#!/usr/bin/ruby
require 'json'
require 'net/http'
require 'yaml'
require 'logger'

$main_branch = "2.7.x"

$log = Logger.new(STDOUT)
$log.level = Logger::WARN

def get_fixed_issues()
  $log.debug "Searching for for forward merge"
  rev=`git rev-parse -q --verify MERGE_HEAD`.strip
  $log.debug "Found #{rev} from git rev-parse"
  return nil unless rev
  fixed = []
  message = `git log -1 --pretty=%B #{rev}`
  message.each_line do |line|
    $log.debug "Checking #{line} for message"
    fixed << line.strip if /^(?:Fixes|Closes) gh-(\d+)/.match(line)
  end
  $log.debug "Found fixed issues #{fixed}"
  return fixed;
end

def rewrite_message(message_file, fixed)
  current_branch = `git rev-parse --abbrev-ref HEAD`.strip
  if current_branch == "main"
    current_branch = $main_branch
  end
  rewritten_message = ""
  message = File.read(message_file)
  message.each_line do |line|
    match = /^Merge.*branch\ '(.*)'(?:\ into\ (.*))?$/.match(line)
    if match
      from_branch = match[1]
      if from_branch.include? "/"
        from_branch = from_branch.partition("/").last
      end
      to_branch = match[2]
      $log.debug "Rewriting merge message"
      line = "Merge branch '#{from_branch}'" + (to_branch ? " into #{to_branch}\n" : "\n")
    end
    if fixed and line.start_with?("#")
      $log.debug "Adding fixed"
      rewritten_message << "\n"
      fixed.each do |fixes|
        rewritten_message << "#{fixes} in #{current_branch}\n"
      end
      fixed = nil
    end
    rewritten_message << line
  end
  return rewritten_message
end

$log.debug "Running prepare-forward-merge hook script"

message_file=ARGV[0]
message_type=ARGV[1]

if message_type != "merge"
  $log.debug "Not a merge commit"
  exit 0;
end

$log.debug "Searching for for forward merge"
fixed = get_fixed_issues()
rewritten_message = rewrite_message(message_file, fixed)
File.write(message_file, rewritten_message)