time_to_leave/REWRITE_PLAN.md

# ÖBB Planner — Next.js Rewrite Plan

> **Status:** Planned
> **Created:** 2024
> **Scope:** Full rewrite from CRA + Express to Next.js App Router with new features

---

## 1. Current State

| Layer | Technology | Files |
|-------|-----------|-------|
| Backend | Express.js + CORS + node-ical | `server/index.js` (~140 lines) |
| Frontend | Create React App (React 19) | `oebb-planner.jsx` (~700 lines monolithic component) |
| Tests | Jest + Supertest | `server/__tests__/*.test.js` |
| Build | Separate `npm start` for server + `react-scripts start` for frontend | Two independent processes |

### Problems with current architecture

- Two separate processes to manage
- Monolithic component (~700 lines) — no component breakdown
- CRA is deprecated; `react-scripts` is unmaintained
- No TypeScript
- Inline styles make theming/maintenance painful
- No proper state management pattern
- Duplication between `oebb-planner.jsx` and `oebb-planner-app/src/App.js`

---

## 2. New Features (Beyond Rewrite)

### 2.1 Calendar View (`/calendar`)

A browsable month view that lets you navigate between months, see events as badges on dates, and click into a day to see event + train details.

**How it works:**

- User imports calendar via the existing ICS flow
- Events are stored in React state / localStorage
- A month grid shows event dots on dates that have events
- Clicking a day shows that day's events with their train info
- Clicking an event scrolls to / expands the full event card

**UI wireframe:**

```
┌──────────────────────┬──────────────────────┐
│  ←  November 2024  → │ [Day] [Week] [Month] │
├──────────────────────┼──────────────────────┤
│ Su Mo Tu We Th Fr Sa │  Thursday, 14 Nov    │
│  1  2  3  4  5  6  7 │                      │
│  8  9 10 11 12 13 14 │  ● 14:00 Graz Hbf    │
│          ●       ●   │     🚂 Leave 13:10   │
│ 15 16 17 18 19 20 21 │     🚲 Leave 11:07   │
│            ●       ● │                      │
│ ...                  │  ● 17:00 Linz Hbf    │
│                      │     🚂 Leave 15:30   │
│                      │     🚲 Leave 15:45   │
└──────────────────────┴──────────────────────┘
```

### 2.2 Bicycle Routing

**API choice: OSRM Public Demo Server** (`router.project-osrm.org`)

- Free, no API key required, open source
- Supports `bicycle` profile
- Returns distance, duration, turn-by-turn steps
- For production: self-host or switch to OpenRouteService

**Geocoding:** Nominatim (OpenStreetMap) to convert station/event location names to coordinates for routing.

**Data flow:**

```
Origin station (name) → already have coords from geolocation
Destination station (name) → geocode via Nominatim → get coordinates
                            → OSRM bicycle route → distance + duration
                            → cache in TripData alongside train journeys
```

### 2.3 Train vs Bicycle Comparison

Each event card shows both travel modes side by side:

```
┌───────────────────────────────────────────────────┐
│ 🏔 Meeting in Graz                               │
│ 📍 Graz Hbf · 14:00 · Thu, 14 Nov                │
├───────────────────────────────────────────────────┤
│  🚂 NEXT BEST TRAIN            🚲 BYCYCLE         │
│  RJX 5234 on time                42 km            │
│  DEP 13:22  ARR 14:35          2h 15min          │
│  PLAT 3                          0 emissions      │
│  Leave by 13:10                 Leave by 11:07    │
└───────────────────────────────────────────────────┘
```

