Fix duplicate dropdown dividers (#32760)

Fix #27466

The problem is that any item in the menu could be hidden, pure CSS won't
work, and dropdown's builtin "hideDividers" doesn't work with our "scope
dividers". The newly introduced "archived" label makes the dividers
regression more.

10 files changed, 179 insertions, 42 deletions

diff --git a/.eslintrc.yaml b/.eslintrc.yaml
index 048ca393d1..04eb023634 100644
--- a/.eslintrc.yaml
+++ b/.eslintrc.yaml
@@ -818,7 +818,7 @@ rules:
   unicorn/consistent-destructuring: [2]
   unicorn/consistent-empty-array-spread: [2]
   unicorn/consistent-existence-index-check: [0]
-  unicorn/consistent-function-scoping: [2]
+  unicorn/consistent-function-scoping: [0]
   unicorn/custom-error-definition: [0]
   unicorn/empty-brace-spaces: [2]
   unicorn/error-message: [0]
diff --git a/modules/templates/helper.go b/modules/templates/helper.go
index fdfb21925a..e262892069 100644
--- a/modules/templates/helper.go
+++ b/modules/templates/helper.go
@@ -294,9 +294,7 @@ func timeEstimateString(timeSec any) string {
 	return util.TimeEstimateString(v)
 }
 
-type QueryString string
-
-func queryBuild(a ...any) QueryString {
+func queryBuild(a ...any) template.URL {
 	var s string
 	if len(a)%2 == 1 {
 		if v, ok := a[0].(string); ok {
@@ -304,7 +302,7 @@ func queryBuild(a ...any) QueryString {
 				panic("queryBuild: invalid argument")
 			}
 			s = v
-		} else if v, ok := a[0].(QueryString); ok {
+		} else if v, ok := a[0].(template.URL); ok {
 			s = string(v)
 		} else {
 			panic("queryBuild: invalid argument")
@@ -356,7 +354,7 @@ func queryBuild(a ...any) QueryString {
 	if s != "" && s != "&" && s[len(s)-1] == '&' {
 		s = s[:len(s)-1]
 	}
-	return QueryString(s)
+	return template.URL(s)
 }
 
