module Acouchi
  class Which
    def self.find_executable *aliases
      if executable = aliases.find {|a| which? a}
        executable
      else
        raise %{Couldn't find any matches for the aliases "#{aliases.join(", ")}"}
      end
    end

    private
      def self.which? command
        exts = ENV['PATHEXT'] ? ENV['PATHEXT'].split(';') : ['']
        ENV['PATH'].split(File::PATH_SEPARATOR).each do |path|
          exts.each { |ext|
            exe = "#{path}/#{command}#{ext}"
            return exe if File.executable? exe
          }
        end
        return nil
      end
  end
end