---

## 3. Target Architecture

```
oebb_planner/
├── package.json
├── next.config.ts
├── tsconfig.json
├── postcss.config.mjs               ← Tailwind v4 uses @tailwindcss/postcss; no tailwind.config.ts needed
├── vitest.config.ts                  ← must exist before Phase 7; deferred from Phase 1
├── src/
│   ├── app/
│   │   ├── layout.tsx                    ← root layout (fonts, providers, navbar)
│   │   ├── page.tsx                      ← main planner page (event cards)
│   │   ├── globals.css
│   │   ├── calendar/
│   │   │   └── page.tsx                  ← browsable calendar view (NEW)
│   │   ├── api/
│   │   │   ├── hafas/
│   │   │   │   └── route.ts              ← POST → proxy to ÖBB HAFAS
│   │   │   ├── calendar/
│   │   │   │   ├── route.ts              ← GET → fetch remote ICS calendar
│   │   │   │   └── parse/
│   │   │   │       └── route.ts          ← POST → parse raw ICS body
│   │   │   ├── geocode/
│   │   │   │   └── route.ts              ← GET → Nominatim geocoding (NEW)
│   │   │   ├── bike-route/
│   │   │   │   └── route.ts              ← GET → OSRM bicycle routing (NEW)
│   │   │   └── health/
│   │   │       └── route.ts              ← GET → liveness check
│   │   └── not-found.tsx
│   ├── components/
│   │   ├── layout/
│   │   │   ├── Header.tsx                ← logo, server status, clock
│   │   │   └── Navbar.tsx                ← navigation between pages (NEW)
│   │   ├── calendar/
│   │   │   ├── CalendarPanel.tsx          ← collapsible import panel
│   │   │   ├── CalendarView.tsx           ← month grid component (NEW)
│   │   │   ├── DayEvents.tsx             ← events for a selected day (NEW)
│   │   │   ├── UrlTab.tsx
│   │   │   └── FileTab.tsx
│   │   ├── event/
│   │   │   ├── EventCard.tsx             ← single event card (with train+bike)
│   │   │   ├── TrainSection.tsx          ← train data in event card
│   │   │   ├── BikeSection.tsx           ← bicycle data in event card (NEW)
│   │   │   ├── JourneyList.tsx           ← all departures table
│   │   │   └── LeaveByBadge.tsx
│   │   ├── add-event/
│   │   │   └── AddEventModal.tsx
│   │   └── ui/
│   │       ├── Chip.tsx
│   │       ├── Button.tsx
│   │       └── LoadingSpinner.tsx
│   ├── hooks/
│   │   ├── useServerHealth.ts             ← polls /api/health every 30s
│   │   ├── useClock.ts                    ← ticking clock (every 10s)
│   │   ├── useGeolocation.ts              ← GPS positioning
│   │   ├── useOriginStation.ts            ← finds nearest ÖBB station
│   │   ├── useJourneys.ts                 ← fetches + caches train data
│   │   ├── useBikeRoute.ts               ← fetches bicycle route (NEW)
│   │   ├── useCalendar.ts                 ← calendar import logic
│   │   └── useEventsStore.ts             ← shared events state (NEW)
│   ├── lib/
│   │   ├── hafas-client.ts               ← HAFAS API client (class HafasClient)
│   │   ├── calendar-utils.ts             ← ICS helpers (extractEvents, cleanLocation)
│   │   ├── countdown-utils.ts            ← calculateCountdown, leaveBy helpers
│   │   ├── formatting.ts                 ← formatTime, formatDate, formatDateTime, formatDuration, formatDistance
│   │   ├── demo.ts                       ← demo journey generator
│   │   ├── constants.ts                  ← HAFAS_URL, NOMINATIM_URL, OSRM_URL, HAFAS_TIMEOUT_MS, DEFAULT_DAYS, APP_VERSION
│   │   ├── status-utils.ts               ← StatusUtils.checkServerStatus() (used by useServerHealth)
│   │   ├── live-status-utils.ts          ← LiveStatusUtils.getLiveStatus() (stub; live data TBD)
│   │   ├── geocoding-client.ts           ← Nominatim client (NEW)
│   │   ├── bike-routing-client.ts        ← OSRM client (NEW)
│   │   └── index.ts                      ← re-exports all lib modules
│   └── types/
│       └── index.ts                       ← all TypeScript interfaces
├── src/lib/__tests__/                     ← unit tests live alongside lib, not at repo root
│   ├── hafas-client.test.ts
│   ├── geocoding-client.test.ts
│   ├── calendar-utils.test.ts
│   ├── countdown-utils.test.ts
│   └── bike-routing-client.test.ts        ← NEW
├── src/app/api/__tests__/                 ← API route tests
│   ├── hafas.test.ts
│   ├── calendar.test.ts
│   ├── geocode.test.ts                    ← NEW
│   ├── bike-route.test.ts                 ← NEW
│   └── health.test.ts
├── public/
│   ├── favicon.ico
│   └── robots.txt
├── .env.example
└── README.md
```

