import Vue from 'vue'
import VueRouter from 'vue-router'
// 1. 插件
// 安裝 <router-view> and <router-link> 組件
// 且給當前應用下所有的組件都注入 $router and $route 對象
Vue.use(VueRouter)
// 2. 定義各個路由下使用的組件，簡稱路由組件
const Home = { template: '<div>home</div>' }
const Foo = { template: '<div>foo</div>' }
const Bar = { template: '<div>bar</div>' }
// 3. 創(chuàng)建 VueRouter 實例 router
const router = new VueRouter({
  mode: 'history',
  base: __dirname,
  routes: [
    { path: '/', component: Home },
    { path: '/foo', component: Foo },
    { path: '/bar', component: Bar }
  ]
})
// 4. 創(chuàng)建 啟動應用
// 一定要確認注入了 router 
// 在 <router-view> 中將會渲染路由組件
new Vue({
  router,
  template: `
    <div id="app">
      <h1>Basic</h1>
      <ul>
        <li><router-link to="/">/</router-link></li>
        <li><router-link to="/foo">/foo</router-link></li>
        <li><router-link to="/bar">/bar</router-link></li>
        <router-link tag="li" to="/bar">/bar</router-link>
      </ul>
      <router-view class="view"></router-view>
    </div>
  `
}).$mount('#app')

/* @flow */
// 導入 install 模塊
import { install } from './install'
// ...
import { inBrowser, supportsHistory } from './util/dom'
// ...
export default class VueRouter {
// ...
}
// 賦值 install
VueRouter.install = install
// 自動使用插件
if (inBrowser && window.Vue) {
  window.Vue.use(VueRouter)
}

// router-view router-link 組件
import View from './components/view'
import Link from './components/link'
// export 一個 Vue 引用
export let _Vue
// 安裝函數(shù)
export function install (Vue) {
  if (install.installed) return
  install.installed = true
  // 賦值私有 Vue 引用
  _Vue = Vue
  // 注入 $router $route
  Object.defineProperty(Vue.prototype, '$router', {
    get () { return this.$root._router }
  })
  Object.defineProperty(Vue.prototype, '$route', {
    get () { return this.$root._route }
  })
  // beforeCreate mixin
  Vue.mixin({
    beforeCreate () {
      // 判斷是否有 router
      if (this.$options.router) {
        // 賦值 _router
        this._router = this.$options.router
        // 初始化 init
        this._router.init(this)
        // 定義響應式的 _route 對象
        Vue.util.defineReactive(this, '_route', this._router.history.current)
      }
    }
  })
  // 注冊組件
  Vue.component('router-view', View)
  Vue.component('router-link', Link)
// ...
}

// ...
import { createMatcher } from './create-matcher'
// ...
export default class VueRouter {
// ...
  constructor (options: RouterOptions = {}) {
    this.app = null
    this.options = options
    this.beforeHooks = []
    this.afterHooks = []
    // 創(chuàng)建 match 匹配函數(shù)
    this.match = createMatcher(options.routes || [])
    // 根據(jù) mode 實例化具體的 History
    let mode = options.mode || 'hash'
    this.fallback = mode === 'history' && !supportsHistory
    if (this.fallback) {
      mode = 'hash'
    }
    if (!inBrowser) {
      mode = 'abstract'
    }
    this.mode = mode
    switch (mode) {
      case 'history':
        this.history = new HTML5History(this, options.base)
        break
      case 'hash':
        this.history = new HashHistory(this, options.base, this.fallback)
        break
      case 'abstract':
        this.history = new AbstractHistory(this)
        break
      default:
        assert(false, `invalid mode: ${mode}`)
    }
  }
// ...
}

/* @flow */
import Regexp from 'path-to-regexp'
// ...
import { createRouteMap } from './create-route-map'
// ...
export function createMatcher (routes: Array<RouteConfig>): Matcher {
  // 創(chuàng)建路由 map
  const { pathMap, nameMap } = createRouteMap(routes)
  // 匹配函數(shù)
  function match (
    raw: RawLocation,
    currentRoute?: Route,
    redirectedFrom?: Location
  ): Route {
// ...
  }
  function redirect (
    record: RouteRecord,
    location: Location
  ): Route {
// ...
  }
  function alias (
    record: RouteRecord,
    location: Location,
    matchAs: string
  ): Route {
// ...
  }
  function _createRoute (
    record: ?RouteRecord,
    location: Location,
    redirectedFrom?: Location
  ): Route {
    if (record && record.redirect) {
      return redirect(record, redirectedFrom || location)
    }
    if (record && record.matchAs) {
      return alias(record, location, record.matchAs)
    }
    return createRoute(record, location, redirectedFrom)
  }
  // 返回
  return match
}
// ...

