(in-package #:cl-user)
(defpackage #:validation
  (:use #:cl
	#:app-constants)
  (:export  #:has-static-assets-extention?
	    #:is-valid-favicon-type?
	    #:favicon-need-resizing?
            #:string-is-nil-or-empty?)
  (:documentation "Package for validating 'stuff'."))
(in-package #:validation)

(defun file-has-valid-static-assets-extention? (filename)
  (cond ((or (string= "css" (pathname-type filename))
	     (string= "js"  (pathname-type filename))
	     (string= "png" (pathname-type filename))
	     (string= "ico" (pathname-type filename))
	     (string= "gif" (pathname-type filename))
	     (string= "jpg" (pathname-type filename))
	     (string= "svg" (pathname-type filename))
	     (string= "txt" (pathname-type filename)))
	 filename)
	 (t nil)))

(defun file-is-valid-favicon-type? (filename)
  "Returns path of file if `FILE' is a valid favicon.
Valid file types are 'ico', 'gif' and 'png'."
  (cond ((or (string= "png" (pathname-type filename))
	     (string= "ico" (pathname-type filename))
	     (string= "gif" (pathname-type filename)))
	 filename)
	 (t nil)))

(defun string-is-nil-or-empty? (string-to-test)
  "Tests to see if `STRING-TO-TEST' is empty of just whitespace.
This is essentially the 'IsNullOrWhiteSpace' function I use in C#. It
expands the 'empty string' check to include a check to see if there is
string with just a '(white) space' in it."
  (if (or (string= string-to-test " ")
	  (zerop (length string-to-test))
	  (null  string-to-test))
      t
      nil))

(defun favicon-need-resizing? (dimensions)
  "Checks to see if the `WIDTH' or `HEIGHT' are greater than 192x192 pixels.
`DIMENSIONS' is a cons list, with the `WIDTH' being first element and
`HEIGHT' being the second. If either of them are, then you look into
scaling down the image, using code in the `UTILS' package probably."
  (cond ((or (< 192 (car dimensions)) (< 192 (cdr dimensions)))
	 t) ; True as in the dimensions are valid
	(t ;; Bit confusing with the use of `T' here but its standard
	   ;; practice to end `COND' with a catch-all `T'. In this
	   ;; case, `T' here means the dimensions are invalid, as in
	   ;; 'yes' the favicon needs resizing. This is confusing
	   ;; Boolean logic but when you call this function, the
	   ;; return types make sense from that point-of-view.
	 nil)))