Refactor diffFileInfo / DiffTreeStore (#24998)

Follow  #21012, #22399

Replace #24983, fix #24938

Help #24956

Now, the `window.config.pageData.diffFileInfo` itself is a reactive
store, so it's quite easy to sync values/states by it, no need to do
"doLoadMoreFiles" or "callback".

Screenshot: these two buttons both work. After complete loading, the UI
is also right.

<details>


![image](https://github.com/go-gitea/gitea/assets/2114189/cc6310fd-7f27-45ea-ab4f-24952a87b421)


![image](https://github.com/go-gitea/gitea/assets/2114189/4c11dd67-ac03-4568-8541-91204d27a4e3)


![image](https://github.com/go-gitea/gitea/assets/2114189/38a22cec-41be-41e6-a209-f347b7a4c1de)

</details>

5 files changed, 51 insertions, 73 deletions

diff --git a/web_src/js/components/DiffFileList.vue b/web_src/js/components/DiffFileList.vue
index 658357a887..131be01811 100644
--- a/web_src/js/components/DiffFileList.vue
+++ b/web_src/js/components/DiffFileList.vue
@@ -1,10 +1,10 @@
 <template>
-  <ol class="diff-detail-box diff-stats gt-m-0" ref="root" v-if="fileListIsVisible">
-    <li v-for="file in files" :key="file.NameHash">
+  <ol class="diff-detail-box diff-stats gt-m-0" ref="root" v-if="store.fileListIsVisible">
+    <li v-for="file in store.files" :key="file.NameHash">
       <div class="gt-font-semibold gt-df gt-ac pull-right">
-        <span v-if="file.IsBin" class="gt-ml-1 gt-mr-3">{{ binaryFileMessage }}</span>
+        <span v-if="file.IsBin" class="gt-ml-1 gt-mr-3">{{ store.binaryFileMessage }}</span>
         {{ file.IsBin ? '' : file.Addition + file.Deletion }}
-        <span v-if="!file.IsBin" class="diff-stats-bar gt-mx-3" :data-tooltip-content="statisticsMessage.replace('%d', (file.Addition + file.Deletion)).replace('%d', file.Addition).replace('%d', file.Deletion)">
+        <span v-if="!file.IsBin" class="diff-stats-bar gt-mx-3" :data-tooltip-content="store.statisticsMessage.replace('%d', (file.Addition + file.Deletion)).replace('%d', file.Addition).replace('%d', file.Deletion)">
           <div class="diff-stats-add-bar" :style="{ 'width': diffStatsWidth(file.Addition, file.Deletion) }"/>
         </span>
       </div>
@@ -12,22 +12,21 @@
       <span :class="['status', diffTypeToString(file.Type)]" :data-tooltip-content="diffTypeToString(file.Type)">&nbsp;</span>
       <a class="file gt-mono" :href="'#diff-' + file.NameHash">{{ file.Name }}</a>
     </li>
-    <li v-if="isIncomplete" id="diff-too-many-files-stats" class="gt-pt-2">
-      <span class="file gt-df gt-ac gt-sb">{{ tooManyFilesMessage }}
-        <a :class="['ui', 'basic', 'tiny', 'button', isLoadingNewData === true ? 'disabled' : '']" id="diff-show-more-files-stats" @click.stop="loadMoreData">{{ showMoreMessage }}</a>
+    <li v-if="store.isIncomplete" class="gt-pt-2">
+      <span class="file gt-df gt-ac gt-sb">{{ store.tooManyFilesMessage }}
+        <a :class="['ui', 'basic', 'tiny', 'button', store.isLoadingNewData ? 'disabled' : '']" @click.stop="loadMoreData">{{ store.showMoreMessage }}</a>
       </span>
     </li>
   </ol>
 </template>
 
 <script>
-import {doLoadMoreFiles} from '../features/repo-diff.js';
-
-const {pageData} = window.config;
+import {loadMoreFiles} from '../features/repo-diff.js';
+import {diffTreeStore} from '../modules/stores.js';
 
