<?php 
    session_start();
    require '../../../assets/utils/db_auth.php';

    // Get warehouse and zone from the form
    $warehouse = isset($data['warehouse']) ? (int)$data['warehouse'] : 0;
    $zone      = isset($data['zone']) ? $data['zone'] : '';
    
    if (isset($data['warehouse_from']) && $data['type'] == "from") {
        $warehouse = (int)$data['warehouse_from'];
        $zone      = $data['zone_from'];
    }
    if (isset($data['warehouse_to']) && $data['type'] == "to") {
        $warehouse = (int)$data['warehouse_to'];
        $zone      = $data['zone_to'];
    }

    // Filter aisles by operation type and optional SKU:
    //   'to'   = destination → aisles with at least one empty rack
    //   'from' + sku → aisles currently holding that specific SKU
    //   'from' (no sku) → aisles with any occupied rack
    //   other  = all aisles in the zone (admin / read-only pages)
    $product_sku_filter = "";
    $params = [
        ":company_id" => $company_id,
        ":warehouse"  => $warehouse,
        ":zone"       => $zone,
    ];

    if ($data["type"] == "to") {
        $product_sku_filter = "AND product_sku IS NULL";

    } elseif ($data["type"] == "from") {
        if (!empty($data["product_sku"])) {
            $product_sku_filter = "AND product_sku = :product_sku";
            $params[":product_sku"] = $data["product_sku"];
        } else {
            $product_sku_filter = "AND product_sku IS NOT NULL";
        }
    }

    if(!empty($data["id"])){
        $product_sku_filter = "";
        unset($params[":product_sku"]);
    }

    $sql = "SELECT DISTINCT aisle
            FROM md_rack
            WHERE 
                company_id = :company_id AND
                warehouse  = :warehouse  AND
                `zone`     = :zone
                $product_sku_filter
            ORDER BY CAST(aisle AS UNSIGNED), aisle";

    $sth = $pdo2->prepare($sql);
    $sth->execute($params);
    db_check($sth, $answer);

    // Return flat array (matches original response shape for the frontend)
    $answer["output"]  = array_column($sth->fetchAll(PDO::FETCH_ASSOC), 'aisle');
    $answer["success"] = 1;
    exit(json_encode($answer));
?>