<?php
// /var/www/html/common.php
// Gemeinsame Helfer für Token-Validierung, Key-Derivation (HKDF) und AES (CBC, IV vorangestellt).

/**
 * Load KEY=value pairs from .env in the project root.
 * Does not override variables already set in the real environment.
 */
function qdb_load_dotenv(string $path): void {
    if (!is_readable($path)) {
        return;
    }
    $lines = file($path, FILE_IGNORE_NEW_LINES);
    if ($lines === false) {
        return;
    }
    foreach ($lines as $line) {
        $line = trim($line);
        if ($line === '' || $line[0] === '#') {
            continue;
        }
        $eq = strpos($line, '=');
        if ($eq === false) {
            continue;
        }
        $name = trim(substr($line, 0, $eq));
        $value = trim(substr($line, $eq + 1));
        if ($name === '') {
            continue;
        }
        $len = strlen($value);
        if ($len >= 2) {
            $q = $value[0];
            if (($q === '"' && $value[$len - 1] === '"') || ($q === "'" && $value[$len - 1] === "'")) {
                $value = substr($value, 1, -1);
            }
        }
        $existing = getenv($name);
        if ($existing !== false && $existing !== '') {
            continue;
        }
        putenv("$name=$value");
        $_ENV[$name] = $value;
    }
}

qdb_load_dotenv(__DIR__ . '/.env');

// --- MASTER-KEY (Server-seitig zum Speichern der DB) ---
// Per ENV 'QDB_MASTER_KEY' (Base64- oder ASCII-String) oder Fallback auf bisherigen Wert.
function get_master_key_bytes(): string {
    $env = getenv('QDB_MASTER_KEY');
    if (!$env || $env === '') {
        throw new RuntimeException('QDB_MASTER_KEY environment variable is not set. Cannot proceed without a master key.');
    }
    $b = base64_decode($env, true);
    if ($b !== false && strlen($b) > 0) {
        return str_pad(substr($b, 0, 32), 32, "\0");
    }
    return str_pad(substr($env, 0, 32), 32, "\0");
}

// --- HKDF (SHA-256) über Token -> Session-Key (32 Byte) ---
// Kompatibel zu Android-Implementierung: salt = leer, info = "qdb-aes"
function hkdf_session_key_from_token(string $tokenHex, string $info = 'qdb-aes', int $len = 32): string {
    $ikm = @hex2bin(trim($tokenHex));
    if ($ikm === false) $ikm = $tokenHex; // Falls bereits binär
    if (function_exists('hash_hkdf')) {
        return hash_hkdf('sha256', $ikm, $len, $info, '');
    }
    // Fallback: eigene HKDF-Implementierung
    $hashLen = 32;
    $salt = str_repeat("\0", $hashLen);
    $prk = hash_hmac('sha256', $ikm, $salt, true);
    $okm = '';
    $t = '';
    $n = (int)ceil($len / $hashLen);
    for ($i = 1; $i <= $n; $i++) {
        $t = hash_hmac('sha256', $t . $info . chr($i), $prk, true);
        $okm .= $t;
    }
    return substr($okm, 0, $len);
}

// --- Token-Storage (DB-backed via session table) ---

function token_add(string $token, int $ttlSeconds = 86400, array $extra = []): void {
    require_once __DIR__ . '/db_init.php';
    [$pdo, $tmpDb, $lockFp] = qdb_open(true);
    $now = time();
    $pdo->prepare(
        "INSERT INTO session (token, userID, role, entityID, createdAt, expiresAt, temp)
         VALUES (:t, :uid, :role, :eid, :ca, :ea, :tmp)"
    )->execute([
        ':t'    => $token,
        ':uid'  => $extra['userID']   ?? '',
        ':role' => $extra['role']     ?? '',
        ':eid'  => $extra['entityID'] ?? '',
        ':ca'   => $now,
        ':ea'   => $now + $ttlSeconds,
        ':tmp'  => (int)(!empty($extra['temp'])),
    ]);
    // Opportunistic cleanup: remove expired sessions
    $pdo->prepare("DELETE FROM session WHERE expiresAt < :now")->execute([':now' => $now]);
    qdb_save($tmpDb, $lockFp);
}

