/*
 * Licensed to Laurent Broudoux (the "Author") under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. Author 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
 *
 *    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 io.github.microcks.util;

import io.github.microcks.domain.ParameterConstraint;
import io.github.microcks.domain.ParameterLocation;

import javax.servlet.http.HttpServletRequest;
import java.util.regex.Pattern;

/**
 * Utility class for holding various case around ParameterConstraints.
 * @author laurent
 */
public class ParameterConstraintUtil {

   /**
    * Validate that a parameter constraint it respected or violated. Return a message if violated.
    * @param request HttpServlet request holding parameters to validate
    * @param constraint Constraint to apply to one request parameter.
    * @return A string representing constraint violation if any. null otherwise.
    */
   public static String validateConstraint(HttpServletRequest request, ParameterConstraint constraint) {
      String value = null;
      if (ParameterLocation.header == constraint.getIn()) {
         value = request.getHeader(constraint.getName());
      } else if (ParameterLocation.query == constraint.getIn()) {
         value = request.getParameter(constraint.getName());
      }

      if (value != null) {
         if (constraint.getMustMatchRegexp() != null) {
            if (!Pattern.matches(constraint.getMustMatchRegexp(), value)) {
               return "Parameter " + constraint.getName() +  " should match " + constraint.getMustMatchRegexp();
            }
         }
      } else  {
         if (constraint.isRequired()) {
            return "Parameter " + constraint.getName() +  " is required";
         }
      }
      return null;
   }
}