# GoodGo Frontend: i18n + A11y Implementation Quick Reference

## 🎯 Key Findings at a Glance

### Current State
- ✅ **Next.js 15** with App Router (well-structured)
- ✅ **React 18** + TypeScript (type-safe)
- ✅ **Tailwind CSS** with dark mode support (HSL-based theme)
- ✅ **Good component library** (~35 components)
- ✅ **Some A11y basics** in place (semantic HTML, ARIA labels, skip link)
- ❌ **NO i18n setup** (everything hardcoded Vietnamese)
- ❌ **A11y gaps** (focus management, some ARIA missing, color contrast TBD)

### Strategic Entry Points for Implementation

#### 1. **i18n Entry Points** (Priority 1)
```
Files to modify for i18n:
├── app/layout.tsx                    → Add i18n provider
├── middleware.ts                     → Add locale routing
├── app/(public)/layout.tsx           → Navigation text
├── app/(auth)/login/page.tsx         → Form labels + errors
├── app/(auth)/register/page.tsx      → Form labels + errors
├── components/listings/listing-form-steps.tsx → Multi-step form labels
├── components/search/filter-bar.tsx  → Filter options + city names
├── lib/validations/*.ts             → Zod error messages
└── [All other components with text]

Total files to update: ~25-30 files with hardcoded strings
```

#### 2. **A11y Critical Fixes** (Priority 1.5)
```
Components needing A11y updates:
├── components/ui/dialog.tsx         → Focus trapping + focus restoration
├── components/listings/image-gallery.tsx → Keyboard nav + ARIA
├── components/search/filter-bar.tsx  → Proper labeling + ARIA
├── app/(dashboard)/layout.tsx        → Tab focus management
└── Across all forms                 → Error message association

Tasks:
- Add focus trapping in modals
- Verify color contrast (WCAG AA)
- Add aria-busy to loading states
- Add proper aria-label to icon buttons
- Link form errors to inputs with aria-describedby
```

#### 3. **Message File Structure for i18n**
```
public/locales/
├── en.json
│   ├── common: { home, search, dashboard, logout, ... }
│   ├── auth: { login, register, email, password, ... }
│   ├── property: { apartment, house, villa, ... }
│   ├── transaction: { sale, rent, ... }
│   ├── directions: { north, south, east, ... }
│   ├── status: { draft, active, sold, ... }
│   ├── validation: { required, min_length, ... }
│   └── errors: { oauth_failed, access_denied, ... }
└── vi.json
    └── [Same structure]
```

---

## 📋 Implementation Checklist

### Phase 1: Setup (2-3 hours)
- [ ] Install `next-intl` package
- [ ] Create message files (en.json, vi.json)
- [ ] Update next.config.js for i18n routing
- [ ] Create i18n config (config.ts)
- [ ] Update middleware.ts for locale detection
- [ ] Wrap root layout with i18n provider

### Phase 2: Core Refactoring (6-8 hours)
- [ ] Update root layout & metadata
- [ ] Refactor all validations (Zod) to use messages
- [ ] Extract component strings to useTranslations()
- [ ] Update all enums (TRANSACTION_TYPES, PROPERTY_TYPES, etc.) to use i18n
- [ ] Update page layouts (public, auth, dashboard)
- [ ] Update all page content

### Phase 3: Component Updates (4-6 hours)
- [ ] Update all UI components
- [ ] Update form components
- [ ] Update navigation components
- [ ] Update search/filter components
- [ ] Update listing form

### Phase 4: A11y Fixes (4-6 hours)
- [ ] Fix focus management in dialogs
- [ ] Add focus trapping
- [ ] Update form error linking (aria-describedby)
- [ ] Add aria-busy to loading states
- [ ] Add aria-labels to icon buttons
- [ ] Verify color contrast
- [ ] Update test setup for i18n

### Phase 5: Testing & QA (3-4 hours)
- [ ] Test both locales on all pages
- [ ] Run axe DevTools accessibility audit
- [ ] Test keyboard navigation
- [ ] Test screen reader compatibility
- [ ] Update unit tests for i18n

---

## 🗣️ Text Content Inventory

### Navigation & Layout (~15 items)
| Location | Text | Status |
|----------|------|--------|
| Public header | Trang chủ, Tìm kiếm, Đăng nhập, Đăng ký | ❌ Hardcoded |
| Dashboard nav | 8 nav items | ❌ Hardcoded |
| Footer | 4 sections | ❌ Hardcoded |

### Forms & Validation (~40+ items)
| Location | Type | Count | Status |
|----------|------|-------|--------|
| Login form | Labels + errors | 8 | ❌ Hardcoded |
| Register form | Labels + errors | 10 | ❌ Hardcoded |
| Listing form | Multi-step labels | 25+ | ❌ Hardcoded |
| Search filters | Option labels | 30+ | ❌ Hardcoded |
| Zod validation | Error messages | 20+ | ❌ Hardcoded |