---

## 4. TypeScript Types

### `src/types/index.ts`

```typescript
// ── HAFAS / Train ───────────────────────────────────────────

interface Journey {
  id: string;
  sD: Date;          // scheduled departure
  rD: Date;          // real departure
  sA: Date;          // scheduled arrival
  rA: Date;          // real arrival
  delay: number;     // minutes
  platform: string;
  changes: number;
  trains: string[];
  cancelled: boolean;
}

interface Station {
  name: string;
  extId: string;
}

// ── Events ───────────────────────────────────────────────────

interface Event {
  id: string;
  title: string;
  destination: string;
  eventTime: Date;
  source: "manual" | "calendar";
}

// ── Trip Data (per event) ────────────────────────────────────

interface TripDataEntry {
  journeys: Journey[];
  destName: string;
  demo: boolean;
  loading: boolean;
  bikeRoute?: BikeRoute | null;       // NEW
  bikeLoading?: boolean;              // NEW
  bikeError?: string | null;          // NEW
  destCoords?: { lat: number; lng: number }; // NEW (cached geocode)
}

// ── Bicycle Routing (NEW) ────────────────────────────────────

interface BikeRoute {
  distance: number;       // meters
  duration: number;       // seconds
  steps?: BikeStep[];
}

interface BikeStep {
  name: string;
  distance: number;
  duration: number;
  instruction: string;
}

// ── Geocoding (NEW) ──────────────────────────────────────────

interface GeocodeResult {
  lat: number;
  lng: number;
  display_name: string;
}

// ── Calendar Import ──────────────────────────────────────────

interface CalendarEvent {
  id: string;
  title: string;
  destination: string;
  eventTime: string;    // ISO string from API
  source: "calendar";
}

// ── UI Helpers ───────────────────────────────────────────────

interface CountdownInfo {
  label: string;
  color: string;
  urgent: boolean;
}

type ServerStatus = null | true | false;
type LiveStatus   = null | true | false;
type LocState     = "pending" | "granted" | "denied";
type CalStatus    = null | "loading" | "ok" | "error";
```

---

## 5. New API Routes

### `POST /api/hafas`

- **Purpose:** Proxy to `fahrplan.oebb.at/bin/mgate.exe`
- **Body:** `{ svcReqL: [...] }` — HAFAS service requests
- **Returns:** HAFAS JSON response
- **Timeout:** 12s

### `GET /api/calendar?url=<ics_url>&days=14`

- **Purpose:** Fetch and parse a remote ICS calendar
- **Returns:** `CalendarEvent[]`
- **Supports:** `https://`, `webcal://`

### `POST /api/calendar/parse`

- **Purpose:** Parse raw ICS content sent in request body
- **Body:** Raw ICS text
- **Returns:** `CalendarEvent[]`

### `GET /api/geocode?name=Graz+Hbf&countrycodes=at` (NEW)

- **Purpose:** Proxy to Nominatim for address→coordinates
- **Upstream:** `nominatim.openstreetmap.org/search?q={name}&format=json&limit=1&countrycodes=at`
- **Returns:** `{ lat, lng, display_name }`
- **Caching:** In-memory cache with TTL to avoid rate limits

### `GET /api/bike-route?fromLat=...&fromLng=...&toLat=...&toLng=...` (NEW)

- **Purpose:** Proxy to OSRM for bicycle routing
- **Upstream:** `router.project-osrm.org/route/v1/bicycle/{lon1},{lat1};{lon2},{lat2}?overview=false`
- **Returns:** `{ distance, duration, steps: [...] }`

### `GET /api/health`

- **Purpose:** Liveness check
- **Returns:** `{ ok: true, ts: ISOString, version: "2.0.0" }`

