docmost/apps/server/src/core/share/share-seo.controller.ts

import { Controller, Get, Param, Req, Res } from '@nestjs/common';
import { ShareService } from './share.service';
import { FastifyReply, FastifyRequest } from 'fastify';
import { join } from 'path';
import * as fs from 'node:fs';
import { validate as isValidUUID } from 'uuid';
import { WorkspaceRepo } from '@docmost/db/repos/workspace/workspace.repo';
import { EnvironmentService } from '../../integrations/environment/environment.service';
import { Workspace } from '@docmost/db/types/entity.types';

@Controller('share')
export class ShareSeoController {
  constructor(
    private readonly shareService: ShareService,
    private workspaceRepo: WorkspaceRepo,
    private environmentService: EnvironmentService,
  ) {}

  /*
   * add meta tags to publicly shared pages
   */
  @Get([':shareId/:pageSlug', 'p/:pageSlug'])
  async getShare(
    @Res({ passthrough: false }) res: FastifyReply,
    @Req() req: FastifyRequest,
    @Param('shareId') shareId: string,
    @Param('pageSlug') pageSlug: string,
  ) {
    // Nestjs does not to apply middlewares to paths excluded from the global /api prefix
    // https://github.com/nestjs/nest/issues/9124
    // https://github.com/nestjs/nest/issues/11572
    // https://github.com/nestjs/nest/issues/13401
    // we have to duplicate the DomainMiddleware code here as a workaround

    let workspace: Workspace = null;
    if (this.environmentService.isSelfHosted()) {
      workspace = await this.workspaceRepo.findFirst();
    } else {
      const header = req.raw.headers.host;
      const subdomain = header.split('.')[0];
      workspace = await this.workspaceRepo.findByHostname(subdomain);
    }

    const clientDistPath = join(
      __dirname,
      '..',
      '..',
      '..',
      '..',
      'client/dist',
    );

    if (fs.existsSync(clientDistPath)) {
      const indexFilePath = join(clientDistPath, 'index.html');

      if (!workspace) {
        return this.sendIndex(indexFilePath, res);
      }

      const pageId = this.extractPageSlugId(pageSlug);

      const share = await this.shareService.getShareForPage(
        pageId,
        workspace.id,
      );

      if (!share) {
        return this.sendIndex(indexFilePath, res);
      }

      const rawTitle = share.sharedPage.title ?? 'untitled';
      const metaTitle =
        rawTitle.length > 80 ? `${rawTitle.slice(0, 77)}…` : rawTitle;

      const metaTagVar = '<!--meta-tags-->';

      const metaTags = [
        `<meta property="og:title" content="${metaTitle}" />`,
        `<meta property="twitter:title" content="${metaTitle}" />`,
        !share.searchIndexing ? `<meta name="robots" content="noindex" />` : '',
      ]
        .filter(Boolean)
        .join('\n    ');

      const html = fs.readFileSync(indexFilePath, 'utf8');
      const transformedHtml = html
        .replace(/<title>[\s\S]*?<\/title>/i, `<title>${metaTitle}</title>`)
        .replace(metaTagVar, metaTags);

      res.type('text/html').send(transformedHtml);
    }
  }

  sendIndex(indexFilePath: string, res: FastifyReply) {
    const stream = fs.createReadStream(indexFilePath);
    res.type('text/html').send(stream);
  }

  extractPageSlugId(slug: string): string {
    if (!slug) {
      return undefined;
    }
    if (isValidUUID(slug)) {
      return slug;
    }
    const parts = slug.split('-');
    return parts.length > 1 ? parts[parts.length - 1] : slug;
  }
}