From 571b67bc84cc8f34f9c506c708bd0dcc51daee34 Mon Sep 17 00:00:00 2001
From: avele <34437766+avele@users.noreply.github.com>
Date: Tue, 26 Nov 2019 17:21:20 +0400
Subject: [PATCH] Client preload rewritten (#417)

---
 front/client/App.vue                          | 25 ++++--
 .../components/ClientServerPrefetch.vue       | 76 +++++++++++++++++++
 front/client/components/SearchBar.vue         | 30 ++++----
 front/client/entry.client.ts                  | 67 ----------------
 front/client/entry.server.ts                  |  2 +
 front/client/page/CategoryPage.vue            | 10 ---
 front/client/page/Index.vue                   |  6 +-
 front/client/page/Page404.vue                 |  4 -
 front/client/page/SearchResults.vue           | 23 ++----
 front/client/router/index.ts                  | 41 ++++++++--
 front/client/store/index.ts                   |  2 +-
 front/client/store/modules/wiki.ts            |  6 +-
 front/index.html                              |  2 +-
 13 files changed, 157 insertions(+), 137 deletions(-)
 create mode 100644 front/client/components/ClientServerPrefetch.vue

diff --git a/front/client/App.vue b/front/client/App.vue
index 54ad1cf..261131a 100644
--- a/front/client/App.vue
+++ b/front/client/App.vue
@@ -2,7 +2,9 @@
   <v-app>
     <toolbar />
     <main class="app-content content-centered">
-      <router-view />
+      <ClientServerPrefetch>
+        <RouterView />
+      </ClientServerPrefetch>
     </main>
     <a-footer />
   </v-app>
@@ -14,24 +16,21 @@ import Component from 'vue-class-component'
 import { Watch } from 'vue-property-decorator'
 import AFooter from 'client/components/AFooter.vue'
 import Toolbar from 'client/components/Toolbar.vue'
+import ClientServerPrefetch from 'client/components/ClientServerPrefetch.vue'
 import * as nprogress from 'nprogress'
 import 'nprogress/nprogress.css'
+import { getRouteDocumentTitle } from 'client/router'
 
 nprogress.configure({ showSpinner: false })
 
