Use frontend fetch for branch dropdown component (#25719)

- Send request to get branch/tag list, use loading icon when waiting for
response.
- Only fetch when the first time branch/tag list shows.
- For backend, removed assignment to `ctx.Data["Branches"]` and
`ctx.Data["Tags"]` from `context/repo.go` and passed these data wherever
needed.
- Changed some `v-if` to `v-show` and used native `svg` as mentioned in
https://github.com/go-gitea/gitea/pull/25719#issuecomment-1631712757 to
improve perfomance when there are a lot of branches.
- Places Used the dropdown component:

     Repo Home Page
    
<img width="1429" alt="Screen Shot 2023-07-06 at 12 17 51"
src="https://github.com/go-gitea/gitea/assets/17645053/6accc7b6-8d37-4e88-ae1a-bd2b3b927ea0">

    Commits Page

<img width="1431" alt="Screen Shot 2023-07-06 at 12 18 34"
src="https://github.com/go-gitea/gitea/assets/17645053/2d0bf306-d1e2-45a8-a784-bc424879f537">

    Specific commit -> operations -> cherry-pick
    
<img width="758" alt="Screen Shot 2023-07-06 at 12 23 28"
src="https://github.com/go-gitea/gitea/assets/17645053/1e557948-3881-4e45-a625-8ef36d45ae2d">

    Release Page
    
<img width="1433" alt="Screen Shot 2023-07-06 at 12 25 05"
src="https://github.com/go-gitea/gitea/assets/17645053/3ec82af1-15a4-4162-a50b-04a9502161bb">

- Demo


https://github.com/go-gitea/gitea/assets/17645053/d45d266b-3eb0-465a-82f9-57f78dc5f9f3

- Note:

UI of dropdown menu could be improved in another PR as it should apply
to more dropdown menus.

Fix #14180

---------

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

3 files changed, 72 insertions, 33 deletions

diff --git a/web_src/js/components/RepoBranchTagSelector.vue b/web_src/js/components/RepoBranchTagSelector.vue
index 4fc3936244..e6e72e3886 100644
--- a/web_src/js/components/RepoBranchTagSelector.vue
+++ b/web_src/js/components/RepoBranchTagSelector.vue
@@ -11,7 +11,7 @@
       </span>
       <svg-icon name="octicon-triangle-down" :size="14" class-name="dropdown icon"/>
     </button>
-    <div class="menu transition" :class="{visible: menuVisible}" v-if="menuVisible" v-cloak>
+    <div class="menu transition" :class="{visible: menuVisible}" v-show="menuVisible" v-cloak>
       <div class="ui icon search input">
         <i class="icon"><svg-icon name="octicon-filter" :size="16"/></i>
         <input name="search" ref="searchField" autocomplete="off" v-model="searchTerm" @keydown="keydown($event)" :placeholder="searchFieldPlaceholder">
@@ -20,13 +20,13 @@
         <div class="header branch-tag-choice">
           <div class="ui grid">
             <div class="two column row">
-              <a class="reference column" href="#" @click="createTag = false; mode = 'branches'; focusSearchField()">
+              <a class="reference column" href="#" @click="handleTabSwitch('branches')">
                 <span class="text" :class="{black: mode === 'branches'}">
                   <svg-icon name="octicon-git-branch" :size="16" class-name="gt-mr-2"/>{{ textBranches }}
                 </span>
               </a>
               <template v-if="!noTag">
-                <a class="reference column" href="#" @click="createTag = true; mode = 'tags'; focusSearchField()">
+                <a class="reference column" href="#" @click="handleTabSwitch('tags')">
                   <span class="text" :class="{black: mode === 'tags'}">
                     <svg-icon name="octicon-tag" :size="16" class-name="gt-mr-2"/>{{ textTags }}
                   </span>
@@ -37,20 +37,23 @@
         </div>
       </template>
       <div class="scrolling menu" ref="scrollContainer">
+        <svg-icon name="octicon-rss" symbol-id="svg-symbol-octicon-rss"/>
+        <div class="loading-indicator is-loading" v-if="isLoading"/>
         <div v-for="(item, index) in filteredItems" :key="item.name" class="item" :class="{selected: item.selected, active: active === index}" @click="selectItem(item)" :ref="'listItem' + index">
           {{ item.name }}
-          <a v-if="enableFeed && mode === 'branches'" role="button" class="rss-icon ui compact right" :href="rssURLPrefix + item.url" target="_blank" @click.stop>
-            <svg-icon name="octicon-rss" :size="14"/>
+          <a v-show="enableFeed && mode === 'branches'" role="button" class="rss-icon ui compact right" :href="rssURLPrefix + item.url" target="_blank" @click.stop>
+            <!-- creating a lot of Vue component is pretty slow, so we use a static SVG here -->
+            <svg width="14" height="14" class="svg octicon-rss"><use href="#svg-symbol-octicon-rss"/></svg>
           </a>
         </div>
         <div class="item" v-if="showCreateNewBranch" :class="{active: active === filteredItems.length}" :ref="'listItem' + filteredItems.length">
           <a href="#" @click="createNewBranch()">
-            <div v-show="createTag">
+            <div v-show="shouldCreateTag">
               <i class="reference tags icon"/>
               <!-- eslint-disable-next-line vue/no-v-html -->
               <span v-html="textCreateTag.replace('%s', searchTerm)"/>
             </div>
-            <div v-show="!createTag">
+            <div v-show="!shouldCreateTag">
               <svg-icon name="octicon-git-branch"/>
               <!-- eslint-disable-next-line vue/no-v-html -->
               <span v-html="textCreateBranch.replace('%s', searchTerm)"/>
@@ -64,12 +67,12 @@
           <form ref="newBranchForm" :action="formActionUrl" method="post">
             <input type="hidden" name="_csrf" :value="csrfToken">
             <input type="hidden" name="new_branch_name" v-model="searchTerm">
-            <input type="hidden" name="create_tag" v-model="createTag">
+            <input type="hidden" name="create_tag" v-model="shouldCreateTag">
             <input type="hidden" name="current_path" v-model="treePath" v-if="treePath">
           </form>
         </div>
       </div>
-      <div class="message" v-if="showNoResults">
+      <div class="message" v-if="showNoResults && !isLoading">
         {{ noResults }}
       </div>
     </div>
@@ -81,6 +84,7 @@ import {createApp, nextTick} from 'vue';
 import $ from 'jquery';
 import {SvgIcon} from '../svg.js';
 import {pathEscapeSegments} from '../utils/url.js';
+import {showErrorToast} from '../modules/toast.js';
 
