apiVersion: v1
kind: ConfigMap
metadata:
  name: varnish-vcl
  namespace: ${NAMESPACE}
data:
  default.vcl: |-
    vcl 4.0;

    import std;
    import digest;

    # Define backend pointing to Home Assistant IP
    backend hass_backend {
        .host = "${HOMEASSISTANT_IP}";
        .port = "8123";
    }

    sub vcl_recv {
        # Handle CORS preflight
        if (req.method == "OPTIONS") {
            return (synth(204, "Preflight"));
        }

        # Rewrite image URL
        if (req.url ~ "^/image/") {
            # Extract everything after /image/ and store it
            set req.http.X-Image-URL = regsub(req.url, "^/image/(.*)", "\1");
            # Rewrite req.url to match backend expectations
            set req.url = regsub(req.http.X-Image-URL, "^http://[^/]+", "");
        }

        # Remove cookies so content is cacheable
        unset req.http.Cookie;
    }

    sub vcl_synth {
        if (resp.status == 204) {
            set resp.http.Access-Control-Allow-Origin = "*";
            set resp.http.Access-Control-Allow-Methods = "GET, OPTIONS";
            set resp.http.Access-Control-Allow-Headers = "Content-Type, X-Cache-ID";
            set resp.http.Content-Length = "0";
            return (deliver);
        }

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

    sub vcl_backend_fetch {
        # Always use the HASS backend
        set bereq.backend = hass_backend;

        # Set proper Host header from original URL
        # if (bereq.http.X-Image-URL) {
        #     set bereq.http.Host = regsub(bereq.http.X-Image-URL, "^http://([^/]+).*", "\1");
        #     set bereq.http.Host = regsub(bereq.http.Host, ":[0-9]+$", "");
        # }
    }

    sub vcl_backend_response {
        set beresp.ttl = 1s;
        set beresp.grace = 60s;
        set beresp.keep = 60s;

        # Ensure ETag is passed to client
        if (beresp.http.ETag) {
            set beresp.http.X-Cache-ETag = beresp.http.ETag;
        } else {
            # Optional: generate one if not provided
            # set beresp.http.ETag = digest.hash_md5(beresp.body);
            set beresp.http.ETag = beresp.http.Content-Length;
            set beresp.http.X-Cache-ETag = beresp.http.ETag;
        }
    }

    sub vcl_hit {
        if (obj.ttl < 0s && std.healthy(req.backend_hint)) {
            return (deliver);
        }
    }

    sub vcl_deliver {
        unset resp.http.X-Image-URL;
        set resp.http.Access-Control-Allow-Origin = "*";

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