gitlab-org--gitlab-foss/app/controllers/projects/compare_controller.rb

require 'addressable/uri'

class Projects::CompareController < Projects::ApplicationController
  include DiffForPath
  include DiffHelper
  include RendersCommits

  # Authorize
  before_action :require_non_empty_project
  before_action :authorize_download_code!
  before_action :define_ref_vars, only: [:index, :show, :diff_for_path]
  before_action :define_diff_vars, only: [:show, :diff_for_path]
  before_action :merge_request, only: [:index, :show]

  def index
  end

  def show
    apply_diff_view_cookie!
    # n+1: https://gitlab.com/gitlab-org/gitlab-ce/issues/37430
    Gitlab::GitalyClient.allow_n_plus_1_calls do
      render
    end
  end

  def diff_for_path
    return render_404 unless @compare

    render_diff_for_path(@compare.diffs(diff_options))
  end

  def create
    if params[:from].blank? || params[:to].blank?
      flash[:alert] = "You must select a Source and a Target revision"
      from_to_vars = {
        from: params[:from].presence,
        to: params[:to].presence
      }
      redirect_to project_compare_index_path(@project, from_to_vars)
    else
      redirect_to project_compare_path(@project,
                                               params[:from], params[:to])
    end
  end

  private

  def define_ref_vars
    @start_ref = Addressable::URI.unescape(params[:from])
    @ref = @head_ref = Addressable::URI.unescape(params[:to])
  end

  def define_diff_vars
    @compare = CompareService.new(@project, @head_ref)
      .execute(@project, @start_ref)

    if @compare
      @commits = prepare_commits_for_rendering(@compare.commits)
      @diffs = @compare.diffs(diff_options)

      environment_params = @repository.branch_exists?(@head_ref) ? { ref: @head_ref } : { commit: @compare.commit }
      @environment = EnvironmentsFinder.new(@project, current_user, environment_params).execute.last

      @diff_notes_disabled = true
    end
  end

  def merge_request
    @merge_request ||= MergeRequestsFinder.new(current_user, project_id: @project.id).execute.opened
      .find_by(source_project: @project, source_branch: @head_ref, target_branch: @start_ref)
  end
end