DataConnector_pdo.php

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<?php

namespace IMSGlobal\LTI\ToolProvider\DataConnector;

use IMSGlobal\LTI\ToolProvider;
use IMSGlobal\LTI\ToolProvider\ConsumerNonce;
use IMSGlobal\LTI\ToolProvider\Context;
use IMSGlobal\LTI\ToolProvider\ResourceLink;
use IMSGlobal\LTI\ToolProvider\ResourceLinkShareKey;
use IMSGlobal\LTI\ToolProvider\ToolConsumer;
use IMSGlobal\LTI\ToolProvider\User;
use PDO;

class DataConnector_pdo extends DataConnector
{

    public function __construct($db, $dbTableNamePrefix = '')
    {

        parent::__construct($db, $dbTableNamePrefix);
        if ($db->getAttribute(PDO::ATTR_DRIVER_NAME) == 'oci') {
            $this->date_format = 'd-M-Y';
        }

    }

###
###  ToolConsumer methods
###

    public function loadToolConsumer($consumer)
    {

        $ok = false;
        if (!empty($consumer->getRecordId())) {
            $sql = 'SELECT consumer_pk, name, consumer_key256, consumer_key, secret, lti_version, ' .
                   'consumer_name, consumer_version, consumer_guid, ' .
                   'profile, tool_proxy, settings, protected, enabled, ' .
                   'enable_from, enable_until, last_access, created, updated ' .
                   "FROM {$this->dbTableNamePrefix}" . DataConnector::CONSUMER_TABLE_NAME . ' ' .
                   'WHERE consumer_pk = :id';
            $query = $this->db->prepare($sql);
            $id = $consumer->getRecordId();
            $query->bindValue('id', $id, PDO::PARAM_INT);
        } else {
            $sql = 'SELECT consumer_pk, name, consumer_key256, consumer_key, secret, lti_version, ' .
                   'consumer_name, consumer_version, consumer_guid, ' .
                   'profile, tool_proxy, settings, protected, enabled, ' .
                   'enable_from, enable_until, last_access, created, updated ' .
                   "FROM {$this->dbTableNamePrefix}" . DataConnector::CONSUMER_TABLE_NAME . ' ' .
                   'WHERE consumer_key256 = :key256';
            $query = $this->db->prepare($sql);
            $key256 = DataConnector::getConsumerKey($consumer->getKey());
            $query->bindValue('key256', $key256, PDO::PARAM_STR);
        }

        if ($query->execute()) {
            while ($row = $query->fetch(PDO::FETCH_ASSOC)) {
                $row = array_change_key_case($row);
                if (empty($key256) || empty($row['consumer_key']) || ($consumer->getKey() === $row['consumer_key'])) {
                    $consumer->setRecordId(intval($row['consumer_pk']));
                    $consumer->name = $row['name'];
                    $consumer->setkey(empty($row['consumer_key']) ? $row['consumer_key256'] : $row['consumer_key']);
                    $consumer->secret = $row['secret'];
                    $consumer->ltiVersion = $row['lti_version'];
                    $consumer->consumerName = $row['consumer_name'];
                    $consumer->consumerVersion = $row['consumer_version'];
                    $consumer->consumerGuid = $row['consumer_guid'];
                    $consumer->profile = json_decode($row['profile']);
                    $consumer->toolProxy = $row['tool_proxy'];
                    $settings = unserialize($row['settings']);
                    if (!is_array($settings)) {
                        $settings = array();
                    }
                    $consumer->setSettings($settings);
                    $consumer->protected = (intval($row['protected']) === 1);
                    $consumer->enabled = (intval($row['enabled']) === 1);
                    $consumer->enableFrom = null;
                    if (!is_null($row['enable_from'])) {
                        $consumer->enableFrom = strtotime($row['enable_from']);
                    }
                    $consumer->enableUntil = null;
                    if (!is_null($row['enable_until'])) {
                        $consumer->enableUntil = strtotime($row['enable_until']);
                    }
                    $consumer->lastAccess = null;
                    if (!is_null($row['last_access'])) {
                        $consumer->lastAccess = strtotime($row['last_access']);
                    }
                    $consumer->created = strtotime($row['created']);
                    $consumer->updated = strtotime($row['updated']);
                    $ok = true;
                    break;
                }
            }
        }

        return $ok;

