feat: ✨ add core function to validate and sanitize context tags

lib/comfpile/core.rb

@@ -13,12 +13,42 @@ module Comfpile
             # First query is stage, second filename.
             @artefacts = {}
 
+            @valid_contexts = {}
+
             # Stack-style processing queue for item processing
             @processing_stack = []
         end
 
-        def find_artefact(stage, file = :none)
-            @artefacts.dig(stage, file)
+        # Sanitize and unify context tags.
+        # This function will take either an array of tags, or a symbol,
+        # and sanitize and unify it to match a predictable context tag
+        # format.
+        #
+        # Context tags are symbols containing a list of unique configs
+        # types to use, separated by underscore ('_')
+        #
+        # @param [Array<Symbol,String>, Symbol] context The context to
+        #  sanitize
+        #
+        # @return [Symbol] Sanitized context. Unique, sorted list
+        #  of tags, joined into a Symbol.
+        #
+        def sanitize_context(context)
+            if context.nil?
+                return :default
+            elsif context.is_a? Array
+                new_context = context.uniq.sort.join('_').to_sym
+                @valid_contexts[new_context] = true
+                
+                return new_context
+            elsif context.is_a? Symbol
+                return context if @valid_contexts[context]
+                return sanitize_context(context.to_s.split('_'))
+            else
+                raise ArgumentError, "Unknown context key type supplied!"
+            end
+        end
+
         end
 
         # Create or find a new artefact.