Hot Coffee: Coffee Shop Management System

Hot Coffee is a RESTful coffee shop management system built in Go.

The application allows managing orders, menu items, and inventory using a layered architecture and JSON file storage.

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Quick Start

# Build
go build -o hot-coffee ./cmd

# Run
./hot-coffee

# Custom configuration
./hot-coffee --port 8080 --dir ./data

Server starts at http://localhost:8080

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Features

• Order Management - Create, update, close orders with automatic inventory deduction
• Menu Management - Add menu items with ingredients and pricing
• Inventory Tracking - Real-time ingredient quantity management
• Sales Reports - Total sales and popular items analytics
• JSON Storage - File-based persistence with atomic operations
• Structured Logging - Comprehensive logging with slog

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Architecture

3-Layer Architecture:

• Handler Layer - HTTP request/response
• Service Layer - Business rules & validation
• Repository Layer - Data persistence

---

Project Structure

hot-coffee/
├── bin
│   └── air
├── cmd
│   └── main.go
├── data
│   ├── inventory.json
│   ├── menu_items.json
│   └── orders.json
├── go.mod
├── go.sum
├── internal
│   ├── config
│   │   └── config.go
│   ├── dal
│   │   ├── inventory_repository.go
│   │   ├── menu_repository.go
│   │   ├── order_repository.go
│   │   ├── report_repository.go
│   │   └── repository.go
│   ├── handler
│   │   ├── handler.go
│   │   ├── inventory_handler.go
│   │   ├── menu_handler.go
│   │   ├── order_handler.go
│   │   └── report_handler.go
│   ├── models            
│   │   ├── inventory_item.go
│   │   ├── menu_item.go
│   │   └── order.go
│   ├── server
│   │   ├── router.go
│   │   └── server.go
│   ├── service
│   │   ├── inventory_service.go
│   │   ├── menu_service.go
│   │   ├── order_service.go
│   │   ├── report_service.go
│   │   └── service.go
│   └── utils
│       └── http.go
├── readme.md

---

API Endpoints

Menu

GET    /menu           - List all menu items
POST   /menu           - Create menu item
GET    /menu/{id}      - Get menu item
PUT    /menu/{id}      - Update menu item
DELETE /menu/{id}      - Delete menu item

Inventory

GET    /inventory      - List all inventory
POST   /inventory      - Add inventory item
GET    /inventory/{id} - Get inventory item
PUT    /inventory/{id} - Update inventory
DELETE /inventory/{id} - Delete inventory item

Orders

GET    /orders         - List all orders
POST   /orders         - Create order
GET    /orders/{id}    - Get order
PUT    /orders/{id}    - Update order
DELETE /orders/{id}    - Delete order
POST   /orders/{id}/close - Close order

Reports

GET    /reports/total-sales    - Total sales amount
GET    /reports/popular-items  - Top 3 popular items

---

Usage Example

# 1. Add menu item
curl -X POST http://localhost:8080/menu \
  -H "Content-Type: application/json" \
  -d '{
    "product_id": "espresso",
    "name": "Эсперссо",
    "price": 1100,
    "ingredients": [
      {"ingredient_id": "beans", "quantity": 0.1},
      {"ingredient_id": "water", "quantity": 0.2}
    ]
  }'

# 2. Stock inventory
curl -X POST http://localhost:8080/inventory \
  -H "Content-Type: application/json" \
  -d '{
    "ingredient_id": "milk",
    "name": "Milk",
    "quantity": 5,
    "unit": "l"
  }'

# 3. Create order
curl -X POST http://localhost:8080/orders \
  -H "Content-Type: application/json" \
  -d '{
    "order_id": "1",
    "customer_name": "Alice",
    "items": [
      {"product_id": "espresso", "quantity": 2}
    ]
  }'

# 4. Close order
curl -X POST http://localhost:8080/orders/1/close

# 5. View total sales
curl http://localhost:8080/reports/total-sales

---

Configuration

Command Line Options

./hot-coffee [OPTIONS]

Options:
  --port N     Port number (default: 8080)
  --dir S      Data directory path (default: ./data)
  --help       Show help message

Example Configurations

# Development
./hot-coffee --port 8080 --dir ./data

# Production
./hot-coffee --port 80 --dir /var/coffee-data

# Testing
./hot-coffee --port 3000 --dir /tmp/test-data

---

Technical Details

Technology Stack

• Language: Go 1.22
• Storage: JSON files
• Logging: slog (structured logging)
• Architecture: 3-layer separation
• Concurrency: RWMutex for safe operations

Key Features

• Atomic Writes - Data integrity with temp file + rename
• Automatic Inventory - Deducts ingredients on order creation
• Validation - Multi-layer input validation
• Structured Logs - Easy debugging with key-value pairs

---

Logging

View application logs:

# Run with logs
./hot-coffee 2>&1 | tee server.log

# Filter errors
grep "ERROR" server.log

# Monitor orders
grep "order" server.log

# View inventory changes
grep "Deducting inventory" server.log

Log Levels:

• INFO - Normal operations
• WARN - Potential issues
• ERROR - Actual errors

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Response Codes

Code	Meaning	Usage
200	OK	Successful GET
201	Created	Successful POST
204	No Content	Successful PUT/DELETE
400	Bad Request	Validation error
404	Not Found	Resource not found
500	Internal Error	Server error

---

Troubleshooting

Common Issues

Port already in use:

./hot-coffee --port 8081

Permission denied:

# Use port > 1024 or run with sudo
./hot-coffee --port 8080

Insufficient inventory error:

# Check current inventory
curl http://localhost:8080/inventory

# Add more stock
curl -X POST http://localhost:8080/inventory \
  -d '{"ingredient_id":"milk","quantity":10000,...}'

---

Authors

• nuramazan
• nualdaber