Add Primer-like Counter Angular component

Ports a simplified `Primer::Beta::Counter` to Angular as
`PrimerCounterLabelComponent` so the `.Counter` badge can be used from
Angular templates. Supports `count`, `scheme`, `limit`, and
`hideIfZero`; the Ruby `text` and `round` options are omitted.

config/locales/js-en.yml

@@ -401,6 +401,7 @@ en:
     label_in_more_than: "in more than"
     label_incoming_emails: "Incoming emails"
     label_information_plural: "Information"
+    label_infinity: "Infinity"
     label_invalid: "Invalid"
     label_import: "Import"
     label_latest_activity: "Latest activity"
@@ -425,6 +426,7 @@ en:
     label_no_value: "No value"
     label_none: "none"
     label_not_contains: "doesn't contain"
+    label_not_available: "Not available"
     label_not_equals: "is not"
     label_on: "on"
     label_open_menu: "Open menu"

frontend/src/app/shared/components/primer/counter.component.html

@@ -0,0 +1,8 @@
+<span
+  class="Counter"
+  [class.Counter--primary]="scheme() === 'primary'"
+  [class.Counter--secondary]="scheme() === 'secondary'"
+  [title]="titleText()"
+  [hidden]="hidden()"
+  [textContent]="value()"
+></span>

frontend/src/app/shared/components/primer/counter.component.spec.ts

@@ -0,0 +1,131 @@
+//-- copyright
+// OpenProject is an open source project management software.
+// Copyright (C) the OpenProject GmbH
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License version 3.
+//
+// OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+// Copyright (C) 2006-2013 Jean-Philippe Lang
+// Copyright (C) 2010-2013 the ChiliProject Team
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License
+// as published by the Free Software Foundation; either version 2
+// of the License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+//
+// See COPYRIGHT and LICENSE files for more details.
+//++
+
+import { ComponentFixture, TestBed } from '@angular/core/testing';
+import { I18nService } from 'core-app/core/i18n/i18n.service';
+import { PrimerCounterComponent } from './counter.component';
+
+describe('PrimerCounterComponent', () => {
+  const I18nStub = {
+    locale: 'en',
+    t(key:string) {
+      return {
+        'js.label_infinity': 'Infinity',
+        'js.label_not_available': 'Not available',
+      }[key] ?? key;
+    },
+  };
+
+  let fixture:ComponentFixture<PrimerCounterComponent>;
+  let span:HTMLSpanElement;
+
+  beforeEach(async () => {
+    await TestBed.configureTestingModule({
+      imports: [PrimerCounterComponent],
+      providers: [
+        { provide: I18nService, useValue: I18nStub },
+      ],
+    }).compileComponents();
+
+    fixture = TestBed.createComponent(PrimerCounterComponent);
+    span = fixture.elementRef.nativeElement.querySelector('span.Counter') as HTMLSpanElement;
+  });
+
+  function render(inputs:Record<string, unknown>):void {
+    Object.entries(inputs).forEach(([key, value]) => fixture.componentRef.setInput(key, value));
+    fixture.detectChanges();
+  }
+
+  it('renders a plain count', () => {
+    render({ count: 12 });
+
+    expect(span.textContent).toEqual('12');
+    expect(span.getAttribute('title')).toEqual('12');
+  });
+
+  it('delimits large numbers', () => {
+    render({ count: 1234, limit: null });
+
+    expect(span.textContent).toEqual('1,234');
+  });
+
+  it('applies the limit with a trailing plus', () => {
+    render({ count: 6000, limit: 5000 });
+
+    expect(span.textContent).toEqual('5,000+');
+    expect(span.getAttribute('title')).toEqual('5,000+');
+  });
+
+  it('renders nothing and a fallback title for a null count', () => {
+    render({ count: null });
+
+    expect(span.textContent).toEqual('');
+    expect(span.getAttribute('title')).toEqual('Not available');
+  });
+
+  it('renders nothing and a fallback title for an undefined count', () => {
+    render({ count: undefined });
+
+    expect(span.textContent).toEqual('');
+    expect(span.getAttribute('title')).toEqual('Not available');
+  });
+
+  it('renders nothing and a fallback title for a NaN count', () => {
+    render({ count: NaN });
+
+    expect(span.textContent).toEqual('');
+    expect(span.getAttribute('title')).toEqual('Not available');
+  });
+
+  it('renders the infinity symbol', () => {
+    render({ count: Infinity });
+
+    expect(span.textContent).toEqual('∞');
+    expect(span.getAttribute('title')).toEqual('Infinity');
+  });
+
+  it('applies the scheme modifier class', () => {
+    render({ count: 1, scheme: 'secondary' });
+
+    expect(span.classList).toContain('Counter--secondary');
+    expect(span.classList).not.toContain('Counter--primary');
+  });
+
+  it('hides a zero count when hideIfZero is set', () => {
+    render({ count: 0, 'hide-if-zero': true });
+
+    expect(span.hidden).toBe(true);
+  });
+
+  it('does not hide a zero count by default', () => {
+    render({ count: 0 });
+
+    expect(span.hidden).toBe(false);
+    expect(span.textContent).toEqual('0');
+  });
+});

