<?php

namespace SimpleSAML\Module\saml\SP;

/**
 * A directory over logout information.
 *
 * @package SimpleSAMLphp
 */

class LogoutStore
{
    /**
     * Create logout table in SQL, if it is missing.
     *
     * @param \SimpleSAML\Store\SQL $store  The datastore.
     */
    private static function createLogoutTable(\SimpleSAML\Store\SQL $store)
    {
        $tableVer = $store->getTableVersion('saml_LogoutStore');
        if ($tableVer === 2) {
            return;
        } elseif ($tableVer === 1) {
            /* TableVersion 2 increased the column size to 255 which is the maximum length of a FQDN. */
            switch ($store->driver) {
                case 'pgsql':
                    // This does not affect the NOT NULL constraint
                    $query = 'ALTER TABLE ' . $store->prefix . '_saml_LogoutStore ALTER COLUMN _authSource TYPE VARCHAR(255)';
                    break;
                default:
                    $query = 'ALTER TABLE ' . $store->prefix . '_saml_LogoutStore MODIFY _authSource VARCHAR(255) NOT NULL';
                    break;
            }

            try {
                $store->pdo->exec($query);
            } catch (\Exception $e) {
                \SimpleSAML\Logger::warning($store->pdo->errorInfo());
                return;
            }
            $store->setTableVersion('saml_LogoutStore', 2);
            return;
        }

        $query = 'CREATE TABLE ' . $store->prefix . '_saml_LogoutStore (
            _authSource VARCHAR(255) NOT NULL,
            _nameId VARCHAR(40) NOT NULL,
            _sessionIndex VARCHAR(50) NOT NULL,
            _expire TIMESTAMP NOT NULL,
            _sessionId VARCHAR(50) NOT NULL,
            UNIQUE (_authSource, _nameID, _sessionIndex)
        )';
        $store->pdo->exec($query);

        $query = 'CREATE INDEX ' . $store->prefix . '_saml_LogoutStore_expire ON '  . $store->prefix . '_saml_LogoutStore (_expire)';
        $store->pdo->exec($query);

        $query = 'CREATE INDEX ' . $store->prefix . '_saml_LogoutStore_nameId ON '  . $store->prefix . '_saml_LogoutStore (_authSource, _nameId)';
        $store->pdo->exec($query);

        $store->setTableVersion('saml_LogoutStore', 2);
    }


    /**
     * Clean the logout table of expired entries.
     *
     * @param \SimpleSAML\Store\SQL $store  The datastore.
     */
    private static function cleanLogoutStore(\SimpleSAML\Store\SQL $store)
    {
        \SimpleSAML\Logger::debug('saml.LogoutStore: Cleaning logout store.');

        $query = 'DELETE FROM ' . $store->prefix . '_saml_LogoutStore WHERE _expire < :now';
        $params = array('now' => gmdate('Y-m-d H:i:s'));

        $query = $store->pdo->prepare($query);
        $query->execute($params);
    }


    /**
     * Register a session in the SQL datastore.
     *
     * @param \SimpleSAML\Store\SQL $store  The datastore.
     * @param string $authId  The authsource ID.
     * @param string $nameId  The hash of the users NameID.
     * @param string $sessionIndex  The SessionIndex of the user.
     */
    private static function addSessionSQL(\SimpleSAML\Store\SQL $store, $authId, $nameId, $sessionIndex, $expire, $sessionId)
    {
        assert(is_string($authId));
        assert(is_string($nameId));
        assert(is_string($sessionIndex));
        assert(is_string($sessionId));
        assert(is_int($expire));

        self::createLogoutTable($store);

        if (rand(0, 1000) < 10) {
            self::cleanLogoutStore($store);
        }

        $data = array(
            '_authSource' => $authId,
            '_nameId' => $nameId,
            '_sessionIndex' => $sessionIndex,
            '_expire' => gmdate('Y-m-d H:i:s', $expire),
            '_sessionId' => $sessionId,
        );
        $store->insertOrUpdate($store->prefix . '_saml_LogoutStore', array('_authSource', '_nameId', '_sessionIndex'), $data);
    }


    /**
     * Retrieve sessions from the SQL datastore.
     *
     * @param \SimpleSAML\Store\SQL $store  The datastore.
     * @param string $authId  The authsource ID.
     * @param string $nameId  The hash of the users NameID.
     * @return array  Associative array of SessionIndex =>  SessionId.
     */
    private static function getSessionsSQL(\SimpleSAML\Store\SQL $store, $authId, $nameId)
    {
        assert(is_string($authId));
        assert(is_string($nameId));

        self::createLogoutTable($store);

        $params = array(
            '_authSource' => $authId,
            '_nameId' => $nameId,
            'now' => gmdate('Y-m-d H:i:s'),
        );

        // We request the columns in lowercase in order to be compatible with PostgreSQL
        $query = 'SELECT _sessionIndex AS _sessionindex, _sessionId AS _sessionid FROM ' . $store->prefix . '_saml_LogoutStore' .
            ' WHERE _authSource = :_authSource AND _nameId = :_nameId AND _expire >= :now';
        $query = $store->pdo->prepare($query);
        $query->execute($params);

        $res = array();
        while ( ($row = $query->fetch(\PDO::FETCH_ASSOC)) !== false) {
            $res[$row['_sessionindex']] = $row['_sessionid'];
        }

        return $res;
    }


    /**
     * Retrieve all session IDs from a key-value store.
     *
     * @param \SimpleSAML\Store $store  The datastore.
     * @param string $authId  The authsource ID.
     * @param string $nameId  The hash of the users NameID.
     * @param array $sessionIndexes  The session indexes.
     * @return array  Associative array of SessionIndex =>  SessionId.
     */
    private static function getSessionsStore(\SimpleSAML\Store $store, $authId, $nameId, array $sessionIndexes)
    {
        assert(is_string($authId));
        assert(is_string($nameId));

