{
  lib,
  config,
  pkgs,
  ...
}:

let
  inherit (lib) mkOption types;

  serviceOptions = {
    options = {
      image = mkOption {
        type = types.nullOr types.package;
        default = null;
      };

      fullImage = mkOption {
        type = with types; nullOr (submodule {
          options = {
            image = mkOption { type = str; };
            imageFile = mkOption { type = package; };
            base = mkOption { type = nullOr anything; };
          };
        });
        default = null;
      };

      ports = mkOption {
        type = with types; listOf (listOf ints.u16);
        default = [ ];
      };

      volumes = mkOption {
        type = with types; listOf (listOf str);
        default = [ ];
      };

      entrypoint = mkOption {
        type = types.nullOr types.str;
        default = null;
      };

      cmd = mkOption {
        type = with types; listOf str;
        default = [ ];
      };

      workdir = mkOption {
        type = types.nullOr types.str;
        default = null;
      };

      environment = mkOption {
        type = types.attrsOf types.str;
        default = { };
      };

      environmentFiles = mkOption {
        type = types.listOf types.path;
        default = [ ];
      };
    };
  };

  cfg = config.foundation;

  mkName =
    {
      group,
      name,
      full ? false,
    }:
    let
      isGroup = group != "";
      isDefault = name == "default" || name == group;

      shortName = if isGroup && isDefault then group else name;

      fullName = if isGroup then (if isDefault then group else "${group}-${name}") else name;
    in
    assert name != "";
    assert isDefault -> isGroup;
    if full then fullName else shortName;

  processServices =
    group: serviceSet:
    lib.mapAttrsToList (
      name: c:
      {
        name = mkName { inherit name group; };
        fullName = mkName {
          inherit name group;
          full = true;
        };
        inherit group;
      }
      // c
    ) serviceSet;

  singleServices = processServices "" cfg.services;

  groupedServices = lib.mapAttrs (
    group: groupServices: processServices group groupServices
  ) cfg.service;

  allServices =
    let
      allSingleServices = singleServices;
      allGroupedServices = lib.flatten (lib.attrValues groupedServices);
    in
    allSingleServices ++ allGroupedServices;

  groupStructure = lib.mapAttrs (
    group: groupServices: lib.catAttrs "fullName" groupServices
  ) groupedServices;
in
{
  options.foundation = {
    service = mkOption {
      type = with types; attrsOf (attrsOf (submodule serviceOptions));
      default = { };
    };

    services = mkOption {
      type = with types; attrsOf (submodule serviceOptions);
      default = { };
    };
  };

  config = lib.mkIf (cfg.service != { } || cfg.services != { }) {
    virtualisation.oci-containers.containers =
      let
        mkOciPort =
          portTuple:
          let
            host = builtins.elemAt portTuple 0;
            container = builtins.elemAt portTuple 1;
          in
          "127.0.0.1:${toString host}:${toString container}";

        mkOciVolume =
          volumeTuple:
          let
            hostPath = builtins.elemAt volumeTuple 0;
            containerPath = builtins.elemAt volumeTuple 1;
          in
          "${hostPath}:${containerPath}";

        mkImage =
          {
            oldImage,
            imageStream,
          }:
          if oldImage != null then
            {
              inherit (oldImage) image imageFile;
            }
          else if imageStream != null then
            {
              inherit imageStream;
            }
          else
            throw "can't use both `fullImage` and `image` together.";

        mkOciContainer =
          {
            name,
            fullImage,
            image,
            ports,
            volumes,
            entrypoint ? null,
            cmd ? null,
            workdir ? null,
            environment ? null,
            environmentFiles ? null,
            group,
            ...
          }:
          {
            inherit
              entrypoint
              cmd
              workdir
              environment
              environmentFiles
              ;
            ports = map mkOciPort ports;
            volumes = map mkOciVolume volumes;
            extraOptions = lib.mkIf (group != "") [
              "--network-alias=${name}"
              "--network=${group}"
            ];
          }
          // (mkImage {
            oldImage = fullImage;
            imageStream = image;
          });
      in
      builtins.listToAttrs (map (v: lib.nameValuePair v.fullName (mkOciContainer v)) allServices);

    systemd =
      let
        mkGroupRootTargetName = group: "docker-${group}-root";
        mkServiceName = fullName: "docker-${fullName}";
        mkNetworkServiceName = group: "docker-${group}-network";

        genericContainerService =
          group:
          let
            network = "${mkNetworkServiceName group}.service";
            root = "${mkGroupRootTargetName group}.target";
          in
          {
            serviceConfig = {
              Restart = lib.mkOverride 90 "always";
              RestartMaxDelaySec = lib.mkOverride 90 "1m";
              RestartSec = lib.mkOverride 90 "100ms";
              RestartSteps = lib.mkOverride 90 9;
            };
            after = [ network ];
            requires = [ network ];
            partOf = [ root ];
            wantedBy = [ root ];
          };

        networkService =
          group:
          let
            root = "${mkGroupRootTargetName group}.target";
          in
          {
            path = [ pkgs.docker ];
            serviceConfig = {
              Type = "oneshot";
              RemainAfterExit = true;
              ExecStop = "docker network rm -f ${group}";
            };
            script = ''
              docker network inspect ${group} || docker network create ${group} --driver=bridge
            '';
            partOf = [ root ];
            wantedBy = [ root ];
          };
      in
      {
        services = lib.concatMapAttrs (
          group: serviceNames:
          {
            ${mkNetworkServiceName group} = networkService group;
          }
          // lib.genAttrs (map mkServiceName serviceNames) (_v: genericContainerService group)
        ) groupStructure;

        targets = lib.mapAttrs' (
          group: _v: lib.nameValuePair (mkGroupRootTargetName group) { wantedBy = [ "multi-user.target" ]; }
        ) groupStructure;
      };
  };
}