{ pkgs, lib, config, host, ... }:
let
  inherit (builtins) baseNameOf readFile;
  inherit (lib) types;
  inherit (pkgs.lib) unlinesAttrs;
  inherit (config) networking;
  inherit (config.services) openldap;
  inherit (config.users) ldap;
  domainSuffix = "dc=" + lib.concatStringsSep ",dc=" (lib.splitString "." networking.domain);
in
{
imports = [
  openldap/sourcephile.fr.nix
  openldap/autogeree.net.nix
];
users.ldap = {
  enable = false;
  # FIXME: reset to ldapi:/// once https://nixpk.gs/pr-tracker.html?pr=179597 is included
  #server = "ldapi:///";
  server = "ldapi://%2Frun%2Fslapd%2Fsock";
  base = "ou=posix,${domainSuffix}";
  bind = {
    #distinguishedName = "cn=admin,${domainSuffix}";
  };
  daemon = {
    enable = false;
    extraConfig = ''
      log syslog info

      sasl_mech EXTERNAL
      # NOTE: nslcd cannot use SASL to bind to rootpwmoddn
      # which is the DN used by nslcd when passwd is run by root
      # to change the userPassword of an LDAP user.
      # SEE: https://www.reddit.com/r/linuxadmin/comments/53sxpl/how_do_i_configure_nslcd_to_use_a_sasl_external/d7w9awd/
      # Thus, use: ldappasswd -H ldapi:// -Y EXTERNAL uid=$user,ou=accounts,ou=posix,dc=sourcephile,dc=fr
    '';
  };
};
services.openldap = {
  enable    = true;
  #dataDir   = "/var/db/ldap";
  #configDir = "/var/db/slapd";
  # FIXME: reset to ldapi:///
  #urlList   = [ "ldapi:///" ]; # UNIX socket
  urlList   = [ "ldapi://%%2Frun%%2Fslapd%%2Fsock" ]; # UNIX socket
  # sudo ldapsearch -LLL -H ldapi:// -D cn=admin,cn=config -Y EXTERNAL -b "" -s base supportedControl
  settings = {
    attrs = {
      objectClass = "olcGlobal";
      olcLogLevel = [ "stats" ];
      # The tool-threads parameter sets the actual amount of CPU's
      # that is used for indexing.
      olcToolThreads = toString host.CPUs;
    };
    children = {
      "cn=schema".includes = [
         "${pkgs.openldap}/etc/schema/core.ldif"
         "${pkgs.openldap}/etc/schema/cosine.ldif"
         "${pkgs.openldap}/etc/schema/nis.ldif"
         "${pkgs.openldap}/etc/schema/inetorgperson.ldif"
         "${openldap/schema/postfix-book.ldif}"
      ];
      # The first database is the special frontend database
      # whose settings are applied globally to all the other databases.
      # Beware that cn={0}module,cn=config must appear before
      # for enabling password schemes provided by the modules in olcPasswordHash.
      # ldapsearch -LLL -H ldapi:// -D cn=admin,cn=config -Y EXTERNAL -b 'olcDatabase={-1}frontend,cn=config' -s sub '*'
      "olcDatabase={-1}frontend".attrs = {
        objectClass = [ "olcDatabaseConfig" "olcFrontendConfig" ];
        olcDatabase = "{-1}frontend";
        # The maximum number of entries that is returned for a search operation
        olcSizeLimit = "500";
        olcAccess = [
          # Allow unlimited access to local connection from the local root user
          ''to *
          by dn.exact=gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth manage
          by * break
          ''
          # Allow unauthenticated read access for schema and base DN autodiscovery
          ''to dn.exact=""
          by * read
          ''
          ''to dn.base="cn=Subschema"
          by * read
          ''
        ];
        # Hash algorithm to be used by LDAP Password Modify Extended Operation or the ppolicy overlay
        #olcPasswordHash = "{PBKDF2-SHA256}";
        olcPasswordHash = "{SSHA}";
      };
      "cn={0}module".attrs = {
        objectClass = [ "olcModuleList" ];
        olcModulePath = "${pkgs.openldap}/lib/modules";
        #olcModuleLoad = "pw-sha2";
        #olcModuleLoad = "pw-pbkdf2";
        olcModuleLoad = "back_mdb";
      };

      "olcDatabase={0}config".attrs = {
        objectClass = "olcDatabaseConfig";
        olcDatabase = "{0}config";
        olcRootDN = "cn=admin,cn=config";
        # Access to cn=config, system root can be manager
        # with SASL mechanism (-Y EXTERNAL) over unix socket (-H ldapi://)
        olcAccess = [
          ''to *
          by dn.exact="gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth" manage
          by * break
          ''
        ];
      };
    };
  };
  /*
  cnConfig = ''
    dn: cn=schema,cn=config
    objectClass: olcSchemaConfig

    dn: olcBackend=mdb,cn=config
    objectClass: olcBackendConfig
  '';
  */
};
}