/* @flow */
import { assert, warn } from './util/warn'
import { cleanPath } from './util/path'
// 創(chuàng)建路由 map
export function createRouteMap (routes: Array<RouteConfig>): {
  pathMap: Dictionary<RouteRecord>,
  nameMap: Dictionary<RouteRecord>
} {
  // path 路由 map
  const pathMap: Dictionary<RouteRecord> = Object.create(null)
  // name 路由 map
  const nameMap: Dictionary<RouteRecord> = Object.create(null)
  // 遍歷路由配置對象 增加 路由記錄
  routes.forEach(route => {
    addRouteRecord(pathMap, nameMap, route)
  })
  return {
    pathMap,
    nameMap
  }
}
// 增加 路由記錄 函數(shù)
function addRouteRecord (
  pathMap: Dictionary<RouteRecord>,
  nameMap: Dictionary<RouteRecord>,
  route: RouteConfig,
  parent?: RouteRecord,
  matchAs?: string
) {
  // 獲取 path 、name
  const { path, name } = route
  assert(path != null, `"path" is required in a route configuration.`)
  // 路由記錄 對象
  const record: RouteRecord = {
    path: normalizePath(path, parent),
    components: route.components || { default: route.component },
    instances: {},
    name,
    parent,
    matchAs,
    redirect: route.redirect,
    beforeEnter: route.beforeEnter,
    meta: route.meta || {}
  }
  // 嵌套子路由 則遞歸增加 記錄
  if (route.children) {
// ...
    route.children.forEach(child => {
      addRouteRecord(pathMap, nameMap, child, record)
    })
  }
  // 處理別名 alias 邏輯 增加對應的 記錄
  if (route.alias !== undefined) {
    if (Array.isArray(route.alias)) {
      route.alias.forEach(alias => {
        addRouteRecord(pathMap, nameMap, { path: alias }, parent, record.path)
      })
    } else {
      addRouteRecord(pathMap, nameMap, { path: route.alias }, parent, record.path)
    }
  }
  // 更新 path map
  pathMap[record.path] = record
  // 更新 name map
  if (name) {
    if (!nameMap[name]) {
      nameMap[name] = record
    } else {
      warn(false, `Duplicate named routes definition: { name: "${name}", path: "${record.path}" }`)
    }
  }
}
function normalizePath (path: string, parent?: RouteRecord): string {
  path = path.replace(/\/$/, '')
  if (path[0] === '/') return path
  if (parent == null) return path
  return cleanPath(`${parent.path}/${path}`)
}

/* @flow */
// ...
import { inBrowser } from '../util/dom'
import { runQueue } from '../util/async'
import { START, isSameRoute } from '../util/route'
// 這里從之前分析過的 install.js 中 export _Vue
import { _Vue } from '../install'
export class History {
// ...
  constructor (router: VueRouter, base: ?string) {
    this.router = router
    this.base = normalizeBase(base)
    // start with a route object that stands for "nowhere"
    this.current = START
    this.pending = null
  }
// ...
}
// 得到 base 值
function normalizeBase (base: ?string): string {
  if (!base) {
    if (inBrowser) {
      // respect <base> tag
      const baseEl = document.querySelector('base')
      base = baseEl ? baseEl.getAttribute('href') : '/'
    } else {
      base = '/'
    }
  }
  // make sure there's the starting slash
  if (base.charAt(0) !== '/') {
    base = '/' + base
  }
  // remove trailing slash
  return base.replace(/\/$/, '')
}
// ...

new Vue({
  router,
  template: `
    <div id="app">
      <h1>Basic</h1>
      <ul>
        <li><router-link to="/">/</router-link></li>
        <li><router-link to="/foo">/foo</router-link></li>
        <li><router-link to="/bar">/bar</router-link></li>
        <router-link tag="li" to="/bar">/bar</router-link>
      </ul>
      <router-view class="view"></router-view>
    </div>
  `
}).$mount('#app')

