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/*-
* ============LICENSE_START=======================================================
* Copyright (C) 2016-2018 Ericsson. All rights reserved.
* Modifications Copyright (C) 2019-2020 Nordix Foundation.
* Modifications Copyright (C) 2021 Bell Canada. All rights reserved.
* ================================================================================
* 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.
*
* SPDX-License-Identifier: Apache-2.0
* ============LICENSE_END=========================================================
*/
package org.onap.policy.apex.plugins.context.schema.avro;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonElement;
import java.io.ByteArrayOutputStream;
import java.util.LinkedHashSet;
import java.util.Set;
import org.apache.avro.Schema;
import org.apache.avro.Schema.Field;
import org.apache.avro.Schema.Type;
import org.apache.avro.generic.GenericDatumReader;
import org.apache.avro.generic.GenericDatumWriter;
import org.apache.avro.generic.GenericRecord;
import org.apache.avro.io.DatumWriter;
import org.apache.avro.io.DecoderFactory;
import org.apache.avro.io.EncoderFactory;
import org.apache.avro.io.JsonDecoder;
import org.apache.avro.io.JsonEncoder;
import org.onap.policy.apex.context.ContextRuntimeException;
import org.onap.policy.apex.context.impl.schema.AbstractSchemaHelper;
import org.onap.policy.apex.model.basicmodel.concepts.AxArtifactKey;
import org.onap.policy.apex.model.basicmodel.concepts.AxKey;
import org.onap.policy.apex.model.contextmodel.concepts.AxContextSchema;
/**
* This class is the implementation of the {@link org.onap.policy.apex.context.SchemaHelper} interface for Avro schemas.
*
* @author Liam Fallon (liam.fallon@ericsson.com)
*/
public class AvroSchemaHelper extends AbstractSchemaHelper {
// Get a reference to the logger
// Recurring string constants
private static final String OBJECT_TAG = ": object \"";
// The Avro schema for this context schema
private Schema avroSchema;
// The mapper that translates between Java and Avro objects
private AvroObjectMapper avroObjectMapper;
@Override
public void init(final AxKey userKey, final AxContextSchema schema) {
super.init(userKey, schema);
// Configure the Avro schema
try {
avroSchema = new Schema.Parser().parse(schema.getSchema());
} catch (final Exception e) {
final String resultSting = userKey.getId() + ": avro context schema \"" + schema.getId()
+ "\" schema is invalid, schema: " + schema.getSchema();
throw new ContextRuntimeException(resultSting, e);
}
// Get the object mapper for the schema type to a Java class
avroObjectMapper = new AvroObjectMapperFactory().get(userKey, avroSchema);
// Get the Java type for this schema, if it is a primitive type then we can do direct
// conversion to JAva
setSchemaClass(avroObjectMapper.getJavaClass());
}
/**
* Getter to get the Avro schema.
*
* @return the Avro schema
*/
public Schema getAvroSchema() {
return avroSchema;
}
@Override
public Object getSchemaObject() {
return getAvroSchema();
}
@Override
public Object createNewInstance() {
// Create a new instance using the Avro object mapper
final Object newInstance = avroObjectMapper.createNewInstance(avroSchema);
// If no new instance is created, use default schema handler behaviour
if (newInstance != null) {
return newInstance;
} else {
return super.createNewInstance();
}
}
@Override
public Object createNewInstance(final String stringValue) {
return unmarshal(stringValue);
}
@Override
public Object createNewInstance(final Object incomingObject) {
if (incomingObject instanceof JsonElement) {
final Gson gson = new GsonBuilder().serializeNulls().create();
final String elementJsonString = gson.toJson((JsonElement) incomingObject);
return createNewInstance(elementJsonString);
} else {
final String returnString =
getUserKey().getId() + ": the object \"" + incomingObject + "\" is not an instance of JsonObject";
throw new ContextRuntimeException(returnString);
}
}
@Override
public Object createNewSubInstance(final String subInstanceType) {
final Set<String> foundTypes = new LinkedHashSet<>();
Object subInstance = createNewSubInstance(avroSchema, subInstanceType, foundTypes);
if (subInstance != null) {
return subInstance;
} else {
final String returnString = getUserKey().getId() + ": the schema \"" + avroSchema.getName()
+ "\" does not have a subtype of type \"" + subInstanceType + "\"";
throw new ContextRuntimeException(returnString);
}
}
/**
* Create an instance of a sub type of this type.
*
* @param schema the Avro schema of the the type
* @param subInstanceType the sub type
* @param foundTypes types we have already found
* @return the sub type schema or null if it is not created
*/
private Object createNewSubInstance(Schema schema, String subInstanceType, final Set<String> foundTypes) {
// Try Array element types
if (Type.ARRAY == schema.getType()) {
Object newInstance = instantiateSubInstance(subInstanceType, schema.getElementType(), foundTypes);
if (newInstance != null) {
return newInstance;
}
}
if (Type.MAP == schema.getType()) {
Object newInstance = instantiateSubInstance(subInstanceType, schema.getValueType(), foundTypes);
if (newInstance != null) {
return newInstance;
}
}
if (Type.RECORD == schema.getType()) {
for (Field field : schema.getFields()) {
Object newInstance = instantiateSubInstance(subInstanceType, field.schema(), foundTypes);
if (newInstance != null) {
return newInstance;
}
}
}
return null;
}
/**
* Instantiate a sub instance of a type.
