const cron = require("node-cron");

async function claimAndArchiveUnusedInvoices(tx, batchSize, unusedDays) {
  return tx.$queryRaw`
    WITH picked AS (
      SELECT id
      FROM "invoice_pool"
      WHERE linked_reimbursement_id IS NULL
        AND status IN ('available', 'ocr_failed')
        AND created_at < NOW() - make_interval(days => ${unusedDays})
      ORDER BY created_at ASC
      LIMIT ${batchSize}
      FOR UPDATE SKIP LOCKED
    )
    UPDATE "invoice_pool" AS i
    SET status = 'archived',
        archived_reason = 'unused_timeout',
        archived_at = NOW(),
        linked_item_id = NULL,
        ocr_locked_at = NULL,
        ocr_lock_owner = NULL,
        updated_by = NULL
    FROM picked
    WHERE i.id = picked.id
      AND i.linked_reimbursement_id IS NULL
      AND i.status IN ('available', 'ocr_failed')
    RETURNING i.id, i.owner_employee_id, i.status, i.archived_at
  `;
}

async function archiveUnusedInvoices(prisma, logger, options = {}) {
  const batchSize = Math.max(1, Number(options.batchSize ?? 200));
  const unusedDays = Math.max(1, Number(options.unusedDays ?? 90));

  let total = 0;
  let round = 0;

  while (true) {
    round += 1;

    const archivedRows = await prisma.$transaction(async (tx) => {
      return claimAndArchiveUnusedInvoices(tx, batchSize, unusedDays);
    });

    if (!archivedRows.length) {
      break;
    }

    total += archivedRows.length;
    logger.info(
      {
        round,
        claimed: archivedRows.length,
        updated: archivedRows.length,
        archived: archivedRows.length,
        unusedDays,
      },
      "Unused invoices archived batch processed",
    );
  }

  if (total > 0) {
    logger.info({ archived: total, unusedDays }, "Unused invoices auto-archived");
  }

  return total;
}

function startInvoiceArchiveJob(fastify) {
  let running = false;

  const task = cron.schedule(fastify.config.invoiceArchiveCron, async () => {
    if (running) {
      return;
    }

    running = true;
    try {
      await archiveUnusedInvoices(fastify.prisma, fastify.log, {
        batchSize: fastify.config.invoiceArchiveBatchSize,
        unusedDays: fastify.config.invoiceArchiveUnusedDays,
      });
    } catch (error) {
      fastify.log.error({ err: error }, "Invoice archive job failed");
    } finally {
      running = false;
    }
  });

  fastify.addHook("onClose", async () => {
    task.stop();
    task.destroy();
  });

  fastify.log.info(
    {
      cron: fastify.config.invoiceArchiveCron,
      unusedDays: fastify.config.invoiceArchiveUnusedDays,
    },
    "Invoice archive job scheduled",
  );

  return task;
}

module.exports = {
  archiveUnusedInvoices,
  startInvoiceArchiveJob,
};