 func panicIfDevOrTesting() {
diff --git a/templates/projects/view.tmpl b/templates/projects/view.tmpl
index 71f9d059ad..acaf45e8d2 100644
--- a/templates/projects/view.tmpl
+++ b/templates/projects/view.tmpl
@@ -36,10 +36,11 @@
 							{{range .Labels}}
 								{{$exclusiveScope := .ExclusiveScope}}
 								{{if and (ne $previousExclusiveScope $exclusiveScope)}}
-									<div class="divider"></div>
+									<div class="divider" data-scope="{{.ExclusiveScope}}"></div>
 								{{end}}
 								{{$previousExclusiveScope = $exclusiveScope}}
-								<a class="item label-filter-item tw-flex tw-items-center" {{if .IsArchived}}data-is-archived{{end}} href="?labels={{.QueryString}}&assignee={{$.AssigneeID}}{{if $.ShowArchivedLabels}}&archived=true{{end}}" data-label-id="{{.ID}}">
+								<a class="item label-filter-item tw-flex tw-items-center" data-label-id="{{.ID}}" data-scope="{{.ExclusiveScope}}" {{if .IsArchived}}data-is-archived{{end}}
+									href="?labels={{.QueryString}}&assignee={{$.AssigneeID}}{{if $.ShowArchivedLabels}}&archived=true{{end}}">
 									{{if .IsExcluded}}
 										{{svg "octicon-circle-slash"}}
 									{{else if .IsSelected}}
diff --git a/templates/repo/issue/filter_list.tmpl b/templates/repo/issue/filter_list.tmpl
index 7335c949f4..e686f1d60f 100644
--- a/templates/repo/issue/filter_list.tmpl
+++ b/templates/repo/issue/filter_list.tmpl
@@ -30,10 +30,11 @@
 		{{range .Labels}}
 			{{$exclusiveScope := .ExclusiveScope}}
 			{{if and (ne $previousExclusiveScope $exclusiveScope)}}
-				<div class="divider"></div>
+				<div class="divider" data-scope="{{.ExclusiveScope}}"></div>
 			{{end}}
 			{{$previousExclusiveScope = $exclusiveScope}}
-			<a class="item label-filter-item tw-flex tw-items-center" {{if .IsArchived}}data-is-archived{{end}} href="{{QueryBuild $queryLink "labels" .QueryString}}" data-label-id="{{.ID}}">
+			<a class="item label-filter-item tw-flex tw-items-center" data-label-id="{{.ID}}" data-scope="{{.ExclusiveScope}}" {{if .IsArchived}}data-is-archived{{end}}
+				href="{{QueryBuild $queryLink "labels" .QueryString}}">
 				{{if .IsExcluded}}
 					{{svg "octicon-circle-slash"}}
 				{{else if .IsSelected}}
diff --git a/templates/repo/issue/sidebar/label_list.tmpl b/templates/repo/issue/sidebar/label_list.tmpl
index fb8f1a667e..9dd83ba188 100644
--- a/templates/repo/issue/sidebar/label_list.tmpl
+++ b/templates/repo/issue/sidebar/label_list.tmpl
@@ -22,7 +22,7 @@
 					{{range $data.RepoLabels}}
 						{{$exclusiveScope := .ExclusiveScope}}
 						{{if and (ne $previousExclusiveScope "_no_scope") (ne $previousExclusiveScope $exclusiveScope)}}
-							<div class="divider"></div>
+							<div class="divider" data-scope="{{.ExclusiveScope}}"></div>
 						{{end}}
 						{{$previousExclusiveScope = $exclusiveScope}}
 						{{template "repo/issue/sidebar/label_list_item" dict "Label" .}}
@@ -32,7 +32,7 @@
 					{{range $data.OrgLabels}}
 						{{$exclusiveScope := .ExclusiveScope}}
 						{{if and (ne $previousExclusiveScope "_no_scope") (ne $previousExclusiveScope $exclusiveScope)}}
-							<div class="divider"></div>
+							<div class="divider" data-scope="{{.ExclusiveScope}}"></div>
 						{{end}}
 						{{$previousExclusiveScope = $exclusiveScope}}
 						{{template "repo/issue/sidebar/label_list_item" dict "Label" .}}
diff --git a/web_src/js/features/repo-issue.ts b/web_src/js/features/repo-issue.ts
index 477edbeb5f..f5a36b7717 100644
--- a/web_src/js/features/repo-issue.ts
+++ b/web_src/js/features/repo-issue.ts
@@ -8,6 +8,7 @@ import {parseIssuePageInfo, toAbsoluteUrl} from '../utils.ts';
 import {GET, POST} from '../modules/fetch.ts';
 import {showErrorToast} from '../modules/toast.ts';
 import {initRepoIssueSidebar} from './repo-issue-sidebar.ts';
+import {fomanticQuery} from '../modules/fomantic/base.ts';
 
 const {appSubUrl} = window.config;
 
