module CliGen::Parser

  macro extended
    {% verbatim do %}
    macro define_parser
      def self.make_parser(parent_parser : OptionParser) : OptionParser
        {% puts "#{@type.name} OptionParser is being generated" %}
        {% name = @type.name.split("::").last %}
        {% var = name.downcase %}
        {% info = @type.annotation(::CliGen::CommandInfo) %}
        {% raise "ERROR : No CommandInfo annotation provided to #{@type.name}" unless info %}
        subparser = OptionParser.new do |parser|
          parser.banner = {{@type.name}}::HEADER
          {% subcommands = @type.class.methods.select(&.annotation(::CliGen::SubCommand)) %}
          {% if subcommands.size > 0 %}
            CliGen.define_section("Subcommands", parser)
            {% for subcommand in subcommands %}
              {% subcommand_anno = subcommand.annotation(::CliGen::SubCommand) %}
              parser.on({{subcommand.name.stringify}}, {{subcommand_anno[:description]}}){
                {{@type.name}}.action= {{subcommand.name.stringify}}
              }
            {% end %}
          {% end %}

          {% arguments =  @type.class.methods.select(&.annotation(::CliGen::CommandArgument)) %}
          {% if arguments.size > 0 %}
            CliGen.define_section("Provide Arguments", parser)
            {% for argument in arguments %}
              {% argument_anno = argument.annotation(::CliGen::CommandArgument) %}
              {% if argument_anno[:short] == "" &&  argument_anno[:long] != "" %}
              parser.on({{argument_anno[:long]}}, {{argument_anno[:description]}}){|val|
              {% elsif argument_anno[:short] != "" &&  argument_anno[:long] == "" %}
              parser.on({{argument_anno[:short]}}, {{argument_anno[:description]}}){|val|
              {% else %}
              parser.on({{argument_anno[:short]}}, {{argument_anno[:long]}}, {{argument_anno[:description]}}){|val|
              {% end %}
                {{@type.name}}.{{argument.name}}(val)
              }
            {% end %}
          {% end %}
          define_default_flags(parser)
        end
        parent_parser.on({{var}}, {{info[:description]}}){
          ARGV.delete({{var}})
          abort {{var.id}} if ARGV.empty?
          subparser.parse
          {{@type.name}}.run
        }
      end
    end
   {% end %}
  end

end