    }

    public function saveToolConsumer($consumer)
    {

        $id = $consumer->getRecordId();
        $key = $consumer->getKey();
        $key256 = $this->getConsumerKey($key);
        if ($key === $key256) {
            $key = null;
        }
        $protected = ($consumer->protected) ? 1 : 0;
        $enabled = ($consumer->enabled)? 1 : 0;
        $profile = (!empty($consumer->profile)) ? json_encode($consumer->profile) : null;
        $settingsValue = serialize($consumer->getSettings());
        $time = time();
        $now = date("{$this->dateFormat} {$this->timeFormat}", $time);
        $from = null;
        if (!is_null($consumer->enableFrom)) {
            $from = date("{$this->dateFormat} {$this->timeFormat}", $consumer->enableFrom);
        }
        $until = null;
        if (!is_null($consumer->enableUntil)) {
            $until = date("{$this->dateFormat} {$this->timeFormat}", $consumer->enableUntil);
        }
        $last = null;
        if (!is_null($consumer->lastAccess)) {
            $last = date($this->dateFormat, $consumer->lastAccess);
        }
        if (empty($id)) {
            $sql = "INSERT INTO {$this->dbTableNamePrefix}" . DataConnector::CONSUMER_TABLE_NAME . ' (consumer_key256, consumer_key, name, ' .
                   'secret, lti_version, consumer_name, consumer_version, consumer_guid, profile, tool_proxy, settings, protected, enabled, ' .
                   'enable_from, enable_until, last_access, created, updated) ' .
                   'VALUES (:key256, :key, :name, :secret, :lti_version, :consumer_name, :consumer_version, :consumer_guid, :profile, :tool_proxy, :settings, ' .
                   ':protected, :enabled, :enable_from, :enable_until, :last_access, :created, :updated)';
            $query = $this->db->prepare($sql);
            $query->bindValue('key256', $key256, PDO::PARAM_STR);
            $query->bindValue('key', $key, PDO::PARAM_STR);
            $query->bindValue('name', $consumer->name, PDO::PARAM_STR);
            $query->bindValue('secret', $consumer->secret, PDO::PARAM_STR);
            $query->bindValue('lti_version', $consumer->ltiVersion, PDO::PARAM_STR);
            $query->bindValue('consumer_name', $consumer->consumerName, PDO::PARAM_STR);
            $query->bindValue('consumer_version', $consumer->consumerVersion, PDO::PARAM_STR);
            $query->bindValue('consumer_guid', $consumer->consumerGuid, PDO::PARAM_STR);
            $query->bindValue('profile', $profile, PDO::PARAM_STR);
            $query->bindValue('tool_proxy', $consumer->toolProxy, PDO::PARAM_STR);
            $query->bindValue('settings', $settingsValue, PDO::PARAM_STR);
            $query->bindValue('protected', $protected, PDO::PARAM_INT);
            $query->bindValue('enabled', $enabled, PDO::PARAM_INT);
            $query->bindValue('enable_from', $from, PDO::PARAM_STR);
            $query->bindValue('enable_until', $until, PDO::PARAM_STR);
            $query->bindValue('last_access', $last, PDO::PARAM_STR);
            $query->bindValue('created', $now, PDO::PARAM_STR);
            $query->bindValue('updated', $now, PDO::PARAM_STR);
        } else {
            $sql = 'UPDATE ' . $this->dbTableNamePrefix . DataConnector::CONSUMER_TABLE_NAME . ' ' .
                   'SET consumer_key256 = :key256, consumer_key = :key, name = :name, secret = :secret, lti_version = :lti_version, ' .
                   'consumer_name = :consumer_name, consumer_version = :consumer_version, consumer_guid = :consumer_guid, ' .
                   'profile = :profile, tool_proxy = :tool_proxy, settings = :settings, ' .
                   'protected = :protected, enabled = :enabled, enable_from = :enable_from, enable_until = :enable_until, last_access = :last_access, updated = :updated ' .
                   'WHERE consumer_pk = :id';
            $query = $this->db->prepare($sql);
            $query->bindValue('key256', $key256, PDO::PARAM_STR);
            $query->bindValue('key', $key, PDO::PARAM_STR);
            $query->bindValue('name', $consumer->name, PDO::PARAM_STR);
            $query->bindValue('secret', $consumer->secret, PDO::PARAM_STR);
            $query->bindValue('lti_version', $consumer->ltiVersion, PDO::PARAM_STR);
            $query->bindValue('consumer_name', $consumer->consumerName, PDO::PARAM_STR);
            $query->bindValue('consumer_version', $consumer->consumerVersion, PDO::PARAM_STR);
            $query->bindValue('consumer_guid', $consumer->consumerGuid, PDO::PARAM_STR);
            $query->bindValue('profile', $profile, PDO::PARAM_STR);
            $query->bindValue('tool_proxy', $consumer->toolProxy, PDO::PARAM_STR);
            $query->bindValue('settings', $settingsValue, PDO::PARAM_STR);
            $query->bindValue('protected', $protected, PDO::PARAM_INT);
            $query->bindValue('enabled', $enabled, PDO::PARAM_INT);
            $query->bindValue('enable_from', $from, PDO::PARAM_STR);
            $query->bindValue('enable_until', $until, PDO::PARAM_STR);
            $query->bindValue('last_access', $last, PDO::PARAM_STR);
            $query->bindValue('updated', $now, PDO::PARAM_STR);
            $query->bindValue('id', $id, PDO::PARAM_INT);
        }
        $ok = $query->execute();
        if ($ok) {
            if (empty($id)) {
                $consumer->setRecordId(intval($this->db->lastInsertId()));
                $consumer->created = $time;
            }
            $consumer->updated = $time;
        }

        return $ok;

    }

    public function deleteToolConsumer($consumer)
    {

        $id = $consumer->getRecordId();

// Delete any nonce values for this consumer
        $sql = "DELETE FROM {$this->dbTableNamePrefix}" . DataConnector::NONCE_TABLE_NAME . ' WHERE consumer_pk = :id';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_INT);
        $query->execute();

// Delete any outstanding share keys for resource links for this consumer
        $sql = 'DELETE sk ' .
               "FROM {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_SHARE_KEY_TABLE_NAME . ' sk ' .
               "INNER JOIN {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' rl ON sk.resource_link_pk = rl.resource_link_pk ' .
               'WHERE rl.consumer_pk = :id';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_INT);
        $query->execute();

