events {
    worker_connections 1024;
}

http {
    upstream frontend {
        server frontend:3000;
    }

    upstream backend {
        server backend:5000;
    }

    # Rate limiting
    limit_req_zone $binary_remote_addr zone=api:10m rate=10r/s;
    limit_req_zone $binary_remote_addr zone=login:10m rate=5r/m;

    server {
        listen 80;
        server_name localhost;

        # Security headers
        add_header X-Frame-Options "SAMEORIGIN" always;
        add_header X-XSS-Protection "1; mode=block" always;
        add_header X-Content-Type-Options "nosniff" always;
        add_header Referrer-Policy "no-referrer-when-downgrade" always;
        add_header Content-Security-Policy "default-src 'self' http: https: data: blob: 'unsafe-inline'" always;

        # Frontend
        location / {
            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;
        }

        # Backend API with rate limiting
        location /api/ {
            limit_req zone=api burst=20 nodelay;
            
            proxy_pass http://backend;
            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;
            
            # CORS headers
            add_header Access-Control-Allow-Origin *;
            add_header Access-Control-Allow-Methods "GET, POST, PUT, DELETE, OPTIONS";
            add_header Access-Control-Allow-Headers "Origin, X-Requested-With, Content-Type, Accept, Authorization";
        }

        # Login endpoint with stricter rate limiting
        location /api/auth/login {
            limit_req zone=login burst=10 nodelay;
            
            proxy_pass http://backend;
            proxy_http_version 1.1;
            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;
        }

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

        # Gzip compression
        gzip on;
        gzip_vary on;
        gzip_min_length 1024;
        gzip_proxied any;
        gzip_comp_level 6;
        gzip_types
            text/plain
            text/css
            text/xml
            text/javascript
            application/javascript
            application/xml+rss
            application/json;
    }
}