module Bhook
  class ArgsParser
    Options = Struct.new(:source, :output, :watch)
        
    def initialize(argv)
      @args = Options.new(nil, nil, false)
      @argv = argv.clone
      @opt_parser = build_opt_parser
    end
    
    def parse!
      begin
        @opt_parser.parse!(@argv)
      rescue OptionParser::InvalidOption => e
        puts
        puts "Error! #{e.message}"
        puts
      end

      if !@argv.empty? || (!@args.source || !@args.output)
        puts @opt_parser
        exit
      end
      @args
    end
    
    private
    def build_opt_parser      
      OptionParser.new do |opts|
        opts.banner = "Usage: bhook --source /source/path --output /output/path"

        opts.on("-sSOURCE", "--source=SOURCE", 
                String, "Path to version controlled directory containing source md files") do |s|
          @args.source = s
        end

        opts.on("-oOUTPUT", "--output=OUTPUT", 
                String, "Path to directory where output files are to be generated") do |o|
          @args.output = o
        end

        opts.on("-w", "--watch", 
                FalseClass, 
                "Continuously watch the source directory for changes and generate output") do |w|
          @args.watch = true
        end

        opts.on("-h", "--help", "Prints this help") do
          puts opts
          exit
        end
      end      
    end
  end
end