### Enums & Constants (~50+ items)
| File | Items | Status |
|------|-------|--------|
| TRANSACTION_TYPES | 2 labels | ❌ Hardcoded |
| PROPERTY_TYPES | 6 labels | ❌ Hardcoded |
| LISTING_STATUSES | 8 labels | ❌ Hardcoded |
| DIRECTIONS | 8 labels | ❌ Hardcoded |
| CITIES | 13 names | ❌ Hardcoded |
| PRICE_RANGES | 6 ranges | ❌ Hardcoded |

### Page Content (~30 items)
| Page | Sections | Status |
|------|----------|--------|
| Landing page | Hero, search, stats, CTA | ❌ Hardcoded |
| Search results | No results, loading, headers | ❌ Hardcoded |
| Dashboard | Section titles, empty states | ❌ Hardcoded |

---

## 🔑 Critical Files for i18n

### Must-Update Files (Blockers)
1. **middleware.ts** — Locale routing
2. **app/layout.tsx** — i18n provider setup
3. **lib/validations/*.ts** — Message integration
4. **lib/*.ts** — Any API error message handling

### High-Priority Files
1. **app/(public)/layout.tsx** — Navigation
2. **app/(auth)/login/page.tsx** — Auth forms
3. **components/listings/listing-form-steps.tsx** — Forms
4. **components/search/filter-bar.tsx** — Filters

### Medium-Priority Files
1. All page components
2. All UI components with text
3. Error boundary components

---

## ♿ A11y Implementation Priority

### WCAG 2.1 AA Critical Fixes
1. **Focus Management** (Level A)
   - Add focus trap in `dialog.tsx`
   - Restore focus on dialog close
   - Visible focus indicator on all buttons

2. **Color Contrast** (Level AA)
   - Run axe DevTools audit
   - Fix any < 4.5:1 ratio text
   - Fix < 3:1 ratio graphics

3. **Form Accessibility** (Level A)
   - Link all error messages with aria-describedby
   - Proper labeling with htmlFor
   - Fieldset grouping for complex forms

4. **Loading States** (Level A)
   - Add aria-busy to spinners
   - Add aria-label with context

5. **Icon Buttons** (Level A)
   - All icon-only buttons need aria-label
   - Theme toggle button already has label ✓

### Nice-to-Have A11y Enhancements
- Skip link already present ✓
- Semantic HTML already used ✓
- Role="alert" on errors ✓
- aria-invalid on form fields ✓

---

## 📦 Dependencies to Add

```bash
npm install next-intl

# No new devDependencies needed if using next-intl
# Testing with mocked i18n available
```

**Total installation footprint:** ~500KB minified

---

## 🧪 Testing Strategy

### Unit Tests
```typescript
// vitest.setup.ts - Mock i18n
vi.mock('next-intl', () => ({
  useTranslations: () => (key) => mockMessages[key]
}));
```

### Component Tests
```typescript
// Test both locales
describe('LoginForm', () => {
  it('renders Vietnamese labels', () => { ... });
  it('renders English labels', () => { ... });
});
```

### E2E Tests
```typescript
// Test locale switching
- /en/login → English
- /vi/login → Vietnamese
- /en/dashboard → English dashboard
```

---

## 📊 Estimated Timeline

| Phase | Duration | Effort |
|-------|----------|--------|
| Setup | 2-3h | Low |
| Core Refactoring | 6-8h | Medium |
| Components | 4-6h | Medium |
| A11y Fixes | 4-6h | Low-Medium |
| Testing | 3-4h | Medium |
| **Total** | **19-27h** | **~3-4 days** |

---

## 🚀 Implementation Order (Recommended)

1. **Setup i18n infrastructure** (creates foundation)
2. **Update middleware + root layout** (enables routing)
3. **Extract & centralize all text** (main work)
4. **Fix A11y issues** (parallelize with #3)
5. **Test thoroughly** (final verification)

---

## 💡 Quick Win Opportunities

These can be done immediately:
1. Create message file structure (30 min)
2. Add focus trap to dialog (30 min)
3. Add aria-busy to spinners (20 min)
4. Color contrast audit (1 hour)
5. Icon button aria-labels (30 min)

---

## 📝 Notes for Implementation

### Locale Detection (middleware)
```typescript
// Check in order: URL > cookie > header > default
function getLocale(request) {
  // 1. URL pathname: /en/* or /vi/*
  // 2. Cookie: goodgo_locale
  // 3. Header: Accept-Language
  // 4. Default: vi
}
```

### Message Fallback Strategy
```typescript
// If translation missing, use English as fallback
// Otherwise fallback to Vietnamese (primary)
```

### Performance Considerations
- Keep message files < 100KB each
- Lazy load per-page messages if needed
- Static generation for SEO-critical pages

---

**Last Updated:** April 9, 2026  
**Version:** 1.0 - Pre-Implementation  
**Confidence:** High