worker_processes auto;
error_log /var/log/nginx/error.log warn;
pid /var/run/nginx.pid;

events {
    worker_connections 1024;
    use epoll;
    multi_accept on;
}

http {
    include /etc/nginx/mime.types;
    default_type application/octet-stream;

    # Logging
    log_format main '$remote_addr - $remote_user [$time_local] "$request" '
                    '$status $body_bytes_sent "$http_referer" '
                    '"$http_user_agent" "$http_x_forwarded_for"';
    access_log /var/log/nginx/access.log main;

    # Performance
    sendfile on;
    tcp_nopush on;
    tcp_nodelay on;
    keepalive_timeout 65;
    gzip on;
    gzip_types text/plain text/css application/json application/javascript text/xml application/xml;

    # Security headers
    add_header X-Frame-Options DENY 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;

    # Rate limiting zones
    limit_req_zone $binary_remote_addr zone=api:10m rate=30r/m;
    limit_req_zone $binary_remote_addr zone=auth:10m rate=10r/m;

    # Upstream servers
    upstream frontend {
        server frontend:3000;
        keepalive 32;
    }

    upstream backend {
        server backend:8000;
        keepalive 32;
    }

    server {
        listen 80;
        server_name _;

        # 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_cache_bypass $http_upgrade;
        }

        # Backend API — rate limited
        location /api/ {
            limit_req zone=api burst=20 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_read_timeout 120s;
        }

        # Auth endpoints — stricter rate limit
        location /api/auth/ {
            limit_req zone=auth burst=5 nodelay;
            proxy_pass http://backend;
            proxy_http_version 1.1;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
        }

        # WebSocket — no rate limit, long timeout
        location /api/ai/chat/ws {
            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_read_timeout 3600s;
            proxy_send_timeout 3600s;
        }

        # Health check (no logging)
        location /health {
            proxy_pass http://backend/health;
            access_log off;
        }

        # API docs
        location /docs {
            proxy_pass http://backend/docs;
        }
    }
}