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/*
 * Copyright 2017-2019 the original author or 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
 *
 *      https://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 org.springframework.data.cassandra.core.query;

import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import org.springframework.core.convert.converter.Converter;
import org.springframework.data.cassandra.core.query.CriteriaDefinition.Operator;
import org.springframework.lang.Nullable;

import com.datastax.driver.core.CodecRegistry;
import com.datastax.driver.core.TypeCodec;

/**
 * Utility methods for CQL serialization.
 *
 * @author Mark Paluch
 * @see org.springframework.core.convert.converter.Converter
 * @see com.datastax.driver.core.CodecRegistry
 * @see com.datastax.driver.core.TypeCodec
 * @since 2.0
 */
abstract class SerializationUtils {

	private SerializationUtils() {}

	/**
	 * Serializes the given object into pseudo-CQL meaning it's trying to create a CQL representation as far as possible
	 * but falling back to the given object's {@link Object#toString()} method if it's not serializable. Useful for
	 * printing raw {@link Criteria}s containing complex values before actually converting them into Mongo native types.
	 *
	 * @param criteria may be {@literal null}.
	 * @return may be {@literal null}.
	 */
	@Nullable
	public static String serializeToCqlSafely(@Nullable CriteriaDefinition criteria) {

		if (criteria == null) {
			return null;
		}

		CriteriaDefinition.Predicate predicate = criteria.getPredicate();

		return String.format("%s %s", criteria.getColumnName(),
				predicate.getOperator().toCql(serializeToCqlSafely(predicate.getValue())));
	}

	/**
	 * Serializes the given object into pseudo-CQL meaning it's trying to create a CQL representation as far as possible
	 * but falling back to the given object's {@link Object#toString()} method if it's not serializable. Useful for
	 * printing raw {@link Criteria}s containing complex values before actually converting them into Mongo native types.
	 *
	 * @param value value to serialize to CQL, may be {@literal null}.
	 * @return the value as a serialized CQL {@link String}, may be {@literal null}.
	 */
	@Nullable
	public static String serializeToCqlSafely(@Nullable Object value) {

		if (value == null) {
			return null;
		}

		try {
			return serialize(value);
		} catch (Exception e) {
			if (value instanceof Set) {
				return toString((Set) value);
			} else if (value instanceof Collection) {
				return toString((Collection) value);
			} else if (value instanceof Map) {
				return toString((Map) value);
			} else {
				return value.toString();
			}
		}
	}

	private static String serialize(@Nullable Object value) {

		if (value == null) {
			return "null";
		}

		TypeCodec