<?php

namespace Longyi\FreeGift\Models;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;
use Longyi\FreeGift\Config\Gift;
use Longyi\FreeGift\Contracts\FreeGiftItem as FreeGiftItemContract;
use Webkul\CartRule\Models\CartRule;
use Webkul\Checkout\Models\Cart;
use Webkul\Checkout\Models\CartItem;

/**
 * 赠品在购物车中的状态（每个 购物车 + SKU + 规则 一行）。
 *
 * 对应 Amasty 的 amasty_ampromo_items_storage。
 */
class FreeGiftItem extends Model implements FreeGiftItemContract
{
    /**
     * The table associated with the model.
     *
     * @var string
     */
    protected $table = 'free_gift_items';

    /**
     * The attributes that are mass assignable.
     *
     * @var array
     */
    protected $fillable = [
        'cart_id',
        'cart_item_id',
        'product_id',
        'sku',
        'rule_id',
        'rule_type',
        'allowed_qty',
        'reserved_qty',
        'discount_amount',
        'auto_add',
        'is_item_deleted',
    ];

    /**
     * The attributes that should be cast.
     *
     * @var array
     */
    protected $casts = [
        'cart_id'         => 'integer',
        'cart_item_id'    => 'integer',
        'product_id'      => 'integer',
        'rule_id'         => 'integer',
        'rule_type'       => 'integer',
        'allowed_qty'     => 'float',
        'reserved_qty'    => 'float',
        'auto_add'        => 'boolean',
        'is_item_deleted' => 'boolean',
    ];

    /**
     * 所属购物车。
     */
    public function cart(): BelongsTo
    {
        return $this->belongsTo(Cart::class, 'cart_id');
    }

    /**
     * 对应的购物车行。
     */
    public function cart_item(): BelongsTo
    {
        return $this->belongsTo(CartItem::class, 'cart_item_id');
    }

    /**
     * 赠送该赠品的规则。
     */
    public function cart_rule(): BelongsTo
    {
        return $this->belongsTo(CartRule::class, 'rule_id');
    }

    /**
     * 规则是否允许「一组合计送 N 个」。
     */
    public function isOneOf(): bool
    {
        return (int) $this->rule_type === Gift::TYPE_ONE;
    }

    /**
     * 规则是否允许「每个 SKU 各送 N 个」。
     */
    public function isAllOf(): bool
    {
        return (int) $this->rule_type === Gift::TYPE_ALL;
    }

    /**
     * 用户是否手动删除过该赠品（删除后不再自动加购，直到购物车清空）。
     */
    public function isDeleted(): bool
    {
        return (bool) $this->is_item_deleted;
    }

    /**
     * 还差几个需要补进购物车。
     */
    public function getQtyToProcessAttribute(): float
    {
        return max(0, (float) $this->allowed_qty - (float) $this->reserved_qty);
    }
}