// Delete any outstanding share keys for resource links for contexts in this consumer
        $sql = 'DELETE sk ' .
               "FROM {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_SHARE_KEY_TABLE_NAME . ' sk ' .
               "INNER JOIN {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' rl ON sk.resource_link_pk = rl.resource_link_pk ' .
               "INNER JOIN {$this->dbTableNamePrefix}" . DataConnector::CONTEXT_TABLE_NAME . ' c ON rl.context_pk = c.context_pk ' .
               'WHERE c.consumer_pk = :id';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_INT);
        $query->execute();

// Delete any users in resource links for this consumer
        $sql = 'DELETE u ' .
               "FROM {$this->dbTableNamePrefix}" . DataConnector::USER_RESULT_TABLE_NAME . ' u ' .
               "INNER JOIN {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' rl ON u.resource_link_pk = rl.resource_link_pk ' .
               'WHERE rl.consumer_pk = :id';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_INT);
        $query->execute();

// Delete any users in resource links for contexts in this consumer
        $sql = 'DELETE u ' .
               "FROM {$this->dbTableNamePrefix}" . DataConnector::USER_RESULT_TABLE_NAME . ' u ' .
               "INNER JOIN {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' rl ON u.resource_link_pk = rl.resource_link_pk ' .
               "INNER JOIN {$this->dbTableNamePrefix}" . DataConnector::CONTEXT_TABLE_NAME . ' c ON rl.context_pk = c.context_pk ' .
               'WHERE c.consumer_pk = :id';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_INT);
        $query->execute();

// Update any resource links for which this consumer is acting as a primary resource link
        $sql = "UPDATE {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' prl ' .
               "INNER JOIN {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' rl ON prl.primary_resource_link_pk = rl.resource_link_pk ' .
               'SET prl.primary_resource_link_pk = NULL, prl.share_approved = NULL ' .
               'WHERE rl.consumer_pk = :id';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_INT);
        $query->execute();

// Update any resource links for contexts in which this consumer is acting as a primary resource link
        $sql = "UPDATE {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' prl ' .
               "INNER JOIN {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' rl ON prl.primary_resource_link_pk = rl.resource_link_pk ' .
               "INNER JOIN {$this->dbTableNamePrefix}" . DataConnector::CONTEXT_TABLE_NAME . ' c ON rl.context_pk = c.context_pk ' .
               'SET prl.primary_resource_link_pk = NULL, prl.share_approved = NULL ' .
               'WHERE c.consumer_pk = :id';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_INT);
        $query->execute();

// Delete any resource links for this consumer
        $sql = 'DELETE rl ' .
               "FROM {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' rl ' .
               'WHERE rl.consumer_pk = :id';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_INT);
        $query->execute();

// Delete any resource links for contexts in this consumer
        $sql = 'DELETE rl ' .
               "FROM {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' rl ' .
               "INNER JOIN {$this->dbTableNamePrefix}" . DataConnector::CONTEXT_TABLE_NAME . ' c ON rl.context_pk = c.context_pk ' .
               'WHERE c.consumer_pk = :id';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_INT);
        $query->execute();

// Delete any contexts for this consumer
        $sql = 'DELETE c ' .
               "FROM {$this->dbTableNamePrefix}" . DataConnector::CONTEXT_TABLE_NAME . ' c ' .
               'WHERE c.consumer_pk = :id';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_INT);
        $query->execute();

// Delete consumer
        $sql = 'DELETE c ' .
               "FROM {$this->dbTableNamePrefix}" . DataConnector::CONSUMER_TABLE_NAME . ' c ' .
               'WHERE c.consumer_pk = :id';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_INT);
        $ok = $query->execute();

        if ($ok) {
            $consumer->initialize();
        }

        return $ok;

    }

###
#    Load all tool consumers from the database
###
    public function getToolConsumers()
    {

        $consumers = array();

        $sql = 'SELECT consumer_pk, name, consumer_key256, consumer_key, secret, lti_version, ' .
               'consumer_name, consumer_version, consumer_guid, ' .
               'profile, tool_proxy, settings, protected, enabled, ' .
               'enable_from, enable_until, last_access, created, updated ' .
               "FROM {$this->dbTableNamePrefix}" . DataConnector::CONSUMER_TABLE_NAME . ' ' .
               'ORDER BY name';
        $query = $this->db->prepare($sql);
        $ok = ($query !== FALSE);

        if ($ok) {
            $ok = $query->execute();
        }

        if ($ok) {
            while ($row = $query->fetch(PDO::FETCH_ASSOC)) {
                $row = array_change_key_case($row);
                $key = empty($row['consumer_key']) ? $row['consumer_key256'] : $row['consumer_key'];
                $consumer = new ToolProvider\ToolConsumer($key, $this);
                $consumer->setRecordId(intval($row['consumer_pk']));
                $consumer->name = $row['name'];
                $consumer->secret = $row['secret'];
                $consumer->ltiVersion = $row['lti_version'];
                $consumer->consumerName = $row['consumer_name'];
                $consumer->consumerVersion = $row['consumer_version'];
                $consumer->consumerGuid = $row['consumer_guid'];
                $consumer->profile = json_decode($row['profile']);
                $consumer->toolProxy = $row['tool_proxy'];
                $settings = unserialize($row['settings']);
                if (!is_array($settings)) {
                    $settings = array();
                }
                $consumer->setSettings($settings);
                $consumer->protected = (intval($row['protected']) === 1);
                $consumer->enabled = (intval($row['enabled']) === 1);
                $consumer->enableFrom = null;
                if (!is_null($row['enable_from'])) {
                    $consumer->enableFrom = strtotime($row['enable_from']);
                }
                $consumer->enableUntil = null;
                if (!is_null($row['enable_until'])) {
                    $consumer->enableUntil = strtotime($row['enable_until']);
                }
                $consumer->lastAccess = null;
                if (!is_null($row['last_access'])) {
                    $consumer->lastAccess = strtotime($row['last_access']);
                }
                $consumer->created = strtotime($row['created']);
                $consumer->updated = strtotime($row['updated']);
                $consumers[] = $consumer;
            }
        }

        return $consumers;

