(module telebot (getMe
                 getUpdates
                 sendMessage
                 forwardMessage
                 sendPhoto
                 sendAudio
                 sendDocument
                 sendSticker
                 sendVideo
                 sendVoice
                 sendLocation
                 sendChatAction
                 getUserProfilePhotos
                 getFile
                 pollUpdates)
  (import chicken scheme)
  (use srfi-1)
  (use openssl)
  (use http-client)
  (use medea)
  (use loops)
  (use vector-lib)

  (define-constant api-base "https://api.telegram.org/bot")

  ;;; helper functions

  (define (get-query-url token method)
    (string-append api-base token "/" method))

  (define (clean-query-parameters parameters)
    (let ((cleaned-parameters (remove (lambda (p) (equal? #f (cdr p)))
                                      parameters)))
      (if (null-list? cleaned-parameters)
        #f
        cleaned-parameters)))

  ;;; plain API wrappers, returning deserialized JSON

  (define-syntax wrap-api-method
    (syntax-rules ()
    ((wrap-api-method method(parameters ...))
     (define (method
              token
              #!key parameters ...)
       (with-input-from-request
         (get-query-url token (symbol->string 'method))
         (clean-query-parameters
           (map (lambda (l) (cons (first l) (second l)))
                (zip '(parameters ...)
                     (list parameters ...))))
         read-json)))))

  (wrap-api-method getMe())

  (wrap-api-method getUpdates(offset limit timeout))

  (wrap-api-method sendMessage(chat_id
                               text
                               parse_mode
                               disable_web_page_preview
                               disable_notification
                               reply_to_message_id
                               reply_markup))

  (wrap-api-method forwardMessage(chat_id
                                  from_chat_id
                                  message_id
                                  disable_notification))

  (wrap-api-method sendPhoto(chat_id
                             photo
                             caption
                             disable_notification
                             reply_to_message_id
                             reply_markup))

  (wrap-api-method sendAudio(chat_id
                             audio
                             duration
                             performer
                             title
                             disable_notification
                             reply_to_message_id
                             reply_markup))

  (wrap-api-method sendDocument(chat_id
                                document
                                caption
                                disable_notification
                                reply_to_message_id
                                reply_markup))

  (wrap-api-method sendSticker(chat_id
                               sticker
                               disable_notification
                               reply_to_message_id
                               reply_markup))

  (wrap-api-method sendVideo(chat_id
                             video
                             duration
                             width
                             height
                             caption
                             disable_notification
                             reply_to_message_id
                             reply_markup))

  (wrap-api-method sendVoice(chat_id
                             voice
                             duration
                             disable_notification
                             reply_to_message_id
                             reply_markup))

  (wrap-api-method sendLocation(chat_id
                                latitude
                                longitude
                                disable_notification
                                reply_to_message_id
                                reply_markup))

  (wrap-api-method sendChatAction(chat_id action))

  (wrap-api-method getUserProfilePhotos(user_id
                                        offset
                                        limit))

  (wrap-api-method getFile(file_id))

  ;;; framework

  (define (pollUpdates token handler)
    (define offset  0)
    (define process (lambda (i u)
                      (begin (handler u)
                             (set! offset (+ 1 (cdr (assv 'update_id u)))))))
    (do-forever
      (vector-for-each process
                       (cdr (assv 'result (getUpdates token
                                                      offset:  offset
                                                      timeout: 60))))))
)