<?php
/**
 * @link http://www.yiiframework.com/
 * @copyright Copyright (c) 2008 Yii Software LLC
 * @license http://www.yiiframework.com/license/
 */

namespace yii\web;

use Yii;
use yii\base\Component;
use yii\base\InvalidConfigException;

/**
 * User is the class for the "user" application component that manages the user authentication status.
 *
 * You may use [[isGuest]] to determine whether the current user is a guest or not.
 * If the user is a guest, the [[identity]] property would return null. Otherwise, it would
 * be an instance of [[IdentityInterface]].
 *
 * You may call various methods to change the user authentication status:
 *
 * - [[login()]]: sets the specified identity and remembers the authentication status in session and cookie.
 * - [[logout()]]: marks the user as a guest and clears the relevant information from session and cookie.
 * - [[setIdentity()]]: changes the user identity without touching session or cookie.
 *   This is best used in stateless RESTful API implementation.
 *
 * Note that User only maintains the user authentication status. It does NOT handle how to authenticate
 * a user. The logic of how to authenticate a user should be done in the class implementing [[IdentityInterface]].
 * You are also required to set [[identityClass]] with the name of this class.
 *
 * User is configured as an application component in [[\yii\web\Application]] by default.
 * You can access that instance via `Yii::$app->user`.
 *
 * You can modify its configuration by adding an array to your application config under `components`
 * as it is shown in the following example:
 *
 * ~~~
 * 'user' => [
 *     'identityClass' => 'app\models\User', // User must implement the IdentityInterface
 *     'enableAutoLogin' => true,
 *     // 'loginUrl' => ['user/login'],
 *     // ...
 * ]
 * ~~~
 *
 * @property string|integer $id The unique identifier for the user. If null, it means the user is a guest.
 * This property is read-only.
 * @property IdentityInterface|null $identity The identity object associated with the currently logged-in
 * user. `null` is returned if the user is not logged in (not authenticated).
 * @property boolean $isGuest Whether the current user is a guest. This property is read-only.
 * @property string $returnUrl The URL that the user should be redirected to after login. Note that the type
 * of this property differs in getter and setter. See [[getReturnUrl()]] and [[setReturnUrl()]] for details.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @since 2.0
 */
class User extends Component
{
    const EVENT_BEFORE_LOGIN = 'beforeLogin';
    const EVENT_AFTER_LOGIN = 'afterLogin';
    const EVENT_BEFORE_LOGOUT = 'beforeLogout';
    const EVENT_AFTER_LOGOUT = 'afterLogout';

    /**
     * @var string the class name of the [[identity]] object.
     */
    public $identityClass;
    /**
     * @var boolean whether to enable cookie-based login. Defaults to false.
     */
    public $enableAutoLogin = false;
    /**
     * @var string|array the URL for login when [[loginRequired()]] is called.
     * If an array is given, [[UrlManager::createUrl()]] will be called to create the corresponding URL.
     * The first element of the array should be the route to the login action, and the rest of
     * the name-value pairs are GET parameters used to construct the login URL. For example,
     *
     * ~~~
     * ['site/login', 'ref' => 1]
     * ~~~
     *
     * If this property is null, a 403 HTTP exception will be raised when [[loginRequired()]] is called.
     */
    public $loginUrl = ['site/login'];
    /**
     * @var array the configuration of the identity cookie. This property is used only when [[enableAutoLogin]] is true.
     * @see Cookie
     */
    public $identityCookie = ['name' => '_identity', 'httpOnly' => true];
    /**
     * @var integer the number of seconds in which the user will be logged out automatically if he
     * remains inactive. If this property is not set, the user will be logged out after
     * the current session expires (c.f. [[Session::timeout]]).
     */
    public $authTimeout;
    /**
     * @var boolean whether to automatically renew the identity cookie each time a page is requested.
     * This property is effective only when [[enableAutoLogin]] is true.
     * When this is false, the identity cookie will expire after the specified duration since the user
     * is initially logged in. When this is true, the identity cookie will expire after the specified duration
     * since the user visits the site the last time.
     * @see enableAutoLogin
     */
    public $autoRenewCookie = true;
    /**
     * @var string the session variable name used to store the value of [[id]].
     */
    public $idParam = '__id';
    /**
     * @var string the session variable name used to store the value of expiration timestamp of the authenticated state.
     * This is used when [[authTimeout]] is set.
     */
    public $authTimeoutParam = '__expire';
    /**
     * @var string the session variable name used to store the value of [[returnUrl]].
     */
    public $returnUrlParam = '__returnUrl';

    private $_access = [];

