<?php
// Core configuration, persistence, authentication, entitlements, and archives.

if (!defined('ROOT_DIR')) define('ROOT_DIR', __DIR__);
if (!defined('CONFIG_FILE')) define('CONFIG_FILE', ROOT_DIR . '/config.json');

set_error_handler(function(int $errno, string $errstr, string $errfile, int $errline): bool {
    if (!(error_reporting() & $errno)) return false;
    if (defined('CYBERCHAT_API') && CYBERCHAT_API) {
        jsonResponse(['error' => 'Server error', 'detail' => basename($errfile) . ':' . $errline], 500);
    }
    return false;
});

set_exception_handler(function(Throwable $e): void {
    if (defined('CYBERCHAT_API') && CYBERCHAT_API) {
        jsonResponse(['error' => 'Server exception', 'detail' => $e->getMessage()], 500);
    }
});

function sendCorsHeaders(): void {
    $origin = $_SERVER['HTTP_ORIGIN'] ?? '';
    $allowed = (array)getConfigVal('security.allowed_origins', []);
    $hostOrigin = requestOrigin();
    if ($origin && ($origin === $hostOrigin || in_array($origin, $allowed, true))) {
        header('Access-Control-Allow-Origin: ' . $origin);
        header('Vary: Origin');
        header('Access-Control-Allow-Credentials: true');
        header('Access-Control-Allow-Methods: GET, POST, OPTIONS');
        header('Access-Control-Allow-Headers: Content-Type, X-Requested-With');
    }
    if (($_SERVER['REQUEST_METHOD'] ?? 'GET') === 'OPTIONS') {
        http_response_code(204);
        exit;
    }
}

function requestOrigin(): string {
    $https = !empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off';
    $scheme = $https ? 'https' : 'http';
    return $scheme . '://' . ($_SERVER['HTTP_HOST'] ?? 'localhost');
}

function appBaseUrl(): string {
    $configured = trim((string)getConfigVal('app.base_url', ''));
    if ($configured !== '') return rtrim($configured, '/');
    $script = str_replace('\\', '/', dirname($_SERVER['SCRIPT_NAME'] ?? '/'));
    if (str_ends_with($script, '/api')) $script = substr($script, 0, -4);
    return requestOrigin() . rtrim($script, '/');
}

function getConfig(bool $reload = false): array {
    static $config = null;
    if ($reload) $config = null;
    if ($config === null) {
        if (!file_exists(CONFIG_FILE)) throw new RuntimeException('config.json not found');
        $config = json_decode((string)file_get_contents(CONFIG_FILE), true);
        if (!is_array($config)) throw new RuntimeException('config.json is invalid: ' . json_last_error_msg());
        if (array_key_exists('groups', $config)) {
            unset($config['groups']);
            $json = json_encode($config, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES);
            if ($json !== false && is_writable(CONFIG_FILE)) {
                file_put_contents(CONFIG_FILE, $json . PHP_EOL, LOCK_EX);
            }
        }
    }
    return $config;
}

function getConfigVal(string $path, mixed $default = null): mixed {
    $value = getConfig();
    foreach (explode('.', $path) as $key) {
        if (!is_array($value) || !array_key_exists($key, $value)) return $default;
        $value = $value[$key];
    }
    return $value;
}

function setConfigValues(array $changes): void {
    $config = getConfig();
    foreach ($changes as $path => $value) {
        $keys = explode('.', $path);
        $cursor =& $config;
        foreach ($keys as $index => $key) {
            if ($index === count($keys) - 1) {
                $cursor[$key] = $value;
            } else {
                if (!isset($cursor[$key]) || !is_array($cursor[$key])) $cursor[$key] = [];
                $cursor =& $cursor[$key];
            }
        }
        unset($cursor);
    }
    $json = json_encode($config, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES);
    if ($json === false || file_put_contents(CONFIG_FILE, $json . PHP_EOL, LOCK_EX) === false) {
        throw new RuntimeException('Could not save config.json');
    }
    getConfig(true);
}

