vcl 4.1;

import std;
import vsthrottle;

# Cache-Status zgodny z RFC 9211. Wymaga vmod_vsthrottle.
backend default {
  .host = "plik";
  .port = "8080";
  .max_connections = 100;
  .probe = {
    .url = "/";
    .interval = 10s;
    .timeout = 5s;
    .window = 5;
    .threshold = 3;
  }
  .connect_timeout       = 5s;
  .first_byte_timeout    = 90s;
  .between_bytes_timeout = 2s;
}

acl purge {
  "localhost";
  "127.0.0.1";
  "::1";
}

sub vcl_recv {
  # Wyczyść nieufne nagłówki diagnostyczne od klienta.
  unset req.http.X-Cache;
  unset req.http.X-Cache-Hits;
  unset req.http.Cache-Status;
  unset req.http.X-CS-Decision;

  if (req.http.Host) {
    set req.http.Host = regsub(req.http.Host, ":[0-9]+$", "");
  }
  unset req.http.Proxy;
  set req.backend_hint = default;
  set req.url = std.querysort(req.url);
  set req.url = regsub(req.url, "\?$", "");

  if (req.restarts == 0) {
    if (req.http.X-Forwarded-For) {
      set req.http.X-Forwarded-For = req.http.X-Forwarded-For + ", " + client.ip;
    } else {
      set req.http.X-Forwarded-For = client.ip;
    }
  }

  if (vsthrottle.is_denied(client.identity, 100, 10s, 10s)) {
    return (synth(429, "Too Many Requests"));
  }

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

  if (req.method == "BAN") {
    if (!client.ip ~ purge) {
      return (synth(405, "Not allowed."));
    }
    # Lokalny BAN zachowuje pierwotną semantykę wyrażenia regularnego.
    ban("req.http.host == " + req.http.host + " && req.url ~ " + req.url);
    return (synth(200, "Banned"));
  }

  # OPTIONS nie jest cache'owalne; inne metody niż GET/HEAD też pomijamy.
  if (req.method != "GET" && req.method != "HEAD") {
    set req.http.X-CS-Decision = "method";
    return (pass);
  }

  if (req.http.Authorization) {
    set req.http.X-CS-Decision = "bypass";
    return (pass);
  }

  # Klient wymaga ponownej walidacji: bezpiecznie kierujemy do backendu.
  if (req.http.Cache-Control ~ "(?i)(^|,)[[:space:]]*(no-cache|max-age=0)([[:space:]]*(,|$))" ||
      req.http.Pragma ~ "(?i)no-cache") {
    set req.http.X-CS-Decision = "request";
    return (pass);
  }

  # upload / status / api / ajax poza cache.
  if (
    req.url ~ "(?i)^/(upload|api|status|progress|session|login|logout)(/|$|\?)" ||
    req.url ~ "(?i)/(ajax|ahah)/"
  ) {
    set req.http.X-CS-Decision = "bypass";
    return (pass);
  }

  if (req.http.Accept-Encoding) {
    if (req.url ~ "(?i)\.(jpg|jpeg|png|gif|webp|ico|svg|woff2?|ttf|eot|mp4|mp3|pdf|zip|7z|gz|bz2)(\?.*)?$") {
      unset req.http.Accept-Encoding;
    } elseif (req.http.Accept-Encoding ~ "(?i)gzip") {
      set req.http.Accept-Encoding = "gzip";
    } else {
      unset req.http.Accept-Encoding;
    }
  }

  # Cookies ignorujemy wyłącznie dla zasobów statycznych.
  if (req.http.Cookie) {
    if (req.url ~ "(?i)\.(jpg|jpeg|png|gif|webp|ico|svg|js|css|woff2?|ttf|eot|pdf|zip|7z|gz|bz2|mp4|mp3)(\?.*)?$") {
      unset req.http.Cookie;
    } else {
      set req.http.X-CS-Decision = "bypass";
      return (pass);
    }
  }

  return (hash);
}

sub vcl_hash {
  # Domyślny VCL dodaje req.url i Host. Dodajemy rozróżnienie HTTP/HTTPS.
  if (req.http.X-Forwarded-Proto) {
    hash_data(req.http.X-Forwarded-Proto);
  }
}

sub vcl_hit {
  if (obj.ttl >= 0s) {
    set req.http.X-CS-Decision = "hit";
    return (deliver);
  }
  if (obj.ttl + obj.grace > 0s) {
    set req.http.X-CS-Decision = "hit";
    return (deliver);
  }
  # Odswiezenie po wyczerpaniu grace to fwd=stale, nie uri-miss.
  set req.http.X-CS-Decision = "stale";
  return (miss);
}

sub vcl_miss {
  if (!req.http.X-CS-Decision) {
    set req.http.X-CS-Decision = "miss";
  }
  return (fetch);
}

sub vcl_pass {
  if (!req.http.X-CS-Decision) {
    set req.http.X-CS-Decision = "bypass";
  }
  return (fetch);
}

sub vcl_backend_fetch {
  # Metadane pomocnicze nie trafiają do aplikacji.
  unset bereq.http.X-CS-Decision;
}

sub vcl_backend_response {
  # Dla PASS nie zmieniaj polityki cache ani cookies aplikacji.
  if (bereq.uncacheable) {
    set beresp.uncacheable = true;
    set beresp.ttl = 0s;
    return (deliver);
  }

