<?php
include 'db.php';

if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $pid = $_POST['pid'] ?? '';
    $pack = $_POST['packname'] ?? '';
    $newQty = $_POST['quan'] ?? '';

    if (!empty($pid) && !empty($pack) && is_numeric($newQty)) {
        // Sanitize inputs
        $pid = (int)$pid;
        $pack = mysqli_real_escape_string($con, $pack);
        $newQty = (int)$newQty;

        // -------- STOCK TABLE --------
        $checkStock = "SELECT totalqty FROM stock WHERE pid = '$pid' AND pack = '$pack'";
        $resultStock = mysqli_query($con, $checkStock);

        if (mysqli_num_rows($resultStock) > 0) {
            // Exists -> Update
            $row = mysqli_fetch_assoc($resultStock);
            $existingQty = $row['totalqty'];
            $updatedQty = $existingQty + $newQty;

            $updateStock = "UPDATE stock SET totalqty = '$updatedQty' WHERE pid = '$pid' AND pack = '$pack'";
            mysqli_query($con, $updateStock);
        } else {
            echo "Stock not found to update.<br>";
        }

        // -------- VARIATION_MULTI TABLE --------
        $checkVar = "SELECT qty FROM variation_multi WHERE pid = '$pid' AND value1 = '$pack'";
        $resultVar = mysqli_query($con, $checkVar);

        if (mysqli_num_rows($resultVar) > 0) {
            $rowVar = mysqli_fetch_assoc($resultVar);
            $existingVarQty = $rowVar['qty'];
            $updatedVarQty = $existingVarQty + $newQty;

            $updateVar = "UPDATE variation_multi SET qty = '$updatedVarQty' WHERE pid = '$pid' AND value1 = '$pack'";
            mysqli_query($con, $updateVar);
        } else {
            echo "Variation not found to update.<br>";
        }

        mysqli_close($con);
    } else {
        echo "Please enter valid PID, Pack name, and Quantity.";
    }
} else {
    echo "Invalid request.";
}
?>