function storagePath(string $configured): string {
    $configured = trim($configured);
    if ($configured === '') throw new RuntimeException('Storage path is empty');
    if (str_starts_with($configured, '/') || preg_match('/^[A-Za-z]:[\\\\\/]/', $configured)) {
        return $configured;
    }
    return ROOT_DIR . '/' . ltrim($configured, '/\\');
}

function ensureWritableDirectory(string $dir, string $label): void {
    if (!is_dir($dir) && !@mkdir($dir, 0775, true) && !is_dir($dir)) {
        throw new RuntimeException("Cannot create $label directory: $dir");
    }
    if (!is_writable($dir)) {
        throw new RuntimeException(
            "$label directory is not writable by PHP: $dir. "
            . "Grant the web-server user write access to this directory."
        );
    }
    $probe = @tempnam($dir, '.cyberchat-write-');
    if ($probe === false) {
        throw new RuntimeException(
            "$label directory cannot create files: $dir. "
            . "Grant the web-server user ownership or write access."
        );
    }
    @unlink($probe);
}

function getDB(): PDO {
    static $db = null;
    if ($db !== null) return $db;

    $path = storagePath((string)getConfigVal('database.main_db', 'db/chat.sqlite'));
    $dir = dirname($path);
    ensureWritableDirectory($dir, 'Database');
    if (is_file($path) && !is_writable($path)) {
        throw new RuntimeException(
            "SQLite database is not writable by PHP: $path. "
            . "Grant the web-server user write access to the file and its directory."
        );
    }
    try {
        $db = new PDO('sqlite:' . $path);
    } catch (PDOException $e) {
        throw new RuntimeException(
            "SQLite cannot open $path. Confirm that PHP can write to $dir.",
            0,
            $e
        );
    }
    $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $db->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
    $db->exec('PRAGMA journal_mode=WAL');
    $db->exec('PRAGMA synchronous=NORMAL');
    $db->exec('PRAGMA foreign_keys=ON');
    initDB($db);
    maybeMirrorToMySQL($db);
    return $db;
}

function tableColumns(PDO $db, string $table): array {
    $columns = [];
    foreach ($db->query("PRAGMA table_info($table)") as $column) $columns[$column['name']] = true;
    return $columns;
}

function ensureColumns(PDO $db, string $table, array $additions): void {
    $columns = tableColumns($db, $table);
    foreach ($additions as $name => $definition) {
        if (!isset($columns[$name])) $db->exec("ALTER TABLE $table ADD COLUMN $name $definition");
    }
}

function removeLegacyGroupSchema(PDO $db, bool $mainDatabase): void {
    $messageColumns = tableColumns($db, 'messages');
    if (isset($messageColumns['group_id'])) {
        $voiceFiles = $db->query("SELECT DISTINCT voice_file FROM messages
            WHERE group_id IS NOT NULL AND voice_file IS NOT NULL AND voice_file != ''")->fetchAll(PDO::FETCH_COLUMN);
        $db->exec('PRAGMA foreign_keys=OFF');
        try {
            $db->beginTransaction();
            $db->exec("DROP TABLE IF EXISTS messages_without_groups");
            $db->exec("CREATE TABLE messages_without_groups (
                id INTEGER PRIMARY KEY" . ($mainDatabase ? ' AUTOINCREMENT' : '') . ",
                user_id INTEGER NOT NULL,
                username TEXT NOT NULL,
                color TEXT NOT NULL,
                message TEXT NOT NULL,
                message_type TEXT NOT NULL DEFAULT 'text',
                voice_file TEXT,
                voice_mime TEXT,
                voice_duration REAL,
                created_at INTEGER NOT NULL DEFAULT (strftime('%s','now')),
                day_key TEXT NOT NULL" .
                ($mainDatabase ? ", FOREIGN KEY(user_id) REFERENCES users(id)" : '') . "
            )");
            $db->exec("INSERT INTO messages_without_groups
                (id,user_id,username,color,message,message_type,voice_file,voice_mime,voice_duration,created_at,day_key)
                SELECT id,user_id,username,color,message,message_type,voice_file,voice_mime,voice_duration,created_at,day_key
                FROM messages WHERE group_id IS NULL");
            $db->exec("DROP TABLE messages");
            $db->exec("ALTER TABLE messages_without_groups RENAME TO messages");
            $db->exec("DROP TABLE IF EXISTS group_members");
            $db->exec("DROP TABLE IF EXISTS chat_groups");
            $db->commit();
            foreach ($voiceFiles as $voiceFile) deleteVoiceFile((string)$voiceFile);
        } catch (Throwable $e) {
            if ($db->inTransaction()) $db->rollBack();
            throw $e;
        } finally {
            $db->exec('PRAGMA foreign_keys=ON');
        }
    } else {
        $db->exec("DROP TABLE IF EXISTS group_members");
        $db->exec("DROP TABLE IF EXISTS chat_groups");
    }
}