// ...
  Vue.mixin({
    beforeCreate () {
      // 判斷是否有 router
      if (this.$options.router) {
        // 賦值 _router
        this._router = this.$options.router
        // 初始化 init
        this._router.init(this)
        // 定義響應式的 _route 對象
        Vue.util.defineReactive(this, '_route', this._router.history.current)
      }
    }
  })

/* @flow */
import { install } from './install'
import { createMatcher } from './create-matcher'
import { HashHistory, getHash } from './history/hash'
import { HTML5History, getLocation } from './history/html5'
import { AbstractHistory } from './history/abstract'
import { inBrowser, supportsHistory } from './util/dom'
import { assert } from './util/warn'
export default class VueRouter {
// ...
  init (app: any /* Vue component instance */) {
// ...
    this.app = app
    const history = this.history
    if (history instanceof HTML5History) {
      history.transitionTo(getLocation(history.base))
    } else if (history instanceof HashHistory) {
      history.transitionTo(getHash(), () => {
        window.addEventListener('hashchange', () => {
          history.onHashChange()
        })
      })
    }
    history.listen(route => {
      this.app._route = route
    })
  }
// ...
}
// ...

/* @flow */
import type VueRouter from '../index'
import { warn } from '../util/warn'
import { inBrowser } from '../util/dom'
import { runQueue } from '../util/async'
import { START, isSameRoute } from '../util/route'
import { _Vue } from '../install'
export class History {
// ...
  transitionTo (location: RawLocation, cb?: Function) {
    // 調(diào)用 match 得到匹配的 route 對象
    const route = this.router.match(location, this.current)
    // 確認過渡
    this.confirmTransition(route, () => {
      // 更新當前 route 對象
      this.updateRoute(route)
      cb && cb(route)
      // 子類實現(xiàn)的更新url地址
      // 對于 hash 模式的話 就是更新 hash 的值
      // 對于 history 模式的話 就是利用 pushstate / replacestate 來更新
      // 瀏覽器地址
      this.ensureURL()
    })
  }
  // 確認過渡
  confirmTransition (route: Route, cb: Function) {
    const current = this.current
    // 如果是相同 直接返回
    if (isSameRoute(route, current)) {
      this.ensureURL()
      return
    }
    // 交叉比對當前路由的路由記錄和現(xiàn)在的這個路由的路由記錄
    // 以便能準確得到父子路由更新的情況下可以確切的知道
    // 哪些組件需要更新 哪些不需要更新
    const {
      deactivated,
      activated
    } = resolveQueue(this.current.matched, route.matched)
    // 整個切換周期的隊列
    const queue: Array<?NavigationGuard> = [].concat(
      // leave 的鉤子
      extractLeaveGuards(deactivated),
      // 全局 router before hooks
      this.router.beforeHooks,
      // 將要更新的路由的 beforeEnter 鉤子
      activated.map(m => m.beforeEnter),
      // 異步組件
      resolveAsyncComponents(activated)
    )
    this.pending = route
    每一個隊列執(zhí)行的 iterator 函數(shù)
    const iterator = (hook: NavigationGuard, next) => {
      // 確保期間還是當前路由
      if (this.pending !== route) return
      hook(route, current, (to: any) => {
        if (to === false) {
          // next(false) -> abort navigation, ensure current URL
          this.ensureURL(true)
        } else if (typeof to === 'string' || typeof to === 'object') {
          // next('/') or next({ path: '/' }) -> redirect
          this.push(to)
        } else {
          // confirm transition and pass on the value
          next(to)
        }
      })
    }
    // 執(zhí)行隊列
    runQueue(queue, iterator, () => {
      const postEnterCbs = []
      // 組件內(nèi)的鉤子
      const enterGuards = extractEnterGuards(activated, postEnterCbs, () => {
        return this.current === route
      })
      // 在上次的隊列執(zhí)行完成后再執(zhí)行組件內(nèi)的鉤子
      // 因為需要等異步組件以及是OK的情況下才能執(zhí)行
      runQueue(enterGuards, iterator, () => {
        // 確保期間還是當前路由
        if (this.pending === route) {
          this.pending = null
          cb(route)
          this.router.app.$nextTick(() => {
            postEnterCbs.forEach(cb => cb())
          })
        }
      })
    })
  }
  // 更新當前 route 對象
  updateRoute (route: Route) {
    const prev = this.current
    this.current = route
    // 注意 cb 的值 
    // 每次更新都會調(diào)用 下邊需要用到！
    this.cb && this.cb(route)
    // 執(zhí)行 after hooks 回調(diào)
    this.router.afterHooks.forEach(hook => {
      hook && hook(route, prev)
    })
  }
}
// ...

