changelog-update-date.rb

#!/usr/bin/ruby

require 'date'

changelog = nil

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

# if no changelog, we don't need any modify
if changelog == nil then
  exit 0
end

str = `git diff HEAD #{changelog}`

if str =~ /^\+(\w.*)$/ then
  date_str = $1
end

# date_str example
# Fri Aug 15 10:13:37 2014  SHIBATA Hiroshi  <shibata.hiroshi@gmail.com>
str =~ /.*\d\d:\d\d:\d\d \d\d\d\d  (\w+(?: \w+)) +<(.+)>/
name = $1
email = $2

d = DateTime.now.new_offset(Rational(9,24))

replace = d.strftime("%a %b %e %H:%M:%S %Y") + "  #{name}  <#{email}>"
`sed -i -e "s/#{date_str}/#{replace}/" #{changelog}`
`git add #{changelog}`

exit 0