/*
    * Copyright 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.openehealth.ipf.commons.ihe.core.payload;
  
  import org.springframework.expression.Expression;
  import org.springframework.expression.ExpressionParser;
  import org.springframework.expression.common.TemplateParserContext;
  import org.springframework.expression.spel.standard.SpelExpressionParser;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * {@link ExpressionResolver} implementation using Spring Expression language. You can also implement your
   * own resolver that is able to evaluate file path patterns
   *
   * @since 3.1
   */
  public class SpringExpressionResolver implements ExpressionResolver {
  
      private final Expression expression;
  
      public SpringExpressionResolver(final String filePathPattern) {
          requireNonNull(filePathPattern, "log file path/name pattern must not be null");
          final ExpressionParser parser = new SpelExpressionParser();
          final TemplateParserContext parserContext = new TemplateParserContext("[", "]");
          parser.parseExpression(filePathPattern, parserContext);
          expression = parser.parseExpression(filePathPattern, parserContext);
      }
  
      @Override
      public String resolveExpression(PayloadLoggingContext context) {
          return expression.getValue(context, String.class);
      }
  
  }