openreader/src/lib/server/compute/local.ts

import type { ComputeBackend, PdfLayoutInput, WhisperAlignInput, WhisperAlignResult } from '@/lib/server/compute/types';
import { getDocumentBlob } from '@/lib/server/documents/blobstore';
import { getTtsSegmentAudioObject } from '@/lib/server/tts/segments-blobstore';
import {
  runPdfLayoutFromPdfBuffer,
  runWhisperAlignmentFromAudioBuffer,
} from '@openreader/compute-core/local-runtime';

export class LocalComputeBackend implements ComputeBackend {
  readonly mode = 'local' as const;

  async alignWords(input: WhisperAlignInput): Promise<WhisperAlignResult> {
    let audioBuffer = input.audioBuffer ?? null;
    if (!audioBuffer && input.audioObjectKey) {
      const bytes = new Uint8Array(await getTtsSegmentAudioObject(input.audioObjectKey));
      audioBuffer = bytes.buffer.slice(bytes.byteOffset, bytes.byteOffset + bytes.byteLength);
    }
    if (!audioBuffer) {
      throw new Error('Local compute alignment requires audioBuffer or audioObjectKey');
    }
    return runWhisperAlignmentFromAudioBuffer({
      audioBuffer,
      text: input.text,
      cacheKey: input.cacheKey,
      lang: input.lang,
    });
  }

  async parsePdfLayout(input: PdfLayoutInput) {
    let pdfBytes = input.pdfBytes ?? null;
    if (!pdfBytes && input.documentId && typeof input.namespace !== 'undefined') {
      const bytes = new Uint8Array(await getDocumentBlob(input.documentId, input.namespace));
      pdfBytes = bytes.buffer.slice(bytes.byteOffset, bytes.byteOffset + bytes.byteLength);
    }
    if (!pdfBytes) {
      throw new Error('Local compute PDF layout requires pdfBytes or (documentId + namespace)');
    }
    return {
      parsed: (await runPdfLayoutFromPdfBuffer({
        documentId: input.documentId,
        pdfBytes,
        onPageParsed: (page) => input.onProgress?.({
          totalPages: page.totalPages,
          pagesParsed: page.pageNumber,
          currentPage: page.pageNumber,
          phase: 'infer',
        }),
      })).parsed,
    };
  }
}