version: '3.8'

services:
  # 1. PostgreSQL Database Service
  postgres:
    image: postgres:16-alpine
    container_name: url_shortener_db
    environment:
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: postgres
      POSTGRES_DB: url_shortener
    ports:
      - "5432:5432"
    volumes:
      # Persistent PostgreSQL data storage volume
      - postgres_data:/var/lib/postgresql/data
      # Automated schema DDL migration script for initial empty data directory
      - ./schema.sql:/docker-entrypoint-initdb.d/01_schema.sql:ro
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U postgres -d url_shortener"]
      interval: 5s
      timeout: 5s
      retries: 5
    restart: unless-stopped

  # 2. Node.js / Express Application Service
  app:
    build: .
    container_name: url_shortener_app
    ports:
      - "3000:3000"
    environment:
      NODE_ENV: production
      PORT: 3000
      # Container-to-container database connection using service name 'postgres'
      DATABASE_URL: postgres://postgres:postgres@postgres:5432/url_shortener
    depends_on:
      postgres:
        condition: service_healthy
    healthcheck:
      test: ["CMD", "node", "-e", "require('http').get('http://localhost:3000/ready', (r) => process.exit(r.statusCode === 200 ? 0 : 1)).on('error', () => process.exit(1))"]
      interval: 10s
      timeout: 5s
      retries: 3
      start_period: 5s
    restart: unless-stopped

volumes:
  # Persistent storage for PostgreSQL data
  postgres_data: