class Chronic::Handler

def ==(other)
  @pattern == other.pattern
end

def initialize(pattern, handler_method)
  @pattern = pattern
  @handler_method = handler_method
end

def invoke(type, tokens, parser, options)
  if Chronic.debug
    puts "-#{type}"
    puts "Handler: #{@handler_method}"
  end
  parser.send(@handler_method, tokens, options)
end

def match(tokens, definitions)
  token_index = 0
  @pattern.each do |elements|
    was_optional = false
    elements = [elements] unless elements.is_a?(Array)
    elements.each_index do |i|
      name = elements[i].to_s
      optional = name[-1, 1] == '?'
      name = name.chop if optional
      case elements[i]
      when Symbol
        if tags_match?(name, tokens, token_index)
          token_index += 1
          break
        else
          if optional
            was_optional = true
            next
          elsif i + 1 < elements.count
            next
          else
            return false unless was_optional
          end
        end
      when String
        return true if optional && token_index == tokens.size
        if definitions.key?(name.to_sym)
          sub_handlers = definitions[name.to_sym]
        else
          raise "Invalid subset #{name} specified"
        end
        sub_handlers.each do |sub_handler|
          return true if sub_handler.match(tokens[token_index..tokens.size], definitions)
        end
      else
        raise "Invalid match type: #{elements[i].class}"
      end
    end
  end
  return false if token_index != tokens.size
  return true
end

def tags_match?(name, tokens, token_index)
  klass = Chronic.const_get(name.to_s.gsub(/(?:^|_)(.)/) { $1.upcase })
  if tokens[token_index]
    !tokens[token_index].tags.select { |o| o.kind_of?(klass) }.empty?
  end
end