# frozen_string_literal: true

# handles service desk issue creation emails with these formats:
#   incoming+gitlab-org-gitlab-ce-20-issue-@incoming.gitlab.com
#   incoming+gitlab-org/gitlab-ce@incoming.gitlab.com (legacy)
module Gitlab
  module Email
    module Handler
      class ServiceDeskHandler < BaseHandler
        include ReplyProcessing
        include Gitlab::Utils::StrongMemoize

        HANDLER_REGEX        = /\A#{HANDLER_ACTION_BASE_REGEX}-issue-\z/.freeze
        HANDLER_REGEX_LEGACY = /\A(?<project_path>[^\+]*)\z/.freeze
        PROJECT_KEY_PATTERN  = /\A(?<slug>.+)-(?<key>[a-z0-9_]+)\z/.freeze

        def initialize(mail, mail_key, service_desk_key: nil)
          super(mail, mail_key)

          if service_desk_key.present?
            @service_desk_key = service_desk_key
          elsif !mail_key&.include?('/') && (matched = HANDLER_REGEX.match(mail_key.to_s))
            @project_slug = matched[:project_slug]
            @project_id   = matched[:project_id]&.to_i
          elsif matched = HANDLER_REGEX_LEGACY.match(mail_key.to_s)
            @project_path = matched[:project_path]
          end
        end

        def can_handle?
          Gitlab::ServiceDesk.supported? && (project_id || can_handle_legacy_format? || service_desk_key)
        end

        def execute
          raise ProjectNotFound if project.nil?

          create_issue!

          if from_address
            add_email_participant
            send_thank_you_email!
          end
        end

        def metrics_params
          super.merge(project: project&.full_path)
        end

        def metrics_event
          :receive_email_service_desk
        end

        private

        attr_reader :project_id, :project_path, :service_desk_key

        def project
          strong_memoize(:project) do
            @project = service_desk_key ? project_from_key : super
            @project = nil unless @project&.service_desk_enabled?
            @project
          end
        end

        def project_from_key
          return unless match = service_desk_key.match(PROJECT_KEY_PATTERN)

          project = Project.find_by_service_desk_project_key(match[:key])
          return unless valid_project_key?(project, match[:slug])

          project
        end

        def valid_project_key?(project, slug)
          project.present? && slug == project.full_path_slug
        end

        def create_issue!
          @issue = Issues::CreateService.new(
            project,
            User.support_bot,
            title: mail.subject,
            description: message_including_template,
            confidential: true,
            external_author: from_address
          ).execute

          raise InvalidIssueError unless @issue.persisted?

          if service_desk_setting&.issue_template_missing?
            create_template_not_found_note(@issue)
          end
        end

        def send_thank_you_email!
          Notify.service_desk_thank_you_email(@issue.id).deliver_later!
        end

        def message_including_template
          description = message_including_reply
          template_content = service_desk_setting&.issue_template_content

          if template_content.present?
            description += "  \n" + template_content
          end

          description
        end

        def service_desk_setting
          strong_memoize(:service_desk_setting) do
            project.service_desk_setting
          end
        end

        def create_template_not_found_note(issue)
          issue_template_key = service_desk_setting&.issue_template_key

          warning_note = <<-MD.strip_heredoc
            WARNING: The template file #{issue_template_key}.md used for service desk issues is empty or could not be found.
            Please check service desk settings and update the file to be used.
          MD

          note_params = {
            noteable: issue,
            note: warning_note
          }

          ::Notes::CreateService.new(
            project,
            User.support_bot,
            note_params
          ).execute
        end

        def from_address
          (mail.reply_to || []).first || mail.from.first || mail.sender
        end

        def can_handle_legacy_format?
          project_path && project_path.include?('/') && !mail_key.include?('+')
        end

        def author
          User.support_bot
        end

        def add_email_participant
          @issue.issue_email_participants.create(email: from_address)
        end
      end
    end
  end
end