# Next.js Migration Complete ✅

## Migration Summary

Successfully migrated Puffin Offset from **Vite 6 + React** to **Next.js 16 App Router** (January 2025).

### What Was Migrated

#### Phase 1-2: Foundation & Configuration
- ✅ Installed Next.js 16.0.1 with Turbopack
- ✅ Created `next.config.mjs` with environment variable mapping
- ✅ Updated `tsconfig.json` for Next.js
- ✅ Created root layout with metadata
- ✅ Set up `app/globals.css`
- ✅ Migrated Header and Footer components

#### Phase 3: Core Pages
- ✅ **Homepage** (`app/page.tsx`) - Static landing page
- ✅ **About** (`app/about/page.tsx`) - Static about page with metadata
- ✅ **How It Works** (`app/how-it-works/page.tsx`) - Static process explanation
- ✅ **Contact** (`app/contact/page.tsx`) - Form with SMTP integration

#### Phase 4: Calculator & Special Routes
- ✅ **Calculator** (`app/calculator/page.tsx`) - Interactive carbon calculator
- ✅ **Mobile App** (`app/mobile-app/page.tsx`) - Custom layout without header/footer
- ✅ **Checkout Success** (`app/checkout/success/page.tsx`) - Stripe success handler
- ✅ **Checkout Cancel** (`app/checkout/cancel/page.tsx`) - Stripe cancel handler

#### Phase 5: SEO Enhancement
- ✅ Added comprehensive metadata to all pages
- ✅ Created `app/sitemap.ts` for search engines
- ✅ Created `app/robots.ts` for crawler rules
- ✅ Extracted client components for proper metadata exports

#### Phase 6: Docker & Deployment
- ✅ Updated `Dockerfile` for Next.js standalone mode
- ✅ Updated `docker-compose.yml` with NEXT_PUBLIC_ environment variables
- ✅ Backward compatibility for VITE_ variables during transition

#### Phase 7: Testing & Verification
- ✅ All routes loading successfully
- ✅ Environment variable migration documented
- ✅ Dev server running with Turbopack
- ✅ Calculator functionality verified

## Architecture Changes

### Before (Vite)
```
- Client-side only rendering (SPA)
- Vite dev server
- Static build output (dist/)
- Environment: import.meta.env.VITE_*
```

### After (Next.js 16)
```
- Server-side and client-side rendering (App Router)
- Next.js with Turbopack
- Standalone server output (.next/)
- Environment: process.env.NEXT_PUBLIC_*
```

## Key Technical Decisions

### 1. Client Component Strategy
**Decision**: Extract client logic to separate component files
**Reason**: Allows page files to export metadata (server components only)

Example:
```
app/about/page.tsx        → Server component with metadata
components/AboutClient.tsx → Client component with interactivity
```

### 2. Environment Variables
**Old**: `import.meta.env.VITE_WREN_API_TOKEN`
**New**: `process.env.NEXT_PUBLIC_WREN_API_TOKEN`

**Fallback Strategy**: `next.config.mjs` includes backward compatibility during transition

### 3. Docker Deployment
**Old**: Static files served by `serve` package
**New**: Next.js standalone server with `node server.js`

## Files Created/Modified

### New Files
```
app/
├── layout.tsx                    # Root layout with metadata
├── page.tsx                      # Homepage
├── globals.css                   # Global styles
├── sitemap.ts                    # Dynamic sitemap
├── robots.ts                     # Crawler rules
├── about/page.tsx                # About page with metadata
├── how-it-works/page.tsx         # How It Works with metadata
├── contact/page.tsx              # Contact with metadata
├── calculator/page.tsx           # Calculator with metadata
├── mobile-app/
│   ├── page.tsx                  # Mobile calculator
│   └── layout.tsx                # Custom layout (no header/footer)
└── checkout/
    ├── success/page.tsx          # Stripe success
    └── cancel/page.tsx           # Stripe cancel

components/
├── Header.tsx                    # Navigation component
├── Footer.tsx                    # Footer component
├── AboutClient.tsx               # About page client logic
├── HowItWorksClient.tsx          # How It Works client logic
├── ContactClient.tsx             # Contact form client logic
└── CalculatorClient.tsx          # Calculator client logic

next.config.mjs                   # Next.js configuration
ENV_MIGRATION.md                  # Environment variable guide
NEXTJS_MIGRATION_COMPLETE.md      # This file
```

### Modified Files
```
package.json                      # Updated dependencies and scripts
tsconfig.json                     # Next.js TypeScript config
Dockerfile                        # Next.js standalone build
docker-compose.yml                # Updated environment variables
src/utils/config.ts               # Environment variable handling
```

### Renamed/Archived
```
src/pages/ → src/old-pages/       # Old Vite page components (kept for reference)
```

## Environment Variable Migration

See **[ENV_MIGRATION.md](./ENV_MIGRATION.md)** for complete guide.

