/*
 * Copyright 2012-2023 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.web.servlet;

import jakarta.servlet.Filter;
import jakarta.servlet.ServletContext;

import org.springframework.util.Assert;

/**
 * A {@link ServletContextInitializer} to register {@link Filter}s in a Servlet 3.0+
 * container. Similar to the {@link ServletContext#addFilter(String, Filter) registration}
 * features provided by {@link ServletContext} but with a Spring Bean friendly design.
 * <p>
 * The {@link #setFilter(Filter) Filter} must be specified before calling
 * {@link #onStartup(ServletContext)}. Registrations can be associated with
 * {@link #setUrlPatterns URL patterns} and/or servlets (either by {@link #setServletNames
 * name} or through a {@link #setServletRegistrationBeans ServletRegistrationBean}s). When
 * no URL pattern or servlets are specified the filter will be associated to '/*'. The
 * filter name will be deduced if not specified.
 *
 * @param <T> the type of {@link Filter} to register
 * @author Phillip Webb
 * @since 1.4.0
 * @see ServletContextInitializer
 * @see ServletContext#addFilter(String, Filter)
 * @see DelegatingFilterProxyRegistrationBean
 */
public class FilterRegistrationBean<T extends Filter> extends AbstractFilterRegistrationBean<T> {

	private T filter;

	/**
	 * Create a new {@link FilterRegistrationBean} instance.
	 */
	public FilterRegistrationBean() {
	}

	/**
	 * Create a new {@link FilterRegistrationBean} instance to be registered with the
	 * specified {@link ServletRegistrationBean}s.
	 * @param filter the filter to register
	 * @param servletRegistrationBeans associate {@link ServletRegistrationBean}s
	 */
	public FilterRegistrationBean(T filter, ServletRegistrationBean<?>... servletRegistrationBeans) {
		super(servletRegistrationBeans);
		Assert.notNull(filter, "Filter must not be null");
		this.filter = filter;
	}

	@Override
	public T getFilter() {
		return this.filter;
	}

	/**
	 * Set the filter to be registered.
	 * @param filter the filter
	 */
	public void setFilter(T filter) {
		Assert.notNull(filter, "Filter must not be null");
		this.filter = filter;
	}

}
