/
DefaultRootHttpRouter.ts
109 lines (98 loc) · 3.13 KB
/
DefaultRootHttpRouter.ts
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/*
* Copyright 2023 The Backstage Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import { RootHttpRouterService } from '@backstage/backend-plugin-api';
import { Handler, Router } from 'express';
import trimEnd from 'lodash/trimEnd';
function normalizePath(path: string): string {
return `${trimEnd(path, '/')}/`;
}
/**
* Options for the {@link DefaultRootHttpRouter} class.
*
* @public
*/
export interface DefaultRootHttpRouterOptions {
/**
* The path to forward all unmatched requests to. Defaults to '/api/app' if
* not given. Disables index path behavior if false is given.
*/
indexPath?: string | false;
}
/**
* The default implementation of the {@link @backstage/backend-plugin-api#RootHttpRouterService} interface for
* {@link @backstage/backend-plugin-api#coreServices.rootHttpRouter}.
*
* @public
*/
export class DefaultRootHttpRouter implements RootHttpRouterService {
#indexPath?: string;
#router = Router();
#namedRoutes = Router();
#indexRouter = Router();
#existingPaths = new Array<string>();
static create(options?: DefaultRootHttpRouterOptions) {
let indexPath;
if (options?.indexPath === false) {
indexPath = undefined;
} else if (options?.indexPath === undefined) {
indexPath = '/api/app';
} else if (options?.indexPath === '') {
throw new Error('indexPath option may not be an empty string');
} else {
indexPath = options.indexPath;
}
return new DefaultRootHttpRouter(indexPath);
}
private constructor(indexPath?: string) {
this.#indexPath = indexPath;
this.#router.use(this.#namedRoutes);
if (this.#indexPath) {
this.#router.use(this.#indexRouter);
}
}
use(path: string, handler: Handler) {
if (path.match(/^[/\s]*$/)) {
throw new Error(`Root router path may not be empty`);
}
const conflictingPath = this.#findConflictingPath(path);
if (conflictingPath) {
throw new Error(
`Path ${path} conflicts with the existing path ${conflictingPath}`,
);
}
this.#existingPaths.push(path);
this.#namedRoutes.use(path, handler);
if (this.#indexPath === path) {
this.#indexRouter.use(handler);
}
}
handler(): Handler {
return this.#router;
}
#findConflictingPath(newPath: string): string | undefined {
const normalizedNewPath = normalizePath(newPath);
for (const path of this.#existingPaths) {
const normalizedPath = normalizePath(path);
if (normalizedPath.startsWith(normalizedNewPath)) {
return path;
}
if (normalizedNewPath.startsWith(normalizedPath)) {
return path;
}
}
return undefined;
}
}