function initDB(PDO $db): void {
    $db->exec("CREATE TABLE IF NOT EXISTS users (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        username TEXT UNIQUE NOT NULL COLLATE NOCASE,
        password_hash TEXT NOT NULL,
        color TEXT NOT NULL,
        email TEXT,
        email_verified_at INTEGER,
        plan_id INTEGER,
        manual_plan_id INTEGER,
        stripe_customer_id TEXT,
        stripe_subscription_id TEXT,
        subscription_status TEXT NOT NULL DEFAULT 'free',
        subscription_period_end INTEGER,
        cancel_at_period_end INTEGER NOT NULL DEFAULT 0,
        two_factor_enabled INTEGER NOT NULL DEFAULT 0,
        created_at INTEGER NOT NULL DEFAULT (strftime('%s','now')),
        last_seen INTEGER
    )");
    ensureColumns($db, 'users', [
        'email' => 'TEXT',
        'email_verified_at' => 'INTEGER',
        'plan_id' => 'INTEGER',
        'manual_plan_id' => 'INTEGER',
        'stripe_customer_id' => 'TEXT',
        'stripe_subscription_id' => 'TEXT',
        'subscription_status' => "TEXT NOT NULL DEFAULT 'free'",
        'subscription_period_end' => 'INTEGER',
        'cancel_at_period_end' => 'INTEGER NOT NULL DEFAULT 0',
        'two_factor_enabled' => 'INTEGER NOT NULL DEFAULT 0',
    ]);

    $db->exec("CREATE TABLE IF NOT EXISTS sessions (
        id TEXT PRIMARY KEY,
        user_id INTEGER NOT NULL,
        ip TEXT NOT NULL,
        created_at INTEGER NOT NULL DEFAULT (strftime('%s','now')),
        last_active INTEGER NOT NULL DEFAULT (strftime('%s','now')),
        FOREIGN KEY(user_id) REFERENCES users(id) ON DELETE CASCADE
    )");

    $db->exec("CREATE TABLE IF NOT EXISTS messages (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        user_id INTEGER NOT NULL,
        username TEXT NOT NULL,
        color TEXT NOT NULL,
        message TEXT NOT NULL,
        message_type TEXT NOT NULL DEFAULT 'text',
        voice_file TEXT,
        voice_mime TEXT,
        voice_duration REAL,
        created_at INTEGER NOT NULL DEFAULT (strftime('%s','now')),
        day_key TEXT NOT NULL,
        FOREIGN KEY(user_id) REFERENCES users(id)
    )");
    ensureColumns($db, 'messages', [
        'message_type' => "TEXT NOT NULL DEFAULT 'text'",
        'voice_file' => 'TEXT',
        'voice_mime' => 'TEXT',
        'voice_duration' => 'REAL',
    ]);
    removeLegacyGroupSchema($db, true);

