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

class ForwardMerge
  attr_reader :issue, :milestone, :message, :line
  def initialize(issue, milestone, message, line)
    @issue = issue
    @milestone = milestone
    @message = message
    @line = line
  end
end

def find_forward_merge(message_file)
  rev=`git rev-parse -q --verify MERGE_HEAD`
  return nil unless rev
  message = File.read(message_file)
  message.each_line do |line|
    match = /^(?:Fixes|Closes) gh-(\d+) in ([\d\.]+(?:(?:M|RC)\d)?)$/.match(line)
    if match then
  	  issue = match[1]
  	  milestone = match[2]
  	  return ForwardMerge.new(issue, milestone, message, line)
    end
  end
  return nil
end

def find_milestone(repository, title)
  milestones = JSON.parse(Net::HTTP.get(URI("https://api.github.com/repos/#{repository}/milestones")))
  milestones.each do |milestone|
    return milestone['number'] if milestone['title'] == title
  end
  puts "Milestone #{title} not found"
  exit 1
end

def get_issue(repository, number)
  uri = URI("https://api.github.com/repos/#{repository}/issues/#{number}")
  http = Net::HTTP.new(uri.host, uri.port)
  http.use_ssl=true
  request = Net::HTTP::Get.new(uri.path)
  response = http.request(request)
  return JSON.parse(response.body) unless response.code != '200'
  puts "Failed to retrieve issue #{number}: #{response.message}"
  exit 1
end

def create_issue(username, password, repository, original, title, labels, milestone, milestone_name, dry_run)
  uri = URI("https://api.github.com/repos/#{repository}/issues")
  http = Net::HTTP.new(uri.host, uri.port)
  http.use_ssl=true
  request = Net::HTTP::Post.new(uri.path, 'Content-Type' => 'application/json')
  request.basic_auth(username, password)
  request.body = {
    title: title,
    labels: labels,
    milestone: milestone.to_i,
    body: "Forward port of issue ##{original} to #{milestone_name}."
  }.to_json
  if dry_run then
    puts "Dry run"
    puts "POSTing to #{uri} with body #{request.body}"
    return "dry-run"
  end
  response = JSON.parse(http.request(request).body)
  return response['number']
end

message_file=ARGV[0]
forward_merge = find_forward_merge(message_file)
exit 0 unless forward_merge
repository = 'spring-projects/spring-boot'
existing_issue = get_issue(repository, forward_merge.issue)
title = existing_issue['title']
labels = existing_issue['labels'].map { |label| label['name'] }
labels << "status: forward-port"
milestone = find_milestone(repository, forward_merge.milestone)
config = YAML.load_file(File.join(Dir.home, '.spring-boot', 'forward-merge.yml'))
username = config['github']['credentials']['username']
password = config['github']['credentials']['password']
dry_run = config['dry_run']
new_issue_number = create_issue(username, password, repository, forward_merge.issue, title, labels, milestone, forward_merge.milestone, dry_run)
puts "Created gh-#{new_issue_number} for forward port of gh-#{forward_merge.issue} into #{forward_merge.milestone}"
rewritten_message = forward_merge.message.sub(forward_merge.line, "Closes gh-#{new_issue_number}\n")
File.write(message_file, rewritten_message)