E-commerce 中促销系统的设计

Schema::create('promotions', function (Blueprint $table) {
    $table->increments('id');
    $table->string('code');

    $table->string('name')->nullable();
    $table->string('description')->nullable();
    $table->string('cover')->nullable()->comment('促销封面');
    $table->string('asset_url')->nullable()->comment('促销详情链接')

    $table->integer('position')->default(0)->comment('权重');
    $table->string('type')->comment('优惠卷/满减促销/品牌促销/秒杀/拼团/通用.');

    $table->json('config')->nullable()->comment('配置');

    $table->timestamp('began_at')->nullable()->comment('促销开始时间');
    $table->timestamp('ended_at')->nullable()->comment('促销结束时间');
    $table->timestamps();
    $table->softDeletes();
});

Schema::create('promotion_rules', function (Blueprint $table) {
    $table->increments('id');
    $table->unsignedInteger('promotion_id');
    $table->string('type');
    $table->json('config')->nullable();
    $table->timestamps();

    $table->index('promotion_id');
});

Schema::create('promotion_actions', function (Blueprint $table) {
     $table->increments('id');
     $table->unsignedInteger('promotion_id');
     $table->string('type');
     $table->json('config')->nullable();
     $table->timestamps();

     $table->index('promotion_id');
 });

Schema::create('promotion_variants', function (Blueprint $table) {
    $table->increments('id');

    $table->unsignedInteger('variant_id')->index();
    $table->unsignedInteger('promotion_id')->index();

    $table->decimal('discount_rate')->nullable()->comment('折扣率, 值为0.3表示打7折');
    $table->unsignedInteger('stock')->nullable()->comment('促销库存');
    $table->unsignedInteger('sold')->default(0)->comment('销售数量');
    $table->unsignedInteger('quantity_limit')->nullable()->comment('购买数量限制');
    $table->boolean('enabled')->default(1)->comment('启用');

    // 冗余
    $table->unsignedInteger('product_id');
    $table->string('promotion_type')->comment('冗余promotion表type');
    $table->json('rest')->nullable()->comment('冗余');

    $table->timestamps();
});

// promotion
{
    id: 1,
    code: '2018-christmas',
    name: '圣诞节满减大促',
    type: 'full_discount',
    description: '促销商品满100减10元',
    cover: null,
    asset_url: null,
    rest: null,
    config: null,
    position: 0,
    began_at: '2018-12-25 00:00:00',
    ended_at: '2018-12-26 00:00:00'
}

// rule
{
    'id': 1,
    'promotion_id': 1,
    'type': 'promotion_items_total', // 订单中促销项总额
    'config': {
        'amount' => 10000, // unit/分 
    }
}

// action
{
    'id': 1,
    'promotion_id': 1,
    'type': 'promotion_items_fixed_discount', // 订单中促销项 固定折扣
    'config': {
        'amount' => 1000, // unit/分 
    }
}

// 获取平台所有有效的促销
$promotions = Promotion::active()->get();

// 通过rule过滤promotion
$promotions = $promotions->filter(function ($promotion) {
    $rules = $promotion->rules
    $order = $this->getOrder();

    // 判定订单是否满足所有rule,当存在一条rule不被订单所满足,应返回false,被过滤器过滤掉

    return true;
});

// 为订单应用action.
$promotion->each(function ($promotion) {
    $actions = $promotion->actions;
    $order = $this->getOrder();

    // 将actions逐条应用于订单
})

<?php

namespace Promotion\Constructs;

interface Checker
{
    public function isEligible(array $configuration): bool;
}

<?php

namespace Promotion\Constructs;

interface Action
{
    public function execute(array $configuration);
}

<?php

namespace Promotion\Checker;

/**
 * 有很多的通用方法 如getOrder,getPromotionOrderItems等. 
 * 因此我创建了一个基类checker来实现interface和通用方法
 */
class PromotionItemsTotalChecker extends Checker
{
    public function isEligible(array $configuration): bool
    {
        return $this->getPromotionOrderItemsTotal() >= $configuration['amount'];
    }
}

<?php

namespace Promotion\Actions;

use Promotion\Helpers\CreateAdjustment;
use Promotion\Helpers\Distribute;

class PromotionItemsFixedDiscountAction extends Action
{
    use Distribute, CreateAdjustment;

    public function execute(array $configuration)
    {
        // 满减的金额
        $amount = $configuration['amount'];

        if ($amount === 0) {
            return false;
        }

        // 格式校验, amount如果小于订单金额时,则使用订单金额作为优惠amount
        $amount = -1 * min($this->getPromotionOrderItemsTotal(), $amount);

        if ($amount === 0) {
            return false;
        }

        $items = $this->getPromotionOrderItems();

        $itemsTotals = [];

        foreach ($items as $item) {
            $itemsTotals[] = $item->total;
        }

        // 促销金额等比例分配.
        $splitAmount = $this->distributeAmountOfItem($itemsTotals, $reduceAmount);

        // 创建adjustments
        $this->createUnitsAdjustment($items, $this->getPromotion(), $splitAmount);

    }
}

// promotion
{
    id: 1,
    code: '10-cash',
    name: '10元代金券',
    type: 'coupon',
    description: '全场可用',
    cover: null,
    asset_url: null,
    config: {
        type: 'cash',
        reduce_amount: 1000, // 冗余自下面action中的config中的amount
        stock: 10000, // 库存数量
        sold: 0, // 已经领取的数量
        catch_limit: 1, // 领取限制
        date_type: 'fix_term', // 固定期限
        fix_term: 30, // 自领取日内30天有效,

        // date_type: 'fix_time_range', 固定时间段
        // began_at: '2018-12-23 00:00:00',
        // ended_at: '2018-12-25 00:00:00',
    },
    position: 0,
    began_at: '2018-12-25 00:00:00',
    ended_at: '2018-12-26 00:00:00'
}

// action
{
    'id': 1,
    'promotion_id': 1,
    'type': 'order_fixed_discount', // 订单中促销项 固定折扣
    'config':{
       'amount' => 1000, // unit/分  
    }
}

// promotion
{
    id: 1,
    code: 'unit-discount-1290',
    name: '1290期直减',
    type: 'unit_discount',
    description: null,
    cover: null,
    asset_url: null,
    config: null,
    position: 0,
    began_at: '2018-12-25 00:00:00',
    ended_at: '2018-12-26 00:00:00'
}

// promotion_variant 
{
    'id': 1,
    'variant_id': 1,
    'prootion_id': 1,
    'discount_rate': 0.35,
    'stock': 100, // 秒杀库存
    'sold': 0,
    'quantity_limit': 1, // 限购
    'enabled': 1,
    'product_id': 1,
    'promotion_type': 'unit_discount',
    'rest': {
        variant_name: 'xxx', // 秒杀期间变体名称
        image: 'xxx', // 秒杀期间变体图片
    }
}

// rule验证阶段
if ($promotion->type === 'unit_discount') {
   return (new UnitDiscountChecker)->isEligible()
}

// 应用action阶段
if ($promotion->type === 'unit_discount') {
    (new UnitDiscountAction)->execute()
}

// action
{
    'id': 1,
    'promotion_id': 1,
    'type': 'promotion_items_ladder_discount',
    'config': {
        "ladder": [
            {
                "least_amount": 10000,
                "reduce_amount": 1000
            }, {
                "least_amount": 15000, 
                "reduce_amount": 2000
            }, {
                "least_amount": 20000, 
                "reduce_amount": 3000
            }
        ]
    }
}