  # Odpowiedzi 5xx i tresci jawnie prywatne nie moga trafic do cache.
  if (beresp.status >= 500 && beresp.status <= 599) {
    set beresp.uncacheable = true;
    set beresp.ttl = 0s;
    return (deliver);
  }

  if (beresp.http.Cache-Control ~ "(?i)(no-store|private|no-cache)" ||
      beresp.http.Surrogate-Control ~ "(?i)no-store" ||
      beresp.http.Vary ~ "^[[:space:]]*\*[[:space:]]*$") {
    set beresp.uncacheable = true;
    set beresp.ttl = 0s;
    return (deliver);
  }

  # Odpowiedź personalizowana z Set-Cookie nie powinna być współdzielona.
  if (bereq.url !~ "(?i)\.(jpg|jpeg|png|gif|webp|ico|svg|js|css|woff2?|ttf|eot|pdf|zip|7z|gz|bz2|mp4|mp3)(\?.*)?$" &&
      beresp.http.Set-Cookie) {
    set beresp.uncacheable = true;
    set beresp.ttl = 0s;
    return (deliver);
  }

  # Krótki cache dla 404, umiarkowany dla przekierowań.
  if (beresp.status == 404) {
    set beresp.ttl = 5s;
  } elseif (beresp.status == 301 || beresp.status == 302) {
    set beresp.ttl = 10m;
  }

  # Wariant: statyki bez jawnej polityki pochodzenia dostają 7 dni.
  if (beresp.status == 200 &&
      bereq.url ~ "(?i)\.(jpg|jpeg|png|gif|webp|ico|svg|js|css|woff2?|ttf|eot|pdf|zip|7z|gz|bz2|mp4|mp3)(\?.*)?$" &&
      !beresp.http.Cache-Control && !beresp.http.Expires) {
    set beresp.ttl = 7d;
    set beresp.http.Cache-Control = "public, max-age=604800, immutable";
  }

  # Gdy Varnish nie ma dodatniego TTL, odczytaj nagłówki cache.
  if (beresp.ttl <= 0s) {
    if (beresp.http.Cache-Control ~ "(?i)s-maxage=[0-9]+") {
      set beresp.ttl = std.duration(
        regsub(beresp.http.Cache-Control, "(?i).*s-maxage=([0-9]+).*", "\1") + "s", 0s
      );
    } elseif (beresp.http.Cache-Control ~ "(?i)max-age=[0-9]+") {
      set beresp.ttl = std.duration(
        regsub(beresp.http.Cache-Control, "(?i).*max-age=([0-9]+).*", "\1") + "s", 0s
      );
    }
  }

  if (beresp.ttl <= 0s) {
    set beresp.ttl = 0s;
    set beresp.uncacheable = true;
    return (deliver);
  }

  # Set-Cookie usuwamy tylko przy odpowiedzi 200 z publicznym plikiem.
  if (beresp.status == 200 &&
      bereq.url ~ "(?i)\.(jpg|jpeg|png|gif|webp|ico|svg|js|css|woff2?|ttf|eot|pdf|zip|7z|gz|bz2|mp4|mp3)(\?.*)?$") {
    unset beresp.http.Set-Cookie;
  }

  # Kompresuj tylko nieskompresowane typy tekstowe.
  if (!beresp.http.Content-Encoding &&
      beresp.http.Content-Type ~ "(?i)^(text/|application/(javascript|json|xml))") {
    set beresp.do_gzip = true;
  } else {
    set beresp.do_gzip = false;
  }

  if (beresp.http.Surrogate-Control ~ "ESI/1.0") {
    unset beresp.http.Surrogate-Control;
    set beresp.do_esi = true;
  }

  set beresp.grace = 10m;
  if (beresp.ttl > 1h) {
    set beresp.keep = 1h;
  } else {
    set beresp.keep = beresp.ttl;
  }

  if (beresp.http.Content-Length && std.integer(beresp.http.Content-Length, 0) > 1048576) {
    set beresp.do_stream = true;
  }

  return (deliver);
}

sub vcl_deliver {
  # Polityka przeglądarki: nie nadpisuj private/no-store backendu na public.
  if (req.url ~ "(?i)\.(jpg|jpeg|png|gif|webp|ico|svg|js|css|woff2?|ttf|eot|pdf|zip|7z|gz|bz2|mp4|mp3)(\?.*)?$" &&
      resp.status == 200 && !obj.uncacheable) {
    if (!resp.http.Cache-Control) {
      set resp.http.Cache-Control = "public, max-age=604800, immutable";
    }
  } elseif (!resp.http.Cache-Control ||
          resp.http.Cache-Control !~ "(?i)(no-store|private)") {
    set resp.http.Cache-Control = "no-store, no-cache, must-revalidate, max-age=0";
  }