@@ -31,34 +32,35 @@ export function initRepoIssueSidebarList() {
   if (crossRepoSearch === 'true') {
     issueSearchUrl = `${appSubUrl}/issues/search?q={query}&priority_repo_id=${issuePageInfo.repoId}&type=${issuePageInfo.issueDependencySearchType}`;
   }
-  $('#new-dependency-drop-list')
-    .dropdown({
-      apiSettings: {
-        url: issueSearchUrl,
-        onResponse(response) {
-          const filteredResponse = {success: true, results: []};
-          const currIssueId = $('#new-dependency-drop-list').data('issue-id');
-          // Parse the response from the api to work with our dropdown
-          $.each(response, (_i, issue) => {
-            // Don't list current issue in the dependency list.
-            if (issue.id === currIssueId) {
-              return;
-            }
-            filteredResponse.results.push({
-              name: `<div class="gt-ellipsis">#${issue.number} ${htmlEscape(issue.title)}</div>
+  fomanticQuery('#new-dependency-drop-list').dropdown({
+    fullTextSearch: true,
+    apiSettings: {
+      url: issueSearchUrl,
+      onResponse(response) {
+        const filteredResponse = {success: true, results: []};
+        const currIssueId = $('#new-dependency-drop-list').data('issue-id');
+        // Parse the response from the api to work with our dropdown
+        $.each(response, (_i, issue) => {
+          // Don't list current issue in the dependency list.
+          if (issue.id === currIssueId) {
+            return;
+          }
+          filteredResponse.results.push({
+            name: `<div class="gt-ellipsis">#${issue.number} ${htmlEscape(issue.title)}</div>
 <div class="text small tw-break-anywhere">${htmlEscape(issue.repository.full_name)}</div>`,
-              value: issue.id,
-            });
+            value: issue.id,
           });
-          return filteredResponse;
-        },
-        cache: false,
+        });
+        return filteredResponse;
       },
+      cache: false,
+    },
+  });
+}
 
-      fullTextSearch: true,
-    });
-
-  $('.menu a.label-filter-item').each(function () {
+export function initRepoIssueLabelFilter() {
+  // the "label-filter" is used in 2 templates: projects/view, issue/filter_list (issue list page including the milestone page)
+  $('.ui.dropdown.label-filter a.label-filter-item').each(function () {
     $(this).on('click', function (e) {
       if (e.altKey) {
         e.preventDefault();
@@ -66,11 +68,9 @@ export function initRepoIssueSidebarList() {
       }
     });
   });
-
-  // FIXME: it is wrong place to init ".ui.dropdown.label-filter"
-  $('.menu .ui.dropdown.label-filter').on('keydown', (e) => {
+  $('.ui.dropdown.label-filter').on('keydown', (e) => {
     if (e.altKey && e.key === 'Enter') {
-      const selectedItem = document.querySelector('.menu .ui.dropdown.label-filter .menu .item.selected');
+      const selectedItem = document.querySelector('.ui.dropdown.label-filter .menu .item.selected');
       if (selectedItem) {
         excludeLabel(selectedItem);
       }
diff --git a/web_src/js/index.ts b/web_src/js/index.ts
index f93c3495af..2964ef5572 100644
--- a/web_src/js/index.ts
+++ b/web_src/js/index.ts