    /**
     * Initializes the application component.
     */
    public function init()
    {
        parent::init();

        if ($this->identityClass === null) {
            throw new InvalidConfigException('User::identityClass must be set.');
        }
        if ($this->enableAutoLogin && !isset($this->identityCookie['name'])) {
            throw new InvalidConfigException('User::identityCookie must contain the "name" element.');
        }
    }

    private $_identity = false;

    /**
     * Returns the identity object associated with the currently logged-in user.
     * @param boolean $checkSession whether to check the session if the identity has never been determined before.
     * If the identity is already determined (e.g., by calling [[setIdentity()]] or [[login()]]),
     * then this parameter has no effect.
     * @return IdentityInterface|null the identity object associated with the currently logged-in user.
     * `null` is returned if the user is not logged in (not authenticated).
     * @see login()
     * @see logout()
     */
    public function getIdentity($checkSession = true)
    {
        if ($this->_identity === false) {
            if ($checkSession) {
                $this->renewAuthStatus();
            } else {
                return null;
            }
        }

        return $this->_identity;
    }

    /**
     * Sets the user identity object.
     *
     * This method does nothing else except storing the specified identity object in the internal variable.
     * For this reason, this method is best used when the user authentication status should not be maintained
     * by session.
     *
     * This method is also called by other more sophisticated methods, such as [[login()]], [[logout()]],
     * [[switchIdentity()]]. Those methods will try to use session and cookie to maintain the user authentication
     * status.
     *
     * @param IdentityInterface|null $identity the identity object associated with the currently logged user.
     */
    public function setIdentity($identity)
    {
        $this->_identity = $identity;
        $this->_access = [];
    }

    /**
     * Logs in a user.
     *
     * By logging in a user, you may obtain the user identity information each time through [[identity]].
     *
     * The login status is maintained according to the `$duration` parameter:
     *
     * - `$duration == 0`: the identity information will be stored in session and will be available
     *   via [[identity]] as long as the session remains active.
     * - `$duration > 0`: the identity information will be stored in session. If [[enableAutoLogin]] is true,
     *   it will also be stored in a cookie which will expire in `$duration` seconds. As long as
     *   the cookie remains valid or the session is active, you may obtain the user identity information
     *   via [[identity]].
     *
     * @param IdentityInterface $identity the user identity (which should already be authenticated)
     * @param integer $duration number of seconds that the user can remain in logged-in status.
     * Defaults to 0, meaning login till the user closes the browser or the session is manually destroyed.
     * If greater than 0 and [[enableAutoLogin]] is true, cookie-based login will be supported.
     * @return boolean whether the user is logged in
     */
    public function login($identity, $duration = 0)
    {
        if ($this->beforeLogin($identity, false, $duration)) {
            $this->switchIdentity($identity, $duration);
            $id = $identity->getId();
            $ip = Yii::$app->getRequest()->getUserIP();
            Yii::info("User '$id' logged in from $ip with duration $duration.", __METHOD__);
            $this->afterLogin($identity, false, $duration);
        }

        return !$this->getIsGuest();
    }

    /**
     * Logs in a user by the given access token.
     * Note that unlike [[login()]], this method will NOT start a session to remember the user authentication status.
     * Also if the access token is invalid, the user will remain as a guest.
     * @param string $token the access token
     * @return IdentityInterface the identity associated with the given access token. Null is returned if
     * the access token is invalid.
     */
    public function loginByAccessToken($token)
    {
        /** @var IdentityInterface $class */
        $class = $this->identityClass;
        $identity = $class::findIdentityByAccessToken($token);
        $this->setIdentity($identity);

