upstream backend {
    server backend:3000;
}

upstream frontend {
    server frontend:80;
}

server {
    listen 80;
    listen [::]:80;
    server_name _;

    # Client upload size limit (adjust as needed)
    client_max_body_size 100M;

    # Logging
    access_log /var/log/nginx/access.log main;
    error_log /var/log/nginx/error.log warn;

    # Security headers
    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;

    # Gzip compression
    gzip on;
    gzip_types text/plain text/css text/xml text/javascript 
               application/x-javascript application/xml+rss 
               application/json application/javascript;
    gzip_min_length 1000;

    # Forward all app requests to the frontend container
    location / {
        proxy_pass http://frontend;
        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_http_version 1.1;
    }

    # API proxy to backend
    location /api/ {
        proxy_pass http://backend/api/;
        
        # Preserve original request information
        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_set_header X-Forwarded-Host $server_name;
        proxy_set_header X-Forwarded-Port $server_port;
        
        # Connection settings
        proxy_connect_timeout 60s;
        proxy_send_timeout 60s;
        proxy_read_timeout 60s;
        
        # Buffering settings
        proxy_buffering on;
        proxy_buffer_size 4k;
        proxy_buffers 8 4k;
        proxy_busy_buffers_size 8k;
    }

    # Uploads proxy to backend
    location /uploads/ {
        proxy_pass http://backend/uploads/;
        
        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;
        
        # Cache uploads
        expires 30d;
        add_header Cache-Control "public";
    }

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

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

    location ~ ~$ {
        deny all;
        access_log off;
        log_not_found off;
    }
}