<?php
session_start();

if (!isset($_SESSION['user_id'])) {
    header("Location: login.php");
    exit();
}

require_once 'db_connection.php';

try {
    header('Content-Type: text/csv; charset=utf-8');
    header('Content-Disposition: attachment; filename="expenses_' . date('Y-m-d') . '.csv"');
    
    $output = fopen('php://output', 'w');
    fprintf($output, chr(0xEF).chr(0xBB).chr(0xBF));
    
    fputcsv($output, array('Date', 'Buyer', 'Category', 'Head', 'Amount'));
    
    $query = "SELECT e.*, b.name as buyer_name, ec.name as category_name, eh.name as head_name 
              FROM expenses e 
              LEFT JOIN buyers b ON e.buyer_id = b.id 
              JOIN expense_categories ec ON e.category_id = ec.id 
              JOIN expense_heads eh ON e.head_id = eh.id 
              ORDER BY e.date DESC";
    $result = $conn->query($query);
    
    while ($row = $result->fetch_assoc()) {
        fputcsv($output, array(
            $row['date'],
            $row['buyer_name'] ? $row['buyer_name'] : 'N/A',
            $row['category_name'],
            $row['head_name'],
            number_format($row['amount'], 2)
        ));
    }

    fclose($output);
    $conn->close();
} catch (Exception $e) {
    header('Content-Type: text/plain');
    echo "Export error";
    error_log("Expenses export error: " . $e->getMessage());
}

exit();
?>