 export default {
   data: () => {
-    return pageData.diffFileInfo;
+    return {store: diffTreeStore()};
   },
   mounted() {
     document.getElementById('show-file-list-btn').addEventListener('click', this.toggleFileList);
@@ -37,7 +36,7 @@ export default {
   },
   methods: {
     toggleFileList() {
-      this.fileListIsVisible = !this.fileListIsVisible;
+      this.store.fileListIsVisible = !this.store.fileListIsVisible;
     },
     diffTypeToString(pType) {
       const diffTypes = {
@@ -53,10 +52,7 @@ export default {
       return `${adds / (adds + dels) * 100}%`;
     },
     loadMoreData() {
-      this.isLoadingNewData = true;
-      doLoadMoreFiles(this.link, this.diffEnd, () => {
-        this.isLoadingNewData = false;
-      });
+      loadMoreFiles(this.store.linkLoadMore);
     }
   },
 };
diff --git a/web_src/js/components/DiffFileTree.vue b/web_src/js/components/DiffFileTree.vue
index 6ac16def99..734ad80e8b 100644
--- a/web_src/js/components/DiffFileTree.vue
+++ b/web_src/js/components/DiffFileTree.vue
@@ -1,42 +1,33 @@
 <template>
-  <div
-    v-if="fileTreeIsVisible"
-    class="gt-mr-3 gt-mt-3 diff-detail-box"
-  >
+  <div v-if="store.fileTreeIsVisible" class="gt-mr-3 gt-mt-3 diff-detail-box">
     <!-- only render the tree if we're visible. in many cases this is something that doesn't change very often -->
     <div class="ui list">
       <DiffFileTreeItem v-for="item in fileTree" :key="item.name" :item="item"/>
     </div>
-    <div v-if="isIncomplete" id="diff-too-many-files-stats" class="gt-pt-2">
-      <span class="gt-mr-2">{{ tooManyFilesMessage }}</span><a :class="['ui', 'basic', 'tiny', 'button', isLoadingNewData === true ? 'disabled' : '']" id="diff-show-more-files-stats" @click.stop="loadMoreData">{{ showMoreMessage }}</a>
+    <div v-if="store.isIncomplete" class="gt-pt-2">
+      <a :class="['ui', 'basic', 'tiny', 'button', store.isLoadingNewData ? 'disabled' : '']" @click.stop="loadMoreData">{{ store.showMoreMessage }}</a>
     </div>
   </div>
 </template>
 
 <script>
 import DiffFileTreeItem from './DiffFileTreeItem.vue';
-import {doLoadMoreFiles} from '../features/repo-diff.js';
+import {loadMoreFiles} from '../features/repo-diff.js';
 import {toggleElem} from '../utils/dom.js';
-import {DiffTreeStore} from '../modules/stores.js';
+import {diffTreeStore} from '../modules/stores.js';
 import {setFileFolding} from '../features/file-fold.js';
 
-const {pageData} = window.config;
 const LOCAL_STORAGE_KEY = 'diff_file_tree_visible';
 
 export default {
   components: {DiffFileTreeItem},
   data: () => {
-    const fileTreeIsVisible = localStorage.getItem(LOCAL_STORAGE_KEY) === 'true';
-    pageData.diffFileInfo.fileTreeIsVisible = fileTreeIsVisible;
-    return {
-      ...pageData.diffFileInfo,
-      store: DiffTreeStore,
-    };
+    return {store: diffTreeStore()};
   },
   computed: {
     fileTree() {
       const result = [];
-      for (const file of this.files) {
+      for (const file of this.store.files) {
         // Split file into directories
         const splits = file.Name.split('/');
         let index = 0;
@@ -98,9 +89,7 @@ export default {
     }
   },
   mounted() {
-    // replace the pageData.diffFileInfo.files with our watched data so we get updates
-    pageData.diffFileInfo.files = this.files;
-
+    this.store.fileTreeIsVisible = localStorage.getItem(LOCAL_STORAGE_KEY) === 'true';
     document.querySelector('.diff-toggle-file-tree-button').addEventListener('click', this.toggleVisibility);
 
     this.hashChangeListener = () => {
@@ -124,12 +113,12 @@ export default {
       }
     },
     toggleVisibility() {
-      this.updateVisibility(!this.fileTreeIsVisible);
+      this.updateVisibility(!this.store.fileTreeIsVisible);
     },
     updateVisibility(visible) {
-      this.fileTreeIsVisible = visible;
-      localStorage.setItem(LOCAL_STORAGE_KEY, this.fileTreeIsVisible);
-      this.updateState(this.fileTreeIsVisible);
+      this.store.fileTreeIsVisible = visible;
+      localStorage.setItem(LOCAL_STORAGE_KEY, this.store.fileTreeIsVisible);
+      this.updateState(this.store.fileTreeIsVisible);
     },
     updateState(visible) {
       const btn = document.querySelector('.diff-toggle-file-tree-button');
@@ -142,12 +131,7 @@ export default {
       toggleElem(toHide, visible);
     },
     loadMoreData() {
-      this.isLoadingNewData = true;
-      doLoadMoreFiles(this.link, this.diffEnd, () => {
-        this.isLoadingNewData = false;
-        const {pageData} = window.config;
-        this.diffEnd = pageData.diffFileInfo.diffEnd;
-      });
+      loadMoreFiles(this.store.linkLoadMore);
     },
   },
 };
diff --git a/web_src/js/components/DiffFileTreeItem.vue b/web_src/js/components/DiffFileTreeItem.vue
index baaa01b782..916b8cdc73 100644
--- a/web_src/js/components/DiffFileTreeItem.vue
+++ b/web_src/js/components/DiffFileTreeItem.vue
@@ -40,7 +40,7 @@
 
