#!/usr/bin/env ruby

## git-show-merges: a simple script to show you which topic branches have
## been merged into the current branch, and which haven't. (Or, specify
## the set of merge branches you're interested in on the command line.)
##
## git-show-merges Copyright 2008 William Morgan <wmorgan-git-wt-add@masanjin.net>. 
## This program is free software: you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation, either version 3 of the License, or (at
## your option) any later version.
##
## This program is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
## GNU General Public License for more details.
##
## You can find the GNU General Public License at:
##   http://www.gnu.org/licenses/
heads = if ARGV.empty?
  [`git symbolic-ref HEAD`.chomp]
else
  ARGV
end.map { |r| r.gsub(/refs\/heads\//, "") }

branches = `git show-ref --heads`.
  scan(/^\S+ refs\/heads\/(\S+)$/).
  map { |a| a.first }

unknown = heads - branches
unless unknown.empty?
  $stderr.puts "Unknown branch: #{unknown.first}"
  exit(-1)
end

branches -= heads

heads.each do |h|
  merged = branches.select { |b| `git log #{h}..#{b}` == "" }
  unmerged = branches - merged

  puts "merged into #{h}:"
  merged.each { |b| puts "  #{b}" }
  puts
  puts "not merged into #{h}: "
  unmerged.each { |b| puts "  #{b}" }

  puts
end