<?php
declare(strict_types=1);

require_once dirname(dirname(__DIR__)) . '/bootstrap.php';

if (!function_exists('task_cert_csv_safe_slug')) {
    function task_cert_csv_safe_slug(string $value): string
    {
        $value = strtolower(trim($value));
        $value = preg_replace('/[^a-z0-9_-]+/', '-', $value) ?? '';
        $value = trim($value, '-_');
        return $value !== '' ? $value : 'export';
    }
}

if (TaskCertRequest::method() !== 'GET') {
    TaskCertResponse::error('Methode nicht erlaubt', 405, false);
}

$auth = TaskCertAuthContext::fromGlobals();
if (!$auth->hasPermission('r-task-cert-admin')) {
    TaskCertResponse::error('Keine Berechtigung', 403, false);
}

$csrfToken = TaskCertRequest::queryString('csrf_token', '');
if (!TaskCertCsrf::validate($csrfToken)) {
    TaskCertResponse::error('CSRF validation failed', 419, false);
}

$taskId = TaskCertRequest::queryInt('id', 0);
if ($taskId <= 0) {
    TaskCertResponse::error('Ungültige Aufgaben-ID.', 400, false);
}

$queryMode = TaskCertRequest::queryString('mode', '');
$queryCycleKey = TaskCertRequest::queryString('cycle_key', '');

try {
    $services = task_cert_services();
    $taskService = $services['taskDefinitionService'] ?? null;
    $monitoringService = $services['taskMonitoringService'] ?? null;

    if (!$taskService instanceof TaskDefinitionService) {
        throw new RuntimeException('TaskDefinitionService konnte nicht geladen werden.');
    }
    if (!$monitoringService instanceof TaskMonitoringService) {
        throw new RuntimeException('TaskMonitoringService konnte nicht geladen werden.');
    }

    $task = $taskService->getTaskDetail($taskId);
    if ($task === null) {
        TaskCertResponse::error('Aufgabe nicht gefunden.', 404, false);
    }

    $export = $monitoringService->buildAnswersExport($task, [
        'mode' => $queryMode,
        'cycle_key' => $queryCycleKey,
    ]);

    $mode = trim((string) ($export['mode'] ?? 'cycle'));
    if (!in_array($mode, ['cycle', 'snapshot'], true)) {
        $mode = 'cycle';
    }
    $selectedCycleKey = trim((string) ($export['cycle_key'] ?? ''));
    $rows = is_array($export['rows'] ?? null) ? $export['rows'] : [];
    $taskTitle = trim((string) ($task['title'] ?? 'Aufgabe'));

    $filenameCyclePart = $mode === 'snapshot'
        ? 'snapshot'
        : ('cycle-' . task_cert_csv_safe_slug($selectedCycleKey !== '' ? $selectedCycleKey : 'none'));
    $filename = sprintf(
        'task-answers-%d-%s-%s.csv',
        $taskId,
        $filenameCyclePart,
        date('Ymd_His')
    );

    while (ob_get_level() > 0) {
        ob_end_clean();
    }

    http_response_code(200);
    header('Content-Type: text/csv; charset=utf-8');
    header('Content-Disposition: attachment; filename="' . $filename . '"');
    header('Cache-Control: no-store, no-cache, must-revalidate');
    header('Pragma: no-cache');
    header('Expires: 0');
    header('X-Content-Type-Options: nosniff');

    $output = fopen('php://output', 'wb');
    if (!is_resource($output)) {
        throw new RuntimeException('CSV-Ausgabe konnte nicht initialisiert werden.');
    }

    // UTF-8 BOM for Excel on German locale systems.
    fwrite($output, "\xEF\xBB\xBF");

    $header = [
        'task_id',
        'task_title',
        'export_mode',
        'selected_cycle_key',
        'row_cycle_key',
        'submission_id',
        'assignment_id',
        'contact_id',
        'contact_name',
        'contact_email',
        'method_type',
        'method_label',
        'submission_status',
        'assignment_status',
        'submitted_at',
        'due_at',
        'overdue_at',
        'completed_at',
        'escalation_level',
        'score',
        'max_score',
        'review_note',
        'answer_summary',
        'answer_detail_json',
    ];
    fputcsv($output, $header, ';');

    $toCsvCell = static function ($value): string {
        if ($value === null) {
            return '';
        }

        if (is_bool($value)) {
            return $value ? '1' : '0';
        }

        if (is_int($value) || is_float($value)) {
            return (string) $value;
        }

        if (is_array($value)) {
            $value = json_encode($value, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
            if ($value === false) {
                $value = '';
            }
        }

        $stringValue = (string) $value;
        $trimmed = ltrim($stringValue);
        if ($trimmed !== '') {
            $firstChar = substr($trimmed, 0, 1);
            if (in_array($firstChar, ['=', '+', '-', '@'], true)) {
                $stringValue = "'" . $stringValue;
            }
        }

        return $stringValue;
    };

    foreach ($rows as $row) {
        $row = is_array($row) ? $row : [];
        $line = [
            $taskId,
            $taskTitle,
            $mode,
            $selectedCycleKey,
            (string) ($row['cycle_key'] ?? ''),
            (int) ($row['submission_id'] ?? 0),
            (int) ($row['assignment_id'] ?? 0),
            (int) ($row['contact_id'] ?? 0),
            (string) ($row['contact_name'] ?? ''),
            (string) ($row['contact_email'] ?? ''),
            (string) ($row['method_type'] ?? ''),
            (string) ($row['method_label'] ?? ''),
            (string) ($row['submission_status'] ?? ''),
            (string) ($row['assignment_status'] ?? ''),
            (string) ($row['submitted_at'] ?? ''),
            (string) ($row['due_at'] ?? ''),
            (string) ($row['overdue_at'] ?? ''),
            (string) ($row['completed_at'] ?? ''),
            (int) ($row['escalation_level'] ?? 0),
            $row['score'] !== null ? (int) $row['score'] : '',
            $row['max_score'] !== null ? (int) $row['max_score'] : '',
            (string) ($row['review_note'] ?? ''),
            (string) ($row['answer_summary'] ?? ''),
            (string) ($row['answer_detail_json'] ?? '{}'),
        ];

        $csvLine = array_map($toCsvCell, $line);
        fputcsv($output, $csvLine, ';');
    }

    fclose($output);
    exit;
} catch (Throwable $throwable) {
    $statusCode = $throwable instanceof InvalidArgumentException ? 400 : 500;
    TaskCertResponse::error($throwable->getMessage(), $statusCode, false);
}