设计翻牌抽奖

摘要：实现功能抽奖需求后台控制每种中奖的概率控制奖品数量备注奖品是以优惠券的形式发放给用户进行兑换，需要考虑到优惠券数量问题以此为例九宫格一个开始，一个谢谢参与，后台设置七个奖品获取每个奖品中奖概率，及该奖品的我是以的总数概率来计算的获取奖品及该

实现功能：抽奖

需求：后台控制每种中奖的概率、控制奖品数量

备注：奖品是以优惠券的形式发放给用户进行兑换，需要考虑到优惠券数量问题

以此为例：
九宫格一个开始btn，一个谢谢参与，后台设置七个奖品

1.获取每个奖品中奖概率，及该奖品的id,我是以1000的总数概率来计算的

/**获取奖品及该奖品的中奖概率
 * Created by PhpStorm.
 * User: Alisa
 * Date: 2018/12/6
 * Time: 18:02
 * @param $extract_prize_id
 * @return mixed
 */
public function user_prize ($extract_prize_id)
{
    $prize = (new Query())
        ->from(["p"=>Prize::tableName()])
        ->leftJoin(["c"=>Coupon::tableName()],"c.id = p.coupon_id")
        ->select("p.prize_pro,p.id")
        ->where(["p.extract_prize_id"=>$extract_prize_id])
        ->andWhere([">","c.surplus_num",0])
        ->all();
    $sum = (new Query())
        ->from(["p"=>Prize::tableName()])
        ->leftJoin(["c"=>Coupon::tableName()],"c.id = p.coupon_id")
        ->where(["p.extract_prize_id"=>$extract_prize_id])
        ->andWhere([">","c.surplus_num",0])
        ->sum("p.prize_pro");

    $count = count($prize);
    foreach ($prize as $k=>$v){
        $list[$k] = $v;
    }
    $list[$count] = [
        "prize_pro"=>Math::sub(1000,$sum,0),
        "id"=>0
    ];
    $res = $this->get_rand($list);
    return $list[$res]["id"];
}

2.进行抽奖计算，返回中奖的奖品id，id是0的话，表示谢谢参与

/**抽奖计算
 * Created by PhpStorm.
 * User: Alisa
 * Date: 2018/12/6
 * Time: 18:10
 * @param $proArr
 * @return int|string
 */
public function get_rand($proArr){
    $result = "";
    foreach ($proArr as $key => $val) {
        $arr[$key] = $val["prize_pro"];
    }
    // 概率数组的总概率
    $proSum = 1000;
    // 概率数组循环
    foreach ($arr as $k => $v) {
        $randNum = mt_rand(1, $proSum);
        if ($randNum <= $v) {
            $result = $k;
            break;
        } else {
            $proSum -= $v;
        }
    }
    return $result;
}

3.进行后续逻辑处理，判断优惠券剩余数量并减去、减去用户抽奖册数、增加用户抽奖记录、中奖的话优惠券到账

/**用户抽奖
 * @param $userId
 * @param $extract_prize_id
 * @return array|bool
 * @throws yiidbException
 */
 public function extractPrize($userId,$extract_prize_id)
{
    $prize_id = $this->user_prize($extract_prize_id);
    $coupon_id = 0;
    $prize_name = "谢谢参与";
    $prize_url = "";
    if($prize_id){
        $coupon = (new Query())
            ->select("c.id,c.name,c.rule,c.validity,c.surplus_num")
            ->from(["pr"=>Prize::tableName()])
            ->leftJoin(["c"=>Coupon::tableName()],"c.id = pr.coupon_id")
            ->where(["pr.id"=>$prize_id])
            ->one();
        if($coupon["surplus_num"] > 0){
            $coupon_id = $coupon["id"];
            $prize_name = $coupon["name"];
            $url = (new Query())
                ->select("pi.url")
                ->from(["pr"=>Prize::tableName()])
                ->leftJoin(["pi"=>Picture::tableName()],"pi.id = pr.img_id")
                ->where(["pr.id"=>$prize_id])
                ->one();
            $prize_url = $url["url"];
        }
    }
    $trans = Yii::$app->db->beginTransaction();
    try{
        $model = new ExtractPrizeRecord();
        $model->prize_id = $prize_id;
        $model->coupon_id = $coupon_id;
        $model->prize_name = $prize_name;
        $model->user_id = $userId;
        $model->type = $extract_prize_id;
        $model->create_at = time();
        $res_ex = $model->save();
        if ( $res_ex ) {
            //减去用户抽奖次数
            Yii::$app->db->createCommand("update users set $str = $str - 1 where $str > 0 and user_id = :user_id",
                [
                    ":user_id" => $userId,
                ]
            )->execute();
            if(($coupon_id > 0) && ($coupon["surplus_num"] > 0)){
                //减去优惠券剩余数量
                Yii::$app->db->createCommand("update coupon set surplus_num = surplus_num -1 where id = :coupon_id and surplus_num > 0",
                    [
                        ":coupon_id" => $coupon_id,
                    ]
                )->execute();
                $myModel = new MyCoupon();
                $myModel->user_id = $userId;
                $myModel->name = $coupon["name"];
                $myModel->rule = $coupon["rule"];
                $myModel->coupon_id = $coupon_id;
                $myModel->create_at = time();
                $myModel->update_at = time();
                $myModel->start_at = time();
                $myModel->end_at = time() + $coupon["validity"]* 86400;
                $myModel->re_code = StringTools::randString(10);
                $myModel->coupon_number = date("YmdHis") . rand(10000000,99999999);
                $myModel->save();
            }
        } else {
            return false;
        }
        $trans ->commit();
        return ["prize_name"=>$prize_name,"prize_url"=>$prize_url];
    }catch (Throwable $t) {
        $trans->rollBack();
        return false;
    }
}

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