<?php

class WarehouseManager {

    private $pdo;
    private $company_id;

    public function __construct($pdo, $company_id) {
        $this->pdo = $pdo;
        $this->company_id = $company_id;
    }

    public function getWarehouseName($warehouse_id) {
        $sql = "SELECT warehouse_name FROM md_warehouse
                WHERE company_id = :company_id AND id = :warehouse_id";

        $sth = $this->pdo->prepare($sql);
        $sth->execute([
            ":company_id"   => $this->company_id,
            ":warehouse_id" => $warehouse_id
        ]);
        return $sth->fetchColumn();
    }

    public function getStockContext($warehouse_id, $id) {
        $name = $this->getWarehouseName($warehouse_id);
        $table = "td_stock_" . $name;

        if (empty($id)) {
            return [
                'table' => $table,
                'name'  => $name,
                'row'   => []
            ];
        }

        $sql = "SELECT * FROM `$table`
                WHERE company_id = :company_id AND id = :id";

        $sth = $this->pdo->prepare($sql);
        $sth->execute([
            ":company_id" => $this->company_id,
            ":id"         => $id
        ]);

        return [
            'table' => $table,
            'name'  => $name,
            'row'   => $sth->fetch(PDO::FETCH_ASSOC) ?: []
        ];
    }

    public function adjustBalance($type, $warehouse_id, $product_sku, $old_qty, $new_qty) {

        // Lock the row — other transactions wait here
        $sql = "SELECT id FROM warehouse_balance
                WHERE company_id = :company_id 
                AND warehouse_id = :warehouse_id 
                AND product_sku = :product_sku
                FOR UPDATE";

        $sth = $this->pdo->prepare($sql);
        $sth->execute([
            ":company_id"   => $this->company_id,
            ":warehouse_id" => $warehouse_id,
            ":product_sku"  => $product_sku
        ]);

        if (!$sth->fetchColumn()) {
            $sql = "INSERT INTO warehouse_balance 
                    (company_id, warehouse_id, product_sku)
                    VALUES (:company_id, :warehouse_id, :product_sku)";

            $sth = $this->pdo->prepare($sql);
            $sth->execute([
                ":company_id"   => $this->company_id,
                ":warehouse_id" => $warehouse_id,
                ":product_sku"  => $product_sku
            ]);
        }

        $column = $type === 'in' ? 'total_in' : 'total_out';

        // This is already atomic since it uses relative update
        $sql = "UPDATE warehouse_balance 
                SET `$column` = `$column` - :old_qty + :new_qty
                WHERE company_id = :company_id 
                AND warehouse_id = :warehouse_id 
                AND product_sku = :product_sku";

        $sth = $this->pdo->prepare($sql);
        $sth->execute([
            ":company_id"   => $this->company_id,
            ":warehouse_id" => $warehouse_id,
            ":product_sku"  => $product_sku,
            ":old_qty"      => $old_qty,
            ":new_qty"      => $new_qty
        ]);
    }
}


?>