lib.php

<?php
function start_session() {
    if (session_status() === PHP_SESSION_NONE) {
        session_start();
    }
}

function require_session_json() {
    start_session();
    if (!isset($_SESSION['id'])) {
        http_response_code(401);
        header('Content-Type: application/json');
        echo json_encode(['success' => false, 'message' => '請先登入']);
        exit;
    }
}

function require_session_redirect() {
    start_session();
    if (!isset($_SESSION['id'])) {
        header('Location: index.php');
        exit;
    }
}

function get_answer_base() {
    static $base = null;
    if ($base !== null) return $base;
    $config = json_decode(file_get_contents(__DIR__ . '/config.json'), true);
    $p = trim($config['answer_path'] ?? '');
    $base = $p !== '' ? rtrim($p, '/\\') : __DIR__ . DIRECTORY_SEPARATOR . 'answers';
    return $base;
}

function get_folder_path() {
    return get_answer_base() . DIRECTORY_SEPARATOR . $_SESSION['folder'];
}

// 建立資料夾並驗證寫入權限，回傳 true 或錯誤訊息字串
function ensure_user_folder($folder_name) {
    $base = get_answer_base();

    // 確保 answers 根目錄存在
    if (!is_dir($base)) {
        if (!@mkdir($base, 0755, true)) {
            return '無法建立答案根目錄：' . $base . '　請確認 Web 伺服器對該路徑有寫入權限。';
        }
    }

    $path = $base . DIRECTORY_SEPARATOR . $folder_name;
    if (!is_dir($path)) {
        if (!@mkdir($path, 0755, true)) {
            return '無法建立考生資料夾：' . $path . '　請確認 Web 伺服器對 NAS 路徑有寫入權限，或請管理員先執行 setup.php。';
        }
    }

    // 寫入測試
    $testFile = $path . DIRECTORY_SEPARATOR . '.writable_test';
    if (@file_put_contents($testFile, '1') === false) {
        return '資料夾存在但無法寫入：' . $path . '　請確認權限後再試，或聯絡管理員執行 setup.php。';
    }
    @unlink($testFile);

    return true;
}

function validate_question($config, $main, $sub) {
    foreach ($config['questions'] as $q) {
        if ($q['no'] == $main) {
            foreach ($q['subs'] as $s) {
                if ($s['no'] == $sub) return $s;
            }
        }
    }
    return null;
}

function find_answer_file($folder_path, $main, $sub) {
    $files = glob($folder_path . '/' . $main . '-' . $sub . '.*');
    if (!$files) return null;
    $files = array_filter($files, fn($f) => pathinfo($f, PATHINFO_EXTENSION) !== 'log');
    return $files ? array_values($files)[0] : null;
}

function get_client_name(): string {
    $ip   = $_SERVER['REMOTE_ADDR'] ?? 'unknown';
    $host = @gethostbyaddr($ip);
    return ($host && $host !== $ip) ? $host . ' (' . $ip . ')' : $ip;
}

function write_log($folder_path, $action, $filename, $label) {
    $client = get_client_name();
    $line   = date('Y-m-d H:i:s') . "\t" . $action . "\t" . $filename . "\t" . $label . "\t" . $client . "\n";
    file_put_contents($folder_path . '/activity.log', $line, FILE_APPEND | LOCK_EX);
}

function parse_question_key($q) {
    if (!preg_match('/^(\d+)-(\d+)$/', $q, $m)) return null;
    return [(int)$m[1], (int)$m[2]];
}

// 讀取各小題最後一次 ANSWER/UPLOAD 的存檔時間，回傳 ['1-1' => 'YYYY-MM-DD HH:MM:SS', ...]
function get_last_save_times(string $folder_path): array {
    $times   = [];
    $logFile = $folder_path . '/activity.log';
    if (!is_file($logFile)) return $times;
    foreach (file($logFile, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES) ?: [] as $line) {
        $p = explode("\t", $line);
        if (count($p) < 4) continue;
        if ($p[1] !== 'ANSWER' && $p[1] !== 'UPLOAD') continue;
        $times[$p[3]] = $p[0]; // label (e.g. '1-1') => datetime
    }
    return $times;
}

// ── 批改相關 ──────────────────────────────────────────────────────────────────

function get_grades_path(string $fp): string { return $fp . '/grades.json'; }

function get_grades(string $fp): array {
    $f = get_grades_path($fp);
    if (!is_file($f)) return ['readonly' => false, 'questions' => []];
    $d = json_decode(file_get_contents($f), true);
    return is_array($d) ? $d : ['readonly' => false, 'questions' => []];
}

function save_grades(string $fp, array $g): void {
    file_put_contents(get_grades_path($fp), json_encode($g, JSON_UNESCAPED_UNICODE | JSON_PRETTY_PRINT), LOCK_EX);
}

function is_readonly(string $fp): bool {
    return !empty(get_grades($fp)['readonly']);
}

function calc_total_score(array $grades): ?int {
    if (empty($grades['questions'])) return null;
    $total = 0; $any = false;
    foreach ($grades['questions'] as $q) {
        if (isset($q['score']) && $q['score'] !== null) {
            $total += (int)$q['score'];
            $any = true;
        }
    }
    return $any ? $total : null;
}

function require_grader_session_redirect(): void {
    start_session();
    if (empty($_SESSION['grader_authed'])) {
        header('Location: grade.php');
        exit;
    }
}

function require_grader_session_json(): void {
    start_session();
    if (empty($_SESSION['grader_authed'])) {
        http_response_code(401);
        header('Content-Type: application/json');
        echo json_encode(['success' => false, 'message' => '請先以批改者身份登入']);
        exit;
    }
}

// ─────────────────────────────────────────────────────────────────────────────

// 將文字中的 URL 轉為可點擊連結（target="_blank"）
function linkify($text) {
    $safe = htmlspecialchars($text, ENT_QUOTES, 'UTF-8');
    return preg_replace(
        '/(https?:\/\/[^\s\，\,\<\>\"\'）\)]+)/iu',
        '<a href="$1" target="_blank" rel="noopener noreferrer">$1</a>',
        $safe
    );
}