<?php
// +----------------------------------------------------------------------
// | YwxApp [ WE CAN DO IT JUST THINK ]
// +----------------------------------------------------------------------
// | Copyright (c) 2026-2036 http://ywxapp.cn All rights reserved.
// +----------------------------------------------------------------------
// | Author: ywxapp<admin@ywxapp.cn>
// +----------------------------------------------------------------------
namespace addon\mqttbroker\service;

use think\facade\Db;

/**
 * 规则引擎：匹配源主题过滤器后，将消息转发到外部 Broker（桥接到 EMQX）
 *
 * 规则表 wxapp_mqttbroker_rule：
 *   source_filter  源主题过滤器（支持 + / #）
 *   target_type    mqtt（当前仅支持转发到外部 MQTT Broker）
 *   target_broker  外部地址 host:port
 *   target_topic   目标主题模板，支持 ${topic} 变量
 *   target_qos     转发 QoS
 *   enabled        1启用 0停用
 *
 * 行为：
 *   - 仅对本地产生的消息生效（distribute 本地路径调用），桥接/外部回流消息不二次转发，避免回环。
 *   - $SYS 系统主题不转发。
 *   - 规则带 30s TTL 缓存，新增/修改后最多 30s 生效。
 */
class RuleEngine
{
    /** @var array */
    protected $config;

    /** @var Forwarder */
    protected $forwarder;

    /** @var array 规则缓存 */
    protected $rules = [];

    /** @var int 缓存刷新时间戳 */
    protected $loadedAt = 0;

    /** @var int 缓存有效期（秒） */
    protected $ttl = 30;

    
    public function __construct(array $config, Forwarder $forwarder)
    {
        $this->config   = $config;
        $this->forwarder = $forwarder;
    }

    
    public function ensureTables(): void
    {
        try {
            Db::execute("CREATE TABLE IF NOT EXISTS `wxapp_mqttbroker_rule` (
                `id` int unsigned NOT NULL AUTO_INCREMENT,
                `name` varchar(191) NOT NULL DEFAULT '',
                `source_filter` varchar(255) NOT NULL DEFAULT '',
                `target_type` varchar(16) NOT NULL DEFAULT 'mqtt',
                `target_broker` varchar(255) NOT NULL DEFAULT '',
                `target_clientid` varchar(191) DEFAULT '',
                `target_username` varchar(191) DEFAULT '',
                `target_password` varchar(191) DEFAULT '',
                `target_topic` varchar(255) NOT NULL DEFAULT '',
                `target_qos` tinyint(1) NOT NULL DEFAULT '0',
                `enabled` tinyint(1) NOT NULL DEFAULT '1',
                `remark` varchar(255) DEFAULT NULL,
                `create_at` int DEFAULT NULL,
                PRIMARY KEY (`id`), KEY `idx_enabled` (`enabled`)
            ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4");
        } catch (\Throwable $e) {
        }
    }

    /**
     * 匹配并转发
     */
    public function matchAndForward(string $topic, string $msg, int $qos): void
    {
        if ((string) ($this->config['rule_enabled'] ?? '1') !== '1') {
            return;
        }
        if (strncmp($topic, '$SYS', 4) === 0) {
            return; // 系统主题不转发
        }
        if (!$this->forwarder->isAvailable()) {
            return;
        }
        foreach ($this->loadRules() as $r) {
            if ((int) $r['enabled'] !== 1 || empty($r['source_filter']) || empty($r['target_broker'])) {
                continue;
            }
            if ($this->topicMatch((string) $r['source_filter'], $topic)) {
                $this->forwarder->forward($r, $topic, $msg, $qos);
            }
        }
    }

    
    protected function loadRules(): array
    {
        $now = time();
        if ($now - $this->loadedAt < $this->ttl && $this->loadedAt > 0) {
            return $this->rules;
        }
        try {
            $this->rules = Db::name('mqttbroker_rule')->where('enabled', 1)
                ->order('id', 'asc')->select()->toArray();
        } catch (\Throwable $e) {
            $this->rules = [];
        }
        $this->loadedAt = $now;
        return $this->rules;
    }

    
    protected function topicMatch(string $filter, string $topic): bool
    {
        if ($filter === $topic) {
            return true;
        }
        $f = explode('/', $filter);
        $t = explode('/', $topic);
        foreach ($f as $i => $seg) {
            if ($seg === '#') {
                return true;
            }
            if ($seg === '+') {
                if (!isset($t[$i])) {
                    return false;
                }
                continue;
            }
            if (!isset($t[$i]) || $seg !== $t[$i]) {
                return false;
            }
        }
        return count($f) === count($t);
    }
}