(use-modules (guix gexp)
             (guix modules)
             (guix records)
             (gnu home services)
             (gnu home services mcron)
             (gnu services)
             (gnu services mcron)
             (ice-9 match)
             (ice-9 receive)
             (ice-9 textual-ports)
             (json)
             (rnrs bytevectors)
             (srfi srfi-1)
             (web client)
             (web uri))

(define dnsimple-url "https://api.dnsimple.com/v2")

(define (dnsimple-whoami headers)
  (receive (header body)
      (http-get (string->uri (string-append dnsimple-url "/whoami"))
                #:headers headers)
    (fold (lambda (a b) (assoc-ref b a))
          (json-string->scm (utf8->string body))
          '("data" "account" "id"))))

(define (get-root-url domain headers)
  (string-join (list dnsimple-url
                     (number->string (dnsimple-whoami headers))
                     "zones"
                     domain
                     "records")
               "/"))

(define (dnsimple-get-records root-url headers ignore-patterns)
  (filter-map
   (lambda (record)
     (and (not (any (lambda (ignore-pattern)
                      (match ignore-pattern
                        ((key . value)
                         (equal? value (assoc-ref record key)))))
                    ignore-patterns))
          (map (lambda (ass)
                 (if (and (equal? (car ass) "content")
                          (equal? (assoc-ref record "type") "TXT"))
                     (cons k (read (open-input-string (assoc-ref record "content"))))
                     ass))
               record)))
   (receive (header body)
       (http-get (string->uri root-url) #:headers headers)
     (vector->list (assoc-ref (json-string->scm (utf8->string body)) "data")))))

(define (duplicate-record-pred record-list)
  (lambda (record)
    (any (lambda (record2)
           (every (lambda (field)
                    (equal? (assoc-ref record1 field)
                            (assoc-ref record2 field)))
                  '("type" "content" "name")))
         record-list)))

(define (dnsimple-delete-record root-url headers record)
  (http-delete (string->uri
                (string-append root-url "/" (number->string
                                             (assoc-ref record "id"))))
               #:headers headers))

(define (dnsimple-post-record root-url headers record)
  (http-post (string->uri root-url) #:headers headers
             #:body (string->utf8 (scm->json-string record))))

(define (dnsimple-update-records api-key-file domain get-records ignore-patterns)
  (let* ((headers
          (list (cons 'Authorization
                      (string-append "Bearer "
                                     (get-line (open-input-file api-key-file))))
                (cons 'Content-Type "application/json")))
         (root-url (get-root-url domain headers))
         (new-records (get-records))
         (old-records (dnsimple-get-records root-url headers ignore-patterns)))
    (for-each
     (lambda (record)
       (dnsimple-post-record root-url headers record))
     (remove (duplicate-record-pred old-records) new-records))
    (display (remove (duplicate-record-pred new-records) old-records))
    (for-each
     (lambda (record)
       (dnsimple-delete-record root-url headers record))
     (remove (duplicate-record-pred new-records) old-records))))

(define-record-type* <ddns-configuration>
  ddns-configuration make-ddns-configuration
  ddns-configuration?
  (api-key-file ddns-configuration-api-key-file)
  (domain ddns-configuration-domain)
  (get-records ddns-configuration-get-records)
  (filter ddns-configuration-filter))

(define ddns-mcron-service
  (match-record-lambda <ddns-configuration> (api-key-file domain get-records filter)
    (list #~(job '(next-minute (range 0 60 10))
                 (lambda () (#$dnsimple-update-records #$api-key-file
                                                  #$domain
                                                  get-records
                                                  #$filter))))))

(define ddns-service-type
  (service-type (name 'ddns)
                (description "automatically update dns entries")
                (extensions (list (service-extension mcron-service-type
                                                     ddns-mcron-service)))))

(define home-ddns-service-type
  (service-type
   (inherit(system->home-service-type ddns-service-type))
   (extensions (list (service-extension home-mcron-service-type
                                        ddns-mcron-service)))))

; library side
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; application side

(define (get-records)
  `((("type" . "A")
     ("name" . "")
     ("content" . ,(get-line
                    (open-input-file
                     "/home/<path to file with ip>")))
     ("ttl" . 600))
    (("type" . "TXT")
     ("name" . "_dmarc.cchae.us")
     ("content" . "v=DMARC1;p=reject;pct=100;rua=mailto:postmaster@zacchae.us")
     ("ttl" . 3600))
    (("type" . "TXT")
     ("name" . "my_ed_sel._domainkey.zacchae.us")
     ("content" . "k=ed25519 p=e4sV1Nfd1IVpVD6LSn7AbFczV0N6geZ6ALMgh18jjog=")
     ("ttl" . 3600))
    (("type" . "TXT")
     ("name" . "my_rsa_sel._domainkey.zacchae.us")
     ("content" . "p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAu2FyBwMXSINLrLbKRz+cMWE42hFBA1u4+IVLkg6LJd5xQpegOd7XOxnZ1/f29UGc+M23lkUmrVaicSujEkky4noks0gg9yruHFAUI/hocgrJN8SMsTTF/X1J9hdVKf2MZ8BW6cqZPhTEFUuZzNJiSWl8HWjLr2RMWKlm+8L71yrzuk5tnMUhLg7l4/kfThvHTIP/nlOitDw+B/erEhg1zy915hdyq/rBlgqp3D+wnXFHeVFwGZ1ekx+XAjorIH2XvXypTmxPpZN13lqvo4jxJRADeFHNv3RRxH7hxEuy9t6U2oxDkT4ETVKWGuuEuHrI4Lu0Gc8wQkB0kSFibY9K5QIDAQAB")
     ("ttl" . 3600))
    (("type" . "TXT")
     ("name" . "")
     ("content" . "v=spf1 a -all")
     ("ttl" . 3600))))

;(dnsimple-update-records "/home/zacchae/.config/guix/dnsimple"
;                         "cchae.us"
;                         get-records
;                         '(("type" . "NS") ("type" . "SOA")))

(use-modules (gnu home)
             (gnu home services shells))
(home-environment
 (services
  (list
   (service home-ddns-service-type
            (ddns-configuration
             (api-key-file "/home/<user>/.config/guix/dnsimple")
             (domain "<domain-here>")
             (get-records get-records)
             (filter '(("type" . "NS") ("type" . "SOA")))))
   (service home-zsh-service-type))))