        return $identity;
    }

    /**
     * Logs in a user by cookie.
     *
     * This method attempts to log in a user using the ID and authKey information
     * provided by the given cookie.
     */
    protected function loginByCookie()
    {
        $name = $this->identityCookie['name'];
        $value = Yii::$app->getRequest()->getCookies()->getValue($name);
        if ($value !== null) {
            $data = json_decode($value, true);
            if (count($data) === 3 && isset($data[0], $data[1], $data[2])) {
                list ($id, $authKey, $duration) = $data;
                /** @var IdentityInterface $class */
                $class = $this->identityClass;
                $identity = $class::findIdentity($id);
                if ($identity !== null && $identity->validateAuthKey($authKey)) {
                    if ($this->beforeLogin($identity, true, $duration)) {
                        $this->switchIdentity($identity, $this->autoRenewCookie ? $duration : 0);
                        $ip = Yii::$app->getRequest()->getUserIP();
                        Yii::info("User '$id' logged in from $ip via cookie.", __METHOD__);
                        $this->afterLogin($identity, true, $duration);
                    }
                } elseif ($identity !== null) {
                    Yii::warning("Invalid auth key attempted for user '$id': $authKey", __METHOD__);
                }
            }
        }
    }

    /**
     * Logs out the current user.
     * This will remove authentication-related session data.
     * If `$destroySession` is true, all session data will be removed.
     * @param boolean $destroySession whether to destroy the whole session. Defaults to true.
     * @return boolean whether the user is logged out
     */
    public function logout($destroySession = true)
    {
        $identity = $this->getIdentity();
        if ($identity !== null && $this->beforeLogout($identity)) {
            $this->switchIdentity(null);
            $id = $identity->getId();
            $ip = Yii::$app->getRequest()->getUserIP();
            Yii::info("User '$id' logged out from $ip.", __METHOD__);
            if ($destroySession) {
                Yii::$app->getSession()->destroy();
            }
            $this->afterLogout($identity);
        }

        return $this->getIsGuest();
    }

    /**
     * Returns a value indicating whether the user is a guest (not authenticated).
     * @param boolean $checkSession whether to check the session to determine if the user is a guest.
     * Note that if this is false, it is possible that the user may not be a guest while this method still returns
     * true. This is because the session is not checked.
     * @return boolean whether the current user is a guest.
     */
    public function getIsGuest($checkSession = true)
    {
        return $this->getIdentity($checkSession) === null;
    }

    /**
     * Returns a value that uniquely represents the user.
     * @param boolean $checkSession whether to check the session to determine the user ID.
     * Note that if this is false, it is possible that this method returns null although the user may not
     * be a guest. This is because the session is not checked.
     * @return string|integer the unique identifier for the user. If null, it means the user is a guest.
     */
    public function getId($checkSession = true)
    {
        $identity = $this->getIdentity($checkSession);

        return $identity !== null ? $identity->getId() : null;
    }

    /**
     * Returns the URL that the user should be redirected to after successful login.
     * This property is usually used by the login action. If the login is successful,
     * the action should read this property and use it to redirect the user browser.
     * @param string|array $defaultUrl the default return URL in case it was not set previously.
     * If this is null and the return URL was not set previously, [[Application::homeUrl]] will be redirected to.
     * Please refer to [[setReturnUrl()]] on accepted format of the URL.
     * @return string the URL that the user should be redirected to after login.
     * @see loginRequired()
     */
    public function getReturnUrl($defaultUrl = null)
    {
        $url = Yii::$app->getSession()->get($this->returnUrlParam, $defaultUrl);
        if (is_array($url)) {
            if (isset($url[0])) {
                return Yii::$app->getUrlManager()->createUrl($url);
            } else {
                $url = null;
            }
        }

        return $url === null ? Yii::$app->getHomeUrl() : $url;
    }

    /**
     * @param string|array $url the URL that the user should be redirected to after login.
     * If an array is given, [[UrlManager::createUrl()]] will be called to create the corresponding URL.
     * The first element of the array should be the route, and the rest of
     * the name-value pairs are GET parameters used to construct the URL. For example,
     *
     * ~~~
     * ['admin/index', 'ref' => 1]
     * ~~~
     */
    public function setReturnUrl($url)
    {
        Yii::$app->getSession()->set($this->returnUrlParam, $url);
    }

