#!/usr/bin/env ruby

abort "No tempfile given" if ARGV.empty?

commit_file = ARGV[0]
commit_msg = File.read(commit_file)

if commit_msg.nil?
  $stderr.puts "Nothing given, aborting"
  exit 0
end

unless commit_msg.lines.first.strip.empty?
  $stderr.puts "Commit message not empty, aborting"
  exit 0
end

branch_match = commit_msg.match(%r{# On branch (?<ticket>[A-Z]{1,10}-\d+)})

if branch_match.nil? or branch_match["ticket"].nil?
  $stderr.puts "Could not extract a ticket from the commit message"
  exit
end

ticket = branch_match["ticket"]
new_commit = "#{ticket}: \n" + commit_msg
File.write(commit_file, new_commit, mode: "w")