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

    // Build filter + params based on operation type.
    // Filter warehouses by occupancy:
    //   'to'   = destination → only warehouses with at least one empty rack
    //   'from' = source      → only warehouses that hold the specific product SKU
    //   other  = all warehouses (for read-only listings, dashboards, etc.)
    $product_sku_filter = "";
    $params = [":company_id" => $company_id];

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

    } elseif ($data["type"] == "from") {
        $product_sku_filter = "AND r.product_sku = :product_sku";
        $params[":product_sku"] = $data["product_sku"];
    }

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

    // Only list warehouses that have racks matching the occupancy filter.
    // EXISTS is efficient here — it stops searching as soon as one match is found.
    $sql = "SELECT w.id, w.warehouse_name
            FROM md_warehouse w
            WHERE w.company_id = :company_id
              AND EXISTS (
                  SELECT 1 FROM md_rack r
                  WHERE r.company_id = w.company_id
                    AND r.warehouse  = w.id
                    $product_sku_filter
              )
            ORDER BY w.warehouse_name";

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

    $answer["output"]  = $sth->fetchAll(PDO::FETCH_ASSOC);
    $answer["success"] = 1;
    exit(json_encode($answer));
?>