zooniverse/Talk-Api

require 'uploader'

module DataExportWorker
  extend ::ActiveSupport::Concern

  included do
    include Sidekiq::Worker
    attr_accessor :data_request, :name
    sidekiq_options retry: false, backtrace: true
  end

  def perform(data_request_id)
    self.data_request = ::DataRequest.find data_request_id
    self.name = "#{ data_request.section }-#{ data_request.kind }_#{ Time.now.utc.to_date.to_s }"
    data_request.started!

    begin
      process_data
    rescue => e
      data_request.failed!
      raise e
    end

    data_request.finished!
  end

  def process_data
    data_file = write_data
    gzip_file = compress data_file
    ::File.unlink data_file
    uploader = ::Uploader.new gzip_file
    uploader.upload
    url = uploader.url
    data_request.notify_user message: "Your data export of #{ name } is ready", url: url
    data_request.update_attributes url: url
    ::File.unlink gzip_file
  end

  def row_from(*args)
    args.as_json
  end

  def find_each
    raise ::NotImplementedError.new 'find_each'
  end

  def row_count
    raise ::NotImplementedError.new 'row_count'
  end

  def batch_size
    [[row_count - 1, 1_000].min, 1].max
  end

  def each_row
    index = 0
    find_each do |*args|
      yield row_from(*args), index
      index += 1
    end
  end

  def write_data
    ::File.open("#{ name }.json", 'w').tap do |file|
      file.write '['
      if row_count > 0
        each_row do |row, index|
          file.write(',') unless index.zero?
          file.write row.to_json
        end
      end
      file.write "]\n"
      file.close
    end
  end

  def compress(in_file)
    out_file = "/tmp/#{ name }.tar.gz"
    in_name = ::File.basename in_file.path
    in_path = ::File.dirname in_file.path
    `cd #{ in_path } && tar czf #{ out_file } #{ in_name }`
    ::File.new out_file
  end
end