---

## 6. Key Technical Decisions

| Decision | Choice | Rationale |
|----------|--------|-----------|
| Framework | Next.js 15 App Router | Modern standard; API routes are serverless-compatible |
| Language | TypeScript (strict) | Type safety across frontend and backend |
| Styling | Tailwind CSS v4 | Replaces 700 lines of inline styles; v4 uses CSS-native config, no `tailwind.config.ts` |
| State | React hooks + Context | No Redux needed for this scale |
| API proxy | Next.js Route Handlers | Same logic as Express, no Express dependency |
| ICS parsing | Keep `node-ical` | Already works, well-tested |
| Bike routing | OSRM public demo | Free, no API key, good enough for dev |
| Geocoding | Nominatim | Free, open source, good Austria coverage |
| Testing | Vitest + Testing Library | Faster than Jest for TS, better DX |
| Deployment | Vercel (recommended) or any Node host | Single artifact |

---

## 7. Migration Phases

### Phase 1 — Scaffold Next.js Project (~30 min)

1. Initialize Next.js 15 with App Router, TypeScript, Tailwind CSS
2. Set up `tsconfig.json` with strict mode
3. Create `.env.example` with `PORT`, `HAFAS_URL`, `NOMINATIM_URL`, `OSRM_URL`
4. Configure `next.config.js` (rewrites if needed)
5. Configure `vitest.config.ts`
6. Set up `postcss.config.mjs`

### Phase 2 — Types + Library Layer (~2 hours)

7. Define TypeScript types in `src/types/index.ts`
8. Port `lib/hafas-client.ts` — `HafasClient` class with `searchStation()` and `fetchJourneys()`
9. Port `lib/calendar-utils.ts` — `extractEvents()` + `cleanLocation()` (reusable in API routes AND tests)
10. Port `lib/countdown-utils.ts`, `lib/formatting.ts`, `lib/constants.ts`, `lib/demo.ts`, `lib/status-utils.ts`, `lib/live-status-utils.ts`
11. Create `lib/geocoding-client.ts` — Nominatim client (NEW)
12. Create `lib/bike-routing-client.ts` — OSRM client (NEW)

### Phase 3 — API Routes (~45 min)

13. `src/app/api/hafas/route.ts` — POST handler, same logic as Express
14. `src/app/api/calendar/route.ts` — GET handler for remote ICS
15. `src/app/api/calendar/parse/route.ts` — POST handler for ICS body
16. `src/app/api/geocode/route.ts` — GET handler for Nominatim (NEW)
17. `src/app/api/bike-route/route.ts` — GET handler for OSRM (NEW)
18. `src/app/api/health/route.ts` — health check

### Phase 4 — Custom Hooks (~2.5 hours)

19. `useServerHealth.ts` — polls `/api/health` every 30s
20. `useClock.ts` — interval that updates `now` every 10s
21. `useGeolocation.ts` — wraps `navigator.geolocation`
22. `useOriginStation.ts` — finds nearest station from geolocation
23. `useJourneys.ts` — the complex `fetchAll` logic, per-event journey fetching
24. `useBikeRoute.ts` — fetches bicycle route for an event (NEW)
25. `useCalendar.ts` — URL/file import with merge logic
26. `useEventsStore.ts` — shared events state via Context (NEW)

### Phase 5 — UI Components (~3.5 hours)

27. `ui/Chip.tsx` — small badge component
28. `ui/Button.tsx` — styled button
29. `ui/LoadingSpinner.tsx` — loading indicator
30. `event/LeaveByBadge.tsx` — countdown badge
31. `event/JourneyList.tsx` — departure rows
32. `event/TrainSection.tsx` — train data in event card
33. `event/BikeSection.tsx` — bicycle data in event card (NEW)
34. `event/EventCard.tsx` — composes train + bike sections
35. `calendar/UrlTab.tsx`
36. `calendar/FileTab.tsx`
37. `calendar/CalendarPanel.tsx`
38. `add-event/AddEventModal.tsx`
39. `layout/Header.tsx`
40. `layout/Navbar.tsx` (NEW)

### Phase 6 — Calendar Page (~1 hour)

41. `calendar/CalendarView.tsx` — month grid component (NEW)
42. `calendar/DayEvents.tsx` — events for a selected day (NEW)
43. `app/calendar/page.tsx` — calendar route (NEW)

### Phase 7 — Tests (~2 hours)

> Install test dependencies first: `npm install -D vitest @vitejs/plugin-react @testing-library/react @testing-library/jest-dom jsdom` and create `vitest.config.ts`. Update the `test` script in `package.json` to `vitest`.