 @Component({
   components: {
     Toolbar,
-    AFooter
+    AFooter,
+    ClientServerPrefetch
   }
 })
 export default class RootComponent extends Vue {
-  beforeMount () {
-    // This package can only be loaded after mounted (on client only) cause it uses "document"
-    // it is used in MarkdownEditor.vue and to make it work faster in that component we preload it here
-    import('easymde')
-  }
-
   get isPageLoading () {
     return this.$store.state.isPageLoading
   }
@@ -39,6 +38,16 @@ export default class RootComponent extends Vue {
   @Watch('isPageLoading')
   toogleLoading (isPageLoading: boolean) {
     isPageLoading ? nprogress.start() : nprogress.done()
+
+    if (!isPageLoading) {
+      document.title = getRouteDocumentTitle(this.$route)
+    }
+  }
+
+  beforeMount () {
+    // This package can only be loaded after mounted (on client only) cause it uses "document"
+    // it is used in MarkdownEditor.vue and to make it work faster in that component we preload it here
+    import('easymde')
   }
 }
 </script>
diff --git a/front/client/components/ClientServerPrefetch.vue b/front/client/components/ClientServerPrefetch.vue
new file mode 100644
index 0000000..e975d0a
--- /dev/null
+++ b/front/client/components/ClientServerPrefetch.vue
@@ -0,0 +1,76 @@
+<script lang="ts">
+import Vue from 'vue'
+import Component from 'vue-class-component'
+import { Watch } from 'vue-property-decorator'
+
+function getComponentAndItsChildren (component, result?) {
+  if (!result) {
+    result = []
+  }
+  if (!result.includes(component)) {
+    result.push(component)
+  }
+  const children = component.$children
+  children.forEach(x => getComponentAndItsChildren(x, result))
+
+  return result
+}
+
+/**
+ * When this component slot (supports only one slot) changes it prerenders new slot in memory
+ * and waits for slot (and its' children) "serverPrefetch" execution before rendering it
+ */
+@Component
+export default class ClientServerPrefetch extends Vue {
+  // vNodeToRender is not set here (as reactive property) to prevent automatic "render" function call when it changes
+  isServerPrefetchProcessing = false
+
+  @Watch('isServerPrefetchProcessing')
+  onServerPrefetch (val) {
+    this.$store.commit('togglePageLoading')
+  }
+
+  onServerPrefetchFinish () {
+    const previousVNode = this.vNodeToRender
+    this.vNodeToRender = this.$slots.default[0]
+    this.$forceUpdate()
+    this.isServerPrefetchProcessing = false
+    previousVNode.data.keepAlive = false
+    previousVNode.componentInstance.$destroy()
+  }
+
+  async preloadSlotComponent () {
+    this.isServerPrefetchProcessing = true
+    try {
+      const slot = this.$slots.default[0]
+      // This is vue's internal function that inits component
+      this._update(slot, false)
+      const componentInstance = slot.componentInstance
+      const components = getComponentAndItsChildren(componentInstance)
+      const getServerPrefetchFunc = x => x.$options.serverPrefetch && x.$options.serverPrefetch[0]
+      const componentsWithServerPrefetch = components.filter(getServerPrefetchFunc)
+      await Promise.all(componentsWithServerPrefetch.map(x => getServerPrefetchFunc(x).call(x)))
+      this.onServerPrefetchFinish()
+    } catch (e) {
+      this.isServerPrefetchProcessing = false
+      this.$router.back()
+    }
+  }
+
+  render (h) {
+    const slot = this.$slots.default[0]
+    // If we don't set keepAlive to true, component will be automatically destroyed when slot changes
+    // and also new slot will be rendered twice: 1 - in preloadSlotComponent func, 2 - when return here
+    slot.data.keepAlive = true
+
+    if (!this.vNodeToRender || slot === this.vNodeToRender || slot.tag === this.vNodeToRender.tag) {
+      this.vNodeToRender = slot
+    } else {
+      // if slot was changed we dont render it immediatly but firstly execute its (and its children) 'serverPrefetch' functions
+      this.preloadSlotComponent()
+    }
+
+    return this.vNodeToRender
+  }
+}
+</script>
\ No newline at end of file
diff --git a/front/client/components/SearchBar.vue b/front/client/components/SearchBar.vue
index 91adaf1..03841ef 100644
--- a/front/client/components/SearchBar.vue
+++ b/front/client/components/SearchBar.vue
@@ -1,7 +1,7 @@
 <template>
   <v-form
     class="search-bar"
-    @keydown.enter.native.prevent="processSearchInput"
+    @keydown.enter.native.prevent="processSearchQuery"
   >
     <v-text-field
       solo
@@ -10,7 +10,7 @@
       label="Search in all pages"
       class="search-bar__input"
       ref="input"
-      v-model="searchInput"
+      v-model="searchQuery"
       @focus="isFocused = true"
       @blur="isFocused= false"
     >
@@ -25,7 +25,7 @@
         size="0.9rem"
         class="search-bar__input__clear-btn"
         :color="inputIconsColor"
-        v-show="searchInput"
+        v-show="searchQuery"
         @click="clear"
       >$vuetify.icons.times</v-icon>
     </v-text-field>
@@ -40,19 +40,17 @@ import Component from 'vue-class-component'
 export default class SearchBar extends Vue {
 
   isFocused = false
+  searchQuery = this.$store.state.wiki.searchQuery
 
-  processSearchInput () {
-    this.$router.push({ name: 'SearchResults', query: { query: this.searchInput } })
-  }
-
-  // TODO investigate is using computed necessary here
-  // TODO serever rendering doesnt render value in text field
-  get searchInput () {
-    return this.$store.state.wiki.searchInput
-  }
-
-  set searchInput (value) {
-    this.$store.commit('wiki/setSearchInput', value)
+  processSearchQuery () {
+    const searchResultsRouteName = 'SearchResults'
+    const isSearchCurrentRoute = this.$route.name === searchResultsRouteName
+    // same commit statement called in router 'SearchResults' route's "beforeEnter", but if its same route its not called
+    // searchQuery is watched used in "SearchResults" component
+    if (isSearchCurrentRoute) {
+      this.$store.commit('wiki/setSearchQuery', this.searchQuery)
+    }
+    this.$router.push({ name: searchResultsRouteName, query: { query: this.searchQuery } })
   }
 
   get inputIconsColor () {
@@ -60,7 +58,7 @@ export default class SearchBar extends Vue {
   }
 
   clear () {
-    this.searchInput = ''
+    this.searchQuery = ''
   }
 
   focus () {
diff --git a/front/client/entry.client.ts b/front/client/entry.client.ts
index bea00d6..03d7952 100644
--- a/front/client/entry.client.ts
+++ b/front/client/entry.client.ts
@@ -1,5 +1,3 @@
-import _get from 'lodash/get'
-
 import { createApp } from './app'
 
 const { app, router, store } = createApp()
@@ -20,70 +18,5 @@ if (store.state.is404) {
 }
 