frontend/src/app/shared/components/primer/counter.component.ts

@@ -0,0 +1,106 @@
+//-- copyright
+// OpenProject is an open source project management software.
+// Copyright (C) the OpenProject GmbH
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License version 3.
+//
+// OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+// Copyright (C) 2006-2013 Jean-Philippe Lang
+// Copyright (C) 2010-2013 the ChiliProject Team
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License
+// as published by the Free Software Foundation; either version 2
+// of the License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+//
+// See COPYRIGHT and LICENSE files for more details.
+//++
+
+/* eslint-disable @angular-eslint/component-selector, @angular-eslint/no-input-rename */
+
+import { ChangeDetectionStrategy, Component, computed, inject, input } from '@angular/core';
+import { I18nService } from 'core-app/core/i18n/i18n.service';
+
+type Scheme = 'default' | 'primary' | 'secondary';
+
+// Angular port of Primer::Beta::Counter, used to add a count to navigational
+// elements. The `text` and `round` options of the Ruby component are not
+// supported.
+@Component({
+  selector: 'primer-counter',
+  templateUrl: './counter.component.html',
+  changeDetection: ChangeDetectionStrategy.OnPush,
+  standalone: true,
+})
+export class PrimerCounterComponent {
+  private readonly I18n = inject(I18nService);
+
+  // The number to be displayed (e.g. # of issues, pull requests).
+  readonly count = input<number | null>(0);
+
+  // Color scheme. One of default | primary | secondary.
+  readonly scheme = input<Scheme>('default');
+
+  // Maximum value to display. Pass `null` for no limit. When `count` exceeds
+  // `limit`, the value is rendered as e.g. "5,000+".
+  readonly limit = input<number | null>(5_000);
+
+  // When true, a `hidden` attribute is added to the counter if `count` is zero.
+  readonly hideIfZero = input(false, { alias: 'hide-if-zero' });
+
+  // Displayed text: "" when no value (CSS hides it), "∞" for infinity,
+  // otherwise the delimited count.
+  readonly value = computed(() => {
+    const count = this.count();
+    if (count === null || count === undefined) {
+      return ''; // CSS will hide it
+    }
+    if (count === Infinity || count === -Infinity) {
+      return '∞';
+    }
+    if (Number.isNaN(count)) {
+      return '';
+    }
+    return this.displayNumber(count);
+  });
+
+  // Title attribute, mirroring the displayed count (including limit capping) as a tooltip.
+  readonly titleText = computed(() => {
+    const count = this.count();
+    if (count === null || count === undefined) {
+      return this.I18n.t('js.label_not_available');
+    }
+    if (count === Infinity || count === -Infinity) {
+      return this.I18n.t('js.label_infinity');
+    }
+    if (Number.isNaN(count)) {
+      return this.I18n.t('js.label_not_available');
+    }
+    return this.displayNumber(count);
+  });
+
+  readonly hidden = computed(() => this.count() === 0 && this.hideIfZero());
+
+  private displayNumber(count:number):string {
+    const value = Math.trunc(count);
+    const limit = this.limit();
+    const capped = limit === null ? value : Math.min(value, limit);
+    const formatter = new Intl.NumberFormat(this.I18n.locale, {
+      maximumFractionDigits: 0,
+      useGrouping: true,
+    });
+    const str = formatter.format(capped);
+
+    return limit !== null && value > limit ? `${str}+` : str;
+  }
+}

frontend/src/app/shared/shared.module.ts

@@ -84,6 +84,7 @@ import { OpenprojectModalModule } from 'core-app/shared/components/modal/modal.m
 import { FullCalendarModule } from '@fullcalendar/angular';
 import { OpDatePickerModule } from 'core-app/shared/components/datepicker/datepicker.module';
 import { OpBreadcrumbsComponent } from './components/breadcrumbs/op-breadcrumbs.component';
+import { PrimerCounterComponent } from './components/primer/counter.component';
 import { PrimerIconButtonComponent } from './components/primer/icon-button.component';
 
 export function bootstrapModule(injector:Injector):void {
@@ -127,6 +128,7 @@ export function bootstrapModule(injector:Injector):void {
     FullCalendarModule,
     OpDatePickerModule,
 
+    PrimerCounterComponent,
     PrimerIconButtonComponent
   ],
   exports: [
@@ -181,6 +183,7 @@ export function bootstrapModule(injector:Injector):void {
 
     OpNonWorkingDaysListComponent,
 
+    PrimerCounterComponent,
     PrimerIconButtonComponent
   ],
   providers: [