function token_get_record(string $token): ?array {
    require_once __DIR__ . '/db_init.php';
    [$pdo, $tmpDb, $lockFp] = qdb_open(false);
    $stmt = $pdo->prepare("SELECT * FROM session WHERE token = :t AND expiresAt >= :now");
    $stmt->execute([':t' => $token, ':now' => time()]);
    $row = $stmt->fetch(PDO::FETCH_ASSOC);
    qdb_discard($tmpDb, $lockFp);
    if (!$row) return null;
    // Map DB columns to the keys the rest of the codebase expects
    return [
        'token'    => $row['token'],
        'role'     => $row['role'],
        'entityID' => $row['entityID'],
        'userID'   => $row['userID'],
        'created'  => (int)$row['createdAt'],
        'exp'      => (int)$row['expiresAt'],
        'temp'     => (int)$row['temp'],
    ];
}

function token_revoke(string $token): void {
    require_once __DIR__ . '/db_init.php';
    [$pdo, $tmpDb, $lockFp] = qdb_open(true);
    $pdo->prepare("DELETE FROM session WHERE token = :t")->execute([':t' => $token]);
    qdb_save($tmpDb, $lockFp);
}

// --- Auth helpers for endpoints ---
function get_bearer_token(): ?string {
    $auth = $_SERVER['HTTP_AUTHORIZATION'] ?? ($_SERVER['Authorization'] ?? '');
    if (stripos($auth, 'Bearer ') === 0) {
        return substr($auth, 7);
    }
    return null;
}

function require_valid_token(): array {
    $token = get_bearer_token();
    if (!$token) {
        http_response_code(401);
        header('Content-Type: application/json; charset=UTF-8');
        echo json_encode(["error" => "Missing Bearer token"]);
        exit;
    }
    $rec = token_get_record($token);
    if (!$rec) {
        http_response_code(403);
        header('Content-Type: application/json; charset=UTF-8');
        echo json_encode(["error" => "Invalid or expired token"]);
        exit;
    }
    if (!empty($rec['temp'])) {
        http_response_code(403);
        header('Content-Type: application/json; charset=UTF-8');
        echo json_encode(["error" => "Password change required before access"]);
        exit;
    }
    $rec['_token'] = $token;
    return $rec;
}

function require_role(array $allowed, array $tokenRecord): void {
    $role = $tokenRecord['role'] ?? '';
    if (!in_array($role, $allowed, true)) {
        http_response_code(403);
        header('Content-Type: application/json; charset=UTF-8');
        echo json_encode(["error" => "Insufficient permissions"]);
        exit;
    }
}

/**
 * Build a SQL WHERE clause fragment that restricts client visibility by role.
 * Returns [string $clause, array $params].
 * $clientAlias is the table alias or name that has a coachID column (e.g. 'client').
 */
function rbac_client_filter(array $tokenRecord, string $clientAlias = 'client'): array {
    $role     = $tokenRecord['role'] ?? '';
    $entityID = $tokenRecord['entityID'] ?? '';
    switch ($role) {
        case 'admin':
            return ['1=1', []];
        case 'supervisor':
            return [
                "$clientAlias.coachID IN (SELECT coachID FROM coach WHERE supervisorID = :rbac_eid)",
                [':rbac_eid' => $entityID]
            ];
        case 'coach':
            return [
                "$clientAlias.coachID = :rbac_eid",
                [':rbac_eid' => $entityID]
            ];
        default:
            return ['0=1', []];
    }
}

