vcl 4.1;

import std;
import directors;

include "vcl_deliver.vcl";
include "includes/x-cache-header.vcl";

{% for ip in haproxy_traefik_ip %}
backend bk_appsrv_static-{{ loop.index }} {
	.host = "{{ ip }}";
	.port = "{{ haproxy_traefik_port }}";
	.connect_timeout = 3s;
	.first_byte_timeout = 10s;
	.between_bytes_timeout = 5s;
	.probe = {
	  .url = "/ping";
		.expected_response = 404;
		.timeout = 1s;
		.interval = 3s;
		.window = 2;
		.threshold = 2;
		.initial = 2;
	}
}

{% endfor %}

/*
 * Who is allowed to PURGE
 */
acl purge {
    "127.0.0.1";
    "localhost";
    # add your admin / app hosts here
}

sub vcl_init {
	new vdir = directors.round_robin();
{% for ip in haproxy_traefik_ip %}
	vdir.add_backend(bk_appsrv_static-{{ loop.index }});
{% endfor %}
}

sub vcl_recv {
    ### Default options

    # Health Checking
    if (req.url == "/varnishcheck") {
        return (synth(200, "health check OK!"));
    }

    # Set default backend
    set req.backend_hint = vdir.backend();

    # grace period (stale content delivery while revalidating)
    set req.grace = 30s;

    # Purge request
    if (req.method == "PURGE") {
        if (client.ip !~ purge) {
            return (synth(405, "Not allowed."));
        }
        return (purge);
    }

    # Accept-Encoding header clean-up
    if (req.http.Accept-Encoding) {
        # use gzip when possible, otherwise use deflate
        if (req.http.Accept-Encoding ~ "gzip") {
            set req.http.Accept-Encoding = "gzip";
        } elsif (req.http.Accept-Encoding ~ "deflate") {
            set req.http.Accept-Encoding = "deflate";
        } else {
            # unknown algorithm, remove accept-encoding header
            unset req.http.Accept-Encoding;
        }

        # Microsoft Internet Explorer 6 is well know to be buggy with compression and css / js
        if (req.url ~ "\.(css|js)(\?.*)?$" && req.http.User-Agent ~ "MSIE 6") {
            unset req.http.Accept-Encoding;
        }
    }

    # Enable debug headers through query param
    if (req.url ~ "(?i)debug=(true|yes|1)") {
      set req.http.X-debug = true;
    }

    ### Per host/application configuration
    # bk_appsrv_static
    # Stale content delivery
    if (std.healthy(req.backend_hint)) {
        set req.grace = 30s;
    } else {
        set req.grace = 1d;
    }

    # Cookie ignored in these static pages
    unset req.http.Cookie;

    ### Common options
    # Static objects are first looked up in the cache
    if (req.url ~ "\.(png|gif|jpg|swf|css|js)(\?.*)?$") {
        return (hash);
    }

    # Default: look for the object in cache
    return (hash);
}

sub vcl_hash {
    hash_data(req.url);

    if (req.http.host) {
        hash_data(req.http.host);
    } else {
        hash_data(server.ip);
    }
}

/*
 * Called after a successful PURGE
 */
sub vcl_purge {
    return (synth(200, "Purged."));
}

sub vcl_backend_response {
    # Stale content delivery
    set beresp.grace = 1d;

    # Hide Server information
    unset beresp.http.Server;

    # Store compressed objects in memory (gzip at fetch time)
    # Varnish can deliver gunzipped/gzipped depending on client support
    if (beresp.http.Content-Type ~ "(?i)(text|application)") {
        set beresp.do_gzip = true;
    }

		###################
    #   cache rules   #
    ###################
    # HTML pages → short cache or no cache
    if (bereq.url ~ "\.html$") {
        set beresp.ttl = 30s;         # Cache briefly
        set beresp.uncacheable = true; # Or disable cache entirely
    }

    # JavaScript & CSS → long cache
    if (bereq.url ~ "\.(js|css)$") {
        set beresp.ttl = 1d;
    }

    # Images under /image/ → long cache
    if (bereq.url ~ "^/images/.*\.(svg|png|jpe?g)$") {
        set beresp.ttl = 1y;
    }

    # Favicons → long cache
    if (bereq.url ~ "^/favicons/") {
        set beresp.ttl = 1y;
    }

    # Fallback: ensure some cache
    if (beresp.ttl <= 0s) {
        set beresp.ttl = 22s;
    }

		set beresp.http.X-TTL = beresp.ttl;

    # remove any cookie on static or pseudo-static objects
    unset beresp.http.Set-Cookie;

    return (deliver);
}

sub vcl_deliver {
    # unset resp.http.Via;
    unset resp.http.X-Varnish;

    # Handle conditional request with ETag
    if (
        req.http.If-None-Match &&
        req.http.If-None-Match == resp.http.ETag
    ) {
        return (synth(304));
    }

    return (deliver);
}

sub vcl_synth {
		if (resp.status == 304) {
        set resp.http.ETag = req.http.If-None-Match;
        # set resp.http.Content-Length = "0";
        return (deliver);
    }

    # Keep defaults; this replaces the old vcl_error.
    # (Your old "obj.status == 751" special case isn't referenced anywhere
    #  in the provided VCL, so it was dropped.)
    return (deliver);
}