module Main
  class Usage < ::Array
    attribute 'chunkname'
    attribute 'upcase'
    attribute 'eos'

    def initialize opts={} 
      self.fields=[]
      self.chunkname = lambda{|chunkname| chunkname.to_s.strip.upcase}
      self.upcase = true 
      self.eos = "\n\n"
      if opts.has_key?(:upcase) or opts.has_key?('upcase')
        self.upcase = opts[:upcase] || opts['optcase']
      end
    end

    def clear
      super
    ensure
      fields.clear
    end

    def delete_at key
      self[key] = nil
    end
    alias_method 'delete', 'delete_at'

    def self.default_synopsis main
      s = "#{ main.name }"

      main.parameters.each do |p|
        if p.type == :argument
          if p.required?
            s << " #{ p.name }"
          else
            s << " [#{ p.name }]"
          end
        end
      end

      main.parameters.each do |p|
        if p.type == :keyword
          if p.required?
            s << " #{ p.name }=#{ p.name }"
          else
            s << " [#{ p.name }=#{ p.name }]"
          end
        end
      end

      n = 0
      main.parameters.each do |p|
        if p.type == :option
          if p.required?
            case p.argument
              when :required
                s << " --#{ p.name }=#{ p.name }"
              when :optional
                s << " --#{ p.name }=[#{ p.name }]"
              else
                s << " --#{ p.name }"
            end
          else
            n += 1
          end
        end
      end
      if n > 0
        s << " [options]+"
      end

      s
    end

    def self.default_usage main
      usage = new

    # name
      usage['name'] =
        if main.version?
          "#{ main.name } v#{ main.version }"
        else
          "#{ main.name }"
        end

    # synopsis
      usage['synopsis'] = main.synopsis

    # description
      usage['description'] = main.description if main.description?

    # parameters
      arguments = main.parameters.select{|p| p.type == :argument}
      keywords = main.parameters.select{|p| p.type == :keyword}
      options = main.parameters.select{|p| p.type == :option}
      environment = main.parameters.select{|p| p.type == :environment}

      help, nothelp = options.partition{|p| p.name == 'help'}
      options = nothelp + help

      parameters = arguments + keywords + options + environment

      s =
        parameters.map do |p|
          ps = ''
          ps << Util.columnize("* #{ p.synopsis }", :indent => 2, :width => 78)
          ps << "\n"
          if p.description?
            ps << Util.columnize(p.description, :indent => 6, :width => 78)
            ps << "\n"
          end
          ps
        end.join("\n")
      usage['parameters'] = s 

    # author
      usage['author'] = main.author if main.author?

      usage
    end
    class << self
      alias_method "default", "default_usage"
    end

    def to_s
      s = '' 
      each_pair do |key, value|
        up, down = key.to_s.upcase, key.to_s.downcase
        if value
          s << (upcase ? up : down) << "\n" 
          s << Util.indent(Util.unindent(value.to_s), 2)
          s << eos 
        end
      end
      s
    end
  end
end