Extend icon plugin with title attribute (#36004)

plugins/icon.rb

@@ -5,7 +5,8 @@ module Jekyll
       def initialize(tag_name, args, tokens)
         super
         if args.strip =~ SYNTAX
-          @icon = Regexp.last_match(1).downcase
+          @icon = Regexp.last_match[:icon].downcase
+          @title = Regexp.last_match[:title]
         else
           raise SyntaxError, <<~MSG
             Syntax error in tag 'icon' while parsing the following options:
@@ -13,18 +14,29 @@ module Jekyll
             #{args}
 
             Valid syntax:
-              {% icon "<icon-set>:<icon-name>" %}
+              {% icon "<icon-set>:<icon-name>" [title="<title>"] %}
           MSG
         end
       end
+      
+      def default_title(icon)
+        # split away "mdi:" part
+        icon_name = icon.split(':').last
+
+        # remove dashes and capitalize e.g. "water-polo" to "Water polo"
+        parts = icon_name.split('-')
+        parts[0] = parts[0].capitalize
+        parts.join(' ')
+      end
 
       def render(_context)
-        "<iconify-icon inline icon='#{@icon}'></iconify-icon>"
+        title = @title || default_title(@icon)
+        "<iconify-icon inline icon='#{@icon}' title='#{title}'></iconify-icon>"
       end
 
       private
 
-      SYNTAX = %r!^"([a-z0-9]+(?:-[a-z0-9]+)*:[a-z0-9]+(?:-[a-z0-9]+)*)"$!.freeze
+      SYNTAX = %r!^"(?<icon>[a-z0-9]+(?:-[a-z0-9]+)*:[a-z0-9]+(?:-[a-z0-9]+)*)"(?:\s+title="(?<title>[^"]+)")?$!.freeze
     end
   end
 end