@@ -29,7 +29,7 @@ import {
   initRepoIssueWipTitle,
   initRepoPullRequestMergeInstruction,
   initRepoPullRequestAllowMaintainerEdit,
-  initRepoPullRequestReview, initRepoIssueSidebarList,
+  initRepoPullRequestReview, initRepoIssueSidebarList, initRepoIssueLabelFilter,
 } from './features/repo-issue.ts';
 import {initRepoEllipsisButton, initCommitStatuses} from './features/repo-commit.ts';
 import {initRepoTopicBar} from './features/repo-home.ts';
@@ -181,6 +181,7 @@ onDomReady(() => {
     initRepoGraphGit,
     initRepoIssueContentHistory,
     initRepoIssueList,
+    initRepoIssueLabelFilter,
     initRepoIssueSidebarList,
     initRepoIssueReferenceRepositorySearch,
     initRepoIssueWipTitle,
diff --git a/web_src/js/modules/fomantic/dropdown.test.ts b/web_src/js/modules/fomantic/dropdown.test.ts
new file mode 100644
index 0000000000..587e0bca7c
--- /dev/null
+++ b/web_src/js/modules/fomantic/dropdown.test.ts
@@ -0,0 +1,56 @@
+import {createElementFromHTML} from '../../utils/dom.ts';
+import {hideScopedEmptyDividers} from './dropdown.ts';
+
+test('hideScopedEmptyDividers-simple', () => {
+  const container = createElementFromHTML(`<div>
+<div class="divider"></div>
+<div class="item">a</div>
+<div class="divider"></div>
+<div class="divider"></div>
+<div class="divider"></div>
+<div class="item">b</div>
+<div class="divider"></div>
+</div>`);
+  hideScopedEmptyDividers(container);
+  expect(container.innerHTML).toEqual(`
+<div class="divider hidden transition"></div>
+<div class="item">a</div>
+<div class="divider hidden transition"></div>
+<div class="divider hidden transition"></div>
+<div class="divider"></div>
+<div class="item">b</div>
+<div class="divider hidden transition"></div>
+`);
+});
+
+test('hideScopedEmptyDividers-hidden1', () => {
+  const container = createElementFromHTML(`<div>
+<div class="item">a</div>
+<div class="divider" data-scope="b"></div>
+<div class="item tw-hidden" data-scope="b">b</div>
+</div>`);
+  hideScopedEmptyDividers(container);
+  expect(container.innerHTML).toEqual(`
+<div class="item">a</div>
+<div class="divider hidden transition" data-scope="b"></div>
+<div class="item tw-hidden" data-scope="b">b</div>
+`);
+});
+
+test('hideScopedEmptyDividers-hidden2', () => {
+  const container = createElementFromHTML(`<div>
+<div class="item" data-scope="">a</div>
+<div class="divider" data-scope="b"></div>
+<div class="item tw-hidden" data-scope="b">b</div>
+<div class="divider" data-scope=""></div>
+<div class="item" data-scope="">c</div>
+</div>`);
+  hideScopedEmptyDividers(container);
+  expect(container.innerHTML).toEqual(`
+<div class="item" data-scope="">a</div>
+<div class="divider hidden transition" data-scope="b"></div>
+<div class="item tw-hidden" data-scope="b">b</div>
+<div class="divider hidden transition" data-scope=""></div>
+<div class="item" data-scope="">c</div>
+`);
+});
diff --git a/web_src/js/modules/fomantic/dropdown.ts b/web_src/js/modules/fomantic/dropdown.ts
index d8fb4d6e6e..6d0f12cb43 100644
--- a/web_src/js/modules/fomantic/dropdown.ts
+++ b/web_src/js/modules/fomantic/dropdown.ts
@@ -59,6 +59,12 @@ function updateSelectionLabel(label: HTMLElement) {
   }
 }
 