// --- Translations: German (de) is the canonical source language ---
define('QDB_SOURCE_LANGUAGE', 'de');

function qdb_ensure_source_language(PDO $pdo): void {
    $pdo->prepare("INSERT INTO language (languageCode, name) VALUES (:lc, :n)
                   ON CONFLICT(languageCode) DO NOTHING")
        ->execute([':lc' => QDB_SOURCE_LANGUAGE, ':n' => 'German']);
}

function qdb_upsert_source_translation(PDO $pdo, string $type, string $id, string $text): void {
    qdb_put_translation($pdo, $type, $id, QDB_SOURCE_LANGUAGE, $text);
}

/** Catalog of global app UI string keys (LanguageManager). */
function qdb_app_string_catalog(): array {
    static $catalog = null;
    if ($catalog !== null) {
        return $catalog;
    }
    $path = __DIR__ . '/data/app_ui_strings.json';
    if (!is_readable($path)) {
        $catalog = ['keys' => [], 'germanDefaults' => []];
        return $catalog;
    }
    $data = json_decode(file_get_contents($path), true);
    $catalog = is_array($data) ? $data : ['keys' => [], 'germanDefaults' => []];
    return $catalog;
}

function qdb_app_string_key_set(): array {
    $keys = qdb_app_string_catalog()['keys'] ?? [];
    return array_flip($keys);
}

/** Keys for dev-only UI (database export, etc.) — excluded from website App UI and app sync catalog. */
function qdb_dev_only_app_string_key_set(): array {
    static $set = null;
    if ($set !== null) {
        return $set;
    }
    $set = array_flip([
        'database',
        'database_clients_title',
        'download_header',
        'export_success_downloads',
        'export_failed',
        'headers',
        'view_missing',
        'no_header_template_found',
        'saved_pdf_csv',
        'no_pdf_viewer',
        'save_error',
        'no_clients_available',
        'questionnaire_id',
        'questionnaires',
        'status',
        'data',
        'data_final_warning',
        'open_client_via_load',
        'ask_before_upload',
        'You have completed questionnaires that have not been uploaded yet.',
        'You have completed questionnaires that have not been uploaded yet. Tap to open the app and upload.',
    ]);
    return $set;
}

/**
 * Global app UI strings (screens, toasts, auth, etc.) for the mobile app.
 * @return list<array{key: string, type: string, entityId: string, sortOrder: int}>
 */
function qdb_app_ui_string_entries(): array {
    $catalog = qdb_app_string_catalog();
    $defaults = $catalog['germanDefaults'] ?? [];
    $entries = [];
    $order = 0;
    foreach ($catalog['keys'] ?? [] as $key) {
        $entries[] = [
            'key'           => $key,
            'displayKey'    => $key,
            'type'          => 'app_string',
            'entityId'      => $key,
            'sortOrder'     => $order++,
            'germanDefault' => $defaults[$key] ?? $key,
        ];
    }
    return $entries;
}

/**
 * All string keys referenced by questionnaire content (questions, options, config).
 * @return array<string, true>
 */
function qdb_all_questionnaire_translation_key_set(PDO $pdo): array {
    static $cache = null;
    if ($cache !== null) {
        return $cache;
    }

    $keys = [];
    $rows = $pdo->query("SELECT defaultText, configJson FROM question")->fetchAll(PDO::FETCH_ASSOC);
    foreach ($rows as $dbQ) {
        if ($dbQ['defaultText'] !== '') {
            $keys[$dbQ['defaultText']] = true;
        }
        $config = json_decode($dbQ['configJson'] ?: '{}', true) ?: [];
        foreach (['textKey', 'textKey1', 'textKey2', 'hint', 'hint1', 'hint2'] as $field) {
            if (!empty($config[$field])) {
                $keys[$config[$field]] = true;
            }
        }
        if (!empty($config['symptoms']) && is_array($config['symptoms'])) {
            foreach ($config['symptoms'] as $s) {
                if ($s !== '') {
                    $keys[$s] = true;
                }
            }
        }
        if (!empty($config['options']) && is_array($config['options'])) {
            foreach ($config['options'] as $opt) {
                if (is_string($opt) && $opt !== '') {
                    $keys[$opt] = true;
                } elseif (is_array($opt) && !empty($opt['key'])) {
                    $keys[$opt['key']] = true;
                }
            }
        }
    }

    foreach ($pdo->query("SELECT defaultText FROM answer_option")->fetchAll(PDO::FETCH_COLUMN) as $text) {
        if ($text !== '') {
            $keys[$text] = true;
        }
    }

