<?php
require_once __DIR__ . '/db/config.php';

$projectId = $_GET['id'] ?? null;
if (!$projectId) {
    die("Project ID is required.");
}

try {
    $pdo = db();
    $stmt = $pdo->prepare("SELECT name FROM projects WHERE id = :id");
    $stmt->execute([':id' => $projectId]);
    $project = $stmt->fetch(PDO::FETCH_ASSOC);
    $projectName = $project ? $project['name'] : 'project';

    $stmt = $pdo->prepare("SELECT month, amount FROM billingMonthly WHERE projectId = :projectId ORDER BY month");
    $stmt->execute([':projectId' => $projectId]);
    $billingData = $stmt->fetchAll(PDO::FETCH_ASSOC);

    $filename = "billing_" . strtolower(str_replace(' ', '_', $projectName)) . ".csv";

    header('Content-Type: text/csv');
    header('Content-Disposition: attachment; filename="' . $filename . '"');

    $output = fopen('php://output', 'w');

    // Header row
    $header = ['Billing'];
    $totalBilling = 0;
    foreach ($billingData as $row) {
        $header[] = date("M Y", strtotime($row['month']));
        $totalBilling += $row['amount'];
    }
    $header[] = 'Total';
    fputcsv($output, $header);

    // Data row
    $data = ['Billing'];
    foreach ($billingData as $row) {
        $data[] = $row['amount'];
    }
    $data[] = $totalBilling;
    fputcsv($output, $data);

    fclose($output);
    exit();

} catch (PDOException $e) {
    die("Database error: " . $e->getMessage());
}