    $db->exec("CREATE TABLE IF NOT EXISTS plans (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        slug TEXT UNIQUE NOT NULL,
        name TEXT NOT NULL,
        description TEXT NOT NULL DEFAULT '',
        price_cents INTEGER NOT NULL DEFAULT 0,
        currency TEXT NOT NULL DEFAULT 'usd',
        billing_interval TEXT NOT NULL DEFAULT 'month',
        stripe_price_id TEXT,
        active INTEGER NOT NULL DEFAULT 1,
        sort_order INTEGER NOT NULL DEFAULT 0,
        created_at INTEGER NOT NULL,
        updated_at INTEGER NOT NULL
    )");
    $db->exec("CREATE TABLE IF NOT EXISTS plan_features (
        plan_id INTEGER NOT NULL,
        feature_key TEXT NOT NULL,
        value_json TEXT NOT NULL,
        PRIMARY KEY(plan_id, feature_key),
        FOREIGN KEY(plan_id) REFERENCES plans(id) ON DELETE CASCADE
    )");
    $db->exec("CREATE TABLE IF NOT EXISTS subscriptions (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        user_id INTEGER UNIQUE NOT NULL,
        plan_id INTEGER,
        stripe_customer_id TEXT,
        stripe_subscription_id TEXT UNIQUE,
        status TEXT NOT NULL DEFAULT 'free',
        current_period_end INTEGER,
        cancel_at_period_end INTEGER NOT NULL DEFAULT 0,
        updated_at INTEGER NOT NULL,
        FOREIGN KEY(user_id) REFERENCES users(id) ON DELETE CASCADE,
        FOREIGN KEY(plan_id) REFERENCES plans(id)
    )");
    $db->exec("CREATE TABLE IF NOT EXISTS email_tokens (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        user_id INTEGER NOT NULL,
        email TEXT NOT NULL,
        purpose TEXT NOT NULL,
        token_hash TEXT NOT NULL,
        code_hash TEXT NOT NULL,
        expires_at INTEGER NOT NULL,
        attempts INTEGER NOT NULL DEFAULT 0,
        used_at INTEGER,
        created_at INTEGER NOT NULL,
        FOREIGN KEY(user_id) REFERENCES users(id) ON DELETE CASCADE
    )");
    ensureColumns($db, 'email_tokens', [
        'attempts' => 'INTEGER NOT NULL DEFAULT 0',
    ]);
    $db->exec("CREATE TABLE IF NOT EXISTS login_challenges (
        id TEXT PRIMARY KEY,
        user_id INTEGER NOT NULL,
        code_hash TEXT NOT NULL,
        expires_at INTEGER NOT NULL,
        attempts INTEGER NOT NULL DEFAULT 0,
        created_at INTEGER NOT NULL,
        FOREIGN KEY(user_id) REFERENCES users(id) ON DELETE CASCADE
    )");
    $recordingColumns = tableColumns($db, 'recording_status');
    if ($recordingColumns && !isset($recordingColumns['channel_key'])) {
        $db->exec("DROP TABLE recording_status");
    }
    $db->exec("CREATE TABLE IF NOT EXISTS recording_status (
        channel_key TEXT NOT NULL,
        user_id INTEGER NOT NULL,
        expires_at INTEGER NOT NULL,
        PRIMARY KEY(channel_key, user_id),
        FOREIGN KEY(user_id) REFERENCES users(id) ON DELETE CASCADE
    )");
    $db->exec("CREATE TABLE IF NOT EXISTS visitor_events (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        user_id INTEGER,
        event_type TEXT NOT NULL,
        path TEXT NOT NULL DEFAULT '',
        ip_hash TEXT NOT NULL,
        user_agent TEXT NOT NULL DEFAULT '',
        created_at INTEGER NOT NULL,
        FOREIGN KEY(user_id) REFERENCES users(id) ON DELETE SET NULL
    )");
    $db->exec("CREATE TABLE IF NOT EXISTS stripe_events (
        event_id TEXT PRIMARY KEY,
        event_type TEXT NOT NULL,
        received_at INTEGER NOT NULL
    )");

    $db->exec("CREATE INDEX IF NOT EXISTS idx_msg_day ON messages(day_key)");
    $db->exec("CREATE INDEX IF NOT EXISTS idx_msg_user_created ON messages(user_id, created_at)");
    $db->exec("CREATE INDEX IF NOT EXISTS idx_sess_user ON sessions(user_id)");
    $db->exec("CREATE INDEX IF NOT EXISTS idx_sess_active ON sessions(last_active)");
    $db->exec("CREATE INDEX IF NOT EXISTS idx_event_created ON visitor_events(created_at)");
    $db->exec("CREATE UNIQUE INDEX IF NOT EXISTS idx_users_email ON users(email) WHERE email IS NOT NULL");

