re-author

#!/usr/bin/env ruby

# Author: Riley Shott
# Date: Nov 13, 2014

require 'optparse'

###
# METHODS
###

def sanity_checks(options)
  raise "#{options[:path]} does not appear to be a directory" unless File.directory? options[:path]
  Dir.chdir options[:path]
  
  check = {}
  error_messages = []

  check['git'] = system 'bash', '-c', 'which git &> /dev/null'
  check['gitrepo'] = system 'bash', '-c', 'git status &> /dev/null'

  error_messages << "This script requires #{key}. Please ensure it's installed and in your PATH." if check['git'] == false
  error_messages << "#{options[:path]} doesn't seem to be a git repo" if check['gitrepo'] == false
  
  unless error_messages.empty?
    puts error_messages
    exit 1
  end
end

###
# ARGUMENT PARSING
###

options = {}

optparse = OptionParser.new do |opts|
  opts.banner = "Usage: #{__FILE__} --path /git/repo --commit hashid --author 'Some User <email@domain.com>'"

  opts.separator ""
  opts.separator "Specific options:"

  opts.on("-p", "--path [/git/repo]", "The location of the git repo.") do |name|
    options[:path] = name
  end

  opts.on("-c", "--commit [hashid]", "The hash of the commit BEFORE where you want to start ammending.") do |name|
    options[:commit] = name
  end

  opts.on("-a", "--author ['Some User <email@domain.com>']", "The author string you want everything to be changed to.") do |owner|
    options[:author] = owner
  end

  opts.on_tail( '-h', '--help', 'Display this screen' ) do
    puts opts
    exit
  end
end

begin
  optparse.parse!
  mandatory = [:path, :commit, :author]
  missing = mandatory.select{ |param| options[param].nil? }
  unless missing.empty?
    puts "Missing options: #{missing.join(', ')}"
    puts optparse
    exit
  end
rescue OptionParser::MissingArgument
  puts $!.to_s
  puts optparse
  exit 1
rescue OptionParser::InvalidOption => e
  puts e.to_s
  exit 1
end

###
# MAIN
###

begin
  sanity_checks(options)
  Dir.chdir options[:path]
  
  if system "git rebase -i -p #{options[:commit]}"
    while File.directory? '.git/rebase-merge' do
      %x{git commit --amend --author '#{options[:author]}' -F .git/rebase-merge/message && git rebase --continue}
    end
  end
rescue => e
  puts "Error\n\nMessage:\n#{e.message}\n\nBacktrace:\n#{e.backtrace}"
  exit 1
end