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/*
* $URL$
* $Id$
*
* Copyright (c) 2015- Charles R. Severance
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
package org.tsugi.basiclti;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Properties;
import java.net.URLEncoder;
import javax.servlet.http.HttpServletRequest;
import net.oauth.OAuthAccessor;
import net.oauth.OAuthConsumer;
import net.oauth.OAuthMessage;
import net.oauth.OAuthValidator;
import net.oauth.SimpleOAuthValidator;
import net.oauth.server.OAuthServlet;
import net.oauth.signature.OAuthSignatureMethod;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.text.StringEscapeUtils;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.JSONValue;
import static org.tsugi.basiclti.BasicLTIUtil.getArray;
import static org.tsugi.basiclti.BasicLTIUtil.getObject;
import static org.tsugi.basiclti.BasicLTIUtil.getString;
import static org.tsugi.basiclti.BasicLTIUtil.getDouble;
// https://www.imsglobal.org/specs/lticiv1p0/specification
/* {
"@context" : [
"http://purl.imsglobal.org/ctx/lti/v1/ContentItem",
{
"lineItem" : "http://purl.imsglobal.org/ctx/lis/v2/LineItem",
"res" : "http://purl.imsglobal.org/ctx/lis/v2p1/Result#"
}
],
"@graph" : [
{ "@type" : "LtiLinkItem",
"mediaType" : "application/vnd.ims.lti.v1.ltilink",
"title" : "Chapter 12 quiz",
"lineItem" : {
"@type" : "LineItem",
"label" : "Chapter 12 quiz",
"reportingMethod" : "res:totalScore",
"assignedActivity" : {
"@id" : "http://toolprovider.example.com/assessment/66400",
"activity_id" : "a-9334df-33"
},
"scoreConstraints" : {
"@type" : "NumericLimits",
"normalMaximum" : 100,
"extraCreditMaximum" : 10,
"totalMaximum" : 110
}
},
{ "@type" : "FileItem",
"url" : "http://www.imsglobal.org/xsd/qti/qtiv2p1/imsqti_v2p1.xsd",
"copyAdvice" : "true",
"expiresAt" : "2014-03-05T00:00:00Z",
"mediaType" : "application/xml",
"title" : "QTI v2.1 Specification Information Model",
"placementAdvice" : {
"windowTarget" : "_blank"
}
}
]
} */
public class ContentItem {
public static final String ACCEPT_MEDIA_TYPES = "accept_media_types";
public static String MEDIA_LTILINKITEM = "application/vnd.ims.lti.v1.ltilink";
public static String MEDIA_ALL = "*/*";
public static String ACCEPT_MULTIPLE = "accept_multiple";
// http://www.iana.org/assignments/media-types/media-types.xhtml
public static final String MEDIA_CC_1_1 = "application/vnd.ims.imsccv1p1";
public static final String MEDIA_CC_1_2 = "application/vnd.ims.imsccv1p2";
public static final String MEDIA_CC_1_3 = "application/vnd.ims.imsccv1p3";
public static final String MEDIA_CC = MEDIA_CC_1_1+","+MEDIA_CC_1_2+","+MEDIA_CC_1_3;
public static final String TYPE_LTILINKITEM = "LtiLinkItem";
public static final String TYPE_CONTENTITEM = "ContentItem";
public static final String TYPE_FILEITEM = "FileItem";
public static final String TYPE_IMPORTITEM = "ImportItem";
public static final String TITLE = "title";
public static final String TEXT = "text";
public static final String URL = "url";
public static final String LINEITEM = "lineItem";
public static final String SCORE_CONSTRAINTS = "scoreConstraints";
public static final String SCORE_CONSTRAINTS_NORMAL_MAXIMUM = "normalMaximum";
public static final String SCORE_CONSTRAINTS_EXTRA_CREDIT_MAXIMUM = "extraCreditMaximum";
public static final String SCORE_CONSTRAINTS_TOTAL_MAXIMUM = "totalMaximum";
public static final String CUSTOM = "custom";
public static final String ICON = "icon";
public static final String CONTENT_ITEMS = "content_items";
public static final String NO_CONTENT_ITEMS = "Missing content_items= parameter from ContentItem return";
public static final String BAD_CONTENT_MESSAGE = "CONTENT_ITEMS is wrong type ";
public static final String NO_DATA_MESSAGE = "Missing data= parameter from ContentItem return";
public static final String NO_GRAPH_MESSAGE = "A content_item must include a @graph";
public static final String BAD_DATA_MESSAGE = "data= parameter is wrong type ";
HttpServletRequest servletRequest = null;
private JSONObject contentItem = null;
private JSONArray graph = null;
private Properties dataProps = new Properties();
private String errorMessage = null;
private String base_string = null;
/**
* We check for the fields essential for the class to operate here.