    /**
     * Redirects the user browser to the login page.
     * Before the redirection, the current URL (if it's not an AJAX url) will be
     * kept as [[returnUrl]] so that the user browser may be redirected back
     * to the current page after successful login. Make sure you set [[loginUrl]]
     * so that the user browser can be redirected to the specified login URL after
     * calling this method.
     *
     * Note that when [[loginUrl]] is set, calling this method will NOT terminate the application execution.
     *
     * @return Response the redirection response if [[loginUrl]] is set
     * @throws ForbiddenHttpException the "Access Denied" HTTP exception if [[loginUrl]] is not set
     */
    public function loginRequired()
    {
        $request = Yii::$app->getRequest();
        if (!$request->getIsAjax()) {
            $this->setReturnUrl($request->getUrl());
        }
        if ($this->loginUrl !== null) {
            return Yii::$app->getResponse()->redirect($this->loginUrl);
        } else {
            throw new ForbiddenHttpException(Yii::t('yii', 'Login Required'));
        }
    }

    /**
     * This method is called before logging in a user.
     * The default implementation will trigger the [[EVENT_BEFORE_LOGIN]] event.
     * If you override this method, make sure you call the parent implementation
     * so that the event is triggered.
     * @param IdentityInterface $identity the user identity information
     * @param boolean $cookieBased whether the login is cookie-based
     * @param integer $duration number of seconds that the user can remain in logged-in status.
     * If 0, it means login till the user closes the browser or the session is manually destroyed.
     * @return boolean whether the user should continue to be logged in
     */
    protected function beforeLogin($identity, $cookieBased, $duration)
    {
        $event = new UserEvent([
            'identity' => $identity,
            'cookieBased' => $cookieBased,
            'duration' => $duration,
        ]);
        $this->trigger(self::EVENT_BEFORE_LOGIN, $event);

        return $event->isValid;
    }

    /**
     * This method is called after the user is successfully logged in.
     * The default implementation will trigger the [[EVENT_AFTER_LOGIN]] event.
     * If you override this method, make sure you call the parent implementation
     * so that the event is triggered.
     * @param IdentityInterface $identity the user identity information
     * @param boolean $cookieBased whether the login is cookie-based
     * @param integer $duration number of seconds that the user can remain in logged-in status.
     * If 0, it means login till the user closes the browser or the session is manually destroyed.
     */
    protected function afterLogin($identity, $cookieBased, $duration)
    {
        $this->trigger(self::EVENT_AFTER_LOGIN, new UserEvent([
            'identity' => $identity,
            'cookieBased' => $cookieBased,
            'duration' => $duration,
        ]));
    }

    /**
     * This method is invoked when calling [[logout()]] to log out a user.
     * The default implementation will trigger the [[EVENT_BEFORE_LOGOUT]] event.
     * If you override this method, make sure you call the parent implementation
     * so that the event is triggered.
     * @param IdentityInterface $identity the user identity information
     * @return boolean whether the user should continue to be logged out
     */
    protected function beforeLogout($identity)
    {
        $event = new UserEvent([
            'identity' => $identity,
        ]);
        $this->trigger(self::EVENT_BEFORE_LOGOUT, $event);

        return $event->isValid;
    }

    /**
     * This method is invoked right after a user is logged out via [[logout()]].
     * The default implementation will trigger the [[EVENT_AFTER_LOGOUT]] event.
     * If you override this method, make sure you call the parent implementation
     * so that the event is triggered.
     * @param IdentityInterface $identity the user identity information
     */
    protected function afterLogout($identity)
    {
        $this->trigger(self::EVENT_AFTER_LOGOUT, new UserEvent([
            'identity' => $identity,
        ]));
    }

    /**
     * Renews the identity cookie.
     * This method will set the expiration time of the identity cookie to be the current time
     * plus the originally specified cookie duration.
     */
    protected function renewIdentityCookie()
    {
        $name = $this->identityCookie['name'];
        $value = Yii::$app->getRequest()->getCookies()->getValue($name);
        if ($value !== null) {
            $data = json_decode($value, true);
            if (is_array($data) && isset($data[2])) {
                $cookie = new Cookie($this->identityCookie);
                $cookie->value = $value;
                $cookie->expire = time() + (int) $data[2];
                Yii::$app->getResponse()->getCookies()->add($cookie);
            }
        }
    }

    /**
     * Sends an identity cookie.
     * This method is used when [[enableAutoLogin]] is true.
     * It saves [[id]], [[IdentityInterface::getAuthKey()|auth key]], and the duration of cookie-based login
     * information in the cookie.
     * @param IdentityInterface $identity
     * @param integer $duration number of seconds that the user can remain in logged-in status.
     * @see loginByCookie()
     */
    protected function sendIdentityCookie($identity, $duration)
    {
        $cookie = new Cookie($this->identityCookie);
        $cookie->value = json_encode([
            $identity->getId(),
            $identity->getAuthKey(),
            $duration,
        ]);
        $cookie->expire = time() + $duration;
        Yii::$app->getResponse()->getCookies()->add($cookie);
    }

