prepare-commit-msg

#!/usr/bin/ruby
# -*- mode: Ruby -*-

# usage: ruby-commit-hook <file>

changelog = nil

# find out ChangeLog file
diff = `git diff --stat HEAD`
diff.scan(/^ (ChangeLog) +\|/) { |ary|
  changelog = ary[0]
}

if changelog == nil then
  exit 1
end

str = `git diff HEAD #{changelog}`

# see http://d.hatena.ne.jp/nurse/20100413
# git add -u && git diff --cached ChangeLog|ruby -e'puts$<.read[/^\+\w.*\n((?:^\+[ \t]?.*\n)+)/,1].to_s.gsub(/\+\t?/,"")'|git commit -F-

#
# * example input
#
#+Fri Aug 15 08:39:38 2014  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
#+
#+	* thread.c (foo): abcd
#+	* fuga.c (fugafuga): example.
#+	  example2
#
# * example output
#
#+
#+	* thread.c (foo): abcd
#+	* fuga.c (fugafuga): example.
#+	  example2
#+

regex = /^\+\w.*\n     # +Fri Aug 15 08:39:38 2014  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
	((?:^\+.*\n)+) # rest + lines
	/x
str = str.match(regex)[1]

# remove whitespace only lines
str.gsub!(/^\+\n/, "")

# remove + and tab
str.gsub!(/^\+\t?/, "")

commit_file = ARGV.shift
open(commit_file, "r+") { |f|
  content = f.read
  f.seek(0)
  f.puts str
  f.puts content
}