/*
    * Copyright 2002-2014 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.web.servlet.mvc.condition;
  
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.LinkedHashSet;
  import java.util.List;
  import java.util.Set;
  import javax.servlet.http.HttpServletRequest;
  
  import org.springframework.web.bind.annotation.RequestMethod;
  
  /**
   * A logical disjunction (' || ') request condition that matches a request
   * against a set of {@link RequestMethod}s.
   *
   * @author Arjen Poutsma
   * @author Rossen Stoyanchev
   * @since 3.1
   */
  public final class RequestMethodsRequestCondition extends AbstractRequestCondition<RequestMethodsRequestCondition> {
  
  	private final Set<RequestMethod> methods;
  
  
  	/**
  	 * Create a new instance with the given request methods.
  	 * @param requestMethods 0 or more HTTP request methods;
  	 * if, 0 the condition will match to every request
  	 */
  	public RequestMethodsRequestCondition(RequestMethod... requestMethods) {
  		this(asList(requestMethods));
  	}
  
  	private RequestMethodsRequestCondition(Collection<RequestMethod> requestMethods) {
  		this.methods = Collections.unmodifiableSet(new LinkedHashSet<RequestMethod>(requestMethods));
  	}
  
  
  	private static List<RequestMethod> asList(RequestMethod... requestMethods) {
  		return (requestMethods != null ? Arrays.asList(requestMethods) : Collections.<RequestMethod>emptyList());
  	}
  
  
  	/**
  	 * Returns all {@link RequestMethod}s contained in this condition.
  	 */
  	public Set<RequestMethod> getMethods() {
  		return this.methods;
  	}
  
  	@Override
  	protected Collection<RequestMethod> getContent() {
  		return this.methods;
  	}
  
  	@Override
  	protected String getToStringInfix() {
  		return " || ";
  	}
  
  	/**
  	 * Returns a new instance with a union of the HTTP request methods
  	 * from "this" and the "other" instance.
  	 */
  	@Override
  	public RequestMethodsRequestCondition combine(RequestMethodsRequestCondition other) {
  		Set<RequestMethod> set = new LinkedHashSet<RequestMethod>(this.methods);
  		set.addAll(other.methods);
  		return new RequestMethodsRequestCondition(set);
  	}
  
  	/**
  	 * Check if any of the HTTP request methods match the given request and
  	 * return an instance that contains the matching HTTP request method only.
  	 * @param request the current request
  	 * @return the same instance if the condition is empty, a new condition with
  	 * the matched request method, or {@code null} if no request methods match
  	 */
  	@Override
  	public RequestMethodsRequestCondition getMatchingCondition(HttpServletRequest request) {
  		if (this.methods.isEmpty()) {
  			return this;
 		}
 		RequestMethod incomingRequestMethod = getRequestMethod(request);
 		if (incomingRequestMethod != null) {
 			for (RequestMethod method : this.methods) {
 				if (method.equals(incomingRequestMethod)) {
 					return new RequestMethodsRequestCondition(method);
 				}
 			}
 		}
 		return null;
 	}
 
 	private RequestMethod getRequestMethod(HttpServletRequest request) {
 		try {
 			return RequestMethod.valueOf(request.getMethod());
 		}
 		catch (IllegalArgumentException ex) {
 			return null;
 		}
 	}
 
 	/**
 	 * Returns:
 	 * <ul>
 	 * <li>0 if the two conditions contain the same number of HTTP request methods
 	 * <li>Less than 0 if "this" instance has an HTTP request method but "other" doesn't
 	 * <li>Greater than 0 "other" has an HTTP request method but "this" doesn't
 	 * </ul>
 	 * <p>It is assumed that both instances have been obtained via
 	 * {@link #getMatchingCondition(HttpServletRequest)} and therefore each instance
 	 * contains the matching HTTP request method only or is otherwise empty.
 	 */
 	@Override
 	public int compareTo(RequestMethodsRequestCondition other, HttpServletRequest request) {
 		return (other.methods.size() - this.methods.size());
 	}
 
 }