require 'set'

module BagIt

  module Info

    @@bag_info_headers = {
      :agent => 'Bag-Software-Agent',
      :org => 'Source-Organization',
      :org_addr => 'Organization-Address',
      :contact_name => 'Contact-Name',
      :contact_phone => 'Contact-Phone',
      :contact_email => 'Contact-Email',
      :ext_desc => 'External-Description',
      :ext_id => 'External-Identifier',
      :size => 'Bag-Size',
      :group_id => 'Bag-Group-Identifier',
      :group_count => 'Bag-Count',
      :sender_id => 'Internal-Sender-Identifier',
      :int_desc => 'Internal-Sender-Description',
      :date => 'Bagging-Date',
      :oxum => 'Payload-Oxum'
    }

    def bag_info_txt_file
      File.join bag_dir, 'bag-info.txt'
    end

    def bag_info
      begin
        read_info_file bag_info_txt_file
      rescue
        {}
      end
    end

    def write_bag_info(hash={})
      hash = bag_info.merge(hash)
      hash[@@bag_info_headers[:agent]] = "BagIt Ruby Gem (http://bagit.rubyforge.org)" if hash[@@bag_info_headers[:agent]].nil?
      hash[@@bag_info_headers[:date]] = Date.today.strftime('%Y-%m-%d') if hash[@@bag_info_headers[:date]].nil?
      hash[@@bag_info_headers[:oxum]] = payload_oxum
      write_info_file bag_info_txt_file, hash
    end

    def bagit_txt_file
      File.join bag_dir, 'bagit.txt'
    end

    def bagit
      read_info_file bagit_txt_file
    end

    def write_bagit(hash)
      write_info_file bagit_txt_file, hash
    end

    def update_bag_date
      hash["Bagging-Date"] = Date.today.strftime('%Y-%m-%d')
      write_bag_info(hash)
    end

    protected

    def read_info_file(file)

      File.open(file) do |io|

        entries = io.read.split /\n(?=[^\s])/

        entries.inject({}) do |hash, line|
          name, value = line.chomp.split /\s*:\s*/, 2
          hash.merge({name => value})
        end

      end

    end

    def write_info_file(file, hash)

      dups = hash.keys.inject(Set.new) do |acc, key|
        a = hash.keys.grep(/#{key}/i)
        acc + (a.size > 1 ? a : [])
      end

      raise "Multiple labels (#{dups.to_a.join ', '}) in #{file}" unless dups.empty?

      File.open(file, 'w') do |io|

        hash.each do |name, value|
          simple_entry = "#{name}: #{value.gsub /\s+/, ' '}"

          entry = if simple_entry.length > 79
                    simple_entry.wrap(77).indent(2)
                  else
                    simple_entry
                  end

          io.puts entry
        end

      end

    end

  end

end