# GEMINI.md - Context for AI Agents

## Project Overview
**Name:** Trekking Packliste
**Type:** PHP Web Application (Native)
**Purpose:** A modern, web-based application for managing packing lists for hiking, trekking, and travel. It focuses on weight optimization, hierarchical packing (containers/nesting), and household collaboration.

## Architecture & Technology
- **Backend:** Native PHP 8.2 (No framework).
- **Frontend:** HTML5, CSS3 (Custom Theme), Bootstrap 5, Vanilla JavaScript.
- **Database:** MariaDB / MySQL.
- **Containerization:** Docker (Apache image).
- **CI/CD:** Gitea Actions (`.gitea/workflows/build-push.yaml`).

## Directory Structure
- `/src/`: Source code root.
    - `*.php`: Application logic and views.
    - `assets/`: CSS, JS, and static images.
    - `uploads/`: User-uploaded images (mounted volume in Docker).
- `Dockerfile`: Defines the application environment.
- `packliste.sql`: Database schema and initial data.
- `.gitea/`: Gitea-specific configurations (workflows).

## Key Files
- `src/db_connect.php`: Handles database connection. Prioritizes environment variables (`DB_HOST`, etc.) over `config.ini`.
- `src/index.php`: Application dashboard.
- `src/api_packing_list_handler.php`: AJAX handler for packing list operations.
- `README.md`: Comprehensive documentation on features and usage.

## Database Schema (Key Tables)
- `articles`: Inventory items (weight, category, image).
- `backpacks`: Transport containers (weight, volume).
- `backpack_compartments`: Sub-sections of backpacks (e.g., "Lid", "Main").
- `packing_lists`: The main lists.
- `packing_list_items`: Link between lists and articles (supports nesting/hierarchy).
- `users` & `households`: User management and sharing scope.

## Development & Deployment

### Local Development (Docker)
1.  **Build:** `docker build -t packliste-app .`
2.  **Run:**
    ```bash
    docker run -d \
      -p 8080:80 \
      -e DB_HOST="host.docker.internal" \
      -e DB_USER="root" \
      -e DB_PASSWORD="password" \
      -e DB_NAME="packliste" \
      -v $(pwd)/src/uploads:/var/www/html/uploads \
      packliste-app
    ```

### Manual Installation
- Configure `config.ini` in the parent directory of the web root (or use env vars).
- Import `packliste.sql` into the database.

### Conventions
- **Code Style:** Native PHP, procedural/functional mix.
- **Frontend:** Bootstrap 5 classes for layout. Custom CSS in `assets/css/style.css`.
- **Database:** Use `mysqli` with prepared statements for security.
- **Security:** Always validate user input. Passwords hashed with `password_hash()`.

## Core Features
- **Weight Calculation:** Real-time summation of weights in lists.
- **Households:** Shared inventory and lists between users.
- **Drag & Drop:** `Sortable.js` used for organizing packing lists.