events {
    worker_connections 1024;
}

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

    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;
    error_log /var/log/nginx/error.log error;

    sendfile on;
    tcp_nopush on;
    tcp_nodelay on;
    keepalive_timeout 65;
    types_hash_max_size 2048;

    gzip on;
    gzip_vary on;
    gzip_min_length 1024;
    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;

    # Rate limiting
    limit_req_zone $binary_remote_addr zone=api:10m rate=10r/s;
    limit_req_zone $binary_remote_addr zone=static:10m rate=30r/s;

    # Use resolver to dynamically resolve backend hostname
    # This allows backend container to start after frontend
    resolver 127.0.0.11 valid=10s;

    server {
        listen 80;
        server_name _;
        root /usr/share/nginx/html;
        index index.html;

        # Set backend upstream address (resolved dynamically)
        set $backend_backend "backend:3000";

        # Rate limited API proxy
        location /api/ {
            limit_req zone=api burst=20 nodelay;
            proxy_pass http://$backend_backend;
            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;
            proxy_read_timeout 86400;
        }

        # Hashed CSS files (cache-busted)
        location ~* ^/css/.*\.css$ {
            limit_req zone=static burst=50 nodelay;
            expires 1y;
            add_header Cache-Control "public, immutable";
        }

        # Hashed JS files (cache-busted)
        location ~* ^/js/.*\.(js|mjs)$ {
            limit_req zone=static burst=50 nodelay;
            expires 1d;
            add_header Cache-Control "public, immutable";
        }

        # Regular static files (non-hashed)
        location ~* \.(png|jpg|jpeg|gif|ico|svg|webp|woff|woff2)$ {
            limit_req zone=static burst=50 nodelay;
            expires 1y;
            add_header Cache-Control "public, immutable";
        }

        # Version file endpoint
        location = /version.txt {
            access_log off;
            add_header Cache-Control "no-store, no-cache, must-revalidate";
            add_header Pragma "no-cache";
            add_header Expires "0";
        }

        # Explicitly handle HTML files - don't fallback to index.html
        location ~* \.html$ {
            limit_req zone=static burst=10 nodelay;
            try_files $uri =404;
        }

        # Main application routes
        location / {
            limit_req zone=static burst=10 nodelay;
            try_files $uri $uri/ /index.html;
        }

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

        # Error pages
        error_page 404 /404.html;
        error_page 500 502 503 504 /50x.html;

        location = /404.html {
            root /usr/share/nginx/html;
            internal;
        }

        location = /50x.html {
            root /usr/share/nginx/html;
            internal;
        }
    }
}