 const sfc = {
   components: {SvgIcon},
@@ -110,12 +114,16 @@ const sfc = {
     formActionUrl() {
       return `${this.repoLink}/branches/_new/${this.branchNameSubURL}`;
     },
+    shouldCreateTag() {
+      return this.mode === 'tags';
+    }
   },
 
   watch: {
     menuVisible(visible) {
       if (visible) {
         this.focusSearchField();
+        this.fetchBranchesOrTags();
       }
     }
   },
@@ -139,7 +147,6 @@ const sfc = {
       }
     });
   },
-
   methods: {
     selectItem(item) {
       const prev = this.getSelected();
@@ -246,7 +253,44 @@ const sfc = {
         event.preventDefault();
         this.menuVisible = false;
       }
-    }
+    },
+    handleTabSwitch(mode) {
+      if (this.isLoading) return;
+      this.mode = mode;
+      this.focusSearchField();
+      this.fetchBranchesOrTags();
+    },
+    async fetchBranchesOrTags() {
+      if (!['branches', 'tags'].includes(this.mode) || this.isLoading) return;
+      // only fetch when branch/tag list has not been initialized
+      if (this.hasListInitialized[this.mode] ||
+        (this.mode === 'branches' && !this.showBranchesInDropdown) ||
+        (this.mode === 'tags' && this.noTag)
+      ) {
+        return;
+      }
+      this.isLoading = true;
+      try {
+        // the "data.defaultBranch" is ambiguous, it could be "branch name" or "tag name"
+        const reqUrl = `${this.repoLink}/${this.mode}/list`;
+        const resp = await fetch(reqUrl);
+        const {results} = await resp.json();
+        for (const result of results) {
+          let selected = false;
+          if (this.mode === 'branches') {
+            selected = result === this.defaultBranch;
+          } else {
+            selected = result === (this.release ? this.release.tagName : this.defaultBranch);
+          }
+          this.items.push({name: result, url: pathEscapeSegments(result), branch: this.mode === 'branches', tag: this.mode === 'tags', selected});
+        }
+        this.hasListInitialized[this.mode] = true;
+      } catch (e) {
+        showErrorToast(`Network error when fetching ${this.mode}, error: ${e}`);
+      } finally {
+        this.isLoading = false;
+      }
+    },
   }
 };
 
