# frozen_string_literal: true

module Chusaku
  # Handles extracting information about the Rails project's routes.
  class Routes
    class << self
      # Example output:
      #
      #   {
      #     'users' => {
      #       'edit' => [
      #         { verb: 'GET', path: '/users/:id', name: 'edit_user' }
      #       ],
      #       'update' => [
      #         { verb: 'PATCH', path: '/users', name: 'edit_user' },
      #         { verb: 'PUT', path: '/users', name: 'edit_user' }
      #       ]
      #     },
      #     'empanadas' => {
      #       'create' => [
      #         { verb: 'POST', path: '/empanadas', name: nil }
      #       ]
      #     }
      #   }
      #
      # @return {Hash} - Routes hash
      def call
        routes = {}

        Rails.application.routes.routes.each do |route|
          controller, action = extract_controller_and_action_from(route)
          routes[controller] ||= {}
          routes[controller][action] ||= []
          routes[controller][action].push(format_route(route))
        end

        backfill_routes(routes)
      end

      private

      # Extract information of a given route.
      #
      # @param {ActionDispatch::Journey::Route} route - Route given by Rails
      # @return {Hash} - { verb: String, path: String, name: String }
      def format_route(route)
        {
          verb: route.verb,
          path: route.path.spec.to_s.gsub('(.:format)', ''),
          name: route.name
        }
      end

      # Given a routes hash, backfill entries that aren't already filled by
      # `Rails.application.routes`.
      #
      # @param {Hash} routes - Routes hash generated by this class
      # @return {Hash} - Backfilled routes hash
      def backfill_routes(routes)
        paths = {}

        routes.each do |_controller, actions|
          actions.each do |_action, data|
            data.each do |datum|
              paths[datum[:path]] ||= datum[:name]
              datum[:name] ||= paths[datum[:path]]
            end
          end
        end

        routes
      end

      # Given a route, extract the controller and action strings.
      #
      # @param {ActionDispatch::Journey::Route} route - Route instance
      # @return {Array<String>} - [String, String]
      def extract_controller_and_action_from(route)
        defaults = route.defaults
        controller = defaults[:controller]
        action = defaults[:action]

        [controller, action]
      end
    end
  end
end