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

events {
    worker_connections 2048;
    use epoll;
    multi_accept on;
}

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

    # Logging
    log_format main '$remote_addr - $remote_user [$time_local] "$request" '
                    '$status $body_bytes_sent "$http_referer" '
                    '"$http_user_agent" "$http_x_forwarded_for"';

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

    # Performance
    sendfile on;
    tcp_nopush on;
    tcp_nodelay on;
    keepalive_timeout 65;
    types_hash_max_size 2048;
    client_max_body_size 100M;

    # Gzip
    gzip on;
    gzip_vary on;
    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;

    # 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 limiting zones
    limit_req_zone $binary_remote_addr zone=api_limit:10m rate=10r/s;
    limit_req_zone $binary_remote_addr zone=auth_limit:10m rate=5r/s;

    # Include site configs
    include /etc/nginx/sites-enabled/*;
}

# Upstream definition
upstream hasura {
    least_conn;
    server localhost:8080 max_fails=3 fail_timeout=30s;
    keepalive 32;
}

# HTTP to HTTPS redirect
server {
    listen 80;
    listen [::]:80;
    server_name api.example.com;

    # Let's Encrypt challenge
    location /.well-known/acme-challenge/ {
        root /var/www/certbot;
    }

    location / {
        return 301 https://$server_name$request_uri;
    }
}

# HTTPS server
server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;
    server_name api.example.com;

    # SSL configuration
    ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;
    ssl_session_timeout 1d;
    ssl_session_cache shared:SSL:50m;
    ssl_session_tickets off;

    # Modern 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;
    ssl_prefer_server_ciphers off;

    # HSTS
    add_header Strict-Transport-Security "max-age=63072000; includeSubDomains; preload" always;

    # Rate limiting
    limit_req zone=api_limit burst=20 nodelay;

    # Hasura GraphQL
    location / {
        proxy_pass http://hasura;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        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 60s;
        proxy_send_timeout 60s;
        proxy_read_timeout 60s;

        # Buffering
        proxy_buffering off;
        proxy_request_buffering off;
    }

    # Health check
    location /healthz {
        access_log off;
        return 200 "healthy\n";
        add_header Content-Type text/plain;
    }
}

upstream auth {
    server localhost:4000 max_fails=3 fail_timeout=30s;
    keepalive 32;
}

server {
    listen 80;
    listen [::]:80;
    server_name auth.example.com;

    location /.well-known/acme-challenge/ {
        root /var/www/certbot;
    }

    location / {
        return 301 https://$server_name$request_uri;
    }
}

server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;
    server_name auth.example.com;

    ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;

    # Rate limiting (stricter for auth)
    limit_req zone=auth_limit burst=10 nodelay;

    location / {
        proxy_pass http://auth;
        proxy_http_version 1.1;
        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;

        # CORS headers (for all apps)
        add_header Access-Control-Allow-Origin "https://chat.example.com" always;
        add_header Access-Control-Allow-Origin "https://notes.example.com" always;
        add_header Access-Control-Allow-Origin "https://tasks.example.com" always;
        add_header Access-Control-Allow-Methods "GET, POST, OPTIONS" always;
        add_header Access-Control-Allow-Headers "Authorization, Content-Type, X-Requested-With" always;
        add_header Access-Control-Allow-Credentials "true" always;
        add_header Access-Control-Max-Age "3600" always;

        if ($request_method = OPTIONS) {
            return 204;
        }

        # Security headers
        add_header X-Frame-Options "DENY" always;
        add_header X-Content-Type-Options "nosniff" always;
    }
}

upstream chat_app {
    server localhost:3001 max_fails=3 fail_timeout=30s;
    keepalive 32;
}

server {
    listen 80;
    listen [::]:80;
    server_name chat.example.com;

    location /.well-known/acme-challenge/ {
        root /var/www/certbot;
    }

    location / {
        return 301 https://$server_name$request_uri;
    }
}

server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;
    server_name chat.example.com;

    ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;

    # Frontend app
    location / {
        proxy_pass http://chat_app;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        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_cache_bypass $http_upgrade;

        # Next.js specific
        proxy_buffering off;
        proxy_request_buffering off;
    }

    # Static assets caching
    location /_next/static/ {
        proxy_pass http://chat_app;
        proxy_cache_valid 200 1y;
        add_header Cache-Control "public, immutable";
    }

    # Images
    location ~* \.(jpg|jpeg|png|gif|ico|svg|webp|avif)$ {
        proxy_pass http://chat_app;
        expires 1y;
        add_header Cache-Control "public, immutable";
    }
}