{ pkgs, lib, config, ... }:
with builtins;
let
  inherit (builtins.extraBuiltins) pass git;
  inherit (pkgs.lib) unlinesAttrs types;
  inherit (config) networking;
  inherit (config.services) knot;
  # Use the Git commit time of the ${domain}.nix file to set the serial number.
  # WARNING: the ${domain}.nix must be committed into Git for this to work.
  # WARNING: this does not take other .nix into account, though they may contribute to the zone's data.
  serial = domain: toString (git ./. [ "log" "-1" "--format=%ct" "--" (domain + ".nix") ]);
  mermetIPv4 = "80.67.180.129";
  domain = "sourcephile.fr";
  # TODO: increase the TTL once things have settled down
in
{
services.knot.zones."${domain}" = {
  conf = ''
    zone:
      - domain: ${domain}
        file: ${domain}.zone
        serial-policy: increment
        semantic-checks: on
        notify: secondary_gandi
        acl: acl_gandi
        acl: acl_localhost
        dnssec-signing: on
        dnssec-policy: rsa
  '';
  data = ''
    $ORIGIN ${domain}.
    $TTL 500

    ; SOA (Start Of Authority)
    @ SOA ns admin (
      ${serial domain} ; Serial number
      24h   ; Refresh
      15m   ; Retry
      1000h ; Expire (1000h)
      1d    ; Negative caching
    )

    ; NS (Name Server)
    @ NS ns
    @ NS ns6.gandi.net.

    ; A (DNS -> IPv4)
    @ A ${mermetIPv4}
    mermet     A ${mermetIPv4}
    autoconfig A ${mermetIPv4}
    code       A ${mermetIPv4}
    git        A ${mermetIPv4}
    imap       A ${mermetIPv4}
    mail       A ${mermetIPv4}
    ns         A ${mermetIPv4}
    pop        A ${mermetIPv4}
    smtp       A ${mermetIPv4}
    submission A ${mermetIPv4}
    www        A ${mermetIPv4}

    ; SPF (Sender Policy Framework)
    @ 3600 IN SPF "v=spf1 mx ip4:${mermetIPv4} -all"
    @ 3600 IN TXT "v=spf1 mx ip4:${mermetIPv4} -all"

    ; MX (Mail eXchange)
    @ 180 MX 5 mail

    ; SRV (SeRVice)
    _git._tcp.git 18000 IN SRV 0 0 9418 git
  '';
};
}