require 'optparse'

class EasyOptionParser
  attr_reader :options, :title

  def initialize(title, arguments)
    @options = {}
    @title = title
    assert_valid_arguments!(arguments, symbol: :name)
    assert_valid_arguments!(arguments, symbol: :short)
    assert_valid_arguments!(arguments, symbol: :long)
    populate_with_default_values(arguments)

    parser = OptionParser.new do |opts|
      opts.banner = @title
      arguments.each do |argument|
        long = "#{argument.long} #{argument.name}"
        description = (argument.required) ? "#{argument.description} *" : argument.description
        opts.on(argument.short, long, description) do |value|
          options[argument.name.to_sym] = value
        end
      end

      opts.on('-h', '--help', 'Displays Help') do
        puts opts
        exit
      end
    end
    parser.parse!
  end

  def contains?(name)
    @options.include?(name.to_sym)
  end

  private

  def assert_valid_arguments!(arguments, symbol:)
    raise 'Arguments cannot be nil' if arguments.nil?
    raise 'Arguments cannot be empty' if arguments.empty?
    raise 'Arguments must be an Array' unless arguments.is_a?(Array)
    argument_names = arguments.map(&symbol)
    raise 'Duplicated value in options' if argument_names.detect{|a| argument_names.count(a) > 1}
  end

  def populate_with_default_values(arguments)
    arguments.each do |argument|
      @options[argument.name.to_sym] = argument.default_value
    end
  end
end