/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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
 * <p/>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p/>
 * 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.apache.flink.streaming.siddhi.schema;

import org.apache.flink.api.java.tuple.Tuple;
import org.apache.flink.api.java.typeutils.TypeExtractor;
import org.apache.flink.util.Preconditions;

import java.io.Serializable;
import java.lang.reflect.Field;

/**
 * Stream Serialization and Field Extraction Methods.
 */
public class StreamSerializer<T> implements Serializable {
    private final StreamSchema<T> schema;

    public StreamSerializer(StreamSchema<T> schema) {
        this.schema = schema;
    }

    public Object[] getRow(T input) {
        Preconditions.checkArgument(input.getClass() == schema.getTypeInfo().getTypeClass(),
            "Invalid input type: " + input + ", expected: " + schema.getTypeInfo());

        Object[] data;
        if (schema.isAtomicType()) {
            data = new Object[]{input};
        } else if (schema.isTupleType()) {
            Tuple tuple = (Tuple) input;
            data = new Object[schema.getFieldIndexes().length];
            for (int i = 0; i < schema.getFieldIndexes().length; i++) {
                data[i] = tuple.getField(schema.getFieldIndexes()[i]);
            }
        } else if (schema.isPojoType() || schema.isCaseClassType()) {
            data = new Object[schema.getFieldIndexes().length];
            for (int i = 0; i < schema.getFieldNames().length; i++) {
                data[i] = getFieldValue(schema.getFieldNames()[i], input);
            }
        } else {
            throw new IllegalArgumentException("Failed to get field values from " + schema.getTypeInfo());
        }
        return data;
    }

    private Object getFieldValue(String fieldName, T input) {
        // TODO: Cache Field Accessor
        Field field = TypeExtractor.getDeclaredField(schema.getTypeInfo().getTypeClass(), fieldName);
        if (field == null) {
            throw new IllegalArgumentException(fieldName + " is not found in " + schema.getTypeInfo());
        }
        if (!field.isAccessible()) {
            field.setAccessible(true);
        }
        try {
            return field.get(input);
        } catch (IllegalAccessException e) {
            throw new IllegalStateException(e.getMessage(), e);
        }
    }
}