<?php

/**
 * This file is part of CodeIgniter 4 framework.
 *
 * (c) CodeIgniter Foundation <admin@codeigniter.com>
 *
 * For the full copyright and license information, please view
 * the LICENSE file that was distributed with this source code.
 */

namespace CodeIgniter\Session;

use CodeIgniter\Cookie\Cookie;
use CodeIgniter\I18n\Time;
use Config\Cookie as CookieConfig;
use Config\Services;
use Config\Session as SessionConfig;
use Psr\Log\LoggerAwareTrait;
use SessionHandlerInterface;

/**
 * Implementation of CodeIgniter session container.
 *
 * Session configuration is done through session variables and cookie related
 * variables in app/config/App.php
 *
 * @property string $session_id
 * @see \CodeIgniter\Session\SessionTest
 */
class Session implements SessionInterface
{
    use LoggerAwareTrait;

    /**
     * Instance of the driver to use.
     *
     * @var SessionHandlerInterface
     */
    protected $driver;

    /**
     * The storage driver to use: files, database, redis, memcached
     *
     * @var string
     *
     * @deprecated Use $this->config->driver.
     */
    protected $sessionDriverName;

    /**
     * The session cookie name, must contain only [0-9a-z_-] characters.
     *
     * @var string
     *
     * @deprecated Use $this->config->cookieName.
     */
    protected $sessionCookieName = 'ci_session';

    /**
     * The number of SECONDS you want the session to last.
     * Setting it to 0 (zero) means expire when the browser is closed.
     *
     * @var int
     *
     * @deprecated Use $this->config->expiration.
     */
    protected $sessionExpiration = 7200;

    /**
     * The location to save sessions to, driver dependent.
     *
     * For the 'files' driver, it's a path to a writable directory.
     * WARNING: Only absolute paths are supported!
     *
     * For the 'database' driver, it's a table name.
     *
     * @todo address memcache & redis needs
     *
     * IMPORTANT: You are REQUIRED to set a valid save path!
     *
     * @var string
     *
     * @deprecated Use $this->config->savePath.
     */
    protected $sessionSavePath;

    /**
     * Whether to match the user's IP address when reading the session data.
     *
     * WARNING: If you're using the database driver, don't forget to update
     * your session table's PRIMARY KEY when changing this setting.
     *
     * @var bool
     *
     * @deprecated Use $this->config->matchIP.
     */
    protected $sessionMatchIP = false;

    /**
     * How many seconds between CI regenerating the session ID.
     *
     * @var int
     *
     * @deprecated Use $this->config->timeToUpdate.
     */
    protected $sessionTimeToUpdate = 300;

    /**
     * Whether to destroy session data associated with the old session ID
     * when auto-regenerating the session ID. When set to FALSE, the data
     * will be later deleted by the garbage collector.
     *
     * @var bool
     *
     * @deprecated Use $this->config->regenerateDestroy.
     */
    protected $sessionRegenerateDestroy = false;

    /**
     * The session cookie instance.
     *
     * @var Cookie
     */
    protected $cookie;

    /**
     * The domain name to use for cookies.
     * Set to .your-domain.com for site-wide cookies.
     *
     * @var string
     *
     * @deprecated No longer used.
     */
    protected $cookieDomain = '';

    /**
     * Path used for storing cookies.
     * Typically will be a forward slash.
     *
     * @var string
     *
     * @deprecated No longer used.
     */
    protected $cookiePath = '/';

    /**
     * Cookie will only be set if a secure HTTPS connection exists.
     *
     * @var bool
     *
     * @deprecated No longer used.
     */
    protected $cookieSecure = false;

    /**
     * Cookie SameSite setting as described in RFC6265
     * Must be 'None', 'Lax' or 'Strict'.
     *
     * @var string
     *
     * @deprecated No longer used.
     */
    protected $cookieSameSite = Cookie::SAMESITE_LAX;

    /**
     * sid regex expression
     *
     * @var string
     */
    protected $sidRegexp;

    /**
     * Session Config
     */
    protected SessionConfig $config;

