/*
 * Copyright 2002