/*
 * Copyright 2012-2019 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.boot.context.embedded.jetty;

import java.io.IOException;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;

import org.eclipse.jetty.http.HttpMethod;
import org.eclipse.jetty.server.Request;
import org.eclipse.jetty.server.handler.ErrorHandler;

/**
 * Variation of Jetty's {@link ErrorHandler} that supports all {@link HttpMethod
 * HttpMethods} rather than just {@code GET}, {@code POST} and {@code HEAD}. Jetty
 * <a href="https://bugs.eclipse.org/bugs/show_bug.cgi?id=446039">intentionally only
 * supports a limited set of HTTP methods</a> for error pages, however, Spring Boot
 * prefers Tomcat, Jetty and Undertow to all behave in the same way.
 *
 * @author Phillip Webb
 * @author Andy Wilkinson
 */
class JettyEmbeddedErrorHandler extends ErrorHandler {

	private static final Set<String> SUPPORTED_METHODS;

	static {
		Set<String> supportedMethods = new HashSet<String>();
		supportedMethods.add("GET");
		supportedMethods.add("HEAD");
		supportedMethods.add("POST");
		SUPPORTED_METHODS = Collections.unmodifiableSet(supportedMethods);
	}

	private final ErrorHandler delegate;

	JettyEmbeddedErrorHandler(ErrorHandler delegate) {
		this.delegate = delegate;
	}

	@Override
	public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response)
			throws IOException {
		if (!isSupported(request.getMethod())) {
			request = new ErrorHttpServletRequest(request);
		}
		this.delegate.handle(target, baseRequest, request, response);
	}

	private boolean isSupported(String method) {
		for (String supportedMethod : SUPPORTED_METHODS) {
			if (supportedMethod.equalsIgnoreCase(method)) {
				return true;
			}
		}
		return false;
	}

	private static class ErrorHttpServletRequest extends HttpServletRequestWrapper {

		private boolean simulateGetMethod = true;

		ErrorHttpServletRequest(HttpServletRequest request) {
			super(request);
		}

		@Override
		public String getMethod() {
			return (this.simulateGetMethod ? HttpMethod.GET.toString() : super.getMethod());
		}

		@Override
		public ServletContext getServletContext() {
			this.simulateGetMethod = false;
			return super.getServletContext();
		}

	}

}
