# Define rate limiting zone (10 requests per second per IP, 10MB memory zone)
limit_req_zone $binary_remote_addr zone=api_limit:10m rate=10r/s;

upstream internal_app_cluster {
    server 127.0.0.1:3000 max_fails=3 fail_timeout=10s;
    server 127.0.0.1:3001 backup;
    keepalive 32;
}

server {
    listen 80;
    listen [::]:80;
    server_name vault.devyield.internal;

    # Force HTTP to HTTPS Permanent Redirect
    return 301 https://$host$request_uri;
}

server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;
    server_name vault.devyield.internal;

    # SSL/TLS Hardening
    ssl_certificate /etc/letsencrypt/live/vault.devyield.internal/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/vault.devyield.internal/privkey.pem;
    ssl_protocols TLSv1.2 TLSv1.3;
    ssl_ciphers 'ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384';
    ssl_prefer_server_ciphers off;
    ssl_session_cache shared:SSL:10m;
    ssl_session_timeout 1d;

    # Security & Hardening 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;
    add_header Content-Security-Policy "default-src 'self' http: https: data: blob: 'unsafe-inline'" always;
    add_header Strict-Transport-Security "max-age=63072000; includeSubDomains; preload" always;

    # Client Payload Limits
    client_max_body_size 50M;
    client_body_buffer_size 128k;

    # Logging Paths
    access_log /var/log/nginx/vault_access.log combined buffer=32k flush=5s;
    error_log /var/log/nginx/vault_error.log warn;

    location / {
        # Apply Rate Limiting
        limit_req zone=api_limit burst=20 nodelay;

        proxy_pass http://internal_app_cluster;
        proxy_http_version 1.1;
        
        # Proxy Headers & WebSockets Support
        proxy_set_header Connection "";
        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;

        # Timeouts
        proxy_connect_timeout 60s;
        proxy_send_timeout 60s;
        proxy_read_timeout 60s;
    }

    # Deny access to hidden system files (.git, .env, etc.)
    location ~ /\. {
        deny all;
        access_log off;
        log_not_found off;
    }
}