(define-module (machines kerberos.metznet.ca)
  #:use-module (srfi srfi-9)
  #:use-module (srfi srfi-1)
  #:use-module (gnu system)
  #:use-module (guix gexp)
  #:use-module (system base-system)
  #:use-module (gnu packages kerberos)
  #:use-module (gnu packages base)
  #:use-module (gnu services)
  #:use-module (gnu services configuration)
  #:use-module (gnu services certbot))

(define (realm-name? val)
  (string? val))

(define (serialize-string field-name val)
  (string-append "    " (symbol->string field-name) " = " val "\n"))
(define-maybe string)

(define list-of-ports?
  (list-of integer?))

(define (serialize-list-of-ports field-name value)
  (string-append "  " (symbol->string field-name) " = " (string-join (map number->string value) ", ") "\n"))

(define (realm-serialize-list-of-ports field-name value)
  (string-append "    " (symbol->string field-name) " = " (string-join (map number->string value) ", ") "\n"))

(define-maybe list-of-ports)
(define-maybe file-like)

(define (serialize-file-like field-name value)
  #~(string-append "    " #$(symbol->string field-name) " = " #$value "\n"))

(define (serialize-none field-name value) "")

(define-configuration kdc-realm-configuration
  (name (string "EXAMPLE.COM") "realm name" serialize-none)
  (database_module maybe-string "database module")
  (acl_file maybe-file-like "acl file")
  (key_stash_file maybe-file-like "key stash file")
  (kdc_ports (list-of-ports '(750 88)) "list of ports to listen on" realm-serialize-list-of-ports)
  (kadmind_ports (list-of-ports '(749)) "list of ports to listen on for kadmin connections" realm-serialize-list-of-ports)
  (max_life (string "10h 0m 0s") "maximum life of granted tickets")
  (max_renewable_type (string "7d 0h 0m 0s") "maximum time to renew ticket")
  (master_key_type (string "des3-hmac-sha1") "master key type")
  (default_principal_flags (string "+preauth") "default flag for new principals"))

(define list-of-kdc-realm-configuration?
  (list-of kdc-realm-configuration?))

(define (serialize-kdc-realm-configuration realm)
  #~(string-append "  " #$(kdc-realm-configuration-name realm) " = {\n"
                     #$(serialize-configuration realm kdc-realm-configuration-fields)
                     "  }\n"))

(define (serialize-list-of-strings field-name value)
  (string-join (append (list (string-append "[" (symbol->string field-name) "]" )) value) "\n"))

(define (serialize-list-of-kdc-realm-configuration field-name value)
  #~(string-join (list "[realms]"
                 #$@(map (lambda (realm) (serialize-kdc-realm-configuration realm)) value))
                  "\n"))

(define-configuration kdc-configuration
                      (krb5 (file-like mit-krb5) "krb5 package to use" serialize-none)
                      (kdc_ports (list-of-ports '(750 88)) "list of ports to listen on")
                      (realms (list-of-kdc-realm-configuration '()) "Realms to configure the KDC with")
                      (extra (list-of-strings '()) "extra lines"))

(define (serialize-kdc-configuration configuration)
  (mixed-text-file
    "kdc.conf"
    #~(string-append "[kdcdefaults]\n"
                     #$(serialize-configuration configuration kdc-configuration-fields))))

(define (kdc-activation configuration)
  #~(symlink #$(serialize-kdc-configuration configuration) "/etc/kdc.conf"))

(define kdc-service-type
  (service-type (name 'kdc-service)
                (description "KDC service")
                (extensions (list (service-extension activation-service-type kdc-activation)))
                (default-value (kdc-configuration))))

(operating-system
  (inherit %metznet-base-server-system)
  (host-name "kerberos-guix.metznet.ca")
  (services
   (append (list (service kdc-service-type
                          (kdc-configuration
                            (realms (list
                                      (kdc-realm-configuration
                                        (name "METZNET.CA")
                                        (database_module "openldap_ldapconf")
                                        (acl_file (plain-file "kadm5.acl" "*/admin@METZNET.CA    *\n")))))))
                 (service certbot-service-type
                          (certbot-configuration (email "admin@metznet.ca")
                                                 (certificates (list (certificate-configuration
                                                                      (domains '
                                                                       ("ldap-guix.metznet.ca"))))))))
           %metznet-server-services)))