        $res = array();
        foreach ($sessionIndexes as $sessionIndex) {
            $sessionId = $store->get('saml.LogoutStore', $nameId . ':' . $sessionIndex);
            if ($sessionId === null) {
                continue;
            }
            assert(is_string($sessionId));
            $res[$sessionIndex] = $sessionId;
        }

        return $res;
    }


    /**
     * Register a new session in the datastore.
     *
     * Please observe the change of the signature in this method. Previously, the second parameter ($nameId) was forced
     * to be an array. However, it has no type restriction now, and the documentation states it must be a
     * \SAML2\XML\saml\NameID object. Currently, this function still accepts an array passed as $nameId, and will
     * silently convert it to a \SAML2\XML\saml\NameID object. This is done to keep backwards-compatibility, though will
     * no longer be possible in the future as the $nameId parameter will be required to be an object.
     *
     * @param string $authId  The authsource ID.
     * @param \SAML2\XML\saml\NameID $nameId The NameID of the user.
     * @param string|null $sessionIndex  The SessionIndex of the user.
     */
    public static function addSession($authId, $nameId, $sessionIndex, $expire)
    {
        assert(is_string($authId));
        assert(is_string($sessionIndex) || $sessionIndex === null);
        assert(is_int($expire));

        if ($sessionIndex === null) {
            /* This IdP apparently did not include a SessionIndex, and thus probably does not
             * support SLO. We still want to add the session to the data store just in case
             * it supports SLO, but we don't want an LogoutRequest with a specific
             * SessionIndex to match this session. We therefore generate our own session index.
             */
            $sessionIndex = \SimpleSAML\Utils\Random::generateID();
        }

        $store = \SimpleSAML\Store::getInstance();
        if ($store === false) {
            // We don't have a datastore.
            return;
        }

        // serialize and anonymize the NameID
        // TODO: remove this conditional statement
        if (is_array($nameId)) {
            $nameId = \SAML2\XML\saml\NameID::fromArray($nameId);
        }
        $strNameId = serialize($nameId);
        $strNameId = sha1($strNameId);

        /* Normalize SessionIndex. */
        if (strlen($sessionIndex) > 50) {
            $sessionIndex = sha1($sessionIndex);
        }

        $session = \SimpleSAML\Session::getSessionFromRequest();
        $sessionId = $session->getSessionId();

        if ($store instanceof \SimpleSAML\Store\SQL) {
            self::addSessionSQL($store, $authId, $strNameId, $sessionIndex, $expire, $sessionId);
        } else {
            $store->set('saml.LogoutStore', $strNameId . ':' . $sessionIndex, $sessionId, $expire);
        }
    }


    /**
     * Log out of the given sessions.
     *
     * @param string $authId  The authsource ID.
     * @param \SAML2\XML\saml\NameID $nameId The NameID of the user.
     * @param array $sessionIndexes  The SessionIndexes we should log out of. Logs out of all if this is empty.
     * @returns int|false  Number of sessions logged out, or FALSE if not supported.
     */
    public static function logoutSessions($authId, $nameId, array $sessionIndexes)
    {
        assert(is_string($authId));

        $store = \SimpleSAML\Store::getInstance();
        if ($store === false) {
            /* We don't have a datastore. */
            return false;
        }

        // serialize and anonymize the NameID
        // TODO: remove this conditional statement
        if (is_array($nameId)) {
            $nameId = \SAML2\XML\saml\NameID::fromArray($nameId);
        }
        $strNameId = serialize($nameId);
        $strNameId = sha1($strNameId);

        /* Normalize SessionIndexes. */
        foreach ($sessionIndexes as &$sessionIndex) {
            assert(is_string($sessionIndex));
            if (strlen($sessionIndex) > 50) {
                $sessionIndex = sha1($sessionIndex);
            }
        }
        unset($sessionIndex); // Remove reference

        if ($store instanceof \SimpleSAML\Store\SQL) {
            $sessions = self::getSessionsSQL($store, $authId, $strNameId);
        } elseif (empty($sessionIndexes)) {
            /* We cannot fetch all sessions without a SQL store. */
            return false;
        } else {
            /** @var \SimpleSAML\Store $sessions At this point the store cannot be false */
            $sessions = self::getSessionsStore($store, $authId, $strNameId, $sessionIndexes);

        }

        if (empty($sessionIndexes)) {
            $sessionIndexes = array_keys($sessions);
        }

        $numLoggedOut = 0;
        foreach ($sessionIndexes as $sessionIndex) {
            if (!isset($sessions[$sessionIndex])) {
                \SimpleSAML\Logger::info('saml.LogoutStore: Logout requested for unknown SessionIndex.');
                continue;
            }

            $sessionId = $sessions[$sessionIndex];

            $session = \SimpleSAML\Session::getSession($sessionId);
            if ($session === null) {
                \SimpleSAML\Logger::info('saml.LogoutStore: Skipping logout of missing session.');
                continue;
            }

            if (!$session->isValid($authId)) {
                \SimpleSAML\Logger::info('saml.LogoutStore: Skipping logout of session because it isn\'t authenticated.');
                continue;
            }

            \SimpleSAML\Logger::info('saml.LogoutStore: Logging out of session with trackId [' . $session->getTrackID() . '].');
            $session->doLogout($authId);
            $numLoggedOut += 1;
        }

        return $numLoggedOut;
    }
}