Concat large text files tool

concat.rb

# frozen_string_literal: true

require 'optparse'
require 'sys/filesystem' # gem install sys-filesystem

class ConcatOptionsParser
  attr_reader :parts, :output, :keep

  def initialize
    opts = OptionParser.new do |parser|
      parser.banner = "\nUsage: ruby sims_concat.rb <pats_path> -o "
      parser.separator ''
      parser.separator 'Options:'

      parser.on('-k', '--keep', TrueClass, 'The keep parts files flag.') do |keep_flag|
        @keep = keep_flag
      end

      parser.on('-o', '--output STR', String, 'The output path.') do |output|
        @output = output
      end

      parser.on_tail('-h', '--help', '--usage', 'Show this usage message and quit.') do
        puts parser.help
        puts ''
        exit
      end
    end

    opts.parse!(ARGV)
    @parts = ARGV

    unless @output
      puts ''
      puts 'Error: -o --output is required'
      puts 'For help: ruby sim.rb -h'
      puts ''
      exit
    end

    unless @parts
      puts ''
      puts 'Error: <pats_path> is required'
      puts 'For help: ruby sim.rb -h'
      puts ''
      exit
    end
  end
end

class Concat
  def initialize(parts_paths, result_path, keep)
    @parts_paths = parts_paths
    @result_path = result_path
    @keep = keep
  end

  def call
    raise 'Output file already exist' if File.exists? @result_path

    result_file = File.new(@result_path, 'w')
    result_file.close

    @parts_paths.
      sort.sort_by(&:length).
      map { |i| i.gsub(/ /, '\ ') }.
      each do |part_path|
      print part_path

      check_free_space!(result_file.path, part_path)

      if @keep
        `cat #{part_path} >> #{result_file.path} `
      else
        `cat #{part_path} >> #{result_file.path} && rm #{part_path}`
      end

      puts ' Ready.'
    end

    puts 'Output: '
    puts result_file.path
  end


  def check_free_space!(folder_path, part_path)
    info = Sys::Filesystem.stat(folder_path)
    available = info.block_size * info.blocks_available
    part_size = File.size(part_path)

    raise "Not enough free space for concat part: #{part_path}" if part_size > available
  end
end

options = ConcatOptionsParser.new
Concat.new(options.parts, options.output, options.keep).call

Example using: ruby concat.rb parts_folder/* -o merged_data.json