 <script>
 import {SvgIcon} from '../svg.js';
-import {DiffTreeStore} from '../modules/stores.js';
+import {diffTreeStore} from '../modules/stores.js';
 
 export default {
   components: {SvgIcon},
@@ -56,7 +56,7 @@ export default {
     },
   },
   data: () => ({
-    store: DiffTreeStore,
+    store: diffTreeStore(),
     collapsed: false,
   }),
   methods: {
diff --git a/web_src/js/features/repo-diff.js b/web_src/js/features/repo-diff.js
index d0622254bf..1d3c24e342 100644
--- a/web_src/js/features/repo-diff.js
+++ b/web_src/js/features/repo-diff.js
@@ -5,7 +5,7 @@ import {initDiffFileTree} from './repo-diff-filetree.js';
 import {validateTextareaNonEmpty} from './comp/ComboMarkdownEditor.js';
 import {initViewedCheckboxListenerFor, countAndUpdateViewedFiles, initExpandAndCollapseFilesButton} from './pull-view-file.js';
 
-const {csrfToken} = window.config;
+const {csrfToken, pageData} = window.config;
 
 function initRepoDiffReviewButton() {
   const $reviewBox = $('#review-box');
@@ -119,37 +119,29 @@ function onShowMoreFiles() {
   countAndUpdateViewedFiles();
 }
 
-export function doLoadMoreFiles(link, diffEnd, callback) {
-  const url = `${link}?skip-to=${diffEnd}&file-only=true`;
-  loadMoreFiles(url, callback);
-}
-
-function loadMoreFiles(url, callback) {
+export function loadMoreFiles(url) {
   const $target = $('a#diff-show-more-files');
-  if ($target.hasClass('disabled')) {
-    callback();
+  if ($target.hasClass('disabled') || pageData.diffFileInfo.isLoadingNewData) {
     return;
   }
+
+  pageData.diffFileInfo.isLoadingNewData = true;
   $target.addClass('disabled');
   $.ajax({
     type: 'GET',
     url,
   }).done((resp) => {
-    if (!resp) {
-      $target.removeClass('disabled');
-      callback(resp);
-      return;
-    }
-    $('#diff-incomplete').replaceWith($(resp).find('#diff-file-boxes').children());
-    // By simply rerunning the script we add the new data to our existing
-    // pagedata object. this triggers vue and the filetree and filelist will
-    // render the new elements.
-    $('body').append($(resp).find('script#diff-data-script'));
+    const $resp = $(resp);
+    // the response is a full HTML page, we need to extract the relevant contents:
+    // 1. append the newly loaded file list items to the existing list
+    $('#diff-incomplete').replaceWith($resp.find('#diff-file-boxes').children());
+    // 2. re-execute the script to append the newly loaded items to the JS variables to refresh the DiffFileTree
+    $('body').append($resp.find('script#diff-data-script'));
+
     onShowMoreFiles();
-    callback(resp);
-  }).fail(() => {
+  }).always(() => {
     $target.removeClass('disabled');
-    callback();
+    pageData.diffFileInfo.isLoadingNewData = false;
   });
 }
 
@@ -158,7 +150,8 @@ function initRepoDiffShowMore() {
     e.preventDefault();
 
     const $target = $(e.target);
-    loadMoreFiles($target.data('href'), () => {});
+    const linkLoadMore = $target.attr('data-href');
+    loadMoreFiles(linkLoadMore);
   });
 
   $(document).on('click', 'a.diff-load-button', (e) => {
diff --git a/web_src/js/modules/stores.js b/web_src/js/modules/stores.js
index 24b913ce11..1a0ed7eda1 100644
--- a/web_src/js/modules/stores.js
+++ b/web_src/js/modules/stores.js
@@ -1,5 +1,10 @@
 import {reactive} from 'vue';
 
-export const DiffTreeStore = reactive({
-  selectedItem: '',
-});
+let diffTreeStoreReactive;
+export function diffTreeStore() {
+  if (!diffTreeStoreReactive) {
+    diffTreeStoreReactive = reactive(window.config.pageData.diffFileInfo);
+    window.config.pageData.diffFileInfo = diffTreeStoreReactive;
+  }
+  return diffTreeStoreReactive;
+}