    seedPlans($db);
}

function seedPlans(PDO $db): void {
    $now = time();
    $defaults = [
        'free' => [
            'name' => 'Free', 'description' => 'Core chat and 30-day personal text history.',
            'price' => 0, 'sort' => 0,
            'features' => [
                'voice_messages' => true, 'recording_status' => false, 'auto_voice_send' => false,
                'auto_voice_play' => false, 'username_color' => false, 'text_archive_days' => 30,
                'text_export' => true, 'voice_archive' => false, 'voice_export' => false, 'email_2fa' => false,
            ],
        ],
        'plus' => [
            'name' => 'Plus', 'description' => 'Premium voice, identity, security, and 90-day personal archives.',
            'price' => 499, 'sort' => 10,
            'features' => [
                'voice_messages' => true, 'recording_status' => true, 'auto_voice_send' => true,
                'auto_voice_play' => true, 'username_color' => true, 'text_archive_days' => 90,
                'text_export' => true, 'voice_archive' => true, 'voice_export' => true, 'email_2fa' => true,
            ],
        ],
        'pro' => [
            'name' => 'Pro', 'description' => 'Premium voice, security, and one year of personal archives.',
            'price' => 999, 'sort' => 20,
            'features' => [
                'voice_messages' => true, 'recording_status' => true, 'auto_voice_send' => true,
                'auto_voice_play' => true, 'username_color' => true, 'text_archive_days' => 365,
                'text_export' => true, 'voice_archive' => true, 'voice_export' => true, 'email_2fa' => true,
            ],
        ],
    ];

    $insertPlan = $db->prepare("INSERT OR IGNORE INTO plans
        (slug,name,description,price_cents,currency,billing_interval,active,sort_order,created_at,updated_at)
        VALUES (?,?,?,?,?,?,?,?,?,?)");
    $insertFeature = $db->prepare("INSERT OR IGNORE INTO plan_features (plan_id,feature_key,value_json) VALUES (?,?,?)");
    foreach ($defaults as $slug => $plan) {
        $insertPlan->execute([$slug, $plan['name'], $plan['description'], $plan['price'], 'usd', 'month', 1, $plan['sort'], $now, $now]);
        $stmt = $db->prepare("SELECT id FROM plans WHERE slug = ?");
        $stmt->execute([$slug]);
        $planId = (int)$stmt->fetchColumn();
        foreach ($plan['features'] as $key => $value) {
            $insertFeature->execute([$planId, $key, json_encode($value)]);
        }
    }
    $db->exec("DELETE FROM plan_features WHERE feature_key LIKE 'group%'");
    $db->exec("UPDATE plans SET description='Configurable premium chat features.'
        WHERE lower(description) LIKE '%group%'");
    $freeId = (int)$db->query("SELECT id FROM plans WHERE slug = 'free'")->fetchColumn();
    $db->prepare("UPDATE users SET plan_id = ? WHERE plan_id IS NULL")->execute([$freeId]);
}

function plans(bool $activeOnly = false): array {
    $db = getDB();
    $sql = "SELECT * FROM plans" . ($activeOnly ? " WHERE active = 1" : "") . " ORDER BY sort_order, price_cents, id";
    $rows = $db->query($sql)->fetchAll();
    $featureStmt = $db->prepare("SELECT feature_key,value_json FROM plan_features WHERE plan_id = ?");
    foreach ($rows as &$row) {
        $featureStmt->execute([$row['id']]);
        $row['features'] = [];
        foreach ($featureStmt->fetchAll() as $feature) {
            $row['features'][$feature['feature_key']] = json_decode($feature['value_json'], true);
        }
        $row['features'] = visiblePlanFeatures($row['features']);
        $row['id'] = (int)$row['id'];
        $row['price_cents'] = (int)$row['price_cents'];
        $row['active'] = (bool)$row['active'];
    }
    return $rows;
}

function visiblePlanFeatures(array $features): array {
    return array_filter(
        $features,
        fn(string $key): bool => !str_starts_with(strtolower($key), 'group'),
        ARRAY_FILTER_USE_KEY
    );
}

function planById(int $planId): ?array {
    foreach (plans(false) as $plan) if ($plan['id'] === $planId) return $plan;
    return null;
}

