package com.epam.wilma.webapp.stub.response.formatter.json;
/*==========================================================================
Copyright 2013-2017 EPAM Systems
This file is part of Wilma.
Wilma is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Wilma is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Wilma. If not, see <http://www.gnu.org/licenses/>.
===========================================================================*/
import java.nio.charset.StandardCharsets;
import java.util.ArrayDeque;
import java.util.Deque;
import java.util.Map;
import org.springframework.stereotype.Component;
import com.epam.wilma.domain.http.WilmaHttpRequest;
import com.epam.wilma.domain.stubconfig.dialog.response.template.TemplateFormatter;
import com.epam.wilma.domain.stubconfig.parameter.ParameterList;
import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;
import com.google.gson.JsonPrimitive;
import com.jayway.jsonpath.JsonPath;
import javax.servlet.http.HttpServletResponse;
/**
* Generates a JSON response from the given template resource by using
* parameters from the request. Properties in the templates with JsonPath value
* will be replaces with the evaluated expression value (e.g.
* {@code"$.persons[0].name"}).
*
* @author Balazs_Berkes
*/
@Component
public class JsonTemplateFormatter implements TemplateFormatter {
@Override
public byte[] formatTemplate(final WilmaHttpRequest wilmaRequest, final HttpServletResponse resp,
final byte[] templateResource, final ParameterList params) throws Exception {
JsonElement response = new JsonParser().parse(new String(templateResource, StandardCharsets.UTF_8));
new NonRecursiveJsonTreeEvaluator(wilmaRequest.getBody()).replaceAllNonRecursive(response);
return response.toString().getBytes();
}
/**
* Iterate through all JSON tree element.
*/
public static class NonRecursiveJsonTreeEvaluator {
private static final String JSON_PATH_PREFIX = "$";
private final String source;
private final Deque<JsonElement> stack;
/**
* Creates an evaluator which will iterate through all JSON tree element an perform custom steps.
* @param source String representation of JSON object.
*/
public NonRecursiveJsonTreeEvaluator(final String source) {
this.source = source;
this.stack = new ArrayDeque<>();
}
/**
* Calls replaceJsonPath() method for this node and all its children.
* @param node root node
*/
public void replaceAllNonRecursive(final JsonElement node) {
stack.push(node);
while (!stack.isEmpty()) {
JsonElement current = stack.pop();
if (current.isJsonArray()) {
pushAllElements(current.getAsJsonArray());
} else if (current.isJsonObject()) {
exploreObject(current.getAsJsonObject());
}
}
}
/**
* Replaces the current node value if needed.
* @param parent parent node
* @param key name of the current node
* @param value the current node
*/
protected void replaceJsonPath(final JsonObject parent, final String key, final JsonPrimitive value) {
if (isExpression(value.getAsString())) {
String requestValue = JsonPath.read(source, value.getAsString());
parent.add(key, new JsonPrimitive(requestValue));
}
}
protected String getSource() {
return source;
}
protected Deque<JsonElement> getStack() {
return stack;
}
private void exploreObject(final JsonObject object) {
for (Map.Entry<String, JsonElement> property : object.entrySet()) {
if (property.getValue().isJsonPrimitive()) {
replaceJsonPath(object, property.getKey(), property.getValue().getAsJsonPrimitive());
} else {
stack.push(property.getValue());
}
}
}
private void pushAllElements(final JsonArray array) {
for (JsonElement element : array) {
stack.push(element);
}
}
private boolean isExpression(final String value) {
return value.startsWith(JSON_PATH_PREFIX);
}
}
}