# CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

## Development Commands

- `npm run dev` - Start development server (Next.js)
- `npm run build` - Build production version  
- `npm start` - Start production server
- `npm run prettier` - Format code with Prettier
- `npm run prettier:check` - Check code formatting
- `npm run seed` - Seed database with initial data

## Deployment Commands

- `./build.sh` - Build Docker image for deployment
- `./deploy.sh` - Deploy Docker service to production
- `./debug-deploy.sh` - Deploy with debug configuration

## Architecture Overview

This is a Next.js 14 utility bills tracking application ("Evidencija Režija") with the following key components:

### Tech Stack
- **Framework**: Next.js 14 with App Router and standalone output for Docker
- **Authentication**: NextAuth v5 with Google OAuth
- **Database**: MongoDB with connection pooling
- **Internationalization**: next-intl (Croatian/English)
- **Styling**: Tailwind CSS with DaisyUI components
- **Deployment**: Docker with MongoDB 4.4.27 (AVX compatibility)

### Core Architecture Patterns

**Multi-user Data Isolation**: All database operations use the `withUser` higher-order function from `app/lib/auth.ts:102` to automatically inject authenticated user ID into queries, ensuring data isolation between users.

**Server Actions Pattern**: Form handling uses Next.js Server Actions with Zod validation. Actions are defined in `app/lib/actions/` and follow the pattern:
```typescript
export const actionName = withUser(async (user: AuthenticatedUser, ...args) => {
  // Server action implementation with automatic user context
});
```

**Internationalization**: Uses next-intl with locale-based routing. Messages are in `messages/` directory. The middleware handles both auth and i18n routing.

### Key Files & Responsibilities

- `middleware.ts` - Handles authentication and i18n routing, defines public pages
- `app/lib/auth.ts` - NextAuth configuration, `withUser` HOF for user context
- `app/lib/dbClient.ts` - MongoDB connection with development/production handling
- `app/lib/actions/` - Server actions for data mutations (locations, bills, months)
- `app/i18n.ts` - Internationalization configuration (Croatian default)
- `next.config.js` - Standalone build config with `serverActions.allowedOrigins` for Docker deployment

### Database Schema
- **Collections**: Locations, Bills, Months (year-month periods)
- **User Association**: All documents include `userId` field for multi-tenant isolation
- **Database Name**: "utility-bills"

### Docker Deployment Notes
- Uses standalone Next.js build for Docker optimization
- MongoDB 4.4.27 required for older CPU compatibility (no AVX instructions)
- `HOSTNAME=0.0.0.0` with `serverActions.allowedOrigins` config to handle reverse proxy headers
- Environment variables: `MONGODB_URI`, `GOOGLE_ID`, `GOOGLE_SECRET`, `AUTH_SECRET`

### Barcode/QR Code Feature
- Uses `@zxing/library` and `@zxing/browser` for PDF document scanning
- Heavy barcode decoding operations should be moved to background threads if performance issues arise
- PDF processing with `pdfjs-dist` for utility bill scanning

### Testing & Code Quality
- ESLint with Next.js and Prettier configurations
- No specific test framework configured - check with user before assuming testing approach