module GitHelper
  class GitLabMergeRequest
    attr_accessor :local_project, :local_branch, :local_code, :cli, :base_branch, :new_mr_title

    def initialize(options)
      @local_project = options[:local_project]
      @local_branch = options[:local_branch]
      @local_code = options[:local_code]
      @cli = options[:cli]
    end

    def create(options)
      @base_branch = options[:base_branch]
      @new_mr_title = options[:new_title]

      begin
        options = {
          source_branch: local_branch,
          target_branch: base_branch,
          squash: squash_merge_request,
          remove_source_branch: remove_source_branch,
          description: new_mr_body
        }

        puts "Creating merge request: #{new_mr_title}"
        mr = gitlab_client.create_merge_request(local_project, new_mr_title, options)

        if mr.diff_refs.base_sha == mr.diff_refs.head_sha
          puts "Merge request was created, but no commits have been pushed to GitLab: #{mr.web_url}"
        else
          puts "Merge request successfully created: #{mr.web_url}"
        end
      rescue Gitlab::Error::Conflict => e
        puts 'Could not create merge request:'
        puts '  A merge request already exists for this branch'
      rescue Exception => e
        puts 'Could not create merge request:'
        puts e.message
      end
    end

    def merge
      begin
        mr_id
        options = {
          should_remove_source_branch: existing_mr.should_remove_source_branch || existing_mr.force_remove_source_branch,
          squash: existing_mr.squash,
          squash_commit_message: existing_mr.title
        }

        puts "Merging merge request: #{mr_id}"
        merge = gitlab_client.accept_merge_request(local_project, mr_id, options)

        if merge.merge_commit_sha.nil?
          options[:squash] = true
          merge = gitlab_client.accept_merge_request(local_project, mr_id, options)
        end

        if merge.merge_commit_sha.nil?
          puts 'Could not merge merge request:'
          puts "  #{merge.merge_error}"
        else
          puts "Merge request successfully merged: #{merge.merge_commit_sha}"
        end
      rescue Gitlab::Error::MethodNotAllowed => e
        puts 'Could not merge merge request:'
        puts '  The merge request is not mergeable'
      rescue Gitlab::Error::NotFound => e
        puts 'Could not merge merge request:'
        puts "  Could not a locate a merge request to merge with ID #{mr_id}"
      rescue Exception => e
        puts 'Could not merge merge request:'
        puts e.message
      end
    end

    private def new_mr_body
      @new_mr_body ||= template_name_to_apply ? local_code.read_template(template_name_to_apply) : ''
    end

    private def template_name_to_apply
      return @template_name_to_apply if @template_name_to_apply
      @template_name_to_apply = nil

      unless mr_template_options.empty?
        if mr_template_options.count == 1
          apply_single_template = cli.apply_template?(mr_template_options.first, 'merge')
          @template_name_to_apply = mr_template_options.first if apply_single_template
        else
          response = cli.template_to_apply(mr_template_options, 'merge')
          @template_name_to_apply = response unless response == 'None'
        end
      end

      @template_name_to_apply
    end

    private def mr_template_options
      @mr_template_options ||= local_code.template_options({
                                 nested_directory_name: 'merge_request_templates',
                                 non_nested_file_name: 'merge_request_template'
                               })
    end

    private def mr_id
      @mr_id ||= cli.code_request_id('Merge')
    end

    private def squash_merge_request
      @squash_merge_request ||= cli.squash_merge_request?
    end

    private def remove_source_branch
      @remove_source_branch ||= existing_project.remove_source_branch_after_merge || cli.remove_source_branch?
    end

    private def existing_project
      @existing_project ||= gitlab_client.project(local_project)
    end

    private def existing_mr
      @existing_mr ||= gitlab_client.merge_request(local_project, mr_id)
    end

    private def gitlab_client
      @gitlab_client ||= GitHelper::GitLabClient.new.client
    end
  end
end