    /**
     * Constructor.
     *
     * Extract configuration settings and save them here.
     */
    public function __construct(SessionHandlerInterface $driver, SessionConfig $config)
    {
        $this->driver = $driver;

        $this->config = $config;

        $cookie = config(CookieConfig::class);

        $this->cookie = (new Cookie($this->config->cookieName, '', [
            'expires'  => $this->config->expiration === 0 ? 0 : Time::now()->getTimestamp() + $this->config->expiration,
            'path'     => $cookie->path,
            'domain'   => $cookie->domain,
            'secure'   => $cookie->secure,
            'httponly' => true, // for security
            'samesite' => $cookie->samesite ?? Cookie::SAMESITE_LAX,
            'raw'      => $cookie->raw ?? false,
        ]))->withPrefix(''); // Cookie prefix should be ignored.

        helper('array');
    }

    /**
     * Initialize the session container and starts up the session.
     *
     * @return $this|void
     */
    public function start()
    {
        if (is_cli() && ENVIRONMENT !== 'testing') {
            // @codeCoverageIgnoreStart
            $this->logger->debug('Session: Initialization under CLI aborted.');

            return;
            // @codeCoverageIgnoreEnd
        }

        if ((bool) ini_get('session.auto_start')) {
            $this->logger->error('Session: session.auto_start is enabled in php.ini. Aborting.');

            return;
        }

        if (session_status() === PHP_SESSION_ACTIVE) {
            $this->logger->warning('Session: Sessions is enabled, and one exists. Please don\'t $session->start();');

            return;
        }

        $this->configure();
        $this->setSaveHandler();

        // Sanitize the cookie, because apparently PHP doesn't do that for userspace handlers
        if (isset($_COOKIE[$this->config->cookieName])
            && (! is_string($_COOKIE[$this->config->cookieName]) || ! preg_match('#\A' . $this->sidRegexp . '\z#', $_COOKIE[$this->config->cookieName]))
        ) {
            unset($_COOKIE[$this->config->cookieName]);
        }

        $this->startSession();

        // Is session ID auto-regeneration configured? (ignoring ajax requests)
        if ((empty($_SERVER['HTTP_X_REQUESTED_WITH']) || strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) !== 'xmlhttprequest')
            && ($regenerateTime = $this->config->timeToUpdate) > 0
        ) {
            if (! isset($_SESSION['__ci_last_regenerate'])) {
                $_SESSION['__ci_last_regenerate'] = Time::now()->getTimestamp();
            } elseif ($_SESSION['__ci_last_regenerate'] < (Time::now()->getTimestamp() - $regenerateTime)) {
                $this->regenerate((bool) $this->config->regenerateDestroy);
            }
        }
        // Another work-around ... PHP doesn't seem to send the session cookie
        // unless it is being currently created or regenerated
        elseif (isset($_COOKIE[$this->config->cookieName]) && $_COOKIE[$this->config->cookieName] === session_id()) {
            $this->setCookie();
        }

        $this->initVars();
        $this->logger->info("Session: Class initialized using '" . $this->config->driver . "' driver.");

        return $this;
    }

    /**
     * Destroys the current session.
     *
     * @deprecated Use destroy() instead.
     */
    public function stop()
    {
        $this->destroy();
    }

    /**
     * Configuration.
     *
     * Handle input binds and configuration defaults.
     */
    protected function configure()
    {
        ini_set('session.name', $this->config->cookieName);

        $sameSite = $this->cookie->getSameSite() ?: ucfirst(Cookie::SAMESITE_LAX);

        $params = [
            'lifetime' => $this->config->expiration,
            'path'     => $this->cookie->getPath(),
            'domain'   => $this->cookie->getDomain(),
            'secure'   => $this->cookie->isSecure(),
            'httponly' => true, // HTTP only; Yes, this is intentional and not configurable for security reasons.
            'samesite' => $sameSite,
        ];

        ini_set('session.cookie_samesite', $sameSite);
        session_set_cookie_params($params);

        if ($this->config->expiration > 0) {
            ini_set('session.gc_maxlifetime', (string) $this->config->expiration);
        }

        if (! empty($this->config->savePath)) {
            ini_set('session.save_path', $this->config->savePath);
        }

