@sls-next/core/src/route/index.ts

Handles Next.js routing independent of provider

import { handleApiReq } from "./api";
import { getUnauthenticatedResponse } from "./auth";
import { normalise } from "./basepath";
import { handleDataReq } from "./data";
import { handlePageReq } from "./page";
import { isValidPreviewRequest } from "./preview";
import {
  createRedirectResponse,
  getDomainRedirectPath,
  getLanguageRedirectPath,
  getRedirectPath,
  getTrailingSlashPath
} from "./redirect";
import {
  ApiManifest,
  ApiRoute,
  ExternalRoute,
  Manifest,
  PageManifest,
  PrerenderManifest,
  RedirectRoute,
  Request,
  Route,
  RoutesManifest,
  UnauthorizedRoute
} from "../types";

export const handleAuth = (
  req: Request,
  manifest: Manifest
): UnauthorizedRoute | undefined => {
  const { headers } = req;
  return getUnauthenticatedResponse(
    headers.authorization,
    manifest.authentication
  );
};

const handleCustomRedirects = (
  req: Request,
  routesManifest: RoutesManifest
): RedirectRoute | undefined => {
  const redirect = getRedirectPath(req, routesManifest);
  if (redirect) {
    const { path, statusCode } = redirect;
    return createRedirectResponse(path, req.querystring, statusCode);
  }
};

export const handleDomainRedirects = (
  req: Request,
  manifest: Manifest
): RedirectRoute | undefined => {
  const path = getDomainRedirectPath(req, manifest);
  if (path) {
    return createRedirectResponse(path, req.querystring, 308);
  }
};

const handleLanguageRedirect = async (
  req: Request,
  manifest: Manifest,
  routesManifest: RoutesManifest
): Promise<RedirectRoute | undefined> => {
  const languageRedirectUri = await getLanguageRedirectPath(
    req,
    manifest,
    routesManifest
  );

  if (languageRedirectUri) {
    return createRedirectResponse(languageRedirectUri, req.querystring, 307);
  }
};

export const handleNextStaticFiles = (uri: string): Route | undefined => {
  if (uri.startsWith("/_next/static")) {
    return {
      isNextStaticFile: true,
      file: uri
    };
  }
};

export const handlePublicFiles = (
  uri: string,
  manifest: Manifest
): Route | undefined => {
  const decodedUri = decodeURI(uri);
  const isPublicFile = manifest.publicFiles && manifest.publicFiles[decodedUri];
  if (isPublicFile) {
    return {
      isPublicFile: true,
      file: uri
    };
  }
};

const handleTrailingSlash = (
  req: Request,
  manifest: Manifest,
  isFile: boolean
): Route | undefined => {
  const path = getTrailingSlashPath(req, manifest, isFile);
  if (path) {
    return createRedirectResponse(path, req.querystring, 308);
  }
};

/*
 * Routes:
 * - auth
 * - redirects
 * - api routes
 * - rewrites (external and api)
 */
export const routeApi = (
  req: Request,
  manifest: ApiManifest,
  routesManifest: RoutesManifest
): ApiRoute | ExternalRoute | RedirectRoute | UnauthorizedRoute | undefined => {
  const auth = handleAuth(req, manifest);
  if (auth) {
    return auth;
  }

  const redirect =
    handleDomainRedirects(req, manifest) ||
    handleCustomRedirects(req, routesManifest);
  if (redirect) {
    return redirect;
  }

  return handleApiReq(req, req.uri, manifest, routesManifest);
};

/*
 * Routes:
 * - auth
 * - redirects
 * - public files
 * - data routes
 * - pages
 * - rewrites (external and page)
 */
export const routeDefault = async (
  req: Request,
  manifest: PageManifest,
  prerenderManifest: PrerenderManifest,
  routesManifest: RoutesManifest
): Promise<Route> => {
  const auth = handleAuth(req, manifest);
  if (auth) {
    return auth;
  }

  const domainRedirect = handleDomainRedirects(req, manifest);
  if (domainRedirect) {
    return domainRedirect;
  }

  const { normalisedUri: uri, missingExpectedBasePath } = normalise(
    req.uri,
    routesManifest
  );
  const is404 = uri.endsWith("/404");
  const isDataReq = uri.startsWith("/_next/data");
  const publicFile = handlePublicFiles(uri, manifest);
  const isPublicFile = !!publicFile;
  const nextStaticFile = handleNextStaticFiles(uri);
  const isNextStaticFile = !!nextStaticFile;

  // Only try to handle trailing slash redirects or public files if the URI isn't missing a base path.
  // This allows us to handle redirects without base paths.
  if (!missingExpectedBasePath) {
    const trailingSlash =
      !is404 &&
      handleTrailingSlash(
        req,
        manifest,
        isDataReq || isPublicFile || isNextStaticFile
      );
    if (trailingSlash) {
      return trailingSlash;
    }

    if (publicFile) {
      return publicFile;
    }

    if (nextStaticFile) {
      return nextStaticFile;
    }
  }

  const otherRedirect =
    handleCustomRedirects(req, routesManifest) ||
    (await handleLanguageRedirect(req, manifest, routesManifest));
  if (otherRedirect) {
    return otherRedirect;
  }

  const isPreview = await isValidPreviewRequest(
    req.headers.cookie,
    prerenderManifest.preview.previewModeSigningKey
  );

  if (isDataReq) {
    return handleDataReq(uri, manifest, routesManifest, isPreview);
  } else {
    return handlePageReq(req, req.uri, manifest, routesManifest, isPreview);
  }
};