# Production Nginx Configuration for GNX Soft
# Place this in /etc/nginx/sites-available/gnxsoft
#
# DEPLOYMENT NOTES:
# 1. Frontend: Next.js production build runs on port 3000
#    - Build: npm run build
#    - Start: npm start (or use PM2: pm2 start npm --name "gnxsoft-frontend" -- start)
# 2. Backend: Django runs on port 8000 (internal only)
#    - Use Gunicorn: gunicorn gnx.wsgi:application --bind 127.0.0.1:8000
#    - Or PM2: pm2 start gunicorn --name "gnxsoft-backend" -- gnx.wsgi:application --bind 127.0.0.1:8000

# Frontend - Public facing (Next.js Production Server)
upstream frontend {
    server 127.0.0.1:3000;
    keepalive 64;
}

# Backend - Internal only (Django)
upstream backend_internal {
    server 127.0.0.1:8000;
    keepalive 64;
}

# Redirect HTTP to HTTPS
server {
    listen 80;
    listen [::]:80;
    server_name gnxsoft.com www.gnxsoft.com;
    
    # Let's Encrypt validation
    location /.well-known/acme-challenge/ {
        root /var/www/certbot;
    }
    
    # Redirect all other traffic to HTTPS
    location / {
        return 301 https://$server_name$request_uri;
    }
}

# HTTPS Frontend
server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;
    server_name gnxsoft.com www.gnxsoft.com;

    # SSL Configuration
    ssl_certificate /etc/letsencrypt/live/gnxsoft.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/gnxsoft.com/privkey.pem;
    ssl_protocols TLSv1.2 TLSv1.3;
    ssl_ciphers ECDHE-RSA-AES256-GCM-SHA512:DHE-RSA-AES256-GCM-SHA512:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-SHA384;
    ssl_prefer_server_ciphers on;
    ssl_session_cache shared:SSL:10m;
    ssl_session_timeout 10m;

    # Security Headers
    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains; preload" always;
    add_header X-Frame-Options "SAMEORIGIN" always;
    add_header X-Content-Type-Options "nosniff" always;
    add_header X-XSS-Protection "1; mode=block" always;
    add_header Referrer-Policy "strict-origin-when-cross-origin" always;
    add_header Permissions-Policy "camera=(), microphone=(), geolocation=(), interest-cohort=()" always;

    # Rate Limiting Zones
    limit_req_zone $binary_remote_addr zone=api_limit:10m rate=10r/s;
    limit_req_zone $binary_remote_addr zone=general_limit:10m rate=100r/s;
    limit_req_status 429;

    # Client settings
    client_max_body_size 10M;
    client_body_timeout 30s;
    client_header_timeout 30s;

    # Logging
    access_log /var/log/nginx/gnxsoft_access.log;
    error_log /var/log/nginx/gnxsoft_error.log warn;

    # Root location - Frontend (Next.js)
    location / {
        limit_req zone=general_limit burst=50 nodelay;
        
        proxy_pass http://frontend;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_cache_bypass $http_upgrade;
        
        # Timeouts
        proxy_connect_timeout 60s;
        proxy_send_timeout 60s;
        proxy_read_timeout 60s;
    }

    # API Proxy - Frontend talks to backend ONLY through this internal proxy
    # Backend port 8000 is BLOCKED from internet by firewall
    location /api/ {
        limit_req zone=api_limit burst=20 nodelay;
        
        # Internal proxy to backend (127.0.0.1:8000)
        # Backend is NOT accessible from public internet
        proxy_pass http://backend_internal/api/;
        proxy_http_version 1.1;
        
        # Backend sees request as coming from localhost
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP 127.0.0.1;
        proxy_set_header X-Forwarded-For 127.0.0.1;
        proxy_set_header X-Forwarded-Proto $scheme;
        
        # Hide backend server info
        proxy_hide_header X-Powered-By;
        proxy_hide_header Server;
        
        # Timeouts
        proxy_connect_timeout 30s;
        proxy_send_timeout 30s;
        proxy_read_timeout 30s;
        
        # CORS headers (if needed)
        add_header Access-Control-Allow-Origin "https://gnxsoft.com" always;
        add_header Access-Control-Allow-Methods "GET, POST, PUT, DELETE, OPTIONS" always;
        add_header Access-Control-Allow-Headers "Authorization, Content-Type" always;
        add_header Access-Control-Allow-Credentials "true" always;
        
        # Handle preflight requests
        if ($request_method = 'OPTIONS') {
            return 204;
        }
    }

    # Media files (served by nginx directly for better performance)
    location /media/ {
        alias /var/www/gnxsoft/media/;
        expires 30d;
        add_header Cache-Control "public, immutable";
        access_log off;
        
        # Security
        location ~ \.(php|py|pl|sh)$ {
            deny all;
        }
    }

    # Static files (served by nginx directly)
    location /static/ {
        alias /var/www/gnxsoft/static/;
        expires 1y;
        add_header Cache-Control "public, immutable";
        access_log off;
    }

    # Next.js static files
    location /_next/static/ {
        proxy_pass http://frontend;
        expires 1y;
        add_header Cache-Control "public, immutable";
        access_log off;
    }

    # Deny access to hidden files
    location ~ /\. {
        deny all;
        access_log off;
        log_not_found off;
    }

    # Deny access to backend admin (extra security)
    location /admin {
        deny all;
        return 404;
    }

    # Health check endpoint
    location /health {
        access_log off;
        return 200 "OK\n";
        add_header Content-Type text/plain;
    }
}

# ==============================================================================
# IMPORTANT SECURITY NOTES:
# ==============================================================================
# 1. Backend runs on 127.0.0.1:8000 (internal only)
# 2. Firewall BLOCKS external access to port 8000
# 3. Only nginx can reach backend (internal network)
# 4. Public internet can ONLY access nginx (ports 80, 443)
# 5. All API calls go through nginx proxy (/api/* → 127.0.0.1:8000/api/*)
# 6. Backend IP whitelist middleware ensures only localhost requests
# ==============================================================================