Lunch Splitter

A full-stack Next.js app for splitting lunch bills among office colleagues. Handles discounts, shared items, per-item discount overrides, fee/coupon adjustments, multi-user accounts, and Czech QR payment codes.

Note: This is a vibe-coded project — built entirely through AI-assisted development with Claude Code.

Features

• People & items — Add people, add their food items with prices
• Global discount — Apply a percentage discount to all items
• Per-item discount override — Click the discount badge on any item to set a custom discount
• Shared items — Share an item across multiple people with equal or custom splits
• Fees & adjustments — Add delivery fees, service charges, and coupons (positive or negative amounts), split equally
• Item & person suggestions — Autocomplete from previously entered names and prices
• Restaurant suggestions — Autocomplete from previously used restaurants
• Summary table — Live-updating breakdown: Subtotal → After Discount → With Fees
• Copy to clipboard — One-click copy of the full text summary
• Order lifecycle — Open orders (editable) and closed orders (read-only with QR codes)
• Auto-save — Debounced auto-save with status indicator, warns on unsaved changes before leaving
• QR Platba — Czech bank QR payment codes generated per person when an order is closed
• Multi-user accounts — User registration, roles (Admin/User), invite system with expiring tokens
• Admin panel — User management, temporary password generation
• User settings — Display name, password change, bank account number for QR payments
• Security — CSRF protection, IDOR prevention, QR/SPD injection sanitization, security headers

Tech Stack

• Next.js 15 + React 19 + TypeScript (strict)
• PostgreSQL + Prisma ORM
• NextAuth (v5 beta) — credentials-based authentication
• styled-components for theming and styling
• React Query for server state management
• react-hook-form + zod for form validation
• qrcode for QR Platba generation
• Vitest for unit testing

Getting Started

Prerequisites

• Node.js 20+
• Docker (for the local Postgres sandbox)

Setup

# Install dependencies
npm install

# Copy environment variables and fill in your values
cp .env.example .env.local

# One-shot dev: starts Postgres on :5433, applies schema, seeds admin,
# and runs Next.js on :3100
npm run dev

Open http://localhost:3100.

Schema management: This project uses prisma db push (not prisma migrate). There is no prisma/migrations/ folder — schema is applied directly from prisma/schema.prisma. The dev script runs db push automatically on every start.

For richer test data (6 users, 4 restaurants, ~9 closed orders with varied participants/discounts/fees), run npm run dev:clean instead — it wipes the sandbox DB and reseeds from prisma/seed.dev.ts. All seeded users have password heslo.

Environment Variables

Variable	Description
DATABASE_URL	PostgreSQL connection string (sandbox: :5433)
NEXTAUTH_SECRET	Random secret for session encryption
NEXTAUTH_URL	App URL (e.g. http://localhost:3100)
DISCORD_BOT_TOKEN	Optional — enables QR DMs and access-request approvals
DISCORD_PUBLIC_KEY	Required when running the Discord interactions endpoint
DISCORD_DRY_RUN	Set to 1 in .env.local to log Discord payloads instead of sending them

Scripts

Command	Description
npm run dev	Start development server
npm run build	Generate Prisma client and build for production
npm run start	Start production server
npm test	Run tests once
npm run test:watch	Run tests in watch mode

Project Structure

src/
├── actions/                        # Next.js server actions
│   ├── auth.ts                     # Registration, passwords, invitations
│   ├── invitations.ts              # Invite token management
│   ├── orderItems.ts               # Item and person CRUD
│   ├── orders.ts                   # Order lifecycle (create, save, close, reopen)
│   └── users.ts                    # User queries
├── app/                            # Next.js app router
│   ├── (app)/                      # Protected routes (require auth)
│   │   ├── admin/users/            # Admin user management
│   │   ├── invite/                 # Invite management
│   │   ├── orders/                 # Order list, create, detail
│   │   └── settings/               # User settings
│   ├── (auth)/                     # Public auth routes
│   │   ├── login/                  # Login / first admin setup
│   │   └── setup-password/         # First-login password change
│   ├── api/auth/[...nextauth]/     # NextAuth API route
│   └── invite/[token]/             # Public invite registration
├── features/
│   ├── lunch/
│   │   ├── components/             # UI components (PersonCard, ItemRow, Summary, QrPlatba, etc.)
│   │   ├── hooks/                  # useLunchSession, useCalculation, useAutoSave
│   │   ├── types.ts                # Data types
│   │   └── utils/                  # Calculations, formatters, QR Platba (with tests)
│   └── ui/
│       ├── components/             # Shared UI (Button, Input, Card, StatusBadge)
│       ├── theme/                  # Theme definition and types
│       ├── Providers.tsx           # React Query, Toastify providers
│       └── StyledComponentsRegistry.tsx  # SSR registry
├── lib/
│   ├── auth.ts                     # NextAuth setup
│   ├── auth.config.ts              # Auth configuration
│   ├── mappers.ts                  # Prisma ↔ app type converters
│   ├── prisma.ts                   # Prisma singleton
│   └── validations.ts             # Zod schemas
├── types/
│   └── next-auth.d.ts              # Session type extensions
├── middleware.ts                    # Auth redirect middleware
└── GlobalStyles.ts
prisma/
├── schema.prisma                   # Database schema (User, Order, Restaurant, etc.)
└── seed.ts                         # Seeds admin user