# NGINX Configuration for BCards Load Balancer
# Configuração principal para produção com SSL e load balancing

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

# Otimizações de performance
worker_rlimit_nofile 65535;

events {
    worker_connections 4096;
    use epoll;
    multi_accept on;
}

http {
    # Configurações básicas
    include /etc/nginx/mime.types;
    default_type application/octet-stream;
    
    # Logging format
    log_format main '$remote_addr - $remote_user [$time_local] "$request" '
                    '$status $body_bytes_sent "$http_referer" '
                    '"$http_user_agent" "$http_x_forwarded_for" '
                    'rt=$request_time uct="$upstream_connect_time" '
                    'uht="$upstream_header_time" urt="$upstream_response_time"';
    
    access_log /var/log/nginx/access.log main;
    
    # Performance settings
    sendfile on;
    tcp_nopush on;
    tcp_nodelay on;
    keepalive_timeout 65;
    types_hash_max_size 2048;
    client_max_body_size 20M;
    
    # 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/json
        application/javascript
        application/xml+rss
        application/atom+xml
        image/svg+xml;
    
    # Rate limiting
    limit_req_zone $binary_remote_addr zone=api:10m rate=10r/s;
    limit_req_zone $binary_remote_addr zone=login:10m rate=1r/s;
    
    # Upstream configuration for load balancing
    upstream bcards_backend {
        # Configuração de load balancing com health checks
        least_conn;
        
        # Servidores backend
        server 172.18.0.2:8080 max_fails=3 fail_timeout=30s;
        server 172.18.0.3:8080 max_fails=3 fail_timeout=30s;
        
        # Manter conexões vivas
        keepalive 32;
    }
    
    # Configuração para health checks dos backends
    upstream bcards_health {
        server 172.18.0.2:8080;
        server 172.18.0.3:8080;
    }
    
    # Rate limiting
    limit_req_zone $binary_remote_addr zone=general:10m rate=10r/s;
    
    # Configuração SSL/TLS
    ssl_protocols TLSv1.2 TLSv1.3;
    ssl_ciphers ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA384;
    ssl_prefer_server_ciphers off;
    ssl_session_cache shared:SSL:10m;
    ssl_session_timeout 10m;
    
    # 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;
    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
    
    # Redirect HTTP to HTTPS
    server {
        listen 80;
        server_name bcards.site www.bcards.site;
        
        # ACME challenge para Let's Encrypt
        location /.well-known/acme-challenge/ {
            root /var/www/certbot;
        }
        
        # Redirect para HTTPS
        location / {
            return 301 https://$server_name$request_uri;
        }
    }
    
    # Main HTTPS server configuration
    server {
        listen 443 ssl http2;
        server_name bcards.site www.bcards.site;
        
        # SSL certificates
        ssl_certificate /etc/letsencrypt/live/bcards.site/fullchain.pem;
        ssl_certificate_key /etc/letsencrypt/live/bcards.site/privkey.pem;
        
        # Trusted certificate for OCSP stapling
        ssl_trusted_certificate /etc/letsencrypt/live/bcards.site/chain.pem;
        ssl_stapling on;
        ssl_stapling_verify on;
        
        # DNS resolver
        resolver 8.8.8.8 8.8.4.4 valid=300s;
        resolver_timeout 5s;
        
        # Rate limiting
        limit_req zone=general burst=20 nodelay;
        
        # Health check endpoint (não passar pelo backend)
        location = /nginx-health {
            access_log off;
            return 200 "nginx ok\n";
            add_header Content-Type text/plain;
        }
        
        # Backend health check
        location = /backend-health {
            access_log off;
            proxy_pass http://bcards_health/health;
            proxy_connect_timeout 5s;
            proxy_read_timeout 5s;
        }
        
        # Main application proxy
        location / {
            # Proxy para o backend
            proxy_pass http://bcards_backend;
            
            # Headers para proxy reverso
            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 $host;
            proxy_set_header X-Forwarded-Port $server_port;
            
            # Timeouts
            proxy_connect_timeout 30s;
            proxy_send_timeout 30s;
            proxy_read_timeout 30s;
            
            # Buffer settings
            proxy_buffering on;
            proxy_buffer_size 4k;
            proxy_buffers 8 4k;
            
            # Retry configuration
            proxy_next_upstream error timeout invalid_header http_500 http_502 http_503 http_504;
            proxy_next_upstream_tries 2;
            proxy_next_upstream_timeout 10s;
        }
        
        # Static files caching
        location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg)$ {
            proxy_pass http://bcards_backend;
            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 headers
            expires 1y;
            add_header Cache-Control "public, immutable";
            
            # Disable logging for static files
            access_log off;
        }
        
        # Error pages
        error_page 500 502 503 504 /50x.html;
        location = /50x.html {
            root /usr/share/nginx/html;
        }
    }
    
    # Servidor para monitoramento interno (apenas localhost)
    server {
        listen 127.0.0.1:8081;
        server_name localhost;
        
        # Status do NGINX
        location /nginx_status {
            stub_status on;
            access_log off;
            allow 127.0.0.1;
            deny all;
        }
        
        # Status detalhado dos upstreams
        location /upstream_status {
            access_log off;
            allow 127.0.0.1;
            deny all;
            
            return 200 "Backend Status Check\n";
            add_header Content-Type text/plain;
        }
    }
}

# Stream configuration for TCP load balancing (se necessário)
# stream {
#     upstream tcp_backend {
#         server 172.18.0.2:9000;
#         server 172.18.0.3:9000;
#     }
#
#     server {
#         listen 9000;
#         proxy_pass tcp_backend;
#         proxy_timeout 1s;
#         proxy_responses 1;
#     }
# }