    $cache = $keys;
    return $cache;
}

/**
 * App UI catalog for the website Translations page (coach-visible, no dev-only keys).
 * Catalog keys always appear here even when also used inside a questionnaire (e.g. "save").
 */
function qdb_app_ui_string_entries_for_website(): array {
    $dev = qdb_dev_only_app_string_key_set();
    $entries = [];
    foreach (qdb_app_ui_string_entries() as $e) {
        if (!isset($dev[$e['key']])) {
            $entries[] = $e;
        }
    }
    return $entries;
}

/** Upsert one translation row; sync German text into defaultText for questions/options. */
function qdb_put_translation(PDO $pdo, string $type, string $id, string $lang, string $text): void {
    if ($type === 'question') {
        $pdo->prepare("INSERT INTO question_translation (questionID, languageCode, text)
                       VALUES (:id, :lang, :t)
                       ON CONFLICT(questionID, languageCode) DO UPDATE SET text = excluded.text")
            ->execute([':id' => $id, ':lang' => $lang, ':t' => $text]);
        if ($lang === QDB_SOURCE_LANGUAGE) {
            $pdo->prepare("UPDATE question SET defaultText = :t WHERE questionID = :id")
                ->execute([':t' => $text, ':id' => $id]);
        }
    } elseif ($type === 'answer_option') {
        $pdo->prepare("INSERT INTO answer_option_translation (answerOptionID, languageCode, text)
                       VALUES (:id, :lang, :t)
                       ON CONFLICT(answerOptionID, languageCode) DO UPDATE SET text = excluded.text")
            ->execute([':id' => $id, ':lang' => $lang, ':t' => $text]);
        if ($lang === QDB_SOURCE_LANGUAGE) {
            $pdo->prepare("UPDATE answer_option SET defaultText = :t WHERE answerOptionID = :id")
                ->execute([':t' => $text, ':id' => $id]);
        }
    } elseif ($type === 'string' || $type === 'app_string') {
        $pdo->prepare("INSERT INTO string_translation (stringKey, languageCode, text)
                       VALUES (:id, :lang, :t)
                       ON CONFLICT(stringKey, languageCode) DO UPDATE SET text = excluded.text")
            ->execute([':id' => $id, ':lang' => $lang, ':t' => $text]);
    }
}

/** Short label for translation UI (Key column); full text stays in `key` for API lookup. */
function qdb_translation_display_key(array $e): string {
    if (!empty($e['displayKey'])) {
        return $e['displayKey'];
    }
    if (($e['type'] ?? '') === 'question' || ($e['type'] ?? '') === 'answer_option') {
        $id = $e['entityId'] ?? '';
        $pos = strrpos($id, '__');
        return $pos !== false ? substr($id, $pos + 2) : $id;
    }
    return $e['key'] ?? '';
}

function qdb_short_entity_label(string $entityId): string {
    $pos = strrpos($entityId, '__');
    return $pos !== false ? substr($entityId, $pos + 2) : $entityId;
}

function qdb_require_non_empty_german(string $text, string $label = 'German text'): void {
    if ($text === '') {
        json_error('MISSING_FIELDS', "$label is required", 400);
    }
}

/**
 * Build translation entry lists for one questionnaire.
 * Returns ['stringEntries' => [...], 'contentEntries' => [...]] (questions + options interleaved).
 */
function qdb_translation_entry_lists(PDO $pdo, string $qnID): array {
    $qStmt = $pdo->prepare("
        SELECT q.questionID, q.defaultText, q.configJson, q.orderIndex
        FROM question q WHERE q.questionnaireID = :id ORDER BY q.orderIndex
    ");
    $qStmt->execute([':id' => $qnID]);
    $dbQuestions = $qStmt->fetchAll(PDO::FETCH_ASSOC);