    /**
     * Switches to a new identity for the current user.
     *
     * This method may use session and/or cookie to store the user identity information,
     * according to the value of `$duration`. Please refer to [[login()]] for more details.
     *
     * This method is mainly called by [[login()]], [[logout()]] and [[loginByCookie()]]
     * when the current user needs to be associated with the corresponding identity information.
     *
     * @param IdentityInterface $identity the identity information to be associated with the current user.
     * If null, it means switching the current user to be a guest.
     * @param integer $duration number of seconds that the user can remain in logged-in status.
     * This parameter is used only when `$identity` is not null.
     */
    public function switchIdentity($identity, $duration = 0)
    {
        $session = Yii::$app->getSession();
        if (!YII_ENV_TEST) {
            $session->regenerateID(true);
        }
        $this->setIdentity($identity);
        $session->remove($this->idParam);
        $session->remove($this->authTimeoutParam);
        if ($identity instanceof IdentityInterface) {
            $session->set($this->idParam, $identity->getId());
            if ($this->authTimeout !== null) {
                $session->set($this->authTimeoutParam, time() + $this->authTimeout);
            }
            if ($duration > 0 && $this->enableAutoLogin) {
                $this->sendIdentityCookie($identity, $duration);
            }
        } elseif ($this->enableAutoLogin) {
            Yii::$app->getResponse()->getCookies()->remove(new Cookie($this->identityCookie));
        }
    }

    /**
     * Updates the authentication status using the information from session and cookie.
     *
     * This method will try to determine the user identity using the [[idParam]] session variable.
     *
     * If [[authTimeout]] is set, this method will refresh the timer.
     *
     * If the user identity cannot be determined by session, this method will try to [[loginByCookie()|login by cookie]]
     * if [[enableAutoLogin]] is true.
     */
    protected function renewAuthStatus()
    {
        $session = Yii::$app->getSession();
        $id = $session->getHasSessionId() || $session->getIsActive() ? $session->get($this->idParam) : null;

        if ($id === null) {
            $identity = null;
        } else {
            /** @var IdentityInterface $class */
            $class = $this->identityClass;
            $identity = $class::findIdentity($id);
        }

        $this->setIdentity($identity);

        if ($this->authTimeout !== null && $identity !== null) {
            $expire = $session->get($this->authTimeoutParam);
            if ($expire !== null && $expire < time()) {
                $this->logout(false);
            } else {
                $session->set($this->authTimeoutParam, time() + $this->authTimeout);
            }
        }

        if ($this->enableAutoLogin) {
            if ($this->getIsGuest()) {
                $this->loginByCookie();
            } elseif ($this->autoRenewCookie) {
                $this->renewIdentityCookie();
            }
        }
    }

    /**
     * Checks if the user can perform the operation as specified by the given permission.
     *
     * Note that you must configure "authManager" application component in order to use this method.
     * Otherwise an exception will be thrown.
     *
     * @param string $permissionName the name of the permission (e.g. "edit post") that needs access check.
     * @param array $params name-value pairs that would be passed to the rules associated
     * with the roles and permissions assigned to the user. A param with name 'user' is added to
     * this array, which holds the value of [[id]].
     * @param boolean $allowCaching whether to allow caching the result of access check.
     * When this parameter is true (default), if the access check of an operation was performed
     * before, its result will be directly returned when calling this method to check the same
     * operation. If this parameter is false, this method will always call
     * [[\yii\rbac\ManagerInterface::checkAccess()]] to obtain the up-to-date access result. Note that this
     * caching is effective only within the same request and only works when `$params = []`.
     * @return boolean whether the user can perform the operation as specified by the given permission.
     */
    public function can($permissionName, $params = [], $allowCaching = true)
    {
        $auth = Yii::$app->getAuthManager();
        if ($allowCaching && empty($params) && isset($this->_access[$permissionName])) {
            return $this->_access[$permissionName];
        }
        $access = $auth->checkAccess($this->getId(), $permissionName, $params);
        if ($allowCaching && empty($params)) {
            $this->_access[$permissionName] = $access;
        }

        return $access;
    }
}