function userPlan(array $user): array {
    $free = null;
    $effectivePlanId = (int)($user['manual_plan_id'] ?? 0) ?: (int)($user['plan_id'] ?? 0);
    foreach (plans(false) as $plan) {
        if ($plan['slug'] === 'free') $free = $plan;
        if ($effectivePlanId === $plan['id']) return $plan;
    }
    return $free ?? ['id' => 0, 'slug' => 'free', 'name' => 'Free', 'features' => []];
}

function featureValue(array $user, string $key, mixed $default = false): mixed {
    $plan = userPlan($user);
    return array_key_exists($key, $plan['features']) ? $plan['features'][$key] : $default;
}

function userPublicPayload(array $user): array {
    $plan = userPlan($user);
    return [
        'id' => (int)$user['id'],
        'username' => $user['username'],
        'color' => $user['color'],
        'email' => $user['email'] ?? null,
        'email_verified' => !empty($user['email_verified_at']),
        'plan' => ['id' => $plan['id'], 'slug' => $plan['slug'], 'name' => $plan['name']],
        'plan_source' => !empty($user['manual_plan_id']) ? 'admin' : 'billing',
        'features' => visiblePlanFeatures($plan['features']),
        'subscription' => [
            'status' => $user['subscription_status'] ?? 'free',
            'period_end' => isset($user['subscription_period_end']) ? (int)$user['subscription_period_end'] : null,
            'cancel_at_period_end' => !empty($user['cancel_at_period_end']),
            'manageable' => !empty($user['stripe_customer_id']),
        ],
        'two_factor_enabled' => !empty($user['two_factor_enabled']),
    ];
}

function userById(int $id): ?array {
    $stmt = getDB()->prepare("SELECT * FROM users WHERE id = ?");
    $stmt->execute([$id]);
    return $stmt->fetch() ?: null;
}

function clientIP(): string {
    foreach (['HTTP_CF_CONNECTING_IP', 'HTTP_X_FORWARDED_FOR', 'HTTP_X_REAL_IP', 'REMOTE_ADDR'] as $key) {
        if (!empty($_SERVER[$key])) {
            $ip = trim(explode(',', (string)$_SERVER[$key])[0]);
            if (filter_var($ip, FILTER_VALIDATE_IP)) return $ip;
        }
    }
    return '0.0.0.0';
}

function jsonResponse(array $data, int $code = 200): never {
    http_response_code($code);
    header('Content-Type: application/json; charset=utf-8');
    header('Cache-Control: no-store');
    echo json_encode($data, JSON_UNESCAPED_SLASHES);
    exit;
}

function authUser(bool $required = true): ?array {
    $sid = $_COOKIE['cyberchat_sid'] ?? '';
    if ($sid === '') {
        if ($required) jsonResponse(['error' => 'Not authenticated'], 401);
        return null;
    }
    $cutoff = time() - ((int)getConfigVal('security.session_timeout_hours', 24) * 3600);
    $stmt = getDB()->prepare("SELECT s.id AS session_id,s.ip,s.last_active,u.*
        FROM sessions s JOIN users u ON u.id=s.user_id WHERE s.id=? AND s.last_active>?");
    $stmt->execute([$sid, $cutoff]);
    $user = $stmt->fetch();
    if (!$user) {
        if ($required) jsonResponse(['error' => 'Session expired'], 401);
        return null;
    }
    if (getConfigVal('chat.session_lock_ip', true) && $user['ip'] !== clientIP()) {
        if ($required) jsonResponse(['error' => 'Session IP mismatch'], 401);
        return null;
    }
    getDB()->prepare("UPDATE sessions SET last_active=? WHERE id=?")->execute([time(), $sid]);
    return $user;
}

function authRequired(): array {
    $user = authUser(true);
    $user['uid'] = $user['id'];
    return $user;
}

