// Files s3d still lists as waiting for Sia whose buffered copy is gone.
//
// s3d keeps every not-yet-uploaded object as uploads/<filename> and marks it
// uploaded by setting sia_object_id. An s3d stopped in the middle of an
// upload has been seen to delete the copies without recording the upload;
// every flush after that fails on them ("failed to open upload"). They hold
// no data any more: not on this computer, never on Sia. Pithos lists them so
// the user can upload the file again or remove the entry.

import fs from 'node:fs';
import path from 'node:path';

async function candidates(dataDir, olderThanMs) {
  const file = path.join(dataDir, 's3d.db');
  if (!fs.existsSync(file)) return [];
  const { DatabaseSync } = await import('node:sqlite');
  const db = new DatabaseSync(file, { readOnly: true });
  try {
    const rows = db.prepare(`SELECT b.name AS bucket, u.name AS user, o.name AS key, o.size AS size, o.filename AS filename, o.updated_at AS updated
      FROM objects o JOIN buckets b ON b.id = o.bucket_id LEFT JOIN users u ON u.id = b.user_id
      WHERE o.sia_object_id IS NULL AND o.is_latest = 1 AND o.is_delete_marker = 0
        AND o.filename IS NOT NULL AND o.filename != ''`).all();
    const uploads = path.join(dataDir, 'uploads');
    const cutoff = Date.now() - olderThanMs;
    return rows
      // updated_at is Unix seconds
      .filter((r) => { const n = Number(r.updated); const t = Number.isFinite(n) ? (n < 1e12 ? n * 1000 : n) : Date.parse(r.updated); return !Number.isFinite(t) || t < cutoff; })
      .filter((r) => !fs.existsSync(path.join(uploads, path.basename(String(r.filename)))))
      .map((r) => ({ bucket: r.bucket, user: r.user, key: r.key, size: Number(r.size), filename: String(r.filename) }));
  } finally { db.close(); }
}

// Only entries missing twice, a moment apart: s3d removes a copy just before
// it records the upload, and a list taken in between would be wrong.
export async function stuckUploads(dataDir, { olderThanMs = 120_000, settleMs = 2000 } = {}) {
  const first = await candidates(dataDir, olderThanMs);
  if (!first.length) return [];
  await new Promise((r) => setTimeout(r, settleMs));
  const again = new Set((await candidates(dataDir, olderThanMs)).map((r) => `${r.bucket}\n${r.key}`));
  return first.filter((r) => again.has(`${r.bucket}\n${r.key}`));
}