rainforestapp/fourchette

class Fourchette::Fork
  include Fourchette::Logger

  def initialize(params)
    @params = params
    @heroku = Fourchette::Heroku.new
    @github = Fourchette::GitHub.new
  end

  def update
    create_unless_exists

    build = @heroku.client.build.create(fork_name, tarball_options)
    monitor_build(build)
  end

  def monitor_build(build)
    logger.info 'Start of the build process on Heroku...'
    build_info = @heroku.client.build.info(fork_name, build['id'])
    # Let's just leave some time to Heroku to download the tarball and start
    # the process. This is some random timing that seems to make sense at first.
    sleep 30
    if build_info['status'] == 'failed'
      @github.comment_pr(
        pr_number, 'The build failed on Heroku. See the activity tab on Heroku.'
      )
      fail Fourchette::DeployException
    end
  end

  def create
    @github.comment_pr(
      pr_number, 'Fourchette is initializing a new fork.') if Fourchette::DEBUG
    create_unless_exists
    update
  end

  def delete
    @heroku.delete(fork_name)
    @github.comment_pr(pr_number, 'Test app deleted!')
  end

  def fork_name
    # It needs to be lowercase only.
    "#{ENV['FOURCHETTE_HEROKU_APP_PREFIX']}-PR-#{pr_number}".downcase
  end

  def branch_name
    @params['pull_request']['head']['ref']
  end

  def pr_number
    @params['pull_request']['number']
  end

  def create_unless_exists
    unless app_exists?
      @heroku.fork(ENV['FOURCHETTE_HEROKU_APP_TO_FORK'], fork_name)
      post_fork_url
    end
  end

  private

  def app_exists?
    @heroku.app_exists?(fork_name)
  end

  def tarball_options
    {
      source_blob: {
        url: tarball_url
      }
    }
  end

  def tarball_url
    Fourchette::Tarball.new.url(
      github_git_url,
      git_branch_name,
      ENV['FOURCHETTE_GITHUB_PROJECT']
    )
  end

  # Update PR with URL. This is a method so that we can override it and just not
  # have that, if we don't want. Use case: we have custom domains, so we post
  # the URLs later on.
  def post_fork_url
    @github.comment_pr(
      pr_number,
      "Test URL: #{@heroku.client.app.info(fork_name)['web_url']}"
    )
  end

  def git_branch_name
    "remotes/origin/#{branch_name}"
  end

  def github_git_url
    @params['pull_request']['head']['repo']['clone_url']
      .gsub(
        '//github.com',
        "//#{ENV['FOURCHETTE_GITHUB_USERNAME']}:" \
        "#{ENV['FOURCHETTE_GITHUB_PERSONAL_TOKEN']}@github.com"
      )
  end
end