openapi.validator.ts

import { Options } from 'ajv';
import ono from 'ono';
import * as express from 'express';
import * as _uniq from 'lodash.uniq';
import * as middlewares from './middlewares';
import { Application, Response, NextFunction, Router } from 'express';
import { OpenApiContext } from './framework/openapi.context';
import { Spec } from './framework/openapi.spec.loader';
import {
  NormalizedOpenApiValidatorOpts,
  OpenApiValidatorOpts,
  ValidateRequestOpts,
  ValidateResponseOpts,
  OpenApiRequest,
  OpenApiRequestHandler,
  OpenApiRequestMetadata,
  ValidateSecurityOpts,
  OpenAPIV3,
} from './framework/types';
import { defaultResolver } from './resolvers';
import { OperationHandlerOptions } from './framework/types';
import { defaultSerDes } from './framework/base.serdes';
import { SchemaPreprocessor } from './middlewares/parsers/schema.preprocessor';
import { AjvOptions } from './framework/ajv/options';

export {
  OpenApiValidatorOpts,
  InternalServerError,
  UnsupportedMediaType,
  RequestEntityTooLarge,
  BadRequest,
  MethodNotAllowed,
  NotAcceptable,
  NotFound,
  Unauthorized,
  Forbidden,
} from './framework/types';

export class OpenApiValidator {
  readonly options: NormalizedOpenApiValidatorOpts;
  readonly ajvOpts: AjvOptions;

  constructor(options: OpenApiValidatorOpts) {
    if (options.validateApiSpec == null) options.validateApiSpec = true;
    if (options.validateRequests == null) options.validateRequests = true;
    if (options.validateResponses == null) options.validateResponses = false;
    if (options.validateSecurity == null) options.validateSecurity = true;
    if (options.fileUploader == null) options.fileUploader = {};
    if (options.$refParser == null) options.$refParser = { mode: 'bundle' };
    if (options.validateFormats == null) options.validateFormats = true;
    if (options.formats == null) options.formats = {};
    if (options.useRequestUrl == null) options.useRequestUrl = false;

    if (typeof options.operationHandlers === 'string') {
      /**
       * Internally, we want to convert this to a value typed OperationHandlerOptions.
       * In this way, we can treat the value as such when we go to install (rather than
       * re-interpreting it over and over).
       */
      options.operationHandlers = {
        basePath: options.operationHandlers,
        resolver: defaultResolver,
      };
    } else if (typeof options.operationHandlers !== 'object') {
      // This covers cases where operationHandlers is null, undefined or false.
      options.operationHandlers = false;
    }

    if (options.validateResponses === true) {
      options.validateResponses = {
        removeAdditional: false,
        coerceTypes: false,
        onError: null,
      };
    }

    if (options.validateRequests === true) {
      options.validateRequests = {
        allowUnknownQueryParameters: false,
        coerceTypes: false,
      };
    }

    if (options.validateSecurity === true) {
      options.validateSecurity = {};
    }

    this.validateOptions(options);

    this.options = this.normalizeOptions(options);
    this.ajvOpts = new AjvOptions(this.options);
  }

  installMiddleware(spec: Promise<Spec>): OpenApiRequestHandler[] {
    const middlewares: OpenApiRequestHandler[] = [];
    const pContext = spec
      .then((spec) => {
        const apiDoc = spec.apiDoc;
        const ajvOpts = this.ajvOpts.preprocessor;
        const resOpts = this.options.validateResponses as ValidateRequestOpts;
        const sp = new SchemaPreprocessor(
          apiDoc,
          ajvOpts,
          resOpts,
        ).preProcess();
        return {
          context: new OpenApiContext(
            spec,
            this.options.ignorePaths,
            this.options.ignoreUndocumented,
            this.options.useRequestUrl,
          ),
          responseApiDoc: sp.apiDocRes,
          error: null,
        };
      })
      .catch((e) => {
        return {
          context: null,
          responseApiDoc: null,
          error: e,
        };
      });

    const self = this; // using named functions instead of anonymous functions to allow traces to be more useful
    let inited = false;
    // install path params
    middlewares.push(function pathParamsMiddleware(req, res, next) {
      return pContext
        .then(({ context, error }) => {
          // Throw if any error occurred during spec load.
          if (error) throw error;
          if (!inited) {
            // Would be nice to pass the current Router object here if the route
            // is attach to a Router and not the app.
            // Doing so would enable path params to be type coerced when provided to
            // the final middleware.
            // Unfortunately, it is not possible to get the current Router from a handler function
            self.installPathParams(req.app, context);
            inited = true;
          }
          next();
        })
        .catch(next);
    });

