<?php
/**
 * Audit Log API Endpoint
 * Handles fetching filtered audit logs and CSV export
 * Admin-only access
 */

require_once dirname(__DIR__) . '/config/config.php';
require_once dirname(__DIR__) . '/helpers/Database.php';
require_once dirname(__DIR__) . '/models/AuditLogModel.php';

session_start();
header('Content-Type: application/json');

// Check authentication
if (!isset($_SESSION['user']) || !isset($_SESSION['user']['user_id'])) {
    http_response_code(401);
    echo json_encode(['success' => false, 'error' => 'Not authenticated']);
    exit;
}

// Check admin status - audit log viewing is admin-only
$isAdmin = $_SESSION['user']['is_admin'] ?? false;
if (!$isAdmin) {
    http_response_code(403);
    echo json_encode(['success' => false, 'error' => 'Admin access required']);
    exit;
}

// Use centralized database connection
$conn = Database::getConnection();

$auditLogModel = new AuditLogModel($conn);

// GET - Fetch filtered audit logs or export to CSV
if ($_SERVER['REQUEST_METHOD'] === 'GET') {
    // Check for CSV export request
    if (isset($_GET['export']) && $_GET['export'] === 'csv') {
        // Build filters
        $filters = [];
        if (isset($_GET['action_type'])) $filters['action_type'] = $_GET['action_type'];
        if (isset($_GET['entity_type'])) $filters['entity_type'] = $_GET['entity_type'];
        if (isset($_GET['user_id'])) $filters['user_id'] = $_GET['user_id'];
        if (isset($_GET['entity_id'])) $filters['entity_id'] = $_GET['entity_id'];
        if (isset($_GET['date_from'])) $filters['date_from'] = $_GET['date_from'];
        if (isset($_GET['date_to'])) $filters['date_to'] = $_GET['date_to'];
        if (isset($_GET['ip_address'])) $filters['ip_address'] = $_GET['ip_address'];

        // Get all matching logs (no limit for CSV export)
        $result = $auditLogModel->getFilteredLogs($filters, 10000, 0);
        $logs = $result['logs'];

        // Set CSV headers
        header('Content-Type: text/csv');
        header('Content-Disposition: attachment; filename="audit_log_' . date('Y-m-d_His') . '.csv"');

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

        // Write CSV header
        fputcsv($output, ['Log ID', 'Timestamp', 'User', 'Action', 'Entity Type', 'Entity ID', 'IP Address', 'Details']);

        // Write data rows
        foreach ($logs as $log) {
            $details = '';
            if (is_array($log['details'])) {
                $details = json_encode($log['details']);
            }

            fputcsv($output, [
                $log['log_id'],
                $log['created_at'],
                $log['display_name'] ?? $log['username'] ?? 'N/A',
                $log['action_type'],
                $log['entity_type'],
                $log['entity_id'] ?? 'N/A',
                $log['ip_address'] ?? 'N/A',
                $details
            ]);
        }

        fclose($output);
        exit;
    }

    // Normal JSON response for filtered logs
    try {
        // Get pagination parameters
        $page = isset($_GET['page']) ? (int)$_GET['page'] : 1;
        $limit = isset($_GET['limit']) ? (int)$_GET['limit'] : 50;
        $offset = ($page - 1) * $limit;

        // Build filters
        $filters = [];
        if (isset($_GET['action_type'])) $filters['action_type'] = $_GET['action_type'];
        if (isset($_GET['entity_type'])) $filters['entity_type'] = $_GET['entity_type'];
        if (isset($_GET['user_id'])) $filters['user_id'] = $_GET['user_id'];
        if (isset($_GET['entity_id'])) $filters['entity_id'] = $_GET['entity_id'];
        if (isset($_GET['date_from'])) $filters['date_from'] = $_GET['date_from'];
        if (isset($_GET['date_to'])) $filters['date_to'] = $_GET['date_to'];
        if (isset($_GET['ip_address'])) $filters['ip_address'] = $_GET['ip_address'];

        // Get filtered logs
        $result = $auditLogModel->getFilteredLogs($filters, $limit, $offset);

        echo json_encode([
            'success' => true,
            'logs' => $result['logs'],
            'total' => $result['total'],
            'pages' => $result['pages'],
            'current_page' => $page
        ]);
    } catch (Exception $e) {
        http_response_code(500);
        echo json_encode(['success' => false, 'error' => 'Failed to fetch audit logs']);
    }
    $conn->close();
    exit;
}

// Method not allowed
http_response_code(405);
echo json_encode(['success' => false, 'error' => 'Method not allowed']);
$conn->close();
?>