(in-package :remote-snake-server-api)

(defclass api ()
  ((gm
    :initform (make-instance 'game-manager))))


(define-condition bad-request (error)                                                                                                               
  ((msg                                                                                                                                             
    :reader bad-request-msg                                                                                                                         
    :initarg :msg                                                                                                                                   
    :initform "Unkown error occurs"))                                                                                                               
  (:report (lambda (condition stream) (format stream "Bad Request: ~a" (bad-request-msg condition)))))                                              


;;; Parse the request and return it as a plist
;;; TODO Check game using game-manager (create the right error condition in gm)
(defun parse-request (request)
  (flet ((normalizer (key) (string-upcase key)))
        (let* ((p-request (parse request :normalize-all t :keyword-normalizer #'normalizer ))
               (type (getf p-request :type :not-found)))
          (cond
           ((eq type :not-found)
            (error 'bad-request :msg "No json \"type\" field provided"))
           ((equal type "update")
            (progn
              (unless (getf p-request :game-id) (error 'bad-request :msg "No json \"game-id\" field provided"))
              (let ((dir (getf p-request :direction :not-found)))
                (when (eq :not-found dir) (error 'bad-request :msg "No json \"direction\" field provided"))
                (unless (or (equal "up" dir) (equal "down" dir) (equal "left" dir) (equal "right" dir) (eq nil dir)) (error 'bad-request :msg "Bad \"direction\" field value"))
                (cond
                 ((equal dir "up") (setf (getf p-request :direction) :up))
                 ((equal dir "down") (setf (getf p-request :direction) :down))
                 ((equal dir "left") (setf (getf p-request :direction) :left))
                 ((equal dir "right") (setf (getf p-request :direction) :right))))))
           ((not (equal type "new-game"))
            (error 'bad-request :msg "Unknown request type")))
          p-request)))


(defmethod handle-new-game ((api api) data)
  (with-slots (gm) api
    (let* ((game-id (create-game gm)))
      (let ((game-dump (dump gm game-id)))
        (setf (getf game-dump :game-over) :null) ; Define nil as null (for json)
        (string-downcase
         (to-json
          (append (list :type "state") game-dump)))))))

(defmethod handle-update ((api api) data)
  (with-slots (gm) api
    (let* ((dir (getf data :direction))
           (game-id (getf data :game-id))
           (game (get-game gm game-id)))
      (if dir
          (refresh game :dir dir)
        (refresh game))
      (string-downcase
       (to-json
        (append (list :type "state") (dump gm game-id)))))))


(defmethod handle-request ((api api) request)
  ;; Catch request error and send it to the client
  (handler-case
      (let* ((data (parse-request request))
             (type (getf data :type)))
        (cond
         ((equal type "new-game") (handle-new-game api data))
         ((equal type "update") (handle-update api data))
         (t (format t "Unknow type"))))            
    (error (condition) ; Send reason to the client
           (let ((reason (make-array 0 
                                     :element-type 'character 
                                     :adjustable t 
                                     :fill-pointer 0)))
             (if (typep condition 'jonathan.error:<jonathan-error>)
                 (format reason "{\"type\":\"error\",\"message\":\"Failed to parse JSON\"}~%" condition :escape nil)
               (format reason "{\"type\":\"error\",\"message\":\"~a\"}~%" condition :escape nil))
             reason))))