    }

###
###  ToolProxy methods
###

###
#    Load the tool proxy from the database
###
    public function loadToolProxy($toolProxy)
    {

        return false;

    }

###
#    Save the tool proxy to the database
###
    public function saveToolProxy($toolProxy)
    {

        return false;

    }

###
#    Delete the tool proxy from the database
###
    public function deleteToolProxy($toolProxy)
    {

        return false;

    }

###
###  Context methods
###

    public function loadContext($context)
    {

        $ok = false;
        if (!empty($context->getRecordId())) {
            $sql = 'SELECT context_pk, consumer_pk, lti_context_id, settings, created, updated ' .
                   "FROM {$this->dbTableNamePrefix}" . DataConnector::CONTEXT_TABLE_NAME . ' ' .
                   'WHERE (context_pk = :id)';
            $query = $this->db->prepare($sql);
            $query->bindValue('id', $context->getRecordId(), PDO::PARAM_INT);
        } else {
            $sql = 'SELECT context_pk, consumer_pk, lti_context_id, settings, created, updated ' .
                   "FROM {$this->dbTableNamePrefix}" . DataConnector::CONTEXT_TABLE_NAME . ' ' .
                   'WHERE (consumer_pk = :cid) AND (lti_context_id = :ctx)';
            $query = $this->db->prepare($sql);
            $query->bindValue('cid', $context->getConsumer()->getRecordId(), PDO::PARAM_INT);
            $query->bindValue('ctx', $context->ltiContextId, PDO::PARAM_STR);
        }
        $ok = $query->execute();
        if ($ok) {
          $row = $query->fetch(PDO::FETCH_ASSOC);
          $ok = ($row !== FALSE);
        }
        if ($ok) {
            $row = array_change_key_case($row);
            $context->setRecordId(intval($row['context_pk']));
            $context->setConsumerId(intval($row['consumer_pk']));
            $context->ltiContextId = $row['lti_context_id'];
            $settings = unserialize($row['settings']);
            if (!is_array($settings)) {
                $settings = array();
            }
            $context->setSettings($settings);
            $context->created = strtotime($row['created']);
            $context->updated = strtotime($row['updated']);
        }

        return $ok;

    }

    public function saveContext($context)
    {

        $time = time();
        $now = date("{$this->dateFormat} {$this->timeFormat}", $time);
        $settingsValue = serialize($context->getSettings());
        $id = $context->getRecordId();
        $consumer_pk = $context->getConsumer()->getRecordId();
        if (empty($id)) {
            $sql = "INSERT INTO {$this->dbTableNamePrefix}" . DataConnector::CONTEXT_TABLE_NAME . ' (consumer_pk, lti_context_id, ' .
                   'settings, created, updated) ' .
                   'VALUES (:cid, :ctx, :settings, :created, :updated)';
            $query = $this->db->prepare($sql);
            $query->bindValue('cid', $consumer_pk, PDO::PARAM_INT);
            $query->bindValue('ctx', $context->ltiContextId, PDO::PARAM_STR);
            $query->bindValue('settings', $settingsValue, PDO::PARAM_STR);
            $query->bindValue('created', $now, PDO::PARAM_STR);
            $query->bindValue('updated', $now, PDO::PARAM_STR);
        } else {
            $sql = "UPDATE {$this->dbTableNamePrefix}" . DataConnector::CONTEXT_TABLE_NAME . ' SET ' .
                   'lti_context_id = :ctx, settings = :settings, '.
                   'updated = :updated ' .
                   'WHERE (consumer_pk = :cid) AND (context_pk = :ctxid)';
            $query = $this->db->prepare($sql);
            $query->bindValue('ctx', $context->ltiContextId, PDO::PARAM_STR);
            $query->bindValue('settings', $settingsValue, PDO::PARAM_STR);
            $query->bindValue('updated', $now, PDO::PARAM_STR);
            $query->bindValue('cid', $consumer_pk, PDO::PARAM_INT);
            $query->bindValue('ctxid', $id, PDO::PARAM_INT);
        }
        $ok = $query->execute();
        if ($ok) {
            if (empty($id)) {
                $context->setRecordId(intval($this->db->lastInsertId()));
                $context->created = $time;
            }
            $context->updated = $time;
        }

        return $ok;

    }

    public function deleteContext($context)
    {

        $id = $context->getRecordId();

// Delete any outstanding share keys for resource links for this context
        $sql = 'DELETE sk ' .
               "FROM {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_SHARE_KEY_TABLE_NAME . ' sk ' .
               "INNER JOIN {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' rl ON sk.resource_link_pk = rl.resource_link_pk ' .
               'WHERE rl.context_pk = :id';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_INT);
        $query->execute();

