{ config, lib, user, secrets, domain, ... }: let 
  calendars = [
    {
      name = "Preservation";
      primary = true;
      url = "https://dav.${domain}/nx2/preservation/";
      color = "#dddddd";
    }
    {
      name = "Effort";
      primary = false;
      url = "https://dav.${domain}/nx2/effort/";
      color = "#dd2222";
    }
    {
      name = "Experience";
      primary = false;
      url = "https://dav.${domain}/nx2/experience/";
      color = "#2222dd";
    }
    {
      name = "Exposure";
      primary = false;
      url = "https://dav.${domain}/nx2/exposure/";
      color = "#22aa22";
    }
    {
      name = "Engagement";
      primary = false;
      url = "https://dav.${domain}/nx2/engagement/";
      color = "#8800CC";
    }
  ];
in {
  accounts.calendar.accounts = let
    makeCalendar = url: primary: color: {
      inherit primary;
      remote = {
        type = "caldav";
        userName = user;
        inherit url;
      };
    };
    m = cc: lib.attrsets.mergeAttrsList ( map (c: { "${c.name}" = makeCalendar c.url c.primary c.color;}) cc );
  in m calendars;


  # TODO: Replace this once https://github.com/nix-community/home-manager/pull/5484 is merged.
  # Make sure it works, though, including the order of calendars.
  programs.thunderbird.settings = let

    makeThunderbirdCalendar = cal: let
      calendarAccountSafeName = (builtins.replaceStrings ["."] ["-"]) cal.name;
    in {
      "calendar.registry.${calendarAccountSafeName}.cache.enabled" = true;
      "calendar.registry.${calendarAccountSafeName}.calendar-main-default" = cal.primary;
      "calendar.registry.${calendarAccountSafeName}.calendar-main-in-composite" = true;
      "calendar.registry.${calendarAccountSafeName}.color" = cal.color;
      "calendar.registry.${calendarAccountSafeName}.name" = cal.name;
      "calendar.registry.${calendarAccountSafeName}.type" = "caldav";
      "calendar.registry.${calendarAccountSafeName}.uri" = config.accounts.calendar.accounts.${cal.name}.remote.url;
      "calendar.registry.${calendarAccountSafeName}.username" = config.accounts.calendar.accounts.${cal.name}.remote.userName;
    };
  in lib.attrsets.mergeAttrsList (
    map (cal: makeThunderbirdCalendar cal) calendars
  ) // {

    "calendar.registry.sleep-as-android.cache.enabled" = true;
    "calendar.registry.sleep-as-android.calendar-main-in-composite" = true;
    "calendar.registry.sleep-as-android.color" = "#222233";
    "calendar.registry.sleep-as-android.name" = "Sleep As Android";
    "calendar.registry.sleep-as-android.type" = "ics";
    "calendar.registry.sleep-as-android.readOnly" = true;
    "calendar.registry.sleep-as-android.uri" = secrets.calendar.sleep-as-android-url;
  
    "calendar.list.sortOrder" = lib.fold (cal: acc: cal.name + " " + acc) "" calendars;

    # Keep these after removing the above.
    "calendar.week.start" = 1;
  };
}