44. Migrate `server/__tests__/*.test.js` → `src/app/api/__tests__/*.test.ts`
45. Add unit tests for `src/lib/calendar-utils.ts`, `src/lib/countdown-utils.ts` in `src/lib/__tests__/`
46. Add API tests for `geocode` and `bike-route` in `src/app/api/__tests__/` (NEW)
47. Add component smoke tests with `@testing-library/react` _(optional)_

### Phase 8 — Cleanup (~30 min)

48. Delete old `server/` directory
49. Delete old `oebb-planner-app/` directory
50. Delete `oebb-planner.jsx`
51. Update `README.md` with new architecture and instructions
52. Final integration test

---

## 8. Dependencies

### Runtime (installed)

```json
{
  "dependencies": {
    "next": "16.2.6",
    "react": "19.2.4",
    "react-dom": "19.2.4",
    "node-ical": "^0.18.0"
  }
}
```

### Development (installed)

```json
{
  "devDependencies": {
    "typescript": "^5",
    "@types/node": "^20",
    "@types/react": "^19",
    "@types/react-dom": "^19",
    "tailwindcss": "^4",
    "@tailwindcss/postcss": "^4",
    "eslint": "^9",
    "eslint-config-next": "16.2.6"
  }
}
```

### To be installed before Phase 7 (tests)

```json
{
  "devDependencies": {
    "vitest": "^2.0.0",
    "@vitejs/plugin-react": "^4.0.0",
    "@testing-library/react": "^16.0.0",
    "@testing-library/jest-dom": "^6.0.0",
    "jsdom": "^25.0.0"
  }
}
```

> Note: Tailwind v4 no longer requires `autoprefixer` or a separate `tailwind.config.ts` — configuration is done via CSS and `@tailwindcss/postcss`.

---

## 9. Environment Variables

```env
# .env.example

# Server port
PORT=3001

# ÖBB HAFAS API
HAFAS_URL=https://fahrplan.oebb.at/bin/mgate.exe

# Nominatim geocoding (OpenStreetMap)
NOMINATIM_URL=https://nominatim.openstreetmap.org

# OSRM bicycle routing
OSRM_URL=https://router.project-osrm.org

# Nominatim user-agent / referer (required by their ToS)
NOMINATIM_USER_AGENT=OebbPlanner/1.0
```

---

## 10. Benefits of the Rewrite

1. **Single process** — `npm run dev` starts everything
2. **Type safety** — TypeScript catches bugs at compile time
3. **Composability** — 700-line component becomes ~15 focused components
4. **Reusability** — `lib/` functions testable independently
5. **Deployable** — one artifact, works on Vercel / any Node host
6. **Maintainable** — hooks encapsulate side effects, components are pure UI
7. **Modern tooling** — no more CRA, no more `react-scripts eject` anxiety
8. **Bicycle routing** — complete picture of train vs bike for each event
9. **Calendar view** — browse events by date, not just a flat list
10. **Train+bike comparison** — side-by-side travel times in each event card

---

## 11. Estimated Effort

| Phase | Description | Est. Time |
|-------|-------------|-----------|
| 1 | Scaffold Next.js + Tailwind + TS | 30 min |
| 2 | Types + lib layer (incl. geocode, bike-route) | 2 hours |
| 3 | API routes (incl. geocode, bike-route) | 45 min |
| 4 | Custom hooks (incl. bike-route, events-store) | 2.5 hours |
| 5 | UI Components (incl. bike section, navbar) | 3.5 hours |
| 6 | Calendar page (incl. month view, day events) | 1 hour |
| 7 | Tests (API + lib + component) | 2 hours |
| 8 | Cleanup (delete old dirs, update README) | 30 min |
| **Total** | | **~13-14 hours** |