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

with lib;
let

  user = import ../types/user.nix { inherit lib; };

  list-includes = list: el: isNull (findFirst (this: this == el) null list);

  filterExistingUsers = users: group-members:
    let user-list = attrNames users;
    in filter (username: list-includes user-list username) group-members;

  ensure-group-directory = group: dir: ''
    if [[ -d ${dir} ]]; then
      GROUP="$(stat --format '%G' "${dir}")"
      if [[ "$GROUP" = "${group}" ]]; then
        echo "${dir} exists and belongs to ${group}"
        exit 0
      else
        echo "setting ownership of ${dir} to ${group}"
        chgrp ${group} ${dir}
        chmod g+rx ${dir}
      fi
    elif [[ ! -e ${dir} ]]; then
      echo "creating ${dir} and setting ownership to ${group}"
      mkdir ${dir}
      chgrp ${group} ${dir}
      chmod g+rx ${dir}
    elif [[ -e ${dir} && ! -d ${dir} ]]; then
      echo "unable to create directory ${dir}, object exists"
      exit 2
    else
      echo "unknown error creating ${dir}"
      exit 3
    fi
  '';

  ensure-group-dirs-script = group: dirs:
    concatStringsSep "\n" (map (ensure-group-directory group) dirs);

  hostname = config.instance.hostname;
  host-cfg = config.fudo.hosts.${hostname};

in {
  options = with types; {
    fudo = {
      users = mkOption {
        type = attrsOf (submodule user.userOpts);
        description = "Users";
        default = { };
      };

      groups = mkOption {
        type = attrsOf (submodule user.groupOpts);
        description = "Groups";
        default = { };
      };

      system-users = mkOption {
        type = attrsOf (submodule user.systemUserOpts);
        description = "System users (probably not what you're looking for!)";
        default = { };
      };
    };
  };

  imports = [ ./users-common.nix ];

  config = let
    sys = config.instance;
  in {
    fudo.auth.ldap-server = let
      ldapUsers = (filterAttrs
        (username: userOpts: userOpts.ldap-hashed-password != null))
        config.fudo.users;

    in {
      users = mapAttrs (username: userOpts: {
        uid = userOpts.uid;
        group = userOpts.primary-group;
        common-name = userOpts.common-name;
        hashed-password = userOpts.ldap-hashed-password;
      }) ldapUsers;

      groups = mapAttrs (groupname: groupOpts: {
        gid = groupOpts.gid-number;
        description = groupOpts.description;
        members = filterExistingUsers ldapUsers groupOpts.members;
      }) config.fudo.groups;

      system-users = mapAttrs (username: userOpts: {
        description = userOpts.description;
        hashed-password = userOpts.ldap-hashed-passwd;
      }) config.fudo.system-users;
    };

    programs.ssh.extraConfig = mkAfter ''
      IdentityFile %h/.ssh/id_rsa
      IdentityFile /etc/ssh/private_keys.d/%u.key
    '';

    environment.etc = mapAttrs' (username: userOpts:
      nameValuePair
        "ssh/private_keys.d/${username}"
        {
          text = concatStringsSep "\n"
            (map (keypair: readFile keypair.public-key)
              userOpts.ssh-keys);
        })
      sys.local-users;

    users = {
      users = mapAttrs (username: userOpts: {
        isNormalUser = true;
        uid = userOpts.uid;
        createHome = true;
        description = userOpts.common-name;
        group = userOpts.primary-group;
        home = if (userOpts.home-directory != null) then
          userOpts.home-directory
        else
          "/home/${userOpts.primary-group}/${username}";
        hashedPassword = userOpts.login-hashed-passwd;
        openssh.authorizedKeys.keys = userOpts.ssh-authorized-keys;
      }) sys.local-users;

      groups = (mapAttrs (groupname: groupOpts: {
        gid = groupOpts.gid;
        members = filterExistingUsers sys.local-users groupOpts.members;
      }) sys.local-groups) // {
        wheel = { members = sys.local-admins; };
        docker = mkIf (host-cfg.docker-server) { members = sys.local-admins; };
      };
    };

    home-manager.useGlobalPkgs = true;
    # home-manager.useGlobalPkgs = {
    #   useGlobalPkgs = true;

    #   users = let
    #     home-manager-users =
    #       filterAttrs (username: userOpts: userOpts.home-manager-generator != null)
    #       sys.local-users;
    #   in mapAttrs (username: userOpts: userOpts.home-manager-generator {
    #     enable-gui = host-cfg.enable-gui;
    #   }) home-manager-users;
    # };

    # Group home directories have to exist, otherwise users can't log in
    systemd.services = let
      ensure-group-directories = group:
        nameValuePair "ensure-group-directories-${group}" {
          script = ensure-group-dirs-script group [ "/home/${group}" ];
          wantedBy = [ "multi-user.target" ];
          requires = [ "local-fs.target" ];
          after = [ "remote-fs.target" ];
        };
      groups-with-members = attrNames
        (filterAttrs (group: groupOpts: (length groupOpts.members) > 0)
          sys.local-groups);
    in listToAttrs (map ensure-group-directories groups-with-members);
  };
}