wc command

05.wc/wc.rb

@@ -0,0 +1,58 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require 'optparse'
+
+STDIN_COL_WIDTH = 7
+
+def main
+  opt = OptionParser.new
+  filter_params = {}
+  opt.on('-l') { |v| filter_params[:lines] = v }
+  opt.on('-w') { |v| filter_params[:words] = v }
+  opt.on('-c') { |v| filter_params[:bytes] = v }
+  opt.parse! ARGV
+  filter_params = { lines: true, words: true, bytes: true } if filter_params.empty?
+
+  contents_with_filename = ARGV.empty? ? [readlines.join] : ARGV.map { |file_name| [File.read(file_name), file_name] }
+  stats = calculate_stats(contents_with_filename)
+  col_width = stats.first[:file_name].nil? ? STDIN_COL_WIDTH : max_col_width(stats)
+  formatted_stats = format_stats(stats:, filter_params:, col_width:)
+  puts formatted_stats
+end
+
+def calculate_stats(contents_with_filename)
+  stats = contents_with_filename.map { |contents, file_name| build_data(contents, file_name) }
+  return stats if stats.length == 1
+
+  add_total(stats)
+end
+
+def build_data(contents, file_name)
+  lines = contents.scan(/(\n|\r)/).count
+  words = contents.split(/[^\s　][\s　]+/).count
+  bytes = contents.bytesize
+  { lines:, words:, bytes:, file_name: }
+end
+
+def add_total(file_stats)
+  total = file_stats[0].merge(*file_stats[1..]) { |_, old_value, new_value| old_value + new_value }
+  total[:file_name] = :total
+  file_stats << total
+end
+
+def format_stats(stats:, filter_params:, col_width:)
+  stats.map do |stat|
+    filtered_stat_values = stat.filter { |k| filter_params.keys[0..].include?(k) }.values
+    formatted_stat_values = filtered_stat_values.map { |v| v.to_s.rjust(col_width) }.join(' ')
+    [formatted_stat_values, stat[:file_name]].compact.join(' ')
+  end.join("\n")
+end
+
+def max_col_width(file_stats)
+  file_stats.map do |stat|
+    stat.reject { |key| key == :file_name }.values.max.to_s.size
+  end.max
+end
+
+main if __FILE__ == $PROGRAM_NAME