        // Security is king
        ini_set('session.use_trans_sid', '0');
        ini_set('session.use_strict_mode', '1');
        ini_set('session.use_cookies', '1');
        ini_set('session.use_only_cookies', '1');

        $this->configureSidLength();
    }

    /**
     * Configure session ID length
     *
     * To make life easier, we used to force SHA-1 and 4 bits per
     * character on everyone. And of course, someone was unhappy.
     *
     * Then PHP 7.1 broke backwards-compatibility because ext/session
     * is such a mess that nobody wants to touch it with a pole stick,
     * and the one guy who does, nobody has the energy to argue with.
     *
     * So we were forced to make changes, and OF COURSE something was
     * going to break and now we have this pile of shit. -- Narf
     */
    protected function configureSidLength()
    {
        $bitsPerCharacter = (int) (ini_get('session.sid_bits_per_character') !== false
            ? ini_get('session.sid_bits_per_character')
            : 4);

        $sidLength = (int) (ini_get('session.sid_length') !== false
            ? ini_get('session.sid_length')
            : 40);

        if (($sidLength * $bitsPerCharacter) < 160) {
            $bits = ($sidLength * $bitsPerCharacter);
            // Add as many more characters as necessary to reach at least 160 bits
            $sidLength += (int) ceil((160 % $bits) / $bitsPerCharacter);
            ini_set('session.sid_length', (string) $sidLength);
        }

        // Yes, 4,5,6 are the only known possible values as of 2016-10-27
        switch ($bitsPerCharacter) {
            case 4:
                $this->sidRegexp = '[0-9a-f]';
                break;

            case 5:
                $this->sidRegexp = '[0-9a-v]';
                break;

            case 6:
                $this->sidRegexp = '[0-9a-zA-Z,-]';
                break;
        }

        $this->sidRegexp .= '{' . $sidLength . '}';
    }

    /**
     * Handle temporary variables
     *
     * Clears old "flash" data, marks the new one for deletion and handles
     * "temp" data deletion.
     */
    protected function initVars()
    {
        if (empty($_SESSION['__ci_vars'])) {
            return;
        }

        $currentTime = Time::now()->getTimestamp();

        foreach ($_SESSION['__ci_vars'] as $key => &$value) {
            if ($value === 'new') {
                $_SESSION['__ci_vars'][$key] = 'old';
            }
            // DO NOT move this above the 'new' check!
            elseif ($value === 'old' || $value < $currentTime) {
                unset($_SESSION[$key], $_SESSION['__ci_vars'][$key]);
            }
        }

        if (empty($_SESSION['__ci_vars'])) {
            unset($_SESSION['__ci_vars']);
        }
    }

    /**
     * Regenerates the session ID.
     *
     * @param bool $destroy Should old session data be destroyed?
     */
    public function regenerate(bool $destroy = false)
    {
        $_SESSION['__ci_last_regenerate'] = Time::now()->getTimestamp();
        session_regenerate_id($destroy);

        $this->removeOldSessionCookie();
    }

    private function removeOldSessionCookie(): void
    {
        $response              = Services::response();
        $cookieStoreInResponse = $response->getCookieStore();

        if (! $cookieStoreInResponse->has($this->config->cookieName)) {
            return;
        }

        // CookieStore is immutable.
        $newCookieStore = $cookieStoreInResponse->remove($this->config->cookieName);

        // But clear() method clears cookies in the object (not immutable).
        $cookieStoreInResponse->clear();

        foreach ($newCookieStore as $cookie) {
            $response->setCookie($cookie);
        }
    }

