/*
 * Copyright 2002-2016 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
 *
 *      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 org.springframework.integration.jpa.support.parametersource;

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

import org.springframework.expression.Expression;
import org.springframework.expression.spel.support.StandardEvaluationContext;
import org.springframework.integration.jpa.support.JpaParameter;
import org.springframework.integration.util.AbstractExpressionEvaluator;
import org.springframework.util.Assert;

/**
 *
 * @author Gunnar Hillert
 * @author Gary Russell
 * @since 2.2
 *
 */
final class ExpressionEvaluatingParameterSourceUtils {

	private ExpressionEvaluatingParameterSourceUtils() {
		throw new AssertionError();
	}


	/**
	 * Utility method that converts a Collection of {@link JpaParameter} to
	 * a Map containing only static parameters.
	 *
	 * @param jpaParameters Must not be null.
	 * @return Map containing only the static parameters. Will never be null.
	 */
	public static Map<String, Object> convertStaticParameters(Collection<JpaParameter> jpaParameters) {

		Assert.notNull(jpaParameters, "The Collection of jpaParameters must not be null.");

		for (JpaParameter parameter : jpaParameters) {
			Assert.notNull(parameter, "'jpaParameters' must not contain null values.");
		}

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

		for (JpaParameter parameter : jpaParameters) {
			if (parameter.getValue() != null) {
				staticParameters.put(parameter.getName(), parameter.getValue());
			}
		}

		return staticParameters;
	}

	/**
	 * Simple {@link AbstractExpressionEvaluator} implementation
	 * to increase the visibility of protected methods.
	 */
	public static class ParameterExpressionEvaluator extends AbstractExpressionEvaluator {

		@Override
		public StandardEvaluationContext getEvaluationContext() {
			return super.getEvaluationContext();
		}

		@Override
		public Object evaluateExpression(Expression expression, Object input) {
			return super.evaluateExpression(expression, input);
		}

	}

}