 router.onReady(() => {
-  registerRouterHooks()
   app.$mount('#app')
 })
-
-function registerRouterHooks () {
-  router.beforeEach(async (to, from, next) => {
-    // This case handles navigation to anchors on same page
-    if (to.path === from.path) {
-      next()
-      return
-    }
-
-    store.commit('tooglePageLoading')
-    if (!to.matched.length) {
-      store.commit('tooglePageLoading')
-      next()
-      return
-    }
-    try {
-      const propsOption = to.matched[0].props.default
-      const props = propsOption
-        ? typeof propsOption === 'function'
-          ? propsOption(to)
-          : typeof propsOption === 'object'
-            ? propsOption
-            : to.params
-        : {}
-      const routeComponent = to.matched[0].components.default
-      const matchedRootComponent = routeComponent.cid // Check if component already imported
-        ? routeComponent
-        : (await routeComponent()).default
-      const matchedComponentsAndChildren = getComponentAndItsChildren(matchedRootComponent)
-      await Promise.all(matchedComponentsAndChildren.map(component => {
-        const serverPrefetch = component.options.serverPrefetch && component.options.serverPrefetch[0]
-        if (typeof serverPrefetch === 'function') {
-          return serverPrefetch.call({
-            $store: store,
-            $router: router,
-            ...component.options.methods,
-            ...props
-          })
-        }
-      }))
-      next()
-    } finally {
-      store.commit('tooglePageLoading')
-    }
-  })
-}
-
-function getComponentAndItsChildren (component, result?) {
-  if (!result) {
-    result = []
-  }
-  if (!component.options) {
-    return result
-  }
-  if (!result.includes(component)) {
-    result.push(component)
-  }
-  const children = Object.values(component.options.components)
-    // Parent component is also presents in components object
-    .filter(x => x !== component)
-  children.forEach(x => getComponentAndItsChildren(x, result))
-
-  return result
-}
diff --git a/front/client/entry.server.ts b/front/client/entry.server.ts
index 11615d5..d846959 100644
--- a/front/client/entry.server.ts
+++ b/front/client/entry.server.ts
@@ -1,5 +1,6 @@
 import _get from 'lodash/get'
 import { createApp } from './app'
+import { getRouteDocumentTitle } from './router'
 
 export default async context => {
   return new Promise((resolve, reject) => {
@@ -19,6 +20,7 @@ export default async context => {
       context.rendered = () => {
         context.state = store.state
       }
+      context.title = getRouteDocumentTitle(router.currentRoute)
       resolve(app)
     }, reject)
   })
diff --git a/front/client/page/CategoryPage.vue b/front/client/page/CategoryPage.vue
index da16b25..5b909b7 100644
--- a/front/client/page/CategoryPage.vue
+++ b/front/client/page/CategoryPage.vue
@@ -28,18 +28,8 @@ export default class CategoryPage extends Vue {
     return this.$store.state.category.category
   }
 
-  beforeMount () {
-    this.$watch('category', this.setDocumentTitle, { immediate: true })
-  }
-
   beforeDestroy () {
     this.$store.commit('category/setCategory', null)
   }
-
-  setDocumentTitle (category) {
-    document.title = category
-      ? `${category.title} – Aelve Guide`
-      : 'Aelve Guide'
-  }
 }
 </script>
diff --git a/front/client/page/Index.vue b/front/client/page/Index.vue
index 78e8262..3506934 100644
--- a/front/client/page/Index.vue
+++ b/front/client/page/Index.vue
@@ -12,9 +12,5 @@ import Component from 'vue-class-component'
     Categories
   }
 })
-export default class Index extends Vue {
-  beforeMount () {
-    document.title = `Aelve Guide`
-  }
-}
+export default class Index extends Vue {}
 </script>
diff --git a/front/client/page/Page404.vue b/front/client/page/Page404.vue
index 7ab8063..1fc3c0b 100644
--- a/front/client/page/Page404.vue
+++ b/front/client/page/Page404.vue
@@ -20,10 +20,6 @@ export default class Page404 extends Vue {
   beforeDestroy () {
     this.$store.commit('set404', false)
   }
-
-  beforeMount () {
-    document.title = `Error 404 – Aelve Guide`
-  }
 }
 </script>
 
diff --git a/front/client/page/SearchResults.vue b/front/client/page/SearchResults.vue
index 508c4ba..5afd698 100644
--- a/front/client/page/SearchResults.vue
+++ b/front/client/page/SearchResults.vue
@@ -76,7 +76,7 @@
 <script lang="ts">
 import Vue from 'vue'
 import Component from 'vue-class-component'
-import { Prop, Watch } from 'vue-property-decorator'
+import { Watch } from 'vue-property-decorator'
 
 const resultTagCodes = {
   category: 'Category',
@@ -85,7 +85,9 @@ const resultTagCodes = {
 
 @Component
 export default class SearchResults extends Vue {
-  @Prop(String) query!: string
+  get query () {
+    return this.$store.state.wiki.searchQuery
+  }
 
   get results () {
     return this.$store.state.wiki.searchResults
@@ -99,26 +101,13 @@ export default class SearchResults extends Vue {
     return this.results.filter(x => x.tag === resultTagCodes.item)
   }
 
