mergeup

#!/usr/bin/env ruby

########################
# Merge Up!
#
# author: Philip Claren
# date: 04.02.2015

def error_and_out(msg)
  puts "#{msg}\n"
  exit
end

error_and_out('Must not be in develop branch!') if `git rev-parse --abbrev-ref HEAD`.strip == 'develop'

error_and_out('Not a clean state!') if `git status -s`.strip != ''

current = `git describe --abbrev=0`.split('-').map(&:strip)
error_and_out("No valid version found! Found: #{current[0].inspect}") unless current[0].match(/^[0-9]{1}\.[0-9]{1,2}$/)

# -> preconditions look good, carry on

major, minor = current[0].split('.').map(&:to_i)

# get list of release branches
command = 'git branch -a | grep -x "^\(\s\s\|\*\s\)release\-[0-9]\{1\}\.[0-9]\{1,2\}$"'

releases = `#{command}`.split("\n").map do |s|
  s.gsub('* ','').strip
end.select do |s|
  parts = s.gsub('release-','').split('.').map(&:to_i)
  parts[0] >= major && parts[1] >= minor
end + ['develop']


format_patch = 'git format-patch $(git merge-base %{to} %{from})..%{from} --stdout'
apply_check  = 'git apply --check -'

def switch_to(branch)
  `git checkout #{branch}`
  `git submodule update`
end

releases.each_index do |index|
  unless releases[index+1].nil?
    switch_to releases[index+1]
    current_patch = format_patch % { from: releases[index], to: releases[index+1]}

    unless `#{current_patch}`.empty? || (`#{current_patch} | #{apply_check}` && $?.exitstatus == 0)
      switch_to releases.first
      error_and_out("There's a problem when trying to merge #{releases[index]} into #{releases[index+1]}. Aborting.")
    end
  end
end

switch_to releases.first

releases.each_index do |index|
  unless releases[index+1].nil?
    switch_to releases[index+1]
    `git merge #{releases[index]}`
    `git push`
  end
end

switch_to releases.first

puts "\n\nAll merged: #{releases.join(' -> ')}"
puts 'Have a nice day!'