refactor to data-source

utils.lisp

@@ -19,3 +19,32 @@
 
 (defun string-to-hash-table-key (s)
   (string-replace " " s ""))
+
+(defclass data-source ()
+  ((cache :initform nil :accessor cache)
+   (file-path :initarg :file-path :accessor file-path)))
+
+(defmacro define-data-source (singular-name)
+  (let* ((class-name (symbolicate singular-name '-data-source))
+         (constructor-name (symbolicate 'make- singular-name '-data-source))
+         (plural-name (concat (symbol-name singular-name) "s"))
+         (file-name (concat (string-downcase plural-name) ".json")))
+    `(progn
+       (defclass ,class-name (data-source) ())
+
+       (defun ,constructor-name ()
+         (make-instance ',class-name :file-path ,file-name)))))
+
+(defgeneric data (data-source))
+(defmethod data ((ds data-source))
+  (or (cache ds)
+      (reload ds)))
+
+(defgeneric reload (data-source))
+(defmethod reload ((ds data-source))
+  (if (uiop:file-exists-p (file-path ds))
+      (let ((data (shasht:read-json (uiop:read-file-string (file-path ds)))))
+        (setf (cache ds) data)
+        data)))
+
+(defgeneric refresh (data-source))