  # Odpowiedz z vcl_backend_error to lokalny synthetic response.
  # RFC 9211 zaleca, aby nie oznaczac jej jako MISS.
  if (resp.http.X-CS-Local-Error) {
    unset resp.http.Cache-Status;
  } else {
    # RFC 9211: status dotyczy obsługi bieżącego żądania (nie obiektu w cache).
    # Dodajemy własny wpis NA KOŃCU, zachowując wpisy wcześniejszych cache.
    if (req.http.X-CS-Decision == "hit") {
      # obj.ttl ma format np. 123.456; RFC wymaga całkowitych sekund.
      # Wariant działa również ze starszym std (Varnish 6.0/6.1).
      set resp.http.X-CS-TTL = obj.ttl;
      set resp.http.X-CS-TTL = regsub(resp.http.X-CS-TTL, "[.][0-9]+$", "");
      set resp.http.X-CS-Entry = "varnish; hit; ttl=" + resp.http.X-CS-TTL;
    } elseif (req.http.X-CS-Decision == "method") {
      set resp.http.X-CS-Entry = "varnish; fwd=method";
    } elseif (req.http.X-CS-Decision == "request") {
      set resp.http.X-CS-Entry = "varnish; fwd=request";
    } elseif (req.http.X-CS-Decision == "bypass") {
      set resp.http.X-CS-Entry = "varnish; fwd=bypass";
    } elseif (req.http.X-CS-Decision == "miss" || req.http.X-CS-Decision == "stale") {
      if (!obj.uncacheable && obj.ttl > 0s) {
        set resp.http.X-CS-Entry = "varnish; fwd=" +
          regsub(req.http.X-CS-Decision, "^miss$", "uri-miss") + "; stored";
      } else {
        set resp.http.X-CS-Entry = "varnish; fwd=" +
          regsub(req.http.X-CS-Decision, "^miss$", "uri-miss") + "; stored=?0";
      }
    } else {
      # Zabezpieczenie na nietypowe ścieżki VCL.
      if (obj.uncacheable) {
        set resp.http.X-CS-Entry = "varnish; fwd=bypass";
      } elseif (obj.hits > 0) {
        set resp.http.X-CS-TTL = obj.ttl;
        set resp.http.X-CS-TTL = regsub(resp.http.X-CS-TTL, "[.][0-9]+$", "");
        set resp.http.X-CS-Entry = "varnish; hit; ttl=" + resp.http.X-CS-TTL;
      } else {
        set resp.http.X-CS-Entry = "varnish; fwd=uri-miss";
      }
    }

    if (resp.http.Cache-Status) {
      set resp.http.Cache-Status = resp.http.Cache-Status + ", " + resp.http.X-CS-Entry;
    } else {
      set resp.http.Cache-Status = resp.http.X-CS-Entry;
    }

  }

  unset resp.http.X-CS-Entry;
  unset resp.http.X-CS-TTL;
  unset resp.http.X-CS-Local-Error;
  unset resp.http.X-Cache;
  unset resp.http.X-Cache-Hits;
  unset resp.http.X-Url;
  unset resp.http.X-Host;
  unset resp.http.Via;
  unset resp.http.X-Varnish;
  unset resp.http.Server;
  unset resp.http.Content-Disposition;

  set resp.http.X-Frame-Options = "SAMEORIGIN";
}

sub vcl_backend_error {
  # Zachowaj standardowa tresc bledu z built-in VCL, bez cache'owania 503.
  set beresp.ttl = 0s;
  set beresp.http.X-CS-Local-Error = "1";
}

sub vcl_synth {
  # Odpowiedzi syntetyczne (np. 429) nie raportują stanu cache.
  unset resp.http.Cache-Status;
  unset resp.http.X-Cache;
  unset resp.http.X-Cache-Hits;
  unset resp.http.X-Varnish;
  set resp.http.Cache-Control = "private, no-store";

  if (resp.status == 429) {
    set resp.http.Content-Type = "text/plain; charset=utf-8";
    return (deliver);
  }
  # Dla PURGE/BAN i innych SYNTH zachowaj tresc built-in VCL.
}