    /**
     * Destroys the current session.
     */
    public function destroy()
    {
        if (ENVIRONMENT === 'testing') {
            return;
        }

        session_destroy();
    }

    /**
     * Writes session data and close the current session.
     *
     * @return void
     */
    public function close()
    {
        if (ENVIRONMENT === 'testing') {
            return;
        }

        session_write_close();
    }

    /**
     * Sets user data into the session.
     *
     * If $data is a string, then it is interpreted as a session property
     * key, and  $value is expected to be non-null.
     *
     * If $data is an array, it is expected to be an array of key/value pairs
     * to be set as session properties.
     *
     * @param array|string                            $data  Property name or associative array of properties
     * @param array|bool|float|int|object|string|null $value Property value if single key provided
     */
    public function set($data, $value = null)
    {
        if (is_array($data)) {
            foreach ($data as $key => &$value) {
                if (is_int($key)) {
                    $_SESSION[$value] = null;
                } else {
                    $_SESSION[$key] = $value;
                }
            }

            return;
        }

        $_SESSION[$data] = $value;
    }

    /**
     * Get user data that has been set in the session.
     *
     * If the property exists as "normal", returns it.
     * Otherwise, returns an array of any temp or flash data values with the
     * property key.
     *
     * Replaces the legacy method $session->userdata();
     *
     * @param string|null $key Identifier of the session property to retrieve
     *
     * @return array|bool|float|int|object|string|null The property value(s)
     */
    public function get(?string $key = null)
    {
        if (! empty($key) && (null !== ($value = $_SESSION[$key] ?? null) || null !== ($value = dot_array_search($key, $_SESSION ?? [])))) {
            return $value;
        }

        if (empty($_SESSION)) {
            return $key === null ? [] : null;
        }

        if (! empty($key)) {
            return null;
        }

        $userdata = [];
        $_exclude = array_merge(['__ci_vars'], $this->getFlashKeys(), $this->getTempKeys());

        $keys = array_keys($_SESSION);

        foreach ($keys as $key) {
            if (! in_array($key, $_exclude, true)) {
                $userdata[$key] = $_SESSION[$key];
            }
        }

        return $userdata;
    }

    /**
     * Returns whether an index exists in the session array.
     *
     * @param string $key Identifier of the session property we are interested in.
     */
    public function has(string $key): bool
    {
        return isset($_SESSION[$key]);
    }

    /**
     * Push new value onto session value that is array.
     *
     * @param string $key  Identifier of the session property we are interested in.
     * @param array  $data value to be pushed to existing session key.
     */
    public function push(string $key, array $data)
    {
        if ($this->has($key) && is_array($value = $this->get($key))) {
            $this->set($key, array_merge($value, $data));
        }
    }

    /**
     * Remove one or more session properties.
     *
     * If $key is an array, it is interpreted as an array of string property
     * identifiers to remove. Otherwise, it is interpreted as the identifier
     * of a specific session property to remove.
     *
     * @param array|string $key Identifier of the session property or properties to remove.
     */
    public function remove($key)
    {
        if (is_array($key)) {
            foreach ($key as $k) {
                unset($_SESSION[$k]);
            }

            return;
        }

        unset($_SESSION[$key]);
    }

    /**
     * Magic method to set variables in the session by simply calling
     *  $session->foo = bar;
     *
     * @param string       $key   Identifier of the session property to set.
     * @param array|string $value
     */
    public function __set(string $key, $value)
    {
        $_SESSION[$key] = $value;
    }

    /**
     * Magic method to get session variables by simply calling
     *  $foo = $session->foo;
     *
     * @param string $key Identifier of the session property to remove.
     *
     * @return string|null
     */
    public function __get(string $key)
    {
        // Note: Keep this order the same, just in case somebody wants to
        // use 'session_id' as a session data key, for whatever reason
        if (isset($_SESSION[$key])) {
            return $_SESSION[$key];
        }

        if ($key === 'session_id') {
            return session_id();
        }

        return null;
    }

    /**
     * Magic method to check for session variables.
     * Different from has() in that it will validate 'session_id' as well.
     * Mostly used by internal PHP functions, users should stick to has()
     *
     * @param string $key Identifier of the session property to remove.
     */
    public function __isset(string $key): bool
    {
        return isset($_SESSION[$key]) || ($key === 'session_id');
    }