-  beforeMount () {
-    // This watch should be added in beforeMount (only on client) hook because setDocumentTitle function uses DOM api which is undefined on server
-    this.$watch('query', this.setDocumentTitle, { immediate: true })
-  }
-
-  mounted () {
-    this.$store.commit('wiki/setSearchInput', this.query)
-  }
-
-  async serverPrefetch () {
-    await this.search()
-  }
-
   @Watch('query')
   async search () {
     await this.$store.dispatch('wiki/search', this.query)
   }
 
-  setDocumentTitle (query) {
-    document.title = `${query} – Search results – Aelve Guide`
+  async serverPrefetch () {
+    await this.search()
   }
 }
 </script>
diff --git a/front/client/router/index.ts b/front/client/router/index.ts
index d7595c8..6b63f66 100644
--- a/front/client/router/index.ts
+++ b/front/client/router/index.ts
@@ -1,5 +1,6 @@
 import Router from 'vue-router'
 import categoryPathToId from 'client/helpers/categoryPathToId'
+import _get from 'lodash/get'
 
 function createRouter (store) {
   return new Router({
@@ -32,23 +33,53 @@ function createRouter (store) {
         path: '/haskell/:category',
         name: 'Category',
         component: () => import('../page/CategoryPage.vue'),
-        props: (route) => ({ categoryId: categoryPathToId(route.params.category) })
+        props: (route) => ({ categoryId: categoryPathToId(route.params.category) }),
+        meta: {
+          documentTitle: () => {
+            const category = store.state.category.category
+            return category
+              ? `${category.title} – Aelve Guide`
+              : 'Aelve Guide'
+          }
+        }
       },
       {
         path: '/haskell/search/results/',
         name: 'SearchResults',
         component: () => import('../page/SearchResults.vue'),
-        props: (route) => ({ query: route.query.query })
+        beforeEnter: (to, from, next) => {
+          store.commit('wiki/setSearchQuery', to.query.query)
+          next()
+        },
+        meta: {
+          documentTitle: (route) => `${route.query.query} – Search results – Aelve Guide`,
+        }
       },
       {
         path: '*',
         name: 'Page404',
-        component: () => import('../page/Page404.vue')
+        component: () => import('../page/Page404.vue'),
+        meta: {
+          documentTitle: 'Error 404 – Aelve Guide'
+        }
       }
     ]
   })
 }
 
-export {
-  createRouter
+function getRouteDocumentTitle (route) {
+  const defaultTitle = 'Aelve Guide'
+  const routeDocumentTitle = _get(route, 'meta.documentTitle')
+  if (routeDocumentTitle) {
+    return typeof routeDocumentTitle === 'function'
+      ? routeDocumentTitle(route)
+      : routeDocumentTitle
+  } else {
+    return defaultTitle
+  }
+}
+
+export {
+  createRouter,
+  getRouteDocumentTitle
 }
diff --git a/front/client/store/index.ts b/front/client/store/index.ts
index e73ae98..099fdfa 100644
--- a/front/client/store/index.ts
+++ b/front/client/store/index.ts
@@ -11,7 +11,7 @@ function createStore () {
     },
     actions: {},
     mutations: {
-      tooglePageLoading (state) {
+      togglePageLoading (state) {
         state.isPageLoading = !state.isPageLoading
       },
       set404 (state, val) {
diff --git a/front/client/store/modules/wiki.ts b/front/client/store/modules/wiki.ts
index 32368ed..51b1ef8 100644
--- a/front/client/store/modules/wiki.ts
+++ b/front/client/store/modules/wiki.ts
@@ -4,12 +4,12 @@ import { set } from '../helpers'
 
 interface IWikiState {
   searchResults: any[],
-  searchInput: string
+  searchQuery: string
 }
 
 const state = (): IWikiState => ({
   searchResults: [],
-  searchInput: ''
+  searchQuery: ''
 })
 
 const getters: GetterTree<IWikiState, any> = {}
@@ -23,7 +23,7 @@ const actions: ActionTree<IWikiState, any> = {
 
 const mutations: MutationTree<IWikiState> = {
   setSearchResults: set('searchResults'),
-  setSearchInput: set('searchInput')
+  setSearchQuery: set('searchQuery')
 }
 
 const wiki: Module<IWikiState, any> = {
diff --git a/front/index.html b/front/index.html
index 2c36e3d..343a188 100644
--- a/front/index.html
+++ b/front/index.html
@@ -3,7 +3,7 @@
   <head>
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
-    <title> Aelve Guide </title>
+    <title> {{ title }} </title>
   </head>
 
   <body>