nest/packages/core/middleware/builder.ts

import { iterate } from 'iterare';
import { RouteInfoPathExtractor } from './route-info-path-extractor.js';
import { RoutesMapper } from './routes-mapper.js';
import { filterMiddleware } from './utils.js';
import type { HttpServer, MiddlewareConsumer, Type } from '@nestjs/common';
import {
  type MiddlewareConfigProxy,
  type MiddlewareConfiguration,
  type RouteInfo,
  stripEndSlash,
} from '@nestjs/common/internal';

export class MiddlewareBuilder implements MiddlewareConsumer {
  private readonly middlewareCollection = new Set<MiddlewareConfiguration>();

  constructor(
    private readonly routesMapper: RoutesMapper,
    private readonly httpAdapter: HttpServer,
    private readonly routeInfoPathExtractor: RouteInfoPathExtractor,
  ) {}

  public apply(
    ...middleware: Array<Type<any> | Function | Array<Type<any> | Function>>
  ): MiddlewareConfigProxy {
    return new MiddlewareBuilder.ConfigProxy(
      this,
      middleware.flat(),
      this.routeInfoPathExtractor,
    );
  }

  public build(): MiddlewareConfiguration[] {
    return [...this.middlewareCollection];
  }

  public getHttpAdapter(): HttpServer {
    return this.httpAdapter;
  }

  private static readonly ConfigProxy = class implements MiddlewareConfigProxy {
    private excludedRoutes: RouteInfo[] = [];

    constructor(
      private readonly builder: MiddlewareBuilder,
      private readonly middleware: Array<Type<any> | Function>,
      private routeInfoPathExtractor: RouteInfoPathExtractor,
    ) {}

    public getExcludedRoutes(): RouteInfo[] {
      return this.excludedRoutes;
    }

    public exclude(
      ...routes: Array<string | RouteInfo>
    ): MiddlewareConfigProxy {
      this.excludedRoutes = [
        ...this.excludedRoutes,
        ...this.getRoutesFlatList(routes).reduce((excludedRoutes, route) => {
          for (const routePath of this.routeInfoPathExtractor.extractPathFrom(
            route,
          )) {
            excludedRoutes.push({
              ...route,
              path: routePath,
            });
          }

          return excludedRoutes;
        }, [] as RouteInfo[]),
      ];

      return this;
    }

    public forRoutes(
      ...routes: Array<string | Type<any> | RouteInfo>
    ): MiddlewareConsumer {
      const { middlewareCollection } = this.builder;

      const flattedRoutes = this.getRoutesFlatList(routes);
      const forRoutes = this.removeOverlappedRoutes(flattedRoutes);
      const configuration = {
        middleware: filterMiddleware(
          this.middleware,
          this.excludedRoutes,
          this.builder.getHttpAdapter(),
        ),
        forRoutes,
      };
      middlewareCollection.add(configuration);
      return this.builder;
    }

    private getRoutesFlatList(
      routes: Array<string | Type<any> | RouteInfo>,
    ): RouteInfo[] {
      const { routesMapper } = this.builder;

      return iterate(routes)
        .map(route => routesMapper.mapRouteToRouteInfo(route))
        .flatten()
        .toArray();
    }

    private removeOverlappedRoutes(routes: RouteInfo[]) {
      const regexMatchParams = /(:[^/]*)/g;
      const wildcard = '([^/]*)';
      const routesWithRegex = routes
        .filter(route => route.path.includes(':'))
        .map(route => ({
          method: route.method,
          path: route.path,
          regex: new RegExp(
            '^(' + route.path.replace(regexMatchParams, wildcard) + ')$',
            'g',
          ),
        }));

      return routes.filter(route => {
        const isOverlapped = (item: { regex: RegExp } & RouteInfo): boolean => {
          if (route.method !== item.method) {
            return false;
          }
          const normalizedRoutePath = stripEndSlash(route.path);
          return (
            normalizedRoutePath !== item.path &&
            item.regex.test(normalizedRoutePath)
          );
        };
        const routeMatch = routesWithRegex.find(isOverlapped);
        return routeMatch === undefined;
      });
    }
  };
}