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 |element|
    name = element.to_s
    optional = name[-1, 1] == '?'
    name = name.chop if optional
    case element
    when Symbol
      if tags_match?(name, tokens, token_index)
        token_index += 1
        next
      else
        if optional
          next
        else
          return false
        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: #{element.class}"
    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