links/patches/application/common/service/SplitNumberWeighService.php

<?php

declare(strict_types=1);

namespace app\common\service;

use app\admin\model\split\Link;

/**
 * 分流链接随机打乱配置与落地页选号
 *
 * - random_shuffle=0：跨工单合并号码池，按 id 顺序全局严格轮转
 * - random_shuffle=1：先按各工单开启号码数比例随机选工单，再在该工单内随机选号
 * - 同步写入时 random_shuffle=1 还会打乱新号码 insert 顺序（影响 id 分布）
 */
class SplitNumberWeighService
{
    /**
     * 链接是否开启随机打乱
     */
    public static function isRandomShuffleEnabled(int $linkId): bool
    {
        if ($linkId <= 0) {
            return false;
        }
        return (int) Link::where('id', $linkId)->value('random_shuffle') === 1;
    }

    /**
     * 解析本次访问应使用的号码下标（0 .. numberCount-1）
     *
     * @param int                   $linkId         分流链接 ID
     * @param int                   $numberCount    可用号码数量
     * @param SplitRoundRobinStore  $roundRobinStore 关闭随机打乱时的轮转计数器
     * @param string                $poolKey        选号池标识（preferred / deferred 等）
     */
    public static function resolvePickIndex(
        int $linkId,
        int $numberCount,
        SplitRoundRobinStore $roundRobinStore,
        string $poolKey = 'main'
    ): int {
        if ($numberCount <= 0) {
            return 0;
        }
        if ($numberCount === 1) {
            return 0;
        }

        if (self::isRandomShuffleEnabled($linkId)) {
            return random_int(0, $numberCount - 1);
        }

        return $roundRobinStore->nextIndex($linkId, $numberCount, $poolKey);
    }

    /**
     * 从号码行列表中按链接配置选一条（严格轮转或随机）
     *
     * @param array<int, array<string, mixed>|Number> $rows
     * @return array<string, mixed>|Number|null
     */
    public static function pickRowFromList(
        int $linkId,
        array $rows,
        SplitRoundRobinStore $roundRobinStore,
        string $poolKey = 'main'
    ) {
        $count = count($rows);
        if ($count === 0) {
            return null;
        }
        $index = self::resolvePickIndex($linkId, $count, $roundRobinStore, $poolKey);
        return $rows[$index] ?? $rows[0];
    }
}