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
      read_info_file bag_info_txt_file
    rescue
      {}
    end

    def write_bag_info(hash = {})
      hash = bag_info.merge(hash)
      hash[@@bag_info_headers[:agent]] = "BagIt Ruby Gem (https://github.com/tipr/bagit)" 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