# ==============================================================================
# ARQUIVO: /etc/nginx/sites-available/monitoramento.itguys.com.br.conf
# AUTOR:   Gemini (Especialista NGINX)
# DATA:    07/10/2025 (Corrigido para herança de proxy headers)
#
# CONTEXTO:
# Configuração consolidada e segura para Proxy Reverso do Grafana.
# Segue a estrutura centralizada: SSL/TLS e Headers diretos no arquivo.
#
# UPSTREAM: 172.16.254.13:3000
# ==============================================================================

# ------------------------------------------------------------------------------
# UPSTREAM: Servidor Grafana
# ------------------------------------------------------------------------------
upstream grafana_backend {
    server 172.16.254.13:3000;
    keepalive 64;
}

# ------------------------------------------------------------------------------
# BLOCO 1: Redirecionamento de HTTP (porta 80) para HTTPS
# ------------------------------------------------------------------------------
server {
    listen 80;
    listen [::]:80;
    server_name monitoramento.itguys.com.br;

    # Aplica o rate limiting (zona global_limit deve estar em nginx.conf)
    limit_req zone=global_limit burst=20 nodelay;

    # Responde ao desafio do Let's Encrypt
    location /.well-known/acme-challenge/ {
        root /var/www/html;
    }

    # Redireciona todo o resto para HTTPS
    location / {
        return 301 https://$host$request_uri;
    }
}

# ------------------------------------------------------------------------------
# BLOCO 2: Servidor Principal - Proxy Reverso para Grafana (HTTPS)
# ------------------------------------------------------------------------------
server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;
    server_name monitoramento.itguys.com.br;

    # ============================================================================
    # LOGS, LIMITAÇÃO E SEGURANÇA BÁSICA
    # ============================================================================
    client_max_body_size 10M;
    access_log /var/log/nginx/monitoramento.itguys.com.br.access.log detailed_proxy;
    error_log /var/log/nginx/monitoramento.itguys.com.br.error.log warn;
    access_log /var/log/nginx/monitoramento.itguys.com.br.bad-bot.log suspicious_bot if=$is_bad_bot;

    # Módulo de Segurança Global (Bloqueia bots e URIs suspeitas de nginx.conf)
    if ($block_request) {
        return 404;
    }

    # Rate Limiting (zona global_limit deve estar em nginx.conf)
    limit_req zone=global_limit burst=100 nodelay;

    # ============================================================================
    # CONFIGURAÇÕES DE SSL/TLS (Hardening)
    # ============================================================================
    ssl_certificate /etc/letsencrypt/live/monitoramento.itguys.com.br/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/monitoramento.itguys.com.br/privkey.pem;
    ssl_protocols TLSv1.3 TLSv1.2;
    ssl_ciphers 'TLS_AES_128_GCM_SHA256:TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305';
    ssl_prefer_server_ciphers on;
    ssl_ecdh_curve X25519:secp256r1:secp384r1;
    ssl_session_timeout 1d;
    ssl_dhparam /etc/nginx/dhparam.pem;
    ssl_session_tickets off;

    # OCSP Stapling
    ssl_stapling on;
    ssl_stapling_verify on;
    ssl_trusted_certificate /etc/letsencrypt/live/monitoramento.itguys.com.br/fullchain.pem;
    resolver 8.8.8.8 8.8.4.4 valid=300s;
    resolver_timeout 5s;

    # ============================================================================
    # HEADERS DE SEGURANÇA
    # ============================================================================
    add_header Strict-Transport-Security "max-age=63072000; includeSubDomains; preload" always;
    add_header X-Content-Type-Options "nosniff" always;
    add_header X-Frame-Options "SAMEORIGIN" always;
    add_header Referrer-Policy "no-referrer" always;
    add_header Permissions-Policy "geolocation=(), microphone=(), camera=(), payment=()" always;

    proxy_hide_header "X-Content-Type-Options";
    proxy_hide_header "X-Frame-Options";
    proxy_hide_header "Content-Security-Policy";

    # ============================================================================
    # COMPRESSÃO
    # ============================================================================
    brotli on;
    brotli_comp_level 6;
    brotli_min_length 256;
    brotli_types application/atom+xml application/javascript application/json application/rss+xml application/vnd.ms-fontobject application/x-font-opentype application/x-font-truetype application/x-font-ttf application/x-javascript application/xhtml+xml application/xml font/eot font/opentype font/otf font/truetype image/svg+xml image/x-icon text/css text/javascript text/plain text/xml;
    gzip on;
    gzip_vary on;
    gzip_proxied any;
    gzip_comp_level 6;
    gzip_min_length 256;
    gzip_types application/atom+xml application/javascript application/json application/rss+xml application/vnd.ms-fontobject application/x-font-opentype application/x-font-truetype application/x-font-ttf application/x-javascript application/xhtml+xml application/xml font/eot font/opentype font/otf font/truetype image/svg+xml image/x-icon text/css text/javascript text/plain text/xml;

    # ----------------------------------------------------------------------------
    # ROTAS ESPECÍFICAS
    # ----------------------------------------------------------------------------

    # 1. Rota para assets estáticos do Grafana (/public/) - CACHE AGRESSIVO
    location /public/ {
        # --- BLOCO DE PROXY PADRÃO ---
        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;
        proxy_pass http://grafana_backend;
        # Para assets estáticos, o buffer é benéfico
        proxy_buffering on;
        proxy_request_buffering on;

        # Headers de Cache
        expires 7d;
        add_header Cache-Control "public, immutable";
    }

    # 2. Rota para WebSockets do Grafana (/api/live/) - SEM CACHE, LONGO TIMEOUT
    location /api/live/ {
        # --- BLOCO DE PROXY PADRÃO ---
        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;
        proxy_pass http://grafana_backend;
        proxy_buffering off;
        proxy_request_buffering off;

        # --- HEADERS ESPECÍFICOS PARA WEBSOCKETS ---
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        proxy_read_timeout 86400s; # Timeout longo (24h)
    }

    # 3. Rota principal para a aplicação (SEM CACHE)
    location / {
        # --- BLOCO DE PROXY PADRÃO ---
        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;
        proxy_pass http://grafana_backend;
        proxy_buffering off; # Essencial para interatividade
        proxy_request_buffering off;
        proxy_read_timeout 90s;
        proxy_send_timeout 90s;
    }
}