// Delete any users in resource links for this context
        $sql = 'DELETE u ' .
               "FROM {$this->dbTableNamePrefix}" . DataConnector::USER_RESULT_TABLE_NAME . ' u ' .
               "INNER JOIN {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' rl ON u.resource_link_pk = rl.resource_link_pk ' .
               'WHERE rl.context_pk = :id';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_INT);
        $query->execute();

// Update any resource links for which this consumer is acting as a primary resource link
        $sql = "UPDATE {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' prl ' .
               "INNER JOIN {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' rl ON prl.primary_resource_link_pk = rl.resource_link_pk ' .
               'SET prl.primary_resource_link_pk = null, prl.share_approved = null ' .
               'WHERE rl.context_pk = :id';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_INT);
        $query->execute();

// Delete any resource links for this consumer
        $sql = 'DELETE rl ' .
               "FROM {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' rl ' .
               'WHERE rl.context_pk = :id';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_INT);
        $query->execute();

// Delete context
        $sql = 'DELETE c ' .
               "FROM {$this->dbTableNamePrefix}" . DataConnector::CONTEXT_TABLE_NAME . ' c ' .
               'WHERE c.context_pk = :id';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_INT);
        $ok = $query->execute();

        if ($ok) {
            $context->initialize();
        }

        return $ok;

    }

###
###  ResourceLink methods
###

    public function loadResourceLink($resourceLink)
    {

        if (!empty($resourceLink->getRecordId())) {
            $sql = 'SELECT resource_link_pk, context_pk, consumer_pk, lti_resource_link_id, settings, primary_resource_link_pk, share_approved, created, updated ' .
                   "FROM {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' ' .
                   'WHERE (resource_link_pk = :id)';
            $query = $this->db->prepare($sql);
            $query->bindValue('id', $resourceLink->getRecordId(), PDO::PARAM_INT);
        } else if (!empty($resourceLink->getContext())) {
            $sql = 'SELECT resource_link_pk, context_pk, consumer_pk, lti_resource_link_id, settings, primary_resource_link_pk, share_approved, created, updated ' .
                   "FROM {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' ' .
                   'WHERE (context_pk = :id) AND (lti_resource_link_id = :rlid)';
            $query = $this->db->prepare($sql);
            $query->bindValue('id', $resourceLink->getContext()->getRecordId(), PDO::PARAM_INT);
            $query->bindValue('rlid', $resourceLink->getId(), PDO::PARAM_STR);
        } else {
            $sql = 'SELECT r.resource_link_pk, r.context_pk, r.consumer_pk, r.lti_resource_link_id, r.settings, r.primary_resource_link_pk, r.share_approved, r.created, r.updated ' .
                   "FROM {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' r LEFT OUTER JOIN ' .
                   $this->dbTableNamePrefix . DataConnector::CONTEXT_TABLE_NAME . ' c ON r.context_pk = c.context_pk ' .
                   ' WHERE ((r.consumer_pk = :id1) OR (c.consumer_pk = :id2)) AND (lti_resource_link_id = :rlid)';
            $query = $this->db->prepare($sql);
            $query->bindValue('id1', $resourceLink->getConsumer()->getRecordId(), PDO::PARAM_INT);
            $query->bindValue('id2', $resourceLink->getConsumer()->getRecordId(), PDO::PARAM_INT);
            $query->bindValue('rlid', $resourceLink->getId(), PDO::PARAM_STR);
        }
        $ok = $query->execute();
        if ($ok) {
          $row = $query->fetch(PDO::FETCH_ASSOC);
          $ok = ($row !== FALSE);
        }

        if ($ok) {
            $row = array_change_key_case($row);
            $resourceLink->setRecordId(intval($row['resource_link_pk']));
            if (!is_null($row['context_pk'])) {
                $resourceLink->setContextId(intval($row['context_pk']));
            } else {
                $resourceLink->setContextId(null);
            }
            if (!is_null($row['consumer_pk'])) {
                $resourceLink->setConsumerId(intval($row['consumer_pk']));
            } else {
                $resourceLink->setConsumerId(null);
            }
            $resourceLink->ltiResourceLinkId = $row['lti_resource_link_id'];
            $settings = unserialize($row['settings']);
            if (!is_array($settings)) {
                $settings = array();
            }
            $resourceLink->setSettings($settings);
            if (!is_null($row['primary_resource_link_pk'])) {
                $resourceLink->primaryResourceLinkId = intval($row['primary_resource_link_pk']);
            } else {
                $resourceLink->primaryResourceLinkId = null;
            }
            $resourceLink->shareApproved = (is_null($row['share_approved'])) ? null : (intval($row['share_approved']) === 1);
            $resourceLink->created = strtotime($row['created']);
            $resourceLink->updated = strtotime($row['updated']);
        }

        return $ok;

