import { execFile } from 'node:child_process';
import { mkdtemp, rm, writeFile } from 'node:fs/promises';
import { tmpdir } from 'node:os';
import { join } from 'node:path';

export async function extractPdfText(pdf: Buffer, bin = 'pdftotext', timeoutMs = 30_000): Promise<string> {
  const dir = await mkdtemp(join(tmpdir(), 'srs-pdf-'));
  try {
    const file = join(dir, 'result.pdf');
    await writeFile(file, pdf);
    return await new Promise<string>((resolve, reject) => {
      execFile(
        bin,
        ['-raw', '-enc', 'UTF-8', file, '-'],
        { encoding: 'utf8', maxBuffer: 20 * 1024 * 1024, timeout: timeoutMs },
        (err, stdout) => {
          if (!err) return resolve(stdout.replace(/\r\n/g, '\n'));
          const missing = (err as NodeJS.ErrnoException).code === 'ENOENT';
          reject(new Error(missing ? 'pdftotext not found: install poppler-utils' : `pdftotext failed: ${err.message}`));
        },
      );
    });
  } finally {
    await rm(dir, { recursive: true, force: true });
  }
}