<?php
header('Content-Type: application/json');
require_once __DIR__ . '/db/config.php';

$response = ['success' => false, 'error' => 'Invalid request'];

if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $projectId = $_POST['projectId'] ?? null;
    $billingDataJson = $_POST['billingData'] ?? null;

    if ($projectId && $billingDataJson) {
        $billingData = json_decode($billingDataJson, true);

        if (is_array($billingData)) {
            try {
                $pdo = db();
                $stmt = $pdo->prepare("UPDATE billingMonthly SET amount = :amount WHERE projectId = :projectId AND month = :month");

                $pdo->beginTransaction();
                foreach ($billingData as $item) {
                    $stmt->execute([
                        ':amount' => $item['amount'],
                        ':projectId' => $projectId,
                        ':month' => $item['month']
                    ]);
                }
                $pdo->commit();

                $response['success'] = true;
                unset($response['error']);

            } catch (PDOException $e) {
                if ($pdo->inTransaction()) {
                    $pdo->rollBack();
                }
                $response['error'] = 'Database error: ' . $e->getMessage();
            } catch (Exception $e) {
                $response['error'] = 'An unexpected error occurred: ' . $e->getMessage();
            }
        } else {
            $response['error'] = 'Invalid billing data format.';
        }
    } else {
        $response['error'] = 'Missing required fields.';
    }
}

echo json_encode($response);