###############################################################################
# TASK: rename_by_csv
#
# read csv, rename files
###############################################################################

desc "rename objects using csv"
task :rename_by_csv, [:csv_file,:filename_current,:filename_new,:input_dir,:output_dir] do |_t, args|
  # set default arguments
  args.with_defaults(
    csv_file: 'rename.csv',
    filename_current: 'filename_old',
    filename_new: 'filename_new',
    input_dir: 'objects/',
    output_dir: 'renamed/'
  )

  # check for csv file
  if !File.exist?(args.csv_file)
    puts "CSV file does not exist! No files renamed and exiting."
  else
    # read csv file
    csv_text = File.read(args.csv_file, :encoding => 'utf-8')
    csv_contents = CSV.parse(csv_text, headers: true)

    # Ensure that the output directory exists.
    FileUtils.mkdir_p(args.output_dir) unless Dir.exist?(args.output_dir)

    # iterate on csv rows
    csv_contents.each do |item|
      # check csv for old and new filenames
      if item[args.filename_current]
        name_old = File.join(args.input_dir, item[args.filename_current])
      else
        puts "no current filename given, skipping!"
        next
      end
      if item[args.filename_new]
        name_new = File.join(args.output_dir, item[args.filename_new])
      else
        puts "no new filename given, skipping!"
        next
      end
      # check if old and new file exist
      if !File.exist?(name_old)
        puts "old file '#{name_old}' does not exist, skipping!"
        next
      end
      if File.exist?(name_new)
        puts "new filename '#{name_new}' already exists, skipping!"
        next
      end
      puts "copying: '#{name_old}' to '#{name_new}'"
      system('cp', name_old, name_new)
    end
    
    puts "done renaming."

  end

end