/*
* Copyright Myrrix Ltd
*
* 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 net.myrrix.web.servlets;
import java.io.BufferedReader;
import java.io.IOException;
import java.util.Iterator;
import java.util.NoSuchElementException;
import javax.servlet.ServletRequest;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.mahout.cf.taste.common.TasteException;
import net.myrrix.common.LangUtils;
import net.myrrix.common.MyrrixRecommender;
/**
* <p>Responds to a POST request to {@code /pref/[userID]/[itemID]} and in turn calls
* {@link MyrrixRecommender#setPreference(long, long, float)}. If the request body is empty,
* the value is 1.0, otherwise the value in the request body's first line is used.</p>
*
* <p>Also responds to a DELETE request to the same path, with the same defaults. This corresponds
* to calling {@link MyrrixRecommender#removePreference(long, long)} instead.</p>
*
* @author Sean Owen
* @since 1.0
*/
public final class PreferenceServlet extends AbstractMyrrixServlet {
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
CharSequence pathInfo = request.getPathInfo();
if (pathInfo == null) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST, "No path");
return;
}
Iterator<String> pathComponents = SLASH.split(pathInfo).iterator();
long userID;
long itemID;
try {
userID = Long.parseLong(pathComponents.next());
itemID = Long.parseLong(pathComponents.next());
} catch (NoSuchElementException nsee) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST, nsee.toString());
return;
} catch (NumberFormatException nfe) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST, nfe.toString());
return;
}
if (pathComponents.hasNext()) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST, "Path too long");
return;
}
float prefValue;
try {
prefValue = readValue(request);
} catch (IllegalArgumentException ignored) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST, "Bad value");
return;
}
MyrrixRecommender recommender = getRecommender();
try {
recommender.setPreference(userID, itemID, prefValue);
} catch (TasteException te) {
response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, te.toString());
getServletContext().log("Unexpected error in " + getClass().getSimpleName(), te);
}
}
@Override
protected void doDelete(HttpServletRequest request, HttpServletResponse response) throws IOException {
CharSequence pathInfo = request.getPathInfo();
if (pathInfo == null) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST, "No path");
return;
}
Iterator<String> pathComponents = SLASH.split(pathInfo).iterator();
long userID;
long itemID;
try {
userID = Long.parseLong(pathComponents.next());
itemID = Long.parseLong(pathComponents.next());
} catch (NoSuchElementException nsee) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST, nsee.toString());
return;
} catch (NumberFormatException nfe) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST, nfe.toString());
return;
}
MyrrixRecommender recommender = getRecommender();
try {
recommender.removePreference(userID, itemID);
} catch (TasteException te) {
response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, te.toString());
getServletContext().log("Unexpected error in " + getClass().getSimpleName(), te);
}
}
static float readValue(ServletRequest request) throws IOException {
String line;
BufferedReader reader = request.getReader();
try {
line = reader.readLine();
} finally {
reader.close();
}
if (line == null || line.isEmpty()) {
return 1.0f;
}
return LangUtils.parseFloat(line);
}
@Override
protected Long getUnnormalizedPartitionToServe(HttpServletRequest request) {
CharSequence pathInfo = request.getPathInfo();
if (pathInfo == null) {
return null;
}
Iterator<String> pathComponents = SLASH.split(pathInfo).iterator();
long userID;
try {
userID = Long.parseLong(pathComponents.next());
} catch (NoSuchElementException ignored) {
return null;
} catch (NumberFormatException ignored) {
return null;
}
return userID;
}
}