@@ -258,7 +302,6 @@ export function initRepoBranchTagSelector(selector) {
       searchTerm: '',
       refNameText: '',
       menuVisible: false,
-      createTag: false,
       release: null,
 
       isViewTag: false,
@@ -266,27 +309,15 @@ export function initRepoBranchTagSelector(selector) {
       isViewTree: false,
 
       active: 0,
-
+      isLoading: false,
+      // This means whether branch list/tag list has initialized
+      hasListInitialized: {
+        'branches': false,
+        'tags': false,
+      },
       ...window.config.pageData.branchDropdownDataList[elIndex],
     };
 
-    // the "data.defaultBranch" is ambiguous, it could be "branch name" or "tag name"
-
-    if (data.showBranchesInDropdown && data.branches) {
-      for (const branch of data.branches) {
-        data.items.push({name: branch, url: pathEscapeSegments(branch), branch: true, tag: false, selected: branch === data.defaultBranch});
-      }
-    }
-    if (!data.noTag && data.tags) {
-      for (const tag of data.tags) {
-        if (data.release) {
-          data.items.push({name: tag, url: pathEscapeSegments(tag), branch: false, tag: true, selected: tag === data.release.tagName});
-        } else {
-          data.items.push({name: tag, url: pathEscapeSegments(tag), branch: false, tag: true, selected: tag === data.defaultBranch});
-        }
-      }
-    }
-
     const comp = {...sfc, data() { return data }};
     createApp(comp).mount(elRoot);
   }
@@ -302,4 +333,8 @@ export default sfc; // activate IDE's Vue plugin
 .menu .item:hover .rss-icon {
   display: inline-block;
 }
+
+.scrolling.menu .loading-indicator {
+  height: 4em;
+}
 </style>
diff --git a/web_src/js/modules/toast.js b/web_src/js/modules/toast.js
index b0d02dc644..b5899052d4 100644
--- a/web_src/js/modules/toast.js
+++ b/web_src/js/modules/toast.js
@@ -1,5 +1,6 @@
 import {htmlEscape} from 'escape-goat';
 import {svg} from '../svg.js';
+import Toastify from 'toastify-js';
 
 const levels = {
   info: {
@@ -23,7 +24,6 @@ const levels = {
 async function showToast(message, level, {gravity, position, duration, ...other} = {}) {
   if (!message) return;
 
-  const {default: Toastify} = await import(/* webpackChunkName: 'toastify' */'toastify-js');
   const {icon, background, duration: levelDuration} = levels[level ?? 'info'];
 
   const toast = Toastify({
diff --git a/web_src/js/svg.js b/web_src/js/svg.js
index b0c55e4e37..2ef839aa21 100644
--- a/web_src/js/svg.js
+++ b/web_src/js/svg.js
@@ -185,9 +185,10 @@ export const SvgIcon = {
     name: {type: String, required: true},
     size: {type: Number, default: 16},
     className: {type: String, default: ''},
+    symbolId: {type: String}
   },
   render() {
-    const {svgOuter, svgInnerHtml} = svgParseOuterInner(this.name);
+    let {svgOuter, svgInnerHtml} = svgParseOuterInner(this.name);
     // https://vuejs.org/guide/extras/render-function.html#creating-vnodes
     // the `^` is used for attr, set SVG attributes like 'width', `aria-hidden`, `viewBox`, etc
     const attrs = {};
@@ -207,7 +208,10 @@ export const SvgIcon = {
     if (this.className) {
       classes.push(...this.className.split(/\s+/).filter(Boolean));
     }
-
+    if (this.symbolId) {
+      classes.push('gt-hidden', 'svg-symbol-container');
+      svgInnerHtml = `<symbol id="${this.symbolId}" viewBox="${attrs['^viewBox']}">${svgInnerHtml}</symbol>`;
+    }
     // create VNode
     return h('svg', {
       ...attrs,