// ...
import { createRoute } from './util/route'
import { createRouteMap } from './create-route-map'
// ...
export function createMatcher (routes: Array<RouteConfig>): Matcher {
  const { pathMap, nameMap } = createRouteMap(routes)
  // 關鍵的 match
  function match (
    raw: RawLocation,
    currentRoute?: Route,
    redirectedFrom?: Location
  ): Route {
    const location = normalizeLocation(raw, currentRoute)
    const { name } = location
    // 命名路由處理
    if (name) {
      // nameMap[name] = 路由記錄
      const record = nameMap[name]
      const paramNames = getParams(record.path)
// ...
      if (record) {
        location.path = fillParams(record.path, location.params, `named route "${name}"`)
        // 創(chuàng)建 route
        return _createRoute(record, location, redirectedFrom)
      }
    } else if (location.path) {
      // 普通路由處理
      location.params = {}
      for (const path in pathMap) {
        if (matchRoute(path, location.params, location.path)) {
          // 匹配成功 創(chuàng)建route
          // pathMap[path] = 路由記錄
          return _createRoute(pathMap[path], location, redirectedFrom)
        }
      }
    }
    // no match
    return _createRoute(null, location)
  }
// ...
  // 創(chuàng)建路由
  function _createRoute (
    record: ?RouteRecord,
    location: Location,
    redirectedFrom?: Location
  ): Route {
    // 重定向和別名邏輯
    if (record && record.redirect) {
      return redirect(record, redirectedFrom || location)
    }
    if (record && record.matchAs) {
      return alias(record, location, record.matchAs)
    }
    // 創(chuàng)建路由對象
    return createRoute(record, location, redirectedFrom)
  }
  return match
}
// ...

// ...
export function createRoute (
  record: ?RouteRecord,
  location: Location,
  redirectedFrom?: Location
): Route {
  // 可以看到就是一個被凍結的普通對象
  const route: Route = {
    name: location.name || (record && record.name),
    meta: (record && record.meta) || {},
    path: location.path || '/',
    hash: location.hash || '',
    query: location.query || {},
    params: location.params || {},
    fullPath: getFullPath(location),
    // 根據(jù)記錄層級的得到所有匹配的 路由記錄
    matched: record ? formatMatch(record) : []
  }
  if (redirectedFrom) {
    route.redirectedFrom = getFullPath(redirectedFrom)
  }
  return Object.freeze(route)
}
// ...
function formatMatch (record: ?RouteRecord): Array<RouteRecord> {
  const res = []
  while (record) {
    res.unshift(record)
    record = record.parent
  }
  return res
}
// ...

history.listen(route => {
  this.app._route = route
})

new Vue({
  router,
  template: `
    <div id="app">
      <h1>Basic</h1>
      <ul>
        <li><router-link to="/">/</router-link></li>
        <li><router-link to="/foo">/foo</router-link></li>
        <li><router-link to="/bar">/bar</router-link></li>
        <router-link tag="li" to="/bar">/bar</router-link>
      </ul>
      <router-view class="view"></router-view>
    </div>
  `
}).$mount('#app')

export default {
  name: 'router-view',
  functional: true, // 功能組件 純粹渲染
  props: {
    name: {
      type: String,
      default: 'default' // 默認default 默認命名視圖的name
    }
  },
  render (h, { props, children, parent, data }) {
    // 解決嵌套深度問題
    data.routerView = true
    // route 對象
    const route = parent.$route
    // 緩存
    const cache = parent._routerViewCache || (parent._routerViewCache = {})
    let depth = 0
    let inactive = false
    // 當前組件的深度
    while (parent) {
      if (parent.$vnode && parent.$vnode.data.routerView) {
        depth++
      }
      處理 keepalive 邏輯
      if (parent._inactive) {
        inactive = true
      }
      parent = parent.$parent
    }
    data.routerViewDepth = depth
    // 得到相匹配的當前組件層級的 路由記錄
    const matched = route.matched[depth]
    if (!matched) {
      return h()
    }
    // 得到要渲染組件
    const name = props.name
    const component = inactive
      ? cache[name]
      : (cache[name] = matched.components[name])
    if (!inactive) {
      // 非 keepalive 模式下 每次都需要設置鉤子
      // 進而更新（賦值&銷毀）匹配了的實例元素
      const hooks = data.hook || (data.hook = {})
      hooks.init = vnode => {
        matched.instances[name] = vnode.child
      }
      hooks.prepatch = (oldVnode, vnode) => {
        matched.instances[name] = vnode.child
      }
      hooks.destroy = vnode => {
        if (matched.instances[name] === vnode.child) {
          matched.instances[name] = undefined
        }
      }
    }
    // 調(diào)用 createElement 函數(shù) 渲染匹配的組件
    return h(component, data, children)
  }
}

