commit-msg

#!/usr/bin/env ruby

# Inspiration from http://chris.beams.io/posts/git-commit/
# On how to make great commit messages

message_file = ARGV[0]
lines = File.readlines(message_file)

lines.map! { |line| line.chomp }

# 1 - Separate subject from body with a blank line
if lines.size > 2 && !lines[1].empty?
  puts "Separate subject from body with a blank line"
  exit 1
end

# 2 - Limit the subject line to 50 characters
first_line_size = lines.first.size
if first_line_size > 50
  puts "Limit the subject line to 50 characters, you have #{first_line_size}"
  exit 1
end

# 3 - Capitalize the subject line
first_word = lines.first.split.first
if !('A'..'Z').include? first_word[0]
  puts "Capitalize the subject line"
  exit 1
end

# 4 - Do not end the subject line with a period
last_word = lines.first.split.last
if last_word.end_with?('.')
  puts "Do not end the subject line with a period"
  exit 1
end

# 5 - Use the imperative mood in the subject line
if first_word.end_with?('ed') || first_word.end_with?('ing')
  puts "Use the imperative mood in the subject line"
  exit 1
end

# 6 - Wrap the body at 72 characters
if lines.detect { |line| line.size > 72 }
  puts "Wrap the body at 72 characters"
  exit 1
end

# 7 - Use the body to explain what and why vs. how
if lines.size > 2 && lines.drop(2).detect { |line| line.empty? }
  puts "Use the body to explain what and why vs. how"
  exit 1
end