    // metadata middleware
    let metamw;
    middlewares.push(function metadataMiddleware(req, res, next) {
      return pContext
        .then(({ context, responseApiDoc }) => {
          metamw = metamw || self.metadataMiddleware(context, responseApiDoc);
          return metamw(req, res, next);
        })
        .catch(next);
    });

    if (this.options.fileUploader) {
      // multipart middleware
      let fumw;
      middlewares.push(function multipartMiddleware(req, res, next) {
        return pContext
          .then(({ context: { apiDoc } }) => {
            fumw = fumw || self.multipartMiddleware(apiDoc);
            return fumw(req, res, next);
          })
          .catch(next);
      });
    }

    // security middlware
    let scmw;
    middlewares.push(function securityMiddleware(req, res, next) {
      return pContext
        .then(({ context: { apiDoc } }) => {
          const components = apiDoc.components;
          if (self.options.validateSecurity && components?.securitySchemes) {
            scmw = scmw || self.securityMiddleware(apiDoc);
            return scmw(req, res, next);
          } else {
            next();
          }
        })
        .catch(next);
    });

    // request middlweare
    if (this.options.validateRequests) {
      let reqmw;
      middlewares.push(function requestMiddleware(req, res, next) {
        return pContext
          .then(({ context: { apiDoc } }) => {
            reqmw = reqmw || self.requestValidationMiddleware(apiDoc);
            return reqmw(req, res, next);
          })
          .catch(next);
      });
    }

    // response middleware
    if (this.options.validateResponses) {
      let resmw;
      middlewares.push(function responseMiddleware(req, res, next) {
        return pContext
          .then(({ responseApiDoc }) => {
            resmw = resmw || self.responseValidationMiddleware(responseApiDoc);
            return resmw(req, res, next);
          })
          .catch(next);
      });
    }

    // op handler middleware
    if (this.options.operationHandlers) {
      let router: Router = null;
      middlewares.push(function operationHandlersMiddleware(req, res, next) {
        if (router) return router(req, res, next);
        return pContext
          .then(
            ({ context }) =>
              (router = self.installOperationHandlers(req.baseUrl, context)),
          )
          .then((router) => router(req, res, next))
          .catch(next);
      });
    }

    return middlewares;
  }

  installPathParams(app: Application | Router, context: OpenApiContext): void {
    const pathParams: string[] = [];
    for (const route of context.routes) {
      if (route.pathParams.length > 0) {
        pathParams.push(...route.pathParams);
      }
    }

    // install param on routes with paths
    for (const p of _uniq(pathParams)) {
      app.param(
        p,
        (
          req: OpenApiRequest,
          res: Response,
          next: NextFunction,
          value: any,
          name: string,
        ) => {
          const openapi = <OpenApiRequestMetadata>req.openapi;
          if (openapi?.pathParams) {
            const { pathParams } = openapi;
            // override path params
            req.params[name] = pathParams[name] || req.params[name];
          }
          next();
        },
      );
    }
  }

  private metadataMiddleware(
    context: OpenApiContext,
    responseApiDoc: OpenAPIV3.Document,
  ) {
    return middlewares.applyOpenApiMetadata(context, responseApiDoc);
  }

  private multipartMiddleware(apiDoc: OpenAPIV3.Document) {
    return middlewares.multipart(apiDoc, {
      multerOpts: this.options.fileUploader,
      ajvOpts: this.ajvOpts.multipart,
    });
  }

  private securityMiddleware(apiDoc: OpenAPIV3.Document) {
    const securityHandlers = (<ValidateSecurityOpts>(
      this.options.validateSecurity
    ))?.handlers;
    return middlewares.security(apiDoc, securityHandlers);
  }

  private requestValidationMiddleware(apiDoc: OpenAPIV3.Document) {
    const requestValidator = new middlewares.RequestValidator(
      apiDoc,
      this.ajvOpts.request,
    );
    return (req, res, next) => requestValidator.validate(req, res, next);
  }

  private responseValidationMiddleware(apiDoc: OpenAPIV3.Document) {
    return new middlewares.ResponseValidator(
      apiDoc,
      this.ajvOpts.response,
      // This has already been converted from boolean if required
      this.options.validateResponses as ValidateResponseOpts,
    ).validate();
  }

  installOperationHandlers(baseUrl: string, context: OpenApiContext): Router {
    const router = express.Router({ mergeParams: true });

    this.installPathParams(router, context);

    for (const route of context.routes) {
      const { method, expressRoute } = route;

