#
# NODE1 API Gateway - Nginx Configuration
# Version: 1.0
# Last Updated: 2026-01-26
#
# Features:
# - Rate limiting per IP (10 req/s, burst 20)
# - Connection limiting (20 concurrent per IP)
# - Security headers
# - Upstream keepalive
# - Heavy endpoint separate limits
#

# === Rate Limit Zones ===
# Standard API: 10 req/s per IP
limit_req_zone $binary_remote_addr zone=api_per_ip:10m rate=10r/s;
# Heavy endpoints (RAG, image, search): 2 req/s per IP
limit_req_zone $binary_remote_addr zone=heavy_per_ip:10m rate=2r/s;
# Connection limit per IP
limit_conn_zone $binary_remote_addr zone=conn_per_ip:10m;

# === Upstreams ===
upstream gateway_upstream {
    server 127.0.0.1:9300;
    keepalive 64;
}

upstream grafana_upstream {
    server 127.0.0.1:3030;
    keepalive 8;
}

upstream prometheus_upstream {
    server 127.0.0.1:9090;
    keepalive 8;
}

# === Main API Server ===
server {
    listen 80;
    server_name api.daarion.io _;
    
    # Redirect to HTTPS (uncomment when SSL is configured)
    # return 301 https://$host$request_uri;
    
    # Security 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;
    
    # Rate limit status page (for debugging)
    location = /nginx-status {
        stub_status on;
        allow 127.0.0.1;
        deny all;
    }
    
    # Health check endpoint (no rate limit)
    location = /health {
        proxy_pass http://gateway_upstream/health;
        proxy_http_version 1.1;
        proxy_set_header Connection "";
    }
    
    # Heavy endpoints - stricter rate limit
    location ~ ^/(v1/rag|v1/image|v1/search|v1/embed) {
        limit_req zone=heavy_per_ip burst=5 nodelay;
        limit_conn conn_per_ip 10;
        
        proxy_pass http://gateway_upstream;
        proxy_http_version 1.1;
        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;
        
        # Longer timeouts for heavy operations
        proxy_connect_timeout 10s;
        proxy_send_timeout 120s;
        proxy_read_timeout 120s;
        
        client_max_body_size 50m;
    }
    
    # Webhook endpoints - higher burst for Telegram
    location ~ ^/(webhook|telegram) {
        limit_req zone=api_per_ip burst=50 nodelay;
        limit_conn conn_per_ip 30;
        
        proxy_pass http://gateway_upstream;
        proxy_http_version 1.1;
        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_connect_timeout 5s;
        proxy_send_timeout 30s;
        proxy_read_timeout 30s;
        
        client_max_body_size 10m;
    }
    
    # Default - standard rate limit
    location / {
        limit_req zone=api_per_ip burst=20 nodelay;
        limit_conn conn_per_ip 20;
        
        proxy_pass http://gateway_upstream;
        proxy_http_version 1.1;
        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_connect_timeout 5s;
        proxy_send_timeout 30s;
        proxy_read_timeout 30s;
        
        client_max_body_size 10m;
    }
    
    # Rate limit exceeded - custom error
    error_page 429 = @rate_limited;
    location @rate_limited {
        default_type application/json;
        return 429 '{"error": "rate_limit_exceeded", "message": "Too many requests. Please slow down.", "retry_after": 1}';
    }
}

# === Admin Panel (Internal Only) ===
# Access via SSH tunnel: ssh -L 3030:localhost:3030 root@node1
# Or via allowlisted IPs
server {
    listen 127.0.0.1:8080;
    server_name localhost;
    
    # Grafana
    location /grafana/ {
        proxy_pass http://grafana_upstream/;
        proxy_http_version 1.1;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
    }
    
    # Prometheus
    location /prometheus/ {
        proxy_pass http://prometheus_upstream/;
        proxy_http_version 1.1;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
    }
}

# === HTTPS Server (uncomment after certbot) ===
# server {
#     listen 443 ssl http2;
#     server_name api.daarion.io;
#     
#     ssl_certificate /etc/letsencrypt/live/api.daarion.io/fullchain.pem;
#     ssl_certificate_key /etc/letsencrypt/live/api.daarion.io/privkey.pem;
#     ssl_session_timeout 1d;
#     ssl_session_cache shared:SSL:50m;
#     ssl_session_tickets off;
#     
#     # Modern SSL config
#     ssl_protocols TLSv1.2 TLSv1.3;
#     ssl_ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256;
#     ssl_prefer_server_ciphers off;
#     
#     # HSTS
#     add_header Strict-Transport-Security "max-age=63072000" always;
#     
#     # (same location blocks as HTTP server above)
#     include /etc/nginx/conf.d/node1-api-locations.conf;
# }