eventType,
  handleRoutingEvent
)

function pushState (url?: string, replace?: boolean) {
  saveScrollPosition()
  const history = window.history
  // safari存在問(wèn)題，路由棧中只能保存100，超過(guò)100個(gè)異常捕獲用location來(lái)替換路由對(duì)象
  try {
    if (replace) {
      const stateCopy = extend({}, history.state)
     stateCopy.key = getStateKey()
     history.replaceState(stateCopy, '', url)
   } else {
     history.pushState({ key: setStateKey(genStateKey()) }, '', url)
   }
 } catch (e) {
    window.location[replace ? 'replace' : 'assign'](url)
  }
}

// src/history/html5.js
this.transitionTo(location, (route) => {
  if (supportsScroll) {
    handleScroll(router, route, current, true)
  }
})
window.addEventListener('popstate', handleRoutingEvent)

// src/history/html5.js
push(location: RawLocation, onComplete?: Function, onAbort?: Function) {
    const { current: fromRoute } = this
    this.transitionTo(
      location,
      (route) => {
        pushState(cleanPath(this.base + route.fullPath))
        handleScroll(this.router, route, fromRoute, false)
        onComplete && onComplete(route)
      },
      onAbort
    )
  }

this.stack = []

// src/history/abstract.js push()方法
route => {
  // 在路由棧中添加一個(gè)新路由
  this.stack = this.stack.slice(0, this.index + 1).concat(route)
  this.index++
  onComplete && onComplete(route)
}

// src/history/abstract.js replace()方法
route => {
  // 在路由棧中替換掉最后一個(gè)路由
  this.stack = this.stack.slice(0, this.index).concat(route)
  this.index++
  onComplete && onComplete(route)
}

// src/history/abstract.js go()方法
const targetIndex = this.index + n
if (targetIndex < 0 || targetIndex >= this.stack.length) {
  return
}

// src/history/abstract.js go()方法
const route = this.stack[targetIndex]
this.confirmTransition(
  route,
  () => {
  this.index = targetIndex
  this.updateRoute(route)
  // ...
)
// src/history/base.js
updateRoute(route: Route) {
  this.current = route
  this.cb && this.cb(route)
}

const routes = [
  {
    path: '/',
    component: { template: `<div>default view</div>` }
  },
  {
    path: '/abstractRoute',
    component: {
      name: "abstract",
      template: '<div><h1 @click="toRoute(1)">跳轉(zhuǎn)到router1</h1><h1 @click="toRoute(2)">跳轉(zhuǎn)到router2</h1><router-view></router-view></div>',
      methods: {
        toRoute(num) {
          this.$router.push(`/route${num}`);
        }
      },
      router: new VueRouter({
        routes: [
          {
            path: '/route1',
            component: {template:'<h1>abstract route 1</h1>'}
          },
          {
            path: '/route2',
            component: { template:'<h1>abstract route 2</h1>'}
          },
        ],
        mode: 'abstract'
      })
    }
  },
]
const app = new Vue({
  router: new VueRouter({
    routes,
    mode: 'hash'
  }),
  template: `<div><router-link to="/">to /</router-link>
    <router-link to="/abstractRoute">to abstractRoute</router-link>
    <router-view></router-view>
    </div>`,
}).$mount('#app')