module Gitlab
  module Routing
    extend ActiveSupport::Concern

    mattr_accessor :_includers
    self._includers = []

    included do
      Gitlab::Routing.includes_helpers(self)

      include Gitlab::Routing.url_helpers
    end

    def self.includes_helpers(klass)
      self._includers << klass
    end

    def self.add_helpers(mod)
      url_helpers.include mod
      url_helpers.extend mod

      GitlabRoutingHelper.include mod
      GitlabRoutingHelper.extend mod

      app_url_helpers = Gitlab::Application.routes.named_routes.url_helpers_module
      app_url_helpers.include mod
      app_url_helpers.extend mod

      _includers.each do |klass|
        klass.include mod
      end
    end

    # Returns the URL helpers Module.
    #
    # This method caches the output as Rails' "url_helpers" method creates an
    # anonymous module every time it's called.
    #
    # Returns a Module.
    def self.url_helpers
      @url_helpers ||= Gitlab::Application.routes.url_helpers
    end

    def self.redirect_legacy_paths(router, *paths)
      build_redirect_path = lambda do |request, _params, path|
        # Only replace the last occurence of `path`.
        #
        # `request.fullpath` includes the querystring
        path = request.path.sub(%r{/#{path}/*(?!.*#{path})}, "/-/#{path}/")
        path << "?#{request.query_string}" if request.query_string.present?

        path
      end

      paths.each do |path|
        router.match "/#{path}(/*rest)",
                     via: [:get, :post, :patch, :delete],
                     to: router.redirect { |params, request| build_redirect_path.call(request, params, path) },
                     as: "legacy_#{path}_redirect"
      end
    end
  end
end
