From 4736db9bd2115c0ae39bc8339f73a3bde4d3823e Mon Sep 17 00:00:00 2001
From: Craig Oates <craig@craigoates.net>
Date: Sun, 18 Sep 2022 23:02:06 +0100
Subject: [PATCH] add validation package.

---
 src/validation.lisp | 57 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 src/validation.lisp

diff --git a/src/validation.lisp b/src/validation.lisp
new file mode 100644
index 0000000..9ae33a6
--- /dev/null
+++ b/src/validation.lisp
@@ -0,0 +1,57 @@
+(in-package #:cl-user)
+(defpackage #:validation
+  (:use #:cl
+	#:app-constants)
+  (:export  #:has-static-assets-extention?
+	    #:is-valid-favicon-type?
+	    #:favicon-need-resizing?)
+  (: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)))
+
+;; TODO: PORT CODE TO CALL THIS VERSION OF STRING-IS-NIL-OR-EMPTY?
+(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)))