+function processMenuItems($dropdown, dropdownCall) {
+  const hideEmptyDividers = dropdownCall('setting', 'hideDividers') === 'empty';
+  const itemsMenu = $dropdown[0].querySelector('.scrolling.menu') || $dropdown[0].querySelector('.menu');
+  if (hideEmptyDividers) hideScopedEmptyDividers(itemsMenu);
+}
+
 // delegate the dropdown's template functions and callback functions to add aria attributes.
 function delegateOne($dropdown: any) {
   const dropdownCall = fomanticDropdownFn.bind($dropdown);
@@ -72,6 +78,18 @@ function delegateOne($dropdown: any) {
   // * If the "dropdown icon" is clicked again when the menu is visible, Fomantic calls "blurSearch", so hide the menu
   dropdownCall('internal', 'blurSearch', function () { oldBlurSearch.call(this); dropdownCall('hide') });
 
+  const oldFilterItems = dropdownCall('internal', 'filterItems');
+  dropdownCall('internal', 'filterItems', function (...args: any[]) {
+    oldFilterItems.call(this, ...args);
+    processMenuItems($dropdown, dropdownCall);
+  });
+
+  const oldShow = dropdownCall('internal', 'show');
+  dropdownCall('internal', 'show', function (...args: any[]) {
+    oldShow.call(this, ...args);
+    processMenuItems($dropdown, dropdownCall);
+  });
+
   // the "template" functions are used for dynamic creation (eg: AJAX)
   const dropdownTemplates = {...dropdownCall('setting', 'templates'), t: performance.now()};
   const dropdownTemplatesMenuOld = dropdownTemplates.menu;
@@ -271,3 +289,65 @@ function attachDomEvents(dropdown: HTMLElement, focusable: HTMLElement, menu: HT
     ignoreClickPreEvents = ignoreClickPreVisible = 0;
   }, true);
 }
+
+// Although Fomantic Dropdown supports "hideDividers", it doesn't really work with our "scoped dividers"
+// At the moment, "label dropdown items" use scopes, a sample case is:
+// * a-label
+// * divider
+// * scope/1
+// * scope/2
+// * divider
+// * z-label
+// when the "scope/*" are filtered out, we'd like to see "a-label" and "z-label" without the divider.
+export function hideScopedEmptyDividers(container: Element) {
+  const visibleItems: Element[] = [];
+  const curScopeVisibleItems: Element[] = [];
+  let curScope: string = '', lastVisibleScope: string = '';
+  const isScopedDivider = (item: Element) => item.matches('.divider') && item.hasAttribute('data-scope');
+  const hideDivider = (item: Element) => item.classList.add('hidden', 'transition'); // dropdown has its own classes to hide items
+
+  const handleScopeSwitch = (itemScope: string) => {
+    if (curScopeVisibleItems.length === 1 && isScopedDivider(curScopeVisibleItems[0])) {
+      hideDivider(curScopeVisibleItems[0]);
+    } else if (curScopeVisibleItems.length) {
+      if (isScopedDivider(curScopeVisibleItems[0]) && lastVisibleScope === curScope) {
+        hideDivider(curScopeVisibleItems[0]);
+        curScopeVisibleItems.shift();
+      }
+      visibleItems.push(...curScopeVisibleItems);
+      lastVisibleScope = curScope;
+    }
+    curScope = itemScope;
+    curScopeVisibleItems.length = 0;
+  };
+
+  // hide the scope dividers if the scope items are empty
+  for (const item of container.children) {
+    const itemScope = item.getAttribute('data-scope') || '';
+    if (itemScope !== curScope) {
+      handleScopeSwitch(itemScope);
+    }
+    if (!item.classList.contains('filtered') && !item.classList.contains('tw-hidden')) {
+      curScopeVisibleItems.push(item as HTMLElement);
+    }
+  }
+  handleScopeSwitch('');
+
+  // hide all leading and trailing dividers
+  while (visibleItems.length) {
+    if (!visibleItems[0].matches('.divider')) break;
+    hideDivider(visibleItems[0]);
+    visibleItems.shift();
+  }
+  while (visibleItems.length) {
+    if (!visibleItems[visibleItems.length - 1].matches('.divider')) break;
+    hideDivider(visibleItems[visibleItems.length - 1]);
+    visibleItems.pop();
+  }
+  // hide all duplicate dividers, hide current divider if next sibling is still divider
+  // no need to update "visibleItems" array since this is the last loop
+  for (const item of visibleItems) {
+    if (!item.matches('.divider')) continue;
+    if (item.nextElementSibling?.matches('.divider')) hideDivider(item);
+  }
+}
diff --git a/web_src/js/webcomponents/overflow-menu.ts b/web_src/js/webcomponents/overflow-menu.ts
index 777d7dc65d..4e729a268a 100644
--- a/web_src/js/webcomponents/overflow-menu.ts
+++ b/web_src/js/webcomponents/overflow-menu.ts
@@ -12,7 +12,7 @@ window.customElements.define('overflow-menu', class extends HTMLElement {
   mutationObserver: MutationObserver;
   lastWidth: number;
 
-  updateItems = throttle(100, () => { // eslint-disable-line unicorn/consistent-function-scoping -- https://github.com/sindresorhus/eslint-plugin-unicorn/issues/2088
+  updateItems = throttle(100, () => {
     if (!this.tippyContent) {
       const div = document.createElement('div');
       div.classList.add('tippy-target');