    $stringKeys = [];
    $stringEntries = [];
    $contentEntries = [];

    foreach ($dbQuestions as $dbQ) {
        $qOrder = (int)($dbQ['orderIndex'] ?? 0);
        $contentEntries[] = [
            'key'        => $dbQ['defaultText'],
            'displayKey' => qdb_short_entity_label($dbQ['questionID']),
            'type'       => 'question',
            'entityId'   => $dbQ['questionID'],
            'sortOrder'  => $qOrder * 1000,
        ];

        $aoStmt = $pdo->prepare("
            SELECT answerOptionID, defaultText, orderIndex
            FROM answer_option WHERE questionID = :qid ORDER BY orderIndex
        ");
        $aoStmt->execute([':qid' => $dbQ['questionID']]);
        foreach ($aoStmt->fetchAll(PDO::FETCH_ASSOC) as $ao) {
            $contentEntries[] = [
                'key'        => $ao['defaultText'],
                'displayKey' => qdb_short_entity_label($ao['answerOptionID']),
                'type'       => 'answer_option',
                'entityId'   => $ao['answerOptionID'],
                'sortOrder'  => $qOrder * 1000 + 10 + (int)($ao['orderIndex'] ?? 0),
            ];
        }

        $config = json_decode($dbQ['configJson'] ?: '{}', true) ?: [];
        foreach (['textKey', 'textKey1', 'textKey2', 'hint', 'hint1', 'hint2'] as $field) {
            if (!empty($config[$field])) {
                $stringKeys[$config[$field]] = true;
            }
        }
        if (!empty($config['symptoms']) && is_array($config['symptoms'])) {
            foreach ($config['symptoms'] as $s) {
                $stringKeys[$s] = true;
            }
        }
    }

    $appKeySet = qdb_app_string_key_set();
    $stringOrder = 0;
    $skList = array_keys($stringKeys);
    sort($skList, SORT_STRING);
    foreach ($skList as $sk) {
        if (isset($appKeySet[$sk])) {
            continue;
        }
        $stringEntries[] = [
            'key'        => $sk,
            'displayKey' => $sk,
            'type'       => 'string',
            'entityId'   => $sk,
            'sortOrder'  => $stringOrder++,
        ];
    }

    return ['stringEntries' => $stringEntries, 'contentEntries' => $contentEntries];
}

/** Attach translation texts and germanText to entry rows. */
function qdb_attach_translation_texts(array &$entries, array $translations): void {
    foreach ($entries as &$e) {
        $tr = $translations[$e['entityId']] ?? [];
        $e['translations'] = (object)$tr;
        $de = trim($tr[QDB_SOURCE_LANGUAGE] ?? '');
        if ($de !== '') {
            $e['germanText'] = $de;
        } elseif (!empty($e['germanDefault'])) {
            $e['germanText'] = $e['germanDefault'];
        } else {
            $e['germanText'] = $e['key'];
        }
        unset($e['germanDefault']);
    }
    unset($e);
}

/** Load all translation rows for a flat entry list. */
function qdb_load_translations_for_entries(PDO $pdo, array $entries): array {
    $translations = [];

    $qIds = array_values(array_filter(array_map(
        fn($e) => $e['type'] === 'question' ? $e['entityId'] : null,
        $entries
    )));
    if ($qIds) {
        $ph = implode(',', array_fill(0, count($qIds), '?'));
        $stmt = $pdo->prepare("SELECT questionID AS entityId, languageCode, text FROM question_translation WHERE questionID IN ($ph)");
        $stmt->execute($qIds);
        foreach ($stmt->fetchAll(PDO::FETCH_ASSOC) as $r) {
            $translations[$r['entityId']][$r['languageCode']] = $r['text'];
        }
    }