    }

    public function saveResourceLink($resourceLink) {

        $time = time();
        $now = date("{$this->dateFormat} {$this->timeFormat}", $time);
        $settingsValue = serialize($resourceLink->getSettings());
        if (!empty($resourceLink->getContext())) {
            $consumerId = null;
            $contextId = strval($resourceLink->getContext()->getRecordId());
        } else if (!empty($resourceLink->getContextId())) {
            $consumerId = null;
            $contextId = strval($resourceLink->getContextId());
        } else {
            $consumerId = strval($resourceLink->getConsumer()->getRecordId());
            $contextId = null;
        }
        if (empty($resourceLink->primaryResourceLinkId)) {
            $primaryResourceLinkId = null;
        } else {
            $primaryResourceLinkId = $resourceLink->primaryResourceLinkId;
        }
        $id = $resourceLink->getRecordId();
        if (empty($id)) {
            $sql = "INSERT INTO {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' (consumer_pk, context_pk, ' .
                   'lti_resource_link_id, settings, primary_resource_link_pk, share_approved, created, updated) ' .
                   'VALUES (:cid, :ctx, :rlid, :settings, :prlid, :share_approved, :created, :updated)';
            $query = $this->db->prepare($sql);
            $query->bindValue('cid', $consumerId, PDO::PARAM_INT);
            $query->bindValue('ctx', $contextId, PDO::PARAM_INT);
            $query->bindValue('rlid', $resourceLink->getId(), PDO::PARAM_STR);
            $query->bindValue('settings', $settingsValue, PDO::PARAM_STR);
            $query->bindValue('prlid', $primaryResourceLinkId, PDO::PARAM_INT);
            $query->bindValue('share_approved', $resourceLink->shareApproved, PDO::PARAM_INT);
            $query->bindValue('created', $now, PDO::PARAM_STR);
            $query->bindValue('updated', $now, PDO::PARAM_STR);
        } else if (!is_null($contextId)) {
            $sql = "UPDATE {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' SET ' .
                   'consumer_pk = NULL, context_pk = :ctx, lti_resource_link_id = :rlid, settings = :settings, '.
                   'primary_resource_link_pk = :prlid, share_approved = :share_approved, updated = :updated ' .
                   'WHERE (resource_link_pk = :id)';
            $query = $this->db->prepare($sql);
            $query->bindValue('ctx', $contextId, PDO::PARAM_INT);
            $query->bindValue('rlid', $resourceLink->getId(), PDO::PARAM_STR);
            $query->bindValue('settings', $settingsValue, PDO::PARAM_STR);
            $query->bindValue('prlid', $primaryResourceLinkId, PDO::PARAM_INT);
            $query->bindValue('share_approved', $resourceLink->shareApproved, PDO::PARAM_INT);
            $query->bindValue('updated', $now, PDO::PARAM_STR);
            $query->bindValue('id', $id, PDO::PARAM_INT);
        } else {
            $sql = "UPDATE {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' SET ' .
                   'context_pk = :ctx, lti_resource_link_id = :rlid, settings = :settings, '.
                   'primary_resource_link_pk = :prlid, share_approved = :share_approved, updated = :updated ' .
                   'WHERE (consumer_pk = :cid) AND (resource_link_pk = :id)';
            $query = $this->db->prepare($sql);
            $query->bindValue('ctx', $contextId, PDO::PARAM_INT);
            $query->bindValue('rlid', $resourceLink->getId(), PDO::PARAM_STR);
            $query->bindValue('settings', $settingsValue, PDO::PARAM_STR);
            $query->bindValue('prlid', $primaryResourceLinkId, PDO::PARAM_INT);
            $query->bindValue('share_approved', $resourceLink->shareApproved, PDO::PARAM_INT);
            $query->bindValue('updated', $now, PDO::PARAM_STR);
            $query->bindValue('cid', $consumerId, PDO::PARAM_INT);
            $query->bindValue('id', $id, PDO::PARAM_INT);
        }
        $ok = $query->execute();
        if ($ok) {
            if (empty($id)) {
                $resourceLink->setRecordId(intval($this->db->lastInsertId()));
                $resourceLink->created = $time;
            }
            $resourceLink->updated = $time;
        }

        return $ok;

    }

    public function deleteResourceLink($resourceLink)
    {

        $id = $resourceLink->getRecordId();

// Delete any outstanding share keys for resource links for this consumer
        $sql = "DELETE FROM {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_SHARE_KEY_TABLE_NAME . ' ' .
               'WHERE (resource_link_pk = :id)';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_INT);
        $ok = $query->execute();

// Delete users
        if ($ok) {
            $sql = "DELETE FROM {$this->dbTableNamePrefix}" . DataConnector::USER_RESULT_TABLE_NAME . ' ' .
                   'WHERE (resource_link_pk = :id)';
            $query = $this->db->prepare($sql);
            $query->bindValue('id', $id, PDO::PARAM_INT);
            $ok = $query->execute();
        }

// Update any resource links for which this is the primary resource link
        if ($ok) {
            $sql = "UPDATE {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' ' .
                   'SET primary_resource_link_pk = NULL ' .
                   'WHERE (primary_resource_link_pk = :id)';
            $query = $this->db->prepare($sql);
            $query->bindValue('id', $id, PDO::PARAM_INT);
            $ok = $query->execute();
        }

// Delete resource link
        if ($ok) {
            $sql = "DELETE FROM {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' ' .
                   'WHERE (resource_link_pk = :id)';
            $query = $this->db->prepare($sql);
            $query->bindValue('id', $id, PDO::PARAM_INT);
            $ok = $query->execute();
        }

        if ($ok) {
            $resourceLink->initialize();
        }

        return $ok;

    }

    public function getUserResultSourcedIDsResourceLink($resourceLink, $localOnly, $idScope)
    {

