<?php
/**
 * QBWS_Queue — drains qbws_sync_queue (see QBWS_DB_Installer for schema).
 *
 * Every WC->QB push and every "sync this one QB entity now" webhook job
 * goes through here instead of running synchronously inline in a hook or
 * REST callback — a slow/rate-limited/down QB API must never fail a
 * customer's checkout or make Intuit's webhook POST time out and retry
 * duplicate deliveries. Failures back off exponentially and stop retrying
 * (status='failed') after MAX_ATTEMPTS, surfaced in the admin "Queue" tab
 * for manual re-run.
 */

if (!defined('ABSPATH')) exit;

// phpcs:disable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- This plugin reads/writes only its own custom tables (live sync state), which must never be served from an object cache.

class QBWS_Queue
{
    const MAX_ATTEMPTS = 6;

    public static function enqueue(string $entityType, int $entityId, string $direction, array $payload = [], int $delaySeconds = 0): void
    {
        global $wpdb;

        // Avoid stacking duplicate pending jobs for the same entity+direction
        // (e.g. three quick order-status changes before the queue drains).
        $already = $wpdb->get_var($wpdb->prepare(
            "SELECT id FROM {$wpdb->prefix}qbws_sync_queue
             WHERE entity_type = %s AND entity_id = %d AND direction = %s AND status = 'pending'",
            $entityType, $entityId, $direction
        ));

        if ($already) {
            // Refresh payload/available_at instead of inserting a duplicate row.
            $wpdb->update($wpdb->prefix . 'qbws_sync_queue', [
                'payload'      => wp_json_encode($payload),
                'available_at' => gmdate('Y-m-d H:i:s', time() + $delaySeconds),
            ], ['id' => $already]);
            return;
        }

        $wpdb->insert($wpdb->prefix . 'qbws_sync_queue', [
            'entity_type'  => $entityType,
            'entity_id'    => $entityId,
            'direction'    => $direction,
            'payload'      => wp_json_encode($payload),
            'status'       => 'pending',
            'attempts'     => 0,
            'available_at' => gmdate('Y-m-d H:i:s', time() + $delaySeconds),
            'created_at'   => current_time('mysql', true),
        ]);
    }

    /** Called from WP-Cron every minute (see QBWS_Cron). */
    public static function process_due_jobs(int $limit = 20): void
    {
        global $wpdb;

        $jobs = $wpdb->get_results($wpdb->prepare(
            "SELECT * FROM {$wpdb->prefix}qbws_sync_queue
             WHERE status = 'pending' AND available_at <= NOW()
             ORDER BY available_at ASC LIMIT %d",
            $limit
        ), ARRAY_A);

        foreach ($jobs as $job) {
            self::run_job($job);
        }
    }

    private static function run_job(array $job): void
    {
        global $wpdb;
        $wpdb->update($wpdb->prefix . 'qbws_sync_queue', ['status' => 'processing'], ['id' => $job['id']]);

        $payload = json_decode($job['payload'] ?: '[]', true) ?: [];

        try {
            $outcome = self::dispatch($job['entity_type'], $job['direction'], (int) $job['entity_id'], $payload);

            if ($outcome === 'conflict') {
                $wpdb->update($wpdb->prefix . 'qbws_sync_queue', ['status' => 'conflict'], ['id' => $job['id']]);
                return;
            }

            $wpdb->update($wpdb->prefix . 'qbws_sync_queue', ['status' => 'done'], ['id' => $job['id']]);

        } catch (\Throwable $e) {
            $attempts = (int) $job['attempts'] + 1;

            if ($attempts >= self::MAX_ATTEMPTS) {
                $wpdb->update($wpdb->prefix . 'qbws_sync_queue', [
                    'status'     => 'failed',
                    'attempts'   => $attempts,
                    'last_error' => $e->getMessage(),
                ], ['id' => $job['id']]);
                QBWS_Logger::error('QUEUE', "Job #{$job['id']} ({$job['entity_type']}/{$job['direction']} #{$job['entity_id']}) failed permanently after {$attempts} attempts: " . $e->getMessage());
                return;
            }

            $backoffMinutes = 2 ** $attempts; // 2, 4, 8, 16, 32 min
            $wpdb->update($wpdb->prefix . 'qbws_sync_queue', [
                'status'       => 'pending',
                'attempts'     => $attempts,
                'last_error'   => $e->getMessage(),
                'available_at' => gmdate('Y-m-d H:i:s', time() + $backoffMinutes * 60),
            ], ['id' => $job['id']]);

            QBWS_Logger::warn('QUEUE', "Job #{$job['id']} failed (attempt {$attempts}/" . self::MAX_ATTEMPTS . "), retrying in {$backoffMinutes}m: " . $e->getMessage());
        }
    }

    /** @return string 'ok'|'conflict' */
    private static function dispatch(string $entityType, string $direction, int $entityId, array $payload): string
    {
        switch ("{$entityType}:{$direction}") {
            case 'order:to_qb':
                return (new QBWS_Sync_Orders_Outbound())->push_order($entityId);

            case 'order:to_woo':
                return (new QBWS_Sync_Orders_Inbound())->sync_single_from_qb($payload['qb_txn_id'], $payload['qb_txn_type'] ?? 'Invoice');

            case 'customer:to_qb':
                (new QBWS_Sync_Customers())->push_to_qb($entityId);
                return 'ok';

            case 'customer:to_woo':
                (new QBWS_Sync_Customers())->sync_single_from_qb($payload['qb_customer_id']);
                return 'ok';

            case 'product:to_woo':
                (new QBWS_Sync_Products())->sync_single($payload['qb_item_id']);
                return 'ok';

            case 'product:to_qb':
                (new QBWS_Sync_Products())->push_to_qb($entityId);
                return 'ok';

            case 'payment:to_qb':
                (new QBWS_Sync_Payments())->push_to_qb($entityId);
                return 'ok';

            case 'payment:to_woo':
                (new QBWS_Sync_Payments())->sync_single_from_qb($payload['qb_payment_id']);
                return 'ok';

            default:
                QBWS_Logger::error('QUEUE', "Unknown job type {$entityType}:{$direction}");
                return 'ok'; // don't retry forever on a bad job type
        }
    }
}