echos-ocr/src/lib/processing-queue.ts

import { processFile } from "./ocr";

const MAX_CONCURRENT = 2;
const queue: QueueItem[] = [];
let running = 0;

type QueueItem = {
  jobId: string;
  fileName: string;
  fileBuffer: Buffer;
  isPdf: boolean;
  resolve: (ids: string[]) => void;
  reject: (err: unknown) => void;
};

function drain() {
  while (running < MAX_CONCURRENT && queue.length > 0) {
    const item = queue.shift()!;
    running++;
    processFile(item.jobId, item.fileName, item.fileBuffer, item.isPdf)
      .then(item.resolve)
      .catch(item.reject)
      .finally(() => {
        running--;
        drain();
      });
  }
}

export function enqueueProcessing(
  jobId: string,
  fileName: string,
  fileBuffer: Buffer,
  isPdf: boolean
): Promise<string[]> {
  return new Promise((resolve, reject) => {
    queue.push({ jobId, fileName, fileBuffer, isPdf, resolve, reject });
    drain();
  });
}

export function getQueueStatus() {
  return { running, queued: queue.length, maxConcurrent: MAX_CONCURRENT };
}