# Nginx Production Configuration
# =============================================================================
# This configuration provides secure reverse proxy with SSL termination,
# security headers, and performance optimizations for production
# =============================================================================

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

# Performance and Security Settings
worker_rlimit_nofile 65535;

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

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

    # Performance Settings
    sendfile on;
    tcp_nopush on;
    tcp_nodelay on;
    keepalive_timeout 65;
    types_hash_max_size 2048;
    server_tokens off;

    # Buffer Settings
    client_body_buffer_size 128k;
    client_max_body_size 10m;
    client_header_buffer_size 1k;
    large_client_header_buffers 4 4k;
    output_buffers 1 32k;
    postpone_output 1460;

    # Timeout Settings
    client_body_timeout 12;
    client_header_timeout 12;
    send_timeout 10;

    # Gzip Compression
    gzip on;
    gzip_vary on;
    gzip_min_length 10240;
    gzip_proxied expired no-cache no-store private must-revalidate auth;
    gzip_types
        text/plain
        text/css
        text/xml
        text/javascript
        application/x-javascript
        application/xml+rss
        application/javascript
        application/json
        application/xml
        application/rss+xml
        application/atom+xml
        image/svg+xml;

    # 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;
    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;

    # Rate Limiting
    limit_req_zone $binary_remote_addr zone=login:10m rate=10r/m;
    limit_req_zone $binary_remote_addr zone=api:10m rate=100r/m;
    limit_req_zone $binary_remote_addr zone=general:10m rate=1000r/m;

    # 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" '
                    '$request_time $upstream_response_time';

    access_log /var/log/nginx/access.log main;

    # SSL Configuration
    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 off;
    ssl_session_cache shared:SSL:10m;
    ssl_session_timeout 10m;
    ssl_session_tickets off;
    ssl_stapling on;
    ssl_stapling_verify on;

    # Upstream Definitions
    upstream keycloak {
        server keycloak:8443;
        keepalive 32;
    }

    upstream grafana {
        server grafana:3000;
        keepalive 32;
    }

    upstream prometheus {
        server prometheus:9090;
        keepalive 32;
    }

    # HTTP to HTTPS Redirect
    server {
        listen 80;
        server_name _;
        return 301 https://$host$request_uri;
    }

    # Health Check Endpoint
    server {
        listen 80;
        server_name localhost;
        location /health {
            access_log off;
            return 200 "healthy\n";
            add_header Content-Type text/plain;
        }
    }

    # Include additional server configurations
    include /etc/nginx/conf.d/*.conf;
}