### Quick Reference
| Old (Vite) | New (Next.js) |
|------------|---------------|
| `VITE_WREN_API_TOKEN` | `NEXT_PUBLIC_WREN_API_TOKEN` |
| `VITE_API_BASE_URL` | `NEXT_PUBLIC_API_BASE_URL` |
| `VITE_STRIPE_PUBLISHABLE_KEY` | `NEXT_PUBLIC_STRIPE_PUBLISHABLE_KEY` |

## Benefits Achieved

### 1. SEO Improvement
- ✅ Server-side rendering for marketing pages
- ✅ Proper metadata and Open Graph tags
- ✅ Dynamic sitemap generation
- ✅ Search engine friendly URLs

### 2. Performance
- ✅ Faster initial page loads (SSR)
- ✅ Turbopack for instant dev server updates
- ✅ Automatic code splitting
- ✅ Image optimization ready

### 3. Developer Experience
- ✅ File-based routing
- ✅ Built-in API routes capability
- ✅ TypeScript integration
- ✅ Modern React 18 features

### 4. Maintainability
- ✅ Clearer separation of client/server code
- ✅ Better component organization
- ✅ Standalone Docker deployment

## Next Steps (Optional Future Enhancements)

### Short Term
- [ ] Add `next/image` for S3 images (already configured in next.config.mjs)
- [ ] Convert remaining inline styles to Tailwind utilities
- [ ] Add loading states with Next.js `loading.tsx` files

### Medium Term
- [ ] Implement API routes for backend proxy (replace direct API calls)
- [ ] Add middleware for request logging
- [ ] Set up incremental static regeneration (ISR) for dynamic content

### Long Term
- [ ] Migrate to App Router streaming (React Suspense)
- [ ] Add Edge runtime for global deployment
- [ ] Implement advanced caching strategies

## Testing Checklist

### Functionality Tests
- ✅ Homepage loads with animations
- ✅ About page displays correctly
- ✅ How It Works page shows all steps
- ✅ Contact form submits via SMTP
- ✅ Calculator computes emissions
- ✅ Offset order flow works
- ✅ Mobile app route renders without header
- ✅ Stripe checkout redirects work

### SEO Tests
- ✅ Metadata appears in `<head>`
- ✅ Sitemap accessible at `/sitemap.xml`
- ✅ Robots.txt accessible at `/robots.txt`
- ✅ Open Graph tags present

### Environment Tests
- ✅ Development with `npm run dev`
- ✅ Production build with `npm run build`
- ✅ Environment variables load correctly

## Deployment Instructions

### Development
```bash
npm run dev
# Runs on http://localhost:3000
```

### Production Build
```bash
npm run build
npm start
# Standalone server runs on port 3000
```

### Docker Build
```bash
docker build -t puffin-app:latest .
docker run -p 3000:3000 \
  -e NEXT_PUBLIC_WREN_API_TOKEN=your_token \
  -e NEXT_PUBLIC_API_BASE_URL=https://api.puffinoffset.com \
  puffin-app:latest
```

### Docker Compose
```bash
docker-compose up -d
# Frontend on port 3800, Backend on port 3801
```

## Rollback Plan

If issues arise, revert to Vite:

1. Check out previous commit before migration started
2. Run `npm install` (will restore Vite dependencies from package-lock.json)
3. Run `npm run dev` (Vite dev server)
4. Update environment variables back to `VITE_` prefix

## Support & Documentation

- **Next.js 16 Docs**: https://nextjs.org/docs
- **App Router Guide**: https://nextjs.org/docs/app
- **Environment Variables**: See `ENV_MIGRATION.md`
- **Troubleshooting**: Check dev server logs for errors

## Migration Completed By

Claude Code Agent
Date: January 31, 2025
Next.js Version: 16.0.1
React Version: 18.3.1

---

**Status**: ✅ **PRODUCTION READY**

All phases completed successfully. Application tested and verified working.