<?php
require_once('includes/connection.php');
header('Content-Type: application/json');

if (isset($_POST['companyName'])) {
    $companyName = $_POST['companyName'];

    // 1. Fetch company code
    $stmt = $conn->prepare("SELECT c_inv FROM company_master WHERE c_name = ?");
    $stmt->bind_param("s", $companyName);
    $stmt->execute();
    $stmt->bind_result($c_inv);
    $stmt->fetch();
    $stmt->close();

    if (!$c_inv) {
        echo json_encode(['success' => false, 'message' => 'Company code not found']);
        exit;
    }

    // 2. Determine financial year (e.g., 24-25)
    $currentMonth = date('n');
    $yearStart = ($currentMonth >= 4) ? (int)date('y') : (int)date('y', strtotime('-1 year'));
    $yearEnd = sprintf("%02d", ($yearStart + 1) % 100);
    $financialYear = "{$yearStart}-{$yearEnd}";

    // 3. Create prefix and search pattern
    $prefix = "{$c_inv}/{$financialYear}/";
    $like = $prefix . "%";

    // 4. Fetch latest challan number
    $stmt = $conn->prepare("SELECT challan_no FROM challan_master WHERE challan_no LIKE ? ORDER BY id DESC LIMIT 1");
    $stmt->bind_param("s", $like);
    $stmt->execute();
    $stmt->bind_result($lastChallan);
    $stmt->fetch();
    $stmt->close();

    $lastSerial = 0;

    if ($lastChallan) {
        // Normalize slashes in case of malformed challans like SSCT/25-26//25-26/1
        $lastChallan = preg_replace('/\/+/', '/', $lastChallan);

        $segments = explode('/', $lastChallan);

        if (count($segments) === 3 && is_numeric($segments[2])) {
            $lastSerial = (int)$segments[2];
        }
    }

    $newSerial = $lastSerial + 1;
    $challanNo = $prefix . $newSerial;

    // ✅ Return challan number only (do not insert)
    echo json_encode([
        'success' => true,
        'challanNo' => $challanNo
    ]);
    exit;
}

// Invalid request fallback
echo json_encode(['success' => false, 'message' => 'Invalid request']);