        $id = $resourceLink->getRecordId();
        $users = array();

        if ($localOnly) {
            $sql = 'SELECT u.user_pk, u.lti_result_sourcedid, u.lti_user_id, u.created, u.updated ' .
                   "FROM {$this->dbTableNamePrefix}" . DataConnector::USER_RESULT_TABLE_NAME . ' AS u '  .
                   "INNER JOIN {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' AS rl '  .
                   'ON u.resource_link_pk = rl.resource_link_pk ' .
                   'WHERE (rl.resource_link_pk = :id) AND (rl.primary_resource_link_pk IS NULL)';
            $query = $this->db->prepare($sql);
            $query->bindValue('id', $id, PDO::PARAM_INT);
        } else {
            $sql = 'SELECT u.user_pk, u.lti_result_sourcedid, u.lti_user_id, u.created, u.updated ' .
                   "FROM {$this->dbTableNamePrefix}" . DataConnector::USER_RESULT_TABLE_NAME . ' AS u '  .
                   "INNER JOIN {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' AS rl '  .
                   'ON u.resource_link_pk = rl.resource_link_pk ' .
                   'WHERE ((rl.resource_link_pk = :id) AND (rl.primary_resource_link_pk IS NULL)) OR ' .
                   '((rl.primary_resource_link_pk = :pid) AND (share_approved = 1))';
            $query = $this->db->prepare($sql);
            $query->bindValue('id', $id, PDO::PARAM_INT);
            $query->bindValue('pid', $id, PDO::PARAM_INT);
        }
        if ($query->execute()) {
            while ($row = $query->fetch(PDO::FETCH_ASSOC)) {
                $row = array_change_key_case($row);
                $user = ToolProvider\User::fromRecordId($row['user_pk'], $resourceLink->getDataConnector());
                if (is_null($idScope)) {
                    $users[] = $user;
                } else {
                    $users[$user->getId($idScope)] = $user;
                }
            }
        }

        return $users;

    }

    public function getSharesResourceLink($resourceLink)
    {

        $id = $resourceLink->getRecordId();

        $shares = array();

        $sql = 'SELECT consumer_pk, resource_link_pk, share_approved ' .
               "FROM {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_TABLE_NAME . ' ' .
               'WHERE (primary_resource_link_pk = :id) ' .
               'ORDER BY consumer_pk';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_INT);
        if ($query->execute()) {
            while ($row = $query->fetch(PDO::FETCH_ASSOC)) {
                $row = array_change_key_case($row);
                $share = new ToolProvider\ResourceLinkShare();
                $share->resourceLinkId = intval($row['resource_link_pk']);
                $share->approved = (intval($row['share_approved']) === 1);
                $shares[] = $share;
            }
        }

        return $shares;

    }


###
###  ConsumerNonce methods
###

    public function loadConsumerNonce($nonce)
    {

        $ok = true;

// Delete any expired nonce values
        $now = date("{$this->dateFormat} {$this->timeFormat}", time());
        $sql = "DELETE FROM {$this->dbTableNamePrefix}" . DataConnector::NONCE_TABLE_NAME . ' WHERE expires <= :now';
        $query = $this->db->prepare($sql);
        $query->bindValue('now', $now, PDO::PARAM_STR);
        $query->execute();

// Load the nonce
        $id = $nonce->getConsumer()->getRecordId();
        $value = $nonce->getValue();
        $sql = "SELECT value T FROM {$this->dbTableNamePrefix}" . DataConnector::NONCE_TABLE_NAME . ' WHERE (consumer_pk = :id) AND (value = :value)';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_INT);
        $query->bindValue('value', $value, PDO::PARAM_STR);
        $ok = $query->execute();
        if ($ok) {
            $row = $query->fetch(PDO::FETCH_ASSOC);
            if ($row === false) {
                $ok = false;
            }
        }

        return $ok;

    }

    public function saveConsumerNonce($nonce)
    {

        $id = $nonce->getConsumer()->getRecordId();
        $value = $nonce->getValue();
        $expires = date("{$this->dateFormat} {$this->timeFormat}", $nonce->expires);
        $sql = "INSERT INTO {$this->dbTableNamePrefix}" . DataConnector::NONCE_TABLE_NAME . ' (consumer_pk, value, expires) VALUES (:id, :value, :expires)';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_INT);
        $query->bindValue('value', $value, PDO::PARAM_STR);
        $query->bindValue('expires', $expires, PDO::PARAM_STR);
        $ok = $query->execute();

        return $ok;

    }


###
###  ResourceLinkShareKey methods
###

    public function loadResourceLinkShareKey($shareKey)
    {

        $ok = false;

// Clear expired share keys
        $now = date("{$this->dateFormat} {$this->timeFormat}", time());
        $sql = "DELETE FROM {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_SHARE_KEY_TABLE_NAME . ' WHERE expires <= :now';
        $query = $this->db->prepare($sql);
        $query->bindValue('now', $now, PDO::PARAM_STR);
        $query->execute();

// Load share key
        $id = $shareKey->getId();
        $sql = 'SELECT resource_link_pk, auto_approve, expires ' .
               "FROM {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_SHARE_KEY_TABLE_NAME . ' ' .
               'WHERE share_key_id = :id';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_STR);
        if ($query->execute()) {
            $row = $query->fetch(PDO::FETCH_ASSOC);
            if ($row !== FALSE) {
                $row = array_change_key_case($row);
                if (intval($row['resource_link_pk']) === $shareKey->resourceLinkId) {
                    $shareKey->autoApprove = ($row['auto_approve'] === 1);
                    $shareKey->expires = strtotime($row['expires']);
                    $ok = true;
                }
            }
        }

        return $ok;