function createUserSession(PDO $db, int $userId): void {
    $sid = bin2hex(random_bytes(32));
    $db->prepare("DELETE FROM sessions WHERE user_id=?")->execute([$userId]);
    $db->prepare("INSERT INTO sessions (id,user_id,ip,created_at,last_active) VALUES (?,?,?,?,?)")
        ->execute([$sid, $userId, clientIP(), time(), time()]);
    $db->prepare("UPDATE users SET last_seen=? WHERE id=?")->execute([time(), $userId]);
    $secure = !empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off';
    setcookie('cyberchat_sid', $sid, [
        'expires' => time() + ((int)getConfigVal('security.session_timeout_hours', 24) * 3600),
        'path' => '/', 'httponly' => true, 'samesite' => 'Strict', 'secure' => $secure,
    ]);
}

function dayKey(): string {
    return date('Y-m-d');
}

function voiceUploadDir(): string {
    return storagePath((string)getConfigVal('voice.upload_dir', 'uploads/voice'));
}

function voicePublicPath(string $filename): string {
    return trim((string)getConfigVal('voice.upload_dir', 'uploads/voice'), '/') . '/' . rawurlencode($filename);
}

function deleteVoiceFile(?string $filename): void {
    if (!$filename || basename($filename) !== $filename) return;
    $path = voiceUploadDir() . '/' . $filename;
    if (is_file($path)) unlink($path);
}

function getArchiveDB(string $year, string $month, string $day): PDO {
    $template = (string)getConfigVal('database.archive_path', 'archive/{year}/{month}/{day}.sqlite');
    $relative = str_replace(['{year}', '{month}', '{day}'], [$year, $month, $day], $template);
    $path = storagePath($relative);
    ensureWritableDirectory(dirname($path), 'Archive');
    $db = new PDO('sqlite:' . $path);
    $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $db->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);
    $db->exec('PRAGMA journal_mode=WAL');
    $db->exec("CREATE TABLE IF NOT EXISTS messages (
        id INTEGER PRIMARY KEY, user_id INTEGER NOT NULL,
        username TEXT NOT NULL,color TEXT NOT NULL,message TEXT NOT NULL,
        message_type TEXT NOT NULL DEFAULT 'text',voice_file TEXT,voice_mime TEXT,
        voice_duration REAL,created_at INTEGER NOT NULL,day_key TEXT NOT NULL
    )");
    ensureColumns($db, 'messages', [
        'message_type' => "TEXT NOT NULL DEFAULT 'text'",
        'voice_file' => 'TEXT', 'voice_mime' => 'TEXT', 'voice_duration' => 'REAL',
    ]);
    removeLegacyGroupSchema($db, false);
    $db->exec("CREATE TABLE IF NOT EXISTS archive_meta (key TEXT PRIMARY KEY,value TEXT)");
    $db->exec("CREATE INDEX IF NOT EXISTS idx_archive_user ON messages(user_id,created_at)");
    return $db;
}

function archiveFilesSince(int $cutoff): array {
    $root = storagePath((string)getConfigVal('archive.archive_dir', 'archive'));
    $files = [];
    if (!is_dir($root)) return $files;
    foreach (glob($root . '/*/*/*.sqlite') ?: [] as $file) {
        if (!preg_match('~/(\d{4})/(\d{2})/(\d{2})\.sqlite$~', $file, $m)) continue;
        $dayTs = strtotime($m[1] . '-' . $m[2] . '-' . $m[3] . ' 23:59:59');
        if ($dayTs !== false && $dayTs >= $cutoff) $files[] = [$file, $m[1], $m[2], $m[3]];
    }
    return $files;
}

