<?php

namespace App\Module\Mex\Logic;

use App\Module\Mex\Models\MexWarehouse;
use Illuminate\Support\Facades\DB;

/**
 * 农贸市场仓库逻辑
 * 
 * 处理仓库相关的核心业务逻辑
 */
class MexWarehouseLogic
{
    /**
     * 获取商品库存信息
     * 
     * @param int $itemId 商品ID
     * @return array|null 库存信息
     */
    public static function getItemStock(int $itemId): ?array
    {
        $warehouse = MexWarehouse::where('item_id', $itemId)->first();
        
        if (!$warehouse) {
            return null;
        }

        return [
            'item_id' => $warehouse->item_id,
            'quantity' => $warehouse->quantity,
            'total_buy_amount' => $warehouse->total_buy_amount,
            'total_sell_amount' => $warehouse->total_sell_amount,
            'total_buy_quantity' => $warehouse->total_buy_quantity,
            'total_sell_quantity' => $warehouse->total_sell_quantity,
            'average_buy_price' => self::calculateAveragePrice($warehouse->total_buy_amount, $warehouse->total_buy_quantity),
            'average_sell_price' => self::calculateAveragePrice($warehouse->total_sell_amount, $warehouse->total_sell_quantity),
            'net_buy_quantity' => $warehouse->total_buy_quantity - $warehouse->total_sell_quantity,
            'net_buy_amount' => bcsub($warehouse->total_buy_amount, $warehouse->total_sell_amount, 5),
            'last_transaction_at' => $warehouse->last_transaction_at,
        ];
    }

    /**
     * 获取多个商品的库存信息
     * 
     * @param array $itemIds 商品ID数组
     * @return array 库存信息列表
     */
    public static function getItemsStock(array $itemIds): array
    {
        $warehouses = MexWarehouse::whereIn('item_id', $itemIds)->get();
        
        $result = [];
        foreach ($warehouses as $warehouse) {
            $result[$warehouse->item_id] = [
                'item_id' => $warehouse->item_id,
                'quantity' => $warehouse->quantity,
                'total_buy_amount' => $warehouse->total_buy_amount,
                'total_sell_amount' => $warehouse->total_sell_amount,
                'total_buy_quantity' => $warehouse->total_buy_quantity,
                'total_sell_quantity' => $warehouse->total_sell_quantity,
                'average_buy_price' => self::calculateAveragePrice($warehouse->total_buy_amount, $warehouse->total_buy_quantity),
                'average_sell_price' => self::calculateAveragePrice($warehouse->total_sell_amount, $warehouse->total_sell_quantity),
                'last_transaction_at' => $warehouse->last_transaction_at,
            ];
        }

        return $result;
    }

    /**
     * 检查库存是否充足
     * 
     * @param int $itemId 商品ID
     * @param int $quantity 需要数量
     * @return bool 是否充足
     */
    public static function checkStockSufficient(int $itemId, int $quantity): bool
    {
        $warehouse = MexWarehouse::where('item_id', $itemId)->first();
        
        if (!$warehouse) {
            return false;
        }

        return $warehouse->quantity >= $quantity;
    }

    /**
     * 获取所有有库存的商品
     * 
     * @return array 商品列表
     */
    public static function getAvailableItems(): array
    {
        $warehouses = MexWarehouse::where('quantity', '>', 0)
            ->orderBy('quantity', 'desc')
            ->get();

        $result = [];
        foreach ($warehouses as $warehouse) {
            $result[] = [
                'item_id' => $warehouse->item_id,
                'quantity' => $warehouse->quantity,
                'average_buy_price' => self::calculateAveragePrice($warehouse->total_buy_amount, $warehouse->total_buy_quantity),
                'last_transaction_at' => $warehouse->last_transaction_at,
            ];
        }

        return $result;
    }

    /**
     * 获取仓库统计信息
     * 
     * @return array 统计信息
     */
    public static function getWarehouseStats(): array
    {
        $stats = MexWarehouse::selectRaw('
            COUNT(*) as total_items,
            COUNT(CASE WHEN quantity > 0 THEN 1 END) as available_items,
            SUM(quantity) as total_quantity,
            SUM(total_buy_amount) as total_buy_amount,
            SUM(total_sell_amount) as total_sell_amount,
            SUM(total_buy_quantity) as total_buy_quantity,
            SUM(total_sell_quantity) as total_sell_quantity
        ')->first();

        return [
            'total_items' => $stats->total_items ?? 0,
            'available_items' => $stats->available_items ?? 0,
            'total_quantity' => $stats->total_quantity ?? 0,
            'total_buy_amount' => $stats->total_buy_amount ?? '0.00000',
            'total_sell_amount' => $stats->total_sell_amount ?? '0.00000',
            'total_buy_quantity' => $stats->total_buy_quantity ?? 0,
            'total_sell_quantity' => $stats->total_sell_quantity ?? 0,
            'net_amount' => bcsub($stats->total_buy_amount ?? '0', $stats->total_sell_amount ?? '0', 5),
            'net_quantity' => ($stats->total_buy_quantity ?? 0) - ($stats->total_sell_quantity ?? 0),
        ];
    }

    /**
     * 增加库存
     * 
     * @param int $itemId 商品ID
     * @param int $quantity 数量
     * @param string $amount 金额
     * @return bool 操作结果
     */
    public static function addStock(int $itemId, int $quantity, string $amount): bool
    {
        try {
            $warehouse = MexWarehouse::firstOrCreate(
                ['item_id' => $itemId],
                [
                    'quantity' => 0,
                    'total_buy_amount' => '0.00000',
                    'total_sell_amount' => '0.00000',
                    'total_buy_quantity' => 0,
                    'total_sell_quantity' => 0,
                ]
            );

            $warehouse->quantity += $quantity;
            $warehouse->total_buy_quantity += $quantity;
            $warehouse->total_buy_amount = bcadd($warehouse->total_buy_amount, $amount, 5);
            $warehouse->last_transaction_at = now();
            
            return $warehouse->save();
        } catch (\Exception $e) {
            return false;
        }
    }

    /**
     * 减少库存
     * 
     * @param int $itemId 商品ID
     * @param int $quantity 数量
     * @param string $amount 金额
     * @return bool 操作结果
     */
    public static function reduceStock(int $itemId, int $quantity, string $amount): bool
    {
        try {
            $warehouse = MexWarehouse::where('item_id', $itemId)->first();
            
            if (!$warehouse || $warehouse->quantity < $quantity) {
                return false;
            }

            $warehouse->quantity -= $quantity;
            $warehouse->total_sell_quantity += $quantity;
            $warehouse->total_sell_amount = bcadd($warehouse->total_sell_amount, $amount, 5);
            $warehouse->last_transaction_at = now();
            
            return $warehouse->save();
        } catch (\Exception $e) {
            return false;
        }
    }

    /**
     * 计算平均价格
     * 
     * @param string $totalAmount 总金额
     * @param int $totalQuantity 总数量
     * @return string 平均价格
     */
    private static function calculateAveragePrice(string $totalAmount, int $totalQuantity): string
    {
        if ($totalQuantity <= 0) {
            return '0.00000';
        }
        
        return bcdiv($totalAmount, $totalQuantity, 5);
    }
}