;;;; limiter.lisp - Rate limiter definitions for the application

(in-package :asteroid)

(defun render-rate-limit-error-page()
  (clip:process-to-string
   (load-template "error")
   :error-message "It seems that your acceleration has elevated your orbit out of your designated path."
   :error-action "Please wait a moment for it to stabilize and try your request again."))

(defun api-limit-error-output ()
  (api-output `(("status" . "error")
                ("message" .  "It seems that your acceleration has elevated your orbit out of your designated path."))
              :message   "It seems that your acceleration has elevated your orbit out of your designated path."
              :status 429))

(defun extract-limit-options (options)
  "Extracts the rate-limit options and forwards the reamaining radiance route options"
  (let ((limit   (getf options :limit))
        (timeout (getf options :timeout))
        (group (getf options :limit-group))
        (rest (loop for (k v) on options by #'cddr
                    unless (member k '(:limit :timeout :limit-group))
                      append (list k v))))
    (values limit timeout group rest)))


(defmacro define-page-with-limit (name uri options &body body)
  "Rate limit for a page route. Defaults to 30 requests per minute."
  (multiple-value-bind (limit timeout group rest) (extract-limit-options options)
    (let* ((limit-name (string-upcase (format nil "~a-route-limit" (or group name))))
           (limit-sym (intern limit-name))
           (limit (or limit 30))
           (timeout (or timeout 60)))
      `(eval-when (:compile-toplevel :load-toplevel :execute)
         (rate:define-limit ,limit-sym (time-left :limit ,limit :timeout ,timeout)
           ;; (format t "Route limit '~a' hit. Wait ~a seconds and retry.~%" ,(string name) time-left)
           (render-rate-limit-error-page))
         (define-page ,name ,uri ,rest
           (rate:with-limitation (,limit-sym)
             ,@body))))))

(defmacro define-api-with-limit (name args options &body body)
  "Rate limit for api routes. Defaults to 60 requests per minute."
  (multiple-value-bind (limit timeout group rest) (extract-limit-options options)
    (let* ((limit-name (string-upcase (format nil "~a-api-limit" (or group name))))
           (limit-sym (intern limit-name))
           (limit (or limit 60))
           (timeout (or timeout 60)))
      `(eval-when (:compile-toplevel :load-toplevel :execute)
         (rate:define-limit ,limit-sym (time-left :limit ,limit :timeout ,timeout)
           ;; (format t "API Rate limit '~a' hit. Wait ~a seconds and retry.~%" ,(string name) time-left)
           (api-limit-error-output))
         (define-api ,name ,args ,rest
           (rate:with-limitation (,limit-sym)
             ,@body))))))