    $aoIds = array_values(array_filter(array_map(
        fn($e) => $e['type'] === 'answer_option' ? $e['entityId'] : null,
        $entries
    )));
    if ($aoIds) {
        $ph = implode(',', array_fill(0, count($aoIds), '?'));
        $stmt = $pdo->prepare("SELECT answerOptionID AS entityId, languageCode, text FROM answer_option_translation WHERE answerOptionID IN ($ph)");
        $stmt->execute($aoIds);
        foreach ($stmt->fetchAll(PDO::FETCH_ASSOC) as $r) {
            $translations[$r['entityId']][$r['languageCode']] = $r['text'];
        }
    }

    $sKeys = array_values(array_filter(array_map(
        fn($e) => ($e['type'] === 'string' || $e['type'] === 'app_string') ? $e['entityId'] : null,
        $entries
    )));
    if ($sKeys) {
        $ph = implode(',', array_fill(0, count($sKeys), '?'));
        $stmt = $pdo->prepare("SELECT stringKey AS entityId, languageCode, text FROM string_translation WHERE stringKey IN ($ph)");
        $stmt->execute($sKeys);
        foreach ($stmt->fetchAll(PDO::FETCH_ASSOC) as $r) {
            $translations[$r['entityId']][$r['languageCode']] = $r['text'];
        }
    }

    return $translations;
}

/**
 * Flat language -> stringKey -> text map for global app UI strings only.
 * @return array<string, array<string, string>>
 */
function qdb_build_app_translations_map(PDO $pdo): array {
    $entries = qdb_app_ui_string_entries();
    $translations = qdb_load_translations_for_entries($pdo, $entries);
    $defaults = qdb_app_string_catalog()['germanDefaults'] ?? [];
    $result = [];
    foreach ($entries as $e) {
        $key = $e['key'];
        foreach ($translations[$e['entityId']] ?? [] as $lang => $text) {
            $result[$lang][$key] = $text;
        }
        if (!isset($result[QDB_SOURCE_LANGUAGE][$key]) && !empty($defaults[$key])) {
            $result[QDB_SOURCE_LANGUAGE][$key] = $defaults[$key];
        }
    }
    return $result;
}

/**
 * Flat language -> stringKey -> text map for one questionnaire (questions, options, config strings).
 * Excludes keys from the global app UI catalog.
 * @return array<string, array<string, string>>
 */
function qdb_build_questionnaire_translations_map(PDO $pdo, string $qnID): array {
    $lists = qdb_translation_entry_lists($pdo, $qnID);
    $entries = array_merge($lists['stringEntries'], $lists['contentEntries']);
    if (!$entries) {
        return [];
    }
    $translations = qdb_load_translations_for_entries($pdo, $entries);
    $result = [];
    foreach ($entries as $e) {
        $key = $e['key'];
        foreach ($translations[$e['entityId']] ?? [] as $lang => $text) {
            $result[$lang][$key] = $text;
        }
    }
    return $result;
}

// --- AES-256-CBC: IV(16) + CIPHERTEXT ---
function aes256_cbc_encrypt_bytes(string $plain, string $key): string {
    $key = str_pad(substr($key, 0, 32), 32, "\0");
    $iv = random_bytes(16);
    $cipher = openssl_encrypt($plain, 'AES-256-CBC', $key, OPENSSL_RAW_DATA, $iv);
    if ($cipher === false) throw new Exception('openssl_encrypt failed');
    return $iv . $cipher;
}
function aes256_cbc_decrypt_bytes(string $data, string $key): string {
    if (strlen($data) < 16) throw new Exception('cipher too short');
    $key = str_pad(substr($key, 0, 32), 32, "\0");
    $iv = substr($data, 0, 16);
    $ct = substr($data, 16);
    $plain = openssl_decrypt($ct, 'AES-256-CBC', $key, OPENSSL_RAW_DATA, $iv);
    if ($plain === false) throw new Exception('openssl_decrypt failed');
    return $plain;
}