*
* @param subInstanceType the type of the sub instance to create
* @param subSchema the sub schema we have received
* @param foundTypes types we have already found
* @return an instance of the type or null if it is the incorrect type
*/
private Object instantiateSubInstance(final String subInstanceType, final Schema subSchema,
final Set<String> foundTypes) {
if (subSchema == null) {
return null;
}
// Check for recursive use of field names in records, if we have already checked a field name
// skip it this time.
if (foundTypes.contains(subSchema.getName())) {
return null;
}
foundTypes.add(subSchema.getName());
if (subSchema.getName().equals(subInstanceType)) {
return new AvroObjectMapperFactory().get(AxArtifactKey.getNullKey(), subSchema)
.createNewInstance(subSchema);
}
return createNewSubInstance(subSchema, subInstanceType, foundTypes);
}
@Override
public Object unmarshal(final Object object) {
// If an object is already in the correct format, just carry on
if (passThroughObject(object)) {
return object;
}
String objectString = getStringObject(object);
// Translate illegal characters in incoming JSON keys to legal Avro values
objectString = AvroSchemaKeyTranslationUtilities.translateIllegalKeys(objectString, false);
// Decode the object
Object decodedObject;
try {
final JsonDecoder jsonDecoder = DecoderFactory.get().jsonDecoder(avroSchema, objectString);
decodedObject = new GenericDatumReader<GenericRecord>(avroSchema).read(null, jsonDecoder);
} catch (final Exception e) {
final String returnString =
getUserKey().getId() + OBJECT_TAG + objectString + "\" Avro unmarshalling failed.";
throw new ContextRuntimeException(returnString, e);
}
// Now map the decoded object into something we can handle
return avroObjectMapper.mapFromAvro(decodedObject);
}
/**
* Check that the incoming object is a string, the incoming object must be a string containing Json.
*
* @param object incoming object
* @return object as String
*/
private String getStringObject(final Object object) {
try {
if (isObjectString(object)) {
return getObjectString(object);
} else {
return (String) object;
}
} catch (final ClassCastException e) {
final String returnString = getUserKey().getId() + OBJECT_TAG + object + "\" of type \""
+ (object != null ? object.getClass().getName() : "null") + "\" must be assignable to \""
+ getSchemaClass().getName() + "\" or be a Json string representation of it for Avro unmarshalling";
throw new ContextRuntimeException(returnString, e);
}
}
/**
* Get a string object.
*
* @param object the string object
* @return the string
*/
private String getObjectString(final Object object) {
String objectString = object.toString().trim();
if (objectString.length() == 0) {
return "\"\"";
} else if (objectString.length() == 1) {
return "\"" + objectString + "\"";
} else {
// All strings must be quoted for decoding
if (objectString.charAt(0) != '"') {
objectString = '"' + objectString;
}
if (objectString.charAt(objectString.length() - 1) != '"') {
objectString += '"';
}
}
return objectString;
}
private boolean isObjectString(final Object object) {
return object != null && avroSchema.getType().equals(Schema.Type.STRING);
}
@Override
public String marshal2String(final Object object) {
// Condition the object for Avro encoding
final Object conditionedObject = avroObjectMapper.mapToAvro(object);
final String jsonString = getJsonString(object, conditionedObject);
return AvroSchemaKeyTranslationUtilities.translateIllegalKeys(jsonString, true);
}
private String getJsonString(final Object object, final Object conditionedObject) {
try (final ByteArrayOutputStream output = new ByteArrayOutputStream()) {
final DatumWriter<Object> writer = new GenericDatumWriter<>(avroSchema);
final JsonEncoder jsonEncoder = EncoderFactory.get().jsonEncoder(avroSchema, output, true);
writer.write(conditionedObject, jsonEncoder);
jsonEncoder.flush();
return new String(output.toByteArray());
} catch (final Exception e) {
final String returnString = getUserKey().getId() + OBJECT_TAG + object + "\" Avro marshalling failed.";
throw new ContextRuntimeException(returnString, e);
}
}
@Override
public JsonElement marshal2Object(final Object schemaObject) {
// Get the object as a Json string
final String schemaObjectAsString = marshal2String(schemaObject);
// Get a Gson instance to convert the Json string to an object created by Json
final Gson gson = new Gson();
// Convert the Json string into an object
final Object schemaObjectAsObject = gson.fromJson(schemaObjectAsString, Object.class);
return gson.toJsonTree(schemaObjectAsObject);
}
/**
* Check if we can pass this object straight through encoding or decoding, is it an object native to the schema.
*
* @param object the object to check
* @return true if it's a straight pass through
*/
private boolean passThroughObject(final Object object) {
if (object == null || getSchemaClass() == null) {
return false;
}
// All strings must be mapped
if (object instanceof String) {
return false;
}
// Now, check if the object is native
return getSchemaClass().isAssignableFrom(object.getClass());
}
}
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