    /**
     * Sets data into the session that will only last for a single request.
     * Perfect for use with single-use status update messages.
     *
     * If $data is an array, it is interpreted as an associative array of
     * key/value pairs for flashdata properties.
     * Otherwise, it is interpreted as the identifier of a specific
     * flashdata property, with $value containing the property value.
     *
     * @param array|string                            $data  Property identifier or associative array of properties
     * @param array|bool|float|int|object|string|null $value Property value if $data is a scalar
     */
    public function setFlashdata($data, $value = null)
    {
        $this->set($data, $value);
        $this->markAsFlashdata(is_array($data) ? array_keys($data) : $data);
    }

    /**
     * Retrieve one or more items of flash data from the session.
     *
     * If the item key is null, return all flashdata.
     *
     * @param string $key Property identifier
     *
     * @return array|null The requested property value, or an associative array  of them
     */
    public function getFlashdata(?string $key = null)
    {
        if (isset($key)) {
            return (isset($_SESSION['__ci_vars'], $_SESSION['__ci_vars'][$key], $_SESSION[$key])
                && ! is_int($_SESSION['__ci_vars'][$key])) ? $_SESSION[$key] : null;
        }

        $flashdata = [];

        if (! empty($_SESSION['__ci_vars'])) {
            foreach ($_SESSION['__ci_vars'] as $key => &$value) {
                if (! is_int($value)) {
                    $flashdata[$key] = $_SESSION[$key];
                }
            }
        }

        return $flashdata;
    }

    /**
     * Keeps a single piece of flash data alive for one more request.
     *
     * @param array|string $key Property identifier or array of them
     */
    public function keepFlashdata($key)
    {
        $this->markAsFlashdata($key);
    }

    /**
     * Mark a session property or properties as flashdata.
     *
     * @param array|string $key Property identifier or array of them
     *
     * @return bool False if any of the properties are not already set
     */
    public function markAsFlashdata($key): bool
    {
        if (is_array($key)) {
            foreach ($key as $sessionKey) {
                if (! isset($_SESSION[$sessionKey])) {
                    return false;
                }
            }

            $new = array_fill_keys($key, 'new');

            $_SESSION['__ci_vars'] = isset($_SESSION['__ci_vars']) ? array_merge($_SESSION['__ci_vars'], $new) : $new;

            return true;
        }

        if (! isset($_SESSION[$key])) {
            return false;
        }

        $_SESSION['__ci_vars'][$key] = 'new';

        return true;
    }

    /**
     * Unmark data in the session as flashdata.
     *
     * @param array|string $key Property identifier or array of them
     */
    public function unmarkFlashdata($key)
    {
        if (empty($_SESSION['__ci_vars'])) {
            return;
        }

        if (! is_array($key)) {
            $key = [$key];
        }

        foreach ($key as $k) {
            if (isset($_SESSION['__ci_vars'][$k]) && ! is_int($_SESSION['__ci_vars'][$k])) {
                unset($_SESSION['__ci_vars'][$k]);
            }
        }

        if (empty($_SESSION['__ci_vars'])) {
            unset($_SESSION['__ci_vars']);
        }
    }

    /**
     * Retrieve all of the keys for session data marked as flashdata.
     *
     * @return array The property names of all flashdata
     */
    public function getFlashKeys(): array
    {
        if (! isset($_SESSION['__ci_vars'])) {
            return [];
        }

        $keys = [];

        foreach (array_keys($_SESSION['__ci_vars']) as $key) {
            if (! is_int($_SESSION['__ci_vars'][$key])) {
                $keys[] = $key;
            }
        }

        return $keys;
    }

    /**
     * Sets new data into the session, and marks it as temporary data
     * with a set lifespan.
     *
     * @param array|string                            $data  Session data key or associative array of items
     * @param array|bool|float|int|object|string|null $value Value to store
     * @param int                                     $ttl   Time-to-live in seconds
     */
    public function setTempdata($data, $value = null, int $ttl = 300)
    {
        $this->set($data, $value);
        $this->markAsTempdata($data, $ttl);
    }

