/**

* Copyright 2012-2018 The Feign Authors

*

* 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 feign;

import feign.codec.EncodeException;

import java.lang.reflect.Field;

import java.util.ArrayList;

import java.util.Collections;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

/**

* A QueryMapEncoder encodes Objects into maps of query parameter names to values.

*/

public interface QueryMapEncoder {

/**

* Encodes the given object into a query map.

*

* @param object the object to encode

* @return the map represented by the object

*/

Map<String, Object> encode(Object object);

class Default implements QueryMapEncoder {

private final Map<Class<?>, ObjectParamMetadata> classToMetadata =

new HashMap<Class<?>, ObjectParamMetadata>();

@Override

public Map<String, Object> encode(Object object) throws EncodeException {

try {

ObjectParamMetadata metadata = getMetadata(object.getClass());

Map<String, Object> fieldNameToValue = new HashMap<String, Object>();

for (Field field : metadata.objectFields) {

Object value = field.get(object);

if (value != null && value != object) {

fieldNameToValue.put(field.getName(), value);

}

}

return fieldNameToValue;

} catch (IllegalAccessException e) {

throw new EncodeException("Failure encoding object into query map", e);

}

}

private ObjectParamMetadata getMetadata(Class<?> objectType) {

ObjectParamMetadata metadata = classToMetadata.get(objectType);

if (metadata == null) {

metadata = ObjectParamMetadata.parseObjectType(objectType);

classToMetadata.put(objectType, metadata);

}

return metadata;

}

private static class ObjectParamMetadata {

private final List<Field> objectFields;

private ObjectParamMetadata(List<Field> objectFields) {

this.objectFields = Collections.unmodifiableList(objectFields);

}

private static ObjectParamMetadata parseObjectType(Class<?> type) {

List<Field> fields = new ArrayList<Field>();

for (Field field : type.getDeclaredFields()) {

if (!field.isAccessible()) {

field.setAccessible(true);

}

fields.add(field);

}

return new ObjectParamMetadata(fields);

}

}

}

}