      /**
       * This if-statement is here to "narrow" the type of options.operationHandlers
       * to OperationHandlerOptions (down from string | false | OperationHandlerOptions)
       * At this point of execution it _should_ be impossible for this to NOT be the correct
       * type as we re-assign during construction to verify this.
       */
      if (this.isOperationHandlerOptions(this.options.operationHandlers)) {
        const { basePath, resolver } = this.options.operationHandlers;
        const path =
          expressRoute.indexOf(baseUrl) === 0
            ? expressRoute.substring(baseUrl.length)
            : expressRoute;
        router[method.toLowerCase()](
          path,
          resolver(basePath, route, context.apiDoc),
        );
      }
    }
    return router;
  }

  private validateOptions(options: OpenApiValidatorOpts): void {
    if (!options.apiSpec) throw ono('apiSpec required.');

    const securityHandlers = (<any>options).securityHandlers;
    if (securityHandlers != null) {
      throw ono(
        'securityHandlers is not supported. Use validateSecurities.handlers instead.',
      );
    }

    if (options.coerceTypes) {
      console.warn('coerceTypes is deprecated.');
    }

    const multerOpts = (<any>options).multerOpts;
    if (multerOpts != null) {
      throw ono('multerOpts is not supported. Use fileUploader instead.');
    }

    const unknownFormats = options.unknownFormats;
    if (unknownFormats !== undefined) {
      if (typeof unknownFormats === 'boolean') {
        if (!unknownFormats) {
          throw ono(
            "unknownFormats must contain an array of unknownFormats, 'ignore' or true",
          );
        }
      } else if (
        typeof unknownFormats === 'string' &&
        unknownFormats !== 'ignore' &&
        !Array.isArray(unknownFormats)
      )
        throw ono(
          "unknownFormats must contain an array of unknownFormats, 'ignore' or true",
        );
      console.warn('unknownFormats is deprecated.');
    }

    if (Array.isArray(options.formats)) {
      console.warn(
        'formats as an array is deprecated. Use object instead https://ajv.js.org/options.html#formats',
      );
    }

    if (typeof options.validateFormats === 'string') {
      console.warn(
        `"validateFormats" as a string is deprecated. Set to a boolean and use "ajvFormats"`,
      );
    }
  }

  private normalizeOptions(
    options: OpenApiValidatorOpts,
  ): NormalizedOpenApiValidatorOpts {
    if (Array.isArray(options.formats)) {
      const formats: Options['formats'] = {};
      for (const { name, type, validate } of options.formats) {
        if (type) {
          const formatValidator:
            | {
                type: 'number';
                validate: (x: number) => boolean;
              }
            | {
                type: 'string';
                validate: (x: string) => boolean;
              } = { type, validate };
          formats[name] = formatValidator;
        } else {
          formats[name] = validate;
        }
      }
      options.formats = formats;
    }

    if (!options.serDes) {
      options.serDes = defaultSerDes;
    } else {
      defaultSerDes.forEach((currentDefaultSerDes) => {
        let defaultSerDesOverride = options.serDes.find(
          (currentOptionSerDes) => {
            return currentDefaultSerDes.format === currentOptionSerDes.format;
          },
        );
        if (!defaultSerDesOverride) {
          options.serDes.push(currentDefaultSerDes);
        }
      });
    }

    if (typeof options.validateFormats === 'string') {
      if (!options.ajvFormats) {
        options.ajvFormats = { mode: options.validateFormats };
      }
      options.validateFormats = true;
    } else if (options.validateFormats && !options.ajvFormats) {
      options.ajvFormats = { mode: 'fast' };
    }

    if (Array.isArray(options.unknownFormats)) {
      for (const format of options.unknownFormats) {
        options.formats[format] = true;
      }
    } else if (options.unknownFormats === 'ignore') {
      options.validateFormats = false;
    }

    return options as NormalizedOpenApiValidatorOpts;
  }

  private isOperationHandlerOptions(
    value: false | string | OperationHandlerOptions,
  ): value is OperationHandlerOptions {
    if ((value as OperationHandlerOptions).resolver) {
      return true;
    } else {
      return false;
    }
  }
}