    /**
     * Returns either a single piece of tempdata, or all temp data currently
     * in the session.
     *
     * @param string $key Session data key
     *
     * @return array|bool|float|int|object|string|null Session data value or null if not found.
     */
    public function getTempdata(?string $key = null)
    {
        if (isset($key)) {
            return (isset($_SESSION['__ci_vars'], $_SESSION['__ci_vars'][$key], $_SESSION[$key])
                    && is_int($_SESSION['__ci_vars'][$key])) ? $_SESSION[$key] : null;
        }

        $tempdata = [];

        if (! empty($_SESSION['__ci_vars'])) {
            foreach ($_SESSION['__ci_vars'] as $key => &$value) {
                if (is_int($value)) {
                    $tempdata[$key] = $_SESSION[$key];
                }
            }
        }

        return $tempdata;
    }

    /**
     * Removes a single piece of temporary data from the session.
     *
     * @param string $key Session data key
     */
    public function removeTempdata(string $key)
    {
        $this->unmarkTempdata($key);
        unset($_SESSION[$key]);
    }

    /**
     * Mark one of more pieces of data as being temporary, meaning that
     * it has a set lifespan within the session.
     *
     * @param array|string $key Property identifier or array of them
     * @param int          $ttl Time to live, in seconds
     *
     * @return bool False if any of the properties were not set
     */
    public function markAsTempdata($key, int $ttl = 300): bool
    {
        $ttl += Time::now()->getTimestamp();

        if (is_array($key)) {
            $temp = [];

            foreach ($key as $k => $v) {
                // Do we have a key => ttl pair, or just a key?
                if (is_int($k)) {
                    $k = $v;
                    $v = $ttl;
                } elseif (is_string($v)) {
                    $v = Time::now()->getTimestamp() + $ttl;
                } else {
                    $v += Time::now()->getTimestamp();
                }

                if (! array_key_exists($k, $_SESSION)) {
                    return false;
                }

                $temp[$k] = $v;
            }

            $_SESSION['__ci_vars'] = isset($_SESSION['__ci_vars']) ? array_merge($_SESSION['__ci_vars'], $temp) : $temp;

            return true;
        }

        if (! isset($_SESSION[$key])) {
            return false;
        }

        $_SESSION['__ci_vars'][$key] = $ttl;

        return true;
    }

    /**
     * Unmarks temporary data in the session, effectively removing its
     * lifespan and allowing it to live as long as the session does.
     *
     * @param array|string $key Property identifier or array of them
     */
    public function unmarkTempdata($key)
    {
        if (empty($_SESSION['__ci_vars'])) {
            return;
        }

        if (! is_array($key)) {
            $key = [$key];
        }

        foreach ($key as $k) {
            if (isset($_SESSION['__ci_vars'][$k]) && is_int($_SESSION['__ci_vars'][$k])) {
                unset($_SESSION['__ci_vars'][$k]);
            }
        }

        if (empty($_SESSION['__ci_vars'])) {
            unset($_SESSION['__ci_vars']);
        }
    }

    /**
     * Retrieve the keys of all session data that have been marked as temporary data.
     */
    public function getTempKeys(): array
    {
        if (! isset($_SESSION['__ci_vars'])) {
            return [];
        }

        $keys = [];

        foreach (array_keys($_SESSION['__ci_vars']) as $key) {
            if (is_int($_SESSION['__ci_vars'][$key])) {
                $keys[] = $key;
            }
        }

        return $keys;
    }

    /**
     * Sets the driver as the session handler in PHP.
     * Extracted for easier testing.
     */
    protected function setSaveHandler()
    {
        session_set_save_handler($this->driver, true);
    }

    /**
     * Starts the session.
     * Extracted for testing reasons.
     */
    protected function startSession()
    {
        if (ENVIRONMENT === 'testing') {
            $_SESSION = [];

            return;
        }

        session_start(); // @codeCoverageIgnore
    }

    /**
     * Takes care of setting the cookie on the client side.
     *
     * @codeCoverageIgnore
     */
    protected function setCookie()
    {
        $expiration   = $this->config->expiration === 0 ? 0 : Time::now()->getTimestamp() + $this->config->expiration;
        $this->cookie = $this->cookie->withValue(session_id())->withExpires($expiration);

        $response = Services::response();
        $response->setCookie($this->cookie);
    }
}
