/*
 * Copyright 2020-2023 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.jdbc.repository.query;

import org.springframework.core.convert.converter.Converter;
import org.springframework.data.convert.DtoInstantiatingConverter;
import org.springframework.data.mapping.context.MappingContext;
import org.springframework.data.mapping.model.EntityInstantiators;
import org.springframework.data.relational.core.mapping.RelationalPersistentEntity;
import org.springframework.data.relational.core.mapping.RelationalPersistentProperty;
import org.springframework.data.repository.query.ResultProcessor;
import org.springframework.data.repository.query.ReturnedType;
import org.springframework.data.util.Lazy;
import org.springframework.jdbc.core.namedparam.SqlParameterSource;
import org.springframework.lang.Nullable;
import org.springframework.util.ClassUtils;

/**
 * Interface specifying a query execution strategy. Implementations encapsulate information how to actually execute the
 * query and how to process the result in order to get the desired return type.
 *
 * @author Mark Paluch
 * @since 2.0
 */
@FunctionalInterface
interface JdbcQueryExecution<T> {

	/**
	 * Execute the given {@code query} and {@code parameter} and transforms the result into a {@code T}.
	 *
	 * @param query the query to be executed. Must not be {@literal null}.
	 * @param parameter the parameters to be bound to the query. Must not be {@literal null}.
	 * @return the result of the query. Might be {@literal null}.
	 */
	@Nullable
	T execute(String query, SqlParameterSource parameter);

	/**
	 * A {@link Converter} to post-process all source objects using the given {@link ResultProcessor}.
	 *
	 * @author Mark Paluch
	 * @since 2.3
	 */
	class ResultProcessingConverter implements Converter<Object, Object> {

		private final ResultProcessor processor;
		private final Lazy<Converter<Object, Object>> converter;

		ResultProcessingConverter(ResultProcessor processor,
				MappingContext<? extends RelationalPersistentEntity<?>, ? extends RelationalPersistentProperty> mappingContext,
				EntityInstantiators instantiators) {
			this.processor = processor;
			this.converter = Lazy.of(() -> new DtoInstantiatingConverter(processor.getReturnedType().getReturnedType(),
					mappingContext, instantiators));
		}

		@Override
		public Object convert(Object source) {

			ReturnedType returnedType = processor.getReturnedType();

			if (ClassUtils.isPrimitiveOrWrapper(returnedType.getReturnedType())
					|| returnedType.getReturnedType().isInstance(source)) {
				return source;
			}

			return processor.processResult(source, converter.get());
		}
	}
}
