require 'find'
require 'fileutils'
require 'bagit' # http://github.com/flazz/bagit

module LyberUtils

  class BagitBag

    attr_reader :bag_dir

    def initialize(bag_dir)
      @bag_dir = bag_dir
      create_bag
    end

    def create_bag()
      if (File.exist?(@bag_dir))
        FileUtils.rm_r(@bag_dir)
      end
      @bag = BagIt::Bag.new @bag_dir
    end

    def add_content_files(source_dir, use_links)
      data_content_dir = File.join(@bag_dir, 'data', 'content')
      copy_dir(source_dir, data_content_dir, use_links)
    end

    def copy_dir(source_dir, target_dir, use_links)
      FileUtils.mkdir_p(target_dir)
      Dir.foreach(source_dir) do |file|
        unless (file == '.' or file == '..')
          source_file = File.join(source_dir, file)
          target_file = File.join(target_dir, file)
          if File.directory?(source_file)
            copy_dir(source_file, target_file, use_links)
          elsif (use_links)
            FileUtils.ln(source_file, target_file, :force => true)
          else
            FileUtils.cp(source_file, target_file)
          end
        end
      end
    end

    def add_metadata_file_from_string(metadata_string, file_name)
      if (not metadata_string.nil?)
        data_file_path = "metadata/#{file_name}"
        @bag.add_file(data_file_path) do |io|
          io.puts metadata_string
        end
      end
    end

    def write_metadata_info(md_hash)
      # make sure none of the md_hash values are nil
      md_hash.each  do |key, value|
        raise "The bag-info.txt value for #{key} is not allowed to be nil" if value.nil?
      end
      payload = bag_payload()
      bag_info_hash = {
          'Bag-Size' => bag_size_human(payload[0]),
          'Payload-Oxum' => "#{payload[0]}.#{payload[1]}",
          'Bagging-Date' => DateTime.now.to_s[0..9]
      }
      @bag.write_bag_info(md_hash.merge(bag_info_hash))
    end

    def bag_payload()
      bytes = 0
      files = 0
      Find.find(@bag.data_dir) do |filepath|
        if (not File.directory?(filepath))
          bytes += File.size(filepath)
          files += 1
        end
      end
      return [bytes, files]
    end

    def bag_size_human(bytes)
      count = 0
      size = bytes
      while (size >= 1000 and count < 4)
        size /= 1000.0
        count += 1
      end
      if (count == 0)
        return sprintf("%d B", size)
      else
        return sprintf("%.2f %s", size, %w[B KB MB GB TB][count])
      end
    end

    def write_manifests()
      @bag.manifest!
      @bag.tagmanifest!
    end

    def validate()
      if not @bag.valid?
        raise "bag not valid: #{@bag_dir}"
      end

    end

  end

end