// ...
import { createRoute, isSameRoute, isIncludedRoute } from '../util/route'
// ...
export default {
  name: 'router-link',
  props: {
    // 傳入的組件屬性們
    to: { // 目標路由的鏈接
      type: toTypes,
      required: true
    },
    // 創(chuàng)建的html標簽
    tag: {
      type: String,
      default: 'a'
    },
    // 完整模式，如果為 true 那么也就意味著
    // 絕對相等的路由才會增加 activeClass
    // 否則是包含關系
    exact: Boolean,
    // 在當前（相對）路徑附加路徑
    append: Boolean,
    // 如果為 true 則調(diào)用 router.replace() 做替換歷史操作
    replace: Boolean,
    // 鏈接激活時使用的 CSS 類名
    activeClass: String
  },
  render (h: Function) {
    // 得到 router 實例以及當前激活的 route 對象
    const router = this.$router
    const current = this.$route
    const to = normalizeLocation(this.to, current, this.append)
    // 根據(jù)當前目標鏈接和當前激活的 route匹配結果
    const resolved = router.match(to, current)
    const fullPath = resolved.redirectedFrom || resolved.fullPath
    const base = router.history.base
    // 創(chuàng)建的 href
    const href = createHref(base, fullPath, router.mode)
    const classes = {}
    // 激活class 優(yōu)先當前組件上獲取 要么就是 router 配置的 linkActiveClass
    // 默認 router-link-active
    const activeClass = this.activeClass || router.options.linkActiveClass || 'router-link-active'
    // 相比較目標
    // 因為有命名路由 所有不一定有path
    const compareTarget = to.path ? createRoute(null, to) : resolved
    // 如果嚴格模式的話 就判斷是否是相同路由（path query params hash）
    // 否則就走包含邏輯（path包含，query包含 hash為空或者相同）
    classes[activeClass] = this.exact
      ? isSameRoute(current, compareTarget)
      : isIncludedRoute(current, compareTarget)
    // 事件綁定
    const on = {
      click: (e) => {
        // 忽略帶有功能鍵的點擊
        if (e.metaKey || e.ctrlKey || e.shiftKey) return
        // 已阻止的返回
        if (e.defaultPrevented) return
        // 右擊
        if (e.button !== 0) return
        // `target="_blank"` 忽略
        const target = e.target.getAttribute('target')
        if (/\b_blank\b/i.test(target)) return
        // 阻止默認行為 防止跳轉
        e.preventDefault()
        if (this.replace) {
          // replace 邏輯
          router.replace(to)
        } else {
          // push 邏輯
          router.push(to)
        }
      }
    }
    // 創(chuàng)建元素需要附加的數(shù)據(jù)們
    const data: any = {
      class: classes
    }
    if (this.tag === 'a') {
      data.on = on
      data.attrs = { href }
    } else {
      // 找到第一個 <a> 給予這個元素事件綁定和href屬性
      const a = findAnchor(this.$slots.default)
      if (a) {
        // in case the <a> is a static node
        a.isStatic = false
        const extend = _Vue.util.extend
        const aData = a.data = extend({}, a.data)
        aData.on = on
        const aAttrs = a.data.attrs = extend({}, a.data.attrs)
        aAttrs.href = href
      } else {
        // 沒有 <a> 的話就給當前元素自身綁定時間
        data.on = on
      }
    }
    // 創(chuàng)建元素
    return h(this.tag, data, this.$slots.default)
  }
}
function findAnchor (children) {
  if (children) {
    let child
    for (let i = 0; i < children.length; i++) {
      child = children[i]
      if (child.tag === 'a') {
        return child
      }
      if (child.children && (child = findAnchor(child.children))) {
        return child
      }
    }
  }
}
function createHref (base, fullPath, mode) {
  var path = mode === 'hash' ? '/#' + fullPath : fullPath
  return base ? cleanPath(base + path) : path
}