function archiveYesterdayIfNeeded(): void {
    if (!getConfigVal('archive.enabled', true)) return;
    $yesterday = date('Y-m-d', strtotime('-1 day'));
    $flag = ROOT_DIR . '/db/.archived_' . $yesterday;
    if (file_exists($flag)) return;
    $db = getDB();
    $stmt = $db->prepare("SELECT * FROM messages WHERE day_key=? ORDER BY id");
    $stmt->execute([$yesterday]);
    $rows = $stmt->fetchAll();
    if ($rows) {
        [$year, $month, $day] = explode('-', $yesterday);
        $archive = getArchiveDB($year, $month, $day);
        $archive->beginTransaction();
        $insert = $archive->prepare("INSERT OR IGNORE INTO messages
            (id,user_id,username,color,message,message_type,voice_file,voice_mime,voice_duration,created_at,day_key)
            VALUES (?,?,?,?,?,?,?,?,?,?,?)");
        foreach ($rows as $row) {
            $insert->execute([
                $row['id'], $row['user_id'], $row['username'], $row['color'],
                $row['message'], $row['message_type'], $row['voice_file'], $row['voice_mime'],
                $row['voice_duration'], $row['created_at'], $row['day_key'],
            ]);
        }
        $meta = $archive->prepare("INSERT OR REPLACE INTO archive_meta(key,value) VALUES (?,?)");
        $meta->execute(['archived_at', (string)time()]);
        $meta->execute(['message_count', (string)count($rows)]);
        $archive->commit();
    }
    $db->prepare("DELETE FROM messages WHERE day_key=?")->execute([$yesterday]);
    file_put_contents($flag, date('c'), LOCK_EX);
}

function personalArchiveRows(array $user, string $search = '', int $limit = 500): array {
    $days = max(30, (int)featureValue($user, 'text_archive_days', 30));
    $cutoff = time() - ($days * 86400);
    $includeVoice = (bool)featureValue($user, 'voice_archive', false);
    $rows = [];
    $db = getDB();
    $sql = "SELECT * FROM messages WHERE user_id=? AND created_at>=?";
    $params = [$user['id'], $cutoff];
    if (!$includeVoice) $sql .= " AND message_type='text'";
    if ($search !== '') { $sql .= " AND message LIKE ?"; $params[] = '%' . $search . '%'; }
    $stmt = $db->prepare($sql . " ORDER BY created_at DESC LIMIT ?");
    $params[] = $limit;
    $stmt->execute($params);
    $rows = $stmt->fetchAll();

    foreach (archiveFilesSince($cutoff) as [, $year, $month, $day]) {
        $archive = getArchiveDB($year, $month, $day);
        $archiveSql = "SELECT * FROM messages WHERE user_id=? AND created_at>=?";
        $archiveParams = [$user['id'], $cutoff];
        if (!$includeVoice) $archiveSql .= " AND message_type='text'";
        if ($search !== '') { $archiveSql .= " AND message LIKE ?"; $archiveParams[] = '%' . $search . '%'; }
        $archiveStmt = $archive->prepare($archiveSql . " ORDER BY created_at DESC LIMIT ?");
        $archiveParams[] = $limit;
        $archiveStmt->execute($archiveParams);
        array_push($rows, ...$archiveStmt->fetchAll());
    }
    usort($rows, fn(array $a, array $b): int => ((int)$b['created_at'] <=> (int)$a['created_at']));
    return array_slice($rows, 0, $limit);
}

function trackEvent(string $type, string $path = '', ?int $userId = null): void {
    if (!getConfigVal('stats.enabled', true)) return;
    $salt = (string)getConfigVal('stats.ip_hash_salt', 'change-this-stat-salt');
    $ipHash = hash('sha256', $salt . '|' . clientIP());
    $agent = substr((string)($_SERVER['HTTP_USER_AGENT'] ?? ''), 0, 255);
    getDB()->prepare("INSERT INTO visitor_events (user_id,event_type,path,ip_hash,user_agent,created_at)
        VALUES (?,?,?,?,?,?)")->execute([$userId, $type, substr($path, 0, 255), $ipHash, $agent, time()]);
}

function maybeMirrorToMySQL(PDO $sqlite): void {
    if (!getConfigVal('database.mysql.enabled', false) || !getConfigVal('database.mysql.auto_import', false)) return;
    static $running = false;
    if ($running) return;
    $flag = ROOT_DIR . '/db/.mysql_mirror';
    $interval = max(60, (int)getConfigVal('database.mysql.sync_interval_seconds', 900));
    if (is_file($flag) && filemtime($flag) > time() - $interval) return;
    $running = true;
    try {
        require_once ROOT_DIR . '/lib/mysql_mirror.php';
        mirrorAllSQLiteDatabases();
        file_put_contents($flag, (string)time(), LOCK_EX);
    } catch (Throwable $e) {
        error_log('CyberChat MySQL mirror failed: ' . $e->getMessage());
    } finally {
        $running = false;
    }
}