用最粗糙的方法，写出了查询简单的商品筛选的 SQL 语句，请问我该如何简化，使他看起来更优雅？？

laravel 版本 5.1

下面是我写的查询语句，可愁死我了，功能实现倒是实现了，写的太难受了，重复好多，请问我该如何简化呢，或者该怎么传入变量查询，或者有什么其他方法简化，请举例，或演示部分，谢谢

public function postTreat(Request $request)
{
    $_page = $request->input("_page"); //页码
    $_path = $request->input("_path"); //第三级 path
    $_sortType = $request->input("_sortType"); //综合类别

    $_sales = $request->input("_sales"); //销售优先
    $_priceSmall = $request->input("_priceSmall"); //最低价
    $_priceBig = $request->input("_priceBig"); //最高价

    $page=($_page-1)*4;

    /**
     * 构建出一个公共的 Query
     *
     * @var $shopGoodsQuery \Illuminate\Database\Query\Builder
     */
    $shopGoodsQuery = DB::table('shop_goods')
                            ->where('goods_cid',$_path)
                            ->where('goods_status',1) // 0未审核 1审核通过 2审核未通过
                            ->where('goods_state',0) // 0已上架 1已下架
                            ->where('goods_recycle',0); // 0正常 1回收站

    // 是否有价格区间限制
    if(empty($_priceSmall)&&empty($_priceBig)){
        // 是否按销量排序
        if(empty($_sales)){
            // 是否有综合排序 判断综合类别
            if($_sortType=="composite" || $_sortType==""){//综合 或 没有
                $data = $shopGoodsQuery->skip($page)->take(4)->get();
            }else if($_sortType=="price_up"){ //价格最低
                $data = $shopGoodsQuery
                            ->orderBy('goods_price','asc') // 价格最低
                            ->skip($page)
                            ->take(4)
                            ->get();
            }else if($_sortType=="price_down"){ //价格最高
                $data = $shopGoodsQuery
                            ->orderBy('goods_price','desc') // 价格最高 
                            ->skip($page)
                            ->take(4)
                            ->get();
            }else if($_sortType=="assess_down"){ // 评价最多
                // 只有在走这个区间的时候,才需要关联查询 评价的数量
                $data = DB::table('shop_goods')
                            ->leftJoin('shop_assess', 'shop_goods.goods_id', '=', 'shop_assess.assess_gcode')
                            ->selectRaw('shop_goods.*,COUNT(shop_assess.assess_id) as assess_num')
                            ->where('shop_goods.goods_cid',$_path)
                            ->where('shop_goods.goods_status',1) // 0未审核 1审核通过 2审核未通过
                            ->where('shop_goods.goods_state',0) // 0已上架 1已下架
                            ->where('shop_goods.goods_recycle',0) // 0正常 1回收站
                            ->groupBy('shop_goods.goods_id')
                            ->orderBy('assess_num','desc')
                            ->skip($page)
                            ->take(4)
                            ->get();
            }else if($_sortType=="publish_new"){ //最新发布
                $data = $shopGoodsQuery
                            ->orderBy('goods_time','desc') // 最新发布
                            ->skip($page)
                            ->take(4)
                            ->get();
            }
        }else{
            $data = $shopGoodsQuery
                        ->orderBy('goods_num','desc') // 销售倒序排列
                        ->skip($page)
                        ->take(4)
                        ->get();
        }
    }else{
        // 是否按销量排序
        if(empty($_sales)){
            // 是否有综合排序 判断综合类别
            if($_sortType=="composite" || $_sortType==""){
                $data = $shopGoodsQuery
                            ->whereBetween('goods_price',[$_priceSmall,$_priceBig]) // 价格区间
                            ->skip($page)
                            ->take(4)
                            ->get();
            }else if($_sortType=="price_up"){
                $data = $shopGoodsQuery
                            ->whereBetween('goods_price',[$_priceSmall,$_priceBig]) // 价格区间
                            ->orderBy('goods_price','asc') // 价格最低
                            ->skip($page)
                            ->take(4)
                            ->get();
            }else if($_sortType=="price_down"){
                $data = $shopGoodsQuery
                            ->whereBetween('goods_price',[$_priceSmall,$_priceBig]) // 价格区间
                            ->orderBy('goods_price','desc') // 价格最高 
                            ->skip($page)
                            ->take(4)
                            ->get();
            }else if($_sortType=="assess_down"){
                $data = DB::table('shop_goods')
                            ->leftJoin('shop_assess', 'shop_goods.goods_id', '=', 'shop_assess.assess_gcode')
                            ->selectRaw('shop_goods.*,COUNT(shop_assess.assess_id) as assess_num') //统计评价的数量
                            ->where('shop_goods.goods_cid',$_path)
                            ->where('shop_goods.goods_status',1) // 0未审核 1审核通过 2审核未通过
                            ->where('shop_goods.goods_state',0) // 0已上架 1已下架
                            ->where('shop_goods.goods_recycle',0) // 0正常 1回收站
                            ->whereBetween('shop_goods.goods_price',[$_priceSmall,$_priceBig]) // 价格区间
                            ->groupBy('shop_goods.goods_id')
                            ->orderBy('assess_num','desc')
                            ->skip($page)
                            ->take(4)
                            ->get();
            }else if($_sortType=="publish_new"){
                $data = $shopGoodsQuery
                            ->whereBetween('goods_price',[$_priceSmall,$_priceBig]) // 价格区间
                            ->orderBy('goods_time','desc') // 最新发布
                            ->skip($page)
                            ->take(4)
                            ->get();
            }
        }else{
            $data = $shopGoodsQuery
                        ->whereBetween('goods_price',[$_priceSmall,$_priceBig])
                        ->orderBy('goods_num','desc')
                        ->skip($page)
                        ->take(4)
                        ->get();
        }
    }

    foreach($data as $key => $value){
        if($value->goods_num>10000){
            $value->goods_num = round(($value->goods_num)/10000,1).'w';
        }
    }
    return $data;
}