同事代码写的很糟糕，该怎么给建议

今天看了同事写的一个周签到的代码，看了之后，心态爆炸了。该怎么给同事建议呢？

    /**
     * 签到列表
     */
    public function getSignStatus(array $params)
    {
        if (!is_array($params)) return $this->failed();
        $this->setRedis($params['gameCode']);
        $this->setHashKey($params);

        $week = [];
        $weekCount = [];
        $rewardConfigs = $this->_redis->get($this->_key) ? json_decode($this->_redis->get($this->_key), true) : [];
        foreach ($rewardConfigs as $item) {
            if ($item['sign_type'] == SignConfig::TYPE_WEEK) {
                $dayName = $item['day'] - 1;
                $ymd = date('ymd', strtotime("+$dayName day", strtotime(Carbon::now()->startOfWeek())));
                if ($this->_week_redis->exists($this->_sign_key)) {
                    $res = $this->_week_redis->getbit($this->_sign_key, $ymd);
                    if ($res == 1) {
                        $sts = SignConfig::SIGN_STATUS_ACQUIRE;
                    } else {
                        if (date('ymd') > $ymd) {
                            $sts = SignConfig::SIGN_STATUS_OVERDUE;
                        } else if (date('ymd') == $ymd) {
                            $sts = SignConfig::SIGN_STATUS_RECEIVE;
                        } else {
                            $sts = SignConfig::SIGN_STATUS_UNCLAIMED;
                        }
                    }
                } else {
                    $sts = (date('ymd') == $ymd) ? SignConfig::SIGN_STATUS_RECEIVE : SignConfig::SIGN_STATUS_UNCLAIMED;
                }
                $week[] = [
                    'day' => $item['day'],
                    'status' => $sts,
                ];
            } else if ($item['sign_type'] == SignConfig::TYPE_WEEKCOUT) {
                if ($this->_week_redis->exists($this->_week_sign_key)) {
                    $sts = $this->_week_redis->getbit($this->_week_sign_key, $item['day']);
                } else {
                    $sts = SignConfig::SIGN_STATUS_UNCLAIMED;
                }
                $weekCount[] = [
                    'day' => $item['day'],
                    'status' => $sts,
                ];
            }
        }

        $returnData = [];
        if ($this->_week_redis->exists($this->_week_sign_key)) {
            $returnData['week_count_days'] = $this->_week_redis->bitcount($this->_week_sign_key);
        } else {
            $returnData['week_count_days'] = 0;
        }
        if ($this->_week_redis->exists($this->_sign_key)) {
            $returnData['week_days'] = ($this->_week_redis->bitcount($this->_sign_key) != 7) ? $this->_week_redis->bitcount($this->_sign_key) : 0;
        } else {
            $returnData['week_days'] = 0;
        }
        $returnData['week'] = $week;
        $returnData['weekCount'] = $weekCount;
        $this->checkSigned();
        return $this->success($returnData);
}

仅对这个方法说下我的看法：

1. 很多无用的代码

//这段代码没什么用的吧，参数不是已经限制是数组了吗？
if (!is_array($params)) return $this->failed();

//这行代码是不是应该被开除
$rewardConfigs = $this->_redis->get($this->_key) ? json_decode($this->_redis->get($this->_key), true) : [];

//这个if判断是不是没用
if ($this->_week_redis->exists($this->_week_sign_key)) {
    $returnData['week_count_days'] = $this->_week_redis->bitcount($this->_week_sign_key);
} else {
    $returnData['week_count_days'] = 0;
}

//写成这样就可以了
$weekCount = $this->_week_redis->bitcount($this->_week_sign_key);

2. 嵌套是不是太深了？ 就不展开说了。我觉得一个好的设计，逻辑是比较简单，代码让人看了很舒服的。

这是一个新项目的，还没上线的，之前同事开发的，因为疫情原因，领导让我暂时接手。