CommunitySolidServer/src/server/notifications/WebHookChannel2023/WebHookWebId.ts

import { Parser } from 'n3';
import { OkResponseDescription } from '../../../http/output/response/OkResponseDescription';
import type { ResponseDescription } from '../../../http/output/response/ResponseDescription';
import { BasicRepresentation } from '../../../http/representation/BasicRepresentation';
import { TEXT_TURTLE } from '../../../util/ContentTypes';
import { createErrorMessage } from '../../../util/errors/ErrorUtil';
import { trimTrailingSlashes } from '../../../util/PathUtil';
import type { OperationHttpHandlerInput } from '../../OperationHttpHandler';
import { OperationHttpHandler } from '../../OperationHttpHandler';

/**
 * Generates a fixed WebID that we use to identify the server for notifications sent using a WebHookChannel2023.
 * This is used in tandem with the tokens generated by the {@link WebHookEmitter}.
 * This is a minimal WebID with only the `solid:oidcIssuer` triple.
 */
export class WebHookWebId extends OperationHttpHandler {
  private readonly turtle: string;

  public constructor(baseUrl: string) {
    super();

    this.turtle = `@prefix solid: <http://www.w3.org/ns/solid/terms#>.
<> solid:oidcIssuer <${trimTrailingSlashes(baseUrl)}>.`;

    // This will throw an error if something is wrong with the issuer URL
    const parser = new Parser();
    try {
      parser.parse(this.turtle);
    } catch (error: unknown) {
      throw new Error(`Invalid issuer URL: ${createErrorMessage(error)}`);
    }
  }

  public async handle(input: OperationHttpHandlerInput): Promise<ResponseDescription> {
    const representation = new BasicRepresentation(this.turtle, input.operation.target, TEXT_TURTLE);
    return new OkResponseDescription(representation.metadata, representation.data);
  }
}