    }

    public function saveResourceLinkShareKey($shareKey)
    {

        $id = $shareKey->getId();
        $expires = date("{$this->dateFormat} {$this->timeFormat}", $shareKey->expires);
        $sql = "INSERT INTO {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_SHARE_KEY_TABLE_NAME . ' ' .
               '(share_key_id, resource_link_pk, auto_approve, expires) ' .
               'VALUES (:id, :prlid, :approve, :expires)';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_STR);
        $query->bindValue('prlid', $shareKey->resourceLinkId, PDO::PARAM_INT);
        $query->bindValue('approve', $shareKey->autoApprove, PDO::PARAM_INT);
        $query->bindValue('expires', $expires, PDO::PARAM_STR);
        $ok = $query->execute();

        return $ok;

    }

    public function deleteResourceLinkShareKey($shareKey)
    {

        $id = $shareKey->getId();
        $sql = "DELETE FROM {$this->dbTableNamePrefix}" . DataConnector::RESOURCE_LINK_SHARE_KEY_TABLE_NAME . ' WHERE share_key_id = :id';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $id, PDO::PARAM_STR);
        $ok = $query->execute();

        if ($ok) {
            $shareKey->initialize();
        }

        return $ok;

    }


###
###  User methods
###

    public function loadUser($user)
    {

        $ok = false;
        if (!empty($user->getRecordId())) {
            $id = $user->getRecordId();
            $sql = 'SELECT user_pk, resource_link_pk, lti_user_id, lti_result_sourcedid, created, updated ' .
                   "FROM {$this->dbTableNamePrefix}" . DataConnector::USER_RESULT_TABLE_NAME . ' ' .
                   'WHERE (user_pk = :id)';
            $query = $this->db->prepare($sql);
            $query->bindValue('id', $id, PDO::PARAM_INT);
        } else {
            $id = $user->getResourceLink()->getRecordId();
            $uid = $user->getId(ToolProvider\ToolProvider::ID_SCOPE_ID_ONLY);
            $sql = 'SELECT user_pk, resource_link_pk, lti_user_id, lti_result_sourcedid, created, updated ' .
                   "FROM {$this->dbTableNamePrefix}" . DataConnector::USER_RESULT_TABLE_NAME . ' ' .
                   'WHERE (resource_link_pk = :id) AND (lti_user_id = :uid)';
            $query = $this->db->prepare($sql);
            $query->bindValue('id', $id, PDO::PARAM_INT);
            $query->bindValue('uid', $uid, PDO::PARAM_STR);
        }
        if ($query->execute()) {
            $row = $query->fetch(PDO::FETCH_ASSOC);
            if ($row !== false) {
                $row = array_change_key_case($row);
                $user->setRecordId(intval($row['user_pk']));
                $user->setResourceLinkId(intval($row['resource_link_pk']));
                $user->ltiUserId = $row['lti_user_id'];
                $user->ltiResultSourcedId = $row['lti_result_sourcedid'];
                $user->created = strtotime($row['created']);
                $user->updated = strtotime($row['updated']);
                $ok = true;
            }
        }

        return $ok;

    }

    public function saveUser($user)
    {

        $time = time();
        $now = date("{$this->dateFormat} {$this->timeFormat}", $time);
        if (is_null($user->created)) {
            $sql = "INSERT INTO {$this->dbTableNamePrefix}" . DataConnector::USER_RESULT_TABLE_NAME . ' (resource_link_pk, ' .
                   'lti_user_id, lti_result_sourcedid, created, updated) ' .
                   'VALUES (:rlid, :uid, :sourcedid, :created, :updated)';
            $query = $this->db->prepare($sql);
            $query->bindValue('rlid', $user->getResourceLink()->getRecordId(), PDO::PARAM_INT);
            $query->bindValue('uid', $user->getId(ToolProvider\ToolProvider::ID_SCOPE_ID_ONLY), PDO::PARAM_STR);
            $query->bindValue('sourcedid', $user->ltiResultSourcedId, PDO::PARAM_STR);
            $query->bindValue('created', $now, PDO::PARAM_STR);
            $query->bindValue('updated', $now, PDO::PARAM_STR);
        } else {
            $sql = "UPDATE {$this->dbTableNamePrefix}" . DataConnector::USER_RESULT_TABLE_NAME . ' ' .
                   'SET lti_result_sourcedid = :sourcedid, updated = :updated ' .
                   'WHERE (user_pk = :id)';
            $query = $this->db->prepare($sql);
            $query->bindValue('sourcedid', $user->ltiResultSourcedId, PDO::PARAM_STR);
            $query->bindValue('updated', $now, PDO::PARAM_STR);
            $query->bindValue('id', $user->getRecordId(), PDO::PARAM_INT);
        }
        $ok = $query->execute();
        if ($ok) {
            if (is_null($user->created)) {
                $user->setRecordId(intval($this->db->lastInsertId()));
                $user->created = $time;
            }
            $user->updated = $time;
        }

        return $ok;

    }

    public function deleteUser($user)
    {

        $sql = "DELETE FROM {$this->dbTableNamePrefix}" . DataConnector::USER_RESULT_TABLE_NAME . ' ' .
               'WHERE (user_pk = :id)';
        $query = $this->db->prepare($sql);
        $query->bindValue('id', $user->getRecordId(), PDO::PARAM_INT);
        $ok = $query->execute();

        if ($ok) {
            $user->initialize();
        }

        return $ok;

    }

}