设计翻牌抽奖

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 $extract_prize_id
 * @return array|bool
 * @throws \yii\db\Exception
 */
 public function extractPrize($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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