*/
public ContentItem(HttpServletRequest req)
{
this.servletRequest = req;
String contentItems = req.getParameter(CONTENT_ITEMS);
if ( StringUtils.isEmpty(contentItems) ) {
throw new java.lang.RuntimeException(NO_CONTENT_ITEMS);
}
Object cit = JSONValue.parse(contentItems);
if ( cit != null && cit instanceof JSONObject ) {
contentItem = (JSONObject) cit;
} else {
throw new java.lang.RuntimeException(BAD_CONTENT_MESSAGE + cit.getClass().getName());
}
String returnedData = req.getParameter("data");
if ( StringUtils.isEmpty(returnedData) ) {
throw new java.lang.RuntimeException(NO_DATA_MESSAGE);
}
returnedData = StringEscapeUtils.unescapeJson(returnedData);
Object dat = JSONValue.parse(returnedData);
JSONObject dataJson = null;
if ( dat != null && dat instanceof JSONObject ) {
dataJson = (JSONObject) dat;
} else {
throw new java.lang.RuntimeException("data= parameter is wrong type "+dat.getClass().getName());
}
Iterator it = dataJson.keySet().iterator();
while (it.hasNext()) {
String key = (String) it.next();
Object value = dataJson.get(key);
if ( value == null || ! (value instanceof String) ) continue;
dataProps.setProperty(key, (String) value);
}
graph = getArray(contentItem,BasicLTIConstants.GRAPH);
if ( graph == null ) {
throw new java.lang.RuntimeException(NO_GRAPH_MESSAGE);
}
}
/**
* Validate the incoming request
*
* @param URL The URL of the incoming request. If this in null, the URL is taken
* from the request object. Sometimes the request object can be misleading when
* sitting behind a load balancer or some kind of proxy.
*/
public boolean validate(String oauth_consumer_key, String oauth_secret, String URL)
{
String req_oauth_consumer_key = servletRequest.getParameter("oauth_consumer_key");
if ( req_oauth_consumer_key == null || req_oauth_consumer_key.length() < 1 ) {
errorMessage = "Missing oauth_consumer_key from incoming request";
return true;
}
if ( ! req_oauth_consumer_key.equals(oauth_consumer_key) ) {
errorMessage = "Mis-match of oauth_consumer_key from incoming request";
return false;
}
// A URL of null is OK
OAuthMessage oam = OAuthServlet.getMessage(servletRequest, URL);
OAuthValidator oav = new SimpleOAuthValidator();
OAuthConsumer cons = new OAuthConsumer("about:blank#OAuth+CallBack+NotUsed", oauth_consumer_key,oauth_secret, null);
OAuthAccessor acc = new OAuthAccessor(cons);
base_string = null;
try {
base_string = OAuthSignatureMethod.getBaseString(oam);
} catch (Exception e) {
base_string = null;
}
try {
oav.validateMessage(oam, acc);
} catch (Exception e) {
errorMessage = e.getLocalizedMessage();
return false;
}
return true;
}
/**
* Return a string
*/
public String toString()
{
return contentItem.toString();
}
/**
* Retrieve the parsed tool_proxy
*/
public JSONObject getContentItem()
{
return contentItem;
}
/**
* Retrieve the @graph from the content item
*/
public JSONArray getGraph()
{
return graph;
}
/**
* Retrieve a particular type from the graph
*
* @param String messageType - Which item type you are looking for
*/
public JSONObject getItemOfType(String itemType)
{
for ( Object i : graph ) {
if ( ! (i instanceof JSONObject) ) continue;
JSONObject item = (JSONObject) i;
String type = getString(item, BasicLTIConstants.TYPE);
if ( type == null ) continue;
if ( type.equals(itemType) ) return item;
}
return null;
}
/**
* Get the data properties from the incoming request
*/
public Properties getDataProperties()
{
return dataProps;
}
/**
* Return the base string
*/
public String getBaseString()
{
return base_string;
}
/**
* Return the error message
*/
public String getErrorMessage()
{
return errorMessage;
}
/**
* Build up a ContentItem launch URL from a base url, return url and extra data
*/
public static String buildLaunch(String contentLaunch, String contentReturn, Properties contentData)
{
StringBuffer sb = new StringBuffer(contentLaunch);
if ( contentLaunch.indexOf("?") > 1 ) {
sb.append("&");
} else {
sb.append("?");
}
sb.append("contentReturn=");
sb.append(URLEncoder.encode(contentReturn));
if ( contentData == null ) return sb.toString();
Enumeration en = contentData.keys();
while (en.hasMoreElements()) {
String key = (String) en.nextElement();
String value = contentData.getProperty(key);
if ( value == null ) continue;
sb.append("&");
sb.append(URLEncoder.encode(key));
sb.append("=");
sb.append(URLEncoder.encode(value));
}
return sb.toString();
}
/**
* Get the maximum score from a lineItem
*
* This logic is to produce the DeepLink equivalent of maxScore from a Content Item
*/
public static Double getScoreMaximum(JSONObject lineItem) {
if ( lineItem == null ) return null;
JSONObject scoreConstraints = getObject(lineItem, SCORE_CONSTRAINTS);
if ( scoreConstraints == null ) return null;
Double normalMaximum = getDouble(scoreConstraints, SCORE_CONSTRAINTS_NORMAL_MAXIMUM);
Double totalMaximum = getDouble(scoreConstraints, SCORE_CONSTRAINTS_TOTAL_MAXIMUM);
if ( totalMaximum == null ) return normalMaximum;
if ( normalMaximum == null ) return totalMaximum;
if ( normalMaximum > totalMaximum ) return normalMaximum;
return totalMaximum;
}
}
