git-submodule-resolve

#!/usr/bin/ruby
me = File.basename($0)
if ARGV[0].nil?
  puts "Usage: #{me} <path-to-submodule>"
  exit 1
end
submodule = ARGV[0].gsub(/\/$/, "")
unless File.directory?(".git")
  STDERR.puts "This command must be run from the base of your git working directory"
  exit 1
end

orig_head_file = %w[.git/MERGE_HEAD .git/rebase-apply/original-commit].select {|f| File.exist?(f) }.first

unless orig_head_file
  STDERR.puts "Error: Not currently resolving a conflict"
end

def read_info(ref, path)
  info, path = %x{git ls-tree "#{ref}" "#{path}"}.split(/\t/)
  return {} if info.nil?
  a = {}
  a[:mode], a[:type], a[:object_id] = info.split(" ") 
  a
end

super_left="HEAD"
super_right=File.read(orig_head_file).chomp
submod_left_id=read_info(super_left, submodule)[:object_id][0..6]
submod_right_id=read_info(super_right, submodule)[:object_id][0..6]

Dir.chdir(submodule) do
  merge_base = %x(git merge-base #{submod_left_id} #{submod_right_id}).chomp
  merge_base_parent = %x{git show #{merge_base} --pretty=%P}.split("\n").first

  # puts "merge_base #{merge_base} merge_base_parent #{merge_base_parent}"
  command = %(git log --pretty="%h - %s" --graph #{submod_left_id} #{submod_right_id}) 
  command << " --not #{merge_base_parent}" unless merge_base_parent.empty?
  #puts command
  output = %x{#{command}}.
    gsub(submod_left_id, "#{submod_left_id} (left)").
    gsub(submod_right_id, "#{submod_right_id} (right)")
  puts output
end


class CheckoutFailed < Exception
  attr_reader :branch, :output
  def initialize(branch, output)
    @branch = branch
    @output = output
  end
end

def git_checkout(branch)
  output = %x(git checkout #{branch} 2>&1)
  raise CheckoutFailed.new(branch, output) unless $? == 0
end

def prompt
  puts "\nPick (l)eft, (r)ight, or (a)bort:"
  STDIN.readline[0..0].downcase
end

Dir.chdir(submodule) do
  begin
    until case prompt
      when /^l/
        git_checkout(submod_left_id)
        true
      when /^r/
        git_checkout(submod_right_id)
        true
      # when /^b/
      #   git_checkout(submod_left_id)
      #   system("git merge #{submod_right_id}")
      #   if $? == 0
      #     puts "Automatic merge failed! `cd #{submodule}` and resolve the conflict. Once done, go back to the super project and issue `git add #{submodule}`"
      #     exit 1
      #   end
      #   true
      when /^a/
        puts "Aborted"
        exit 1
      else
        puts "invalid option."
        false
      end
    end
  rescue CheckoutFailed => e
    puts "ERROR! Failure while checking out branch #{e.branch} in #{submodule}\n--- Output was: ---\n#{e.output}\n------------\nPerhaps you need to stash changes in your submodule? Resolve the issue and then run #{me} again"
    exit 1
  end
end
system("git add #{submodule}")
puts "#{submodule} marked as resolved."