added related tag query model, fixes to related tag calculator

app/logical/related_tag_query.rb

@@ -0,0 +1,46 @@
+class RelatedTagQuery
+  attr_reader :query, :category
+  
+  def initialize(query, category)
+    @query = query
+    @category = category
+  end
+
+  def tags
+    if query =~ /\*/
+      pattern_matching_tags
+    elsif category.present?
+      related_tags_by_category
+    else
+      related_tags
+    end
+  end
+  
+  def wiki_page_tags
+    wiki_page.try(:tags) || []
+  end
+  
+protected
+  
+  def pattern_matching_tags
+    Tag.name_matches(query).order("post_count desc").limit(50).sort_by {|x| x.name}.map(&:name)
+  end
+  
+  def related_tags
+    tag = Tag.named(query).first
+    
+    if tag
+      tag.related_tag_array.map(&:first)
+    else
+      []
+    end
+  end
+  
+  def related_tags_by_category
+    RelatedTagCalculator.calculate_from_sample_to_array(query, Tag.categories.value_for(category)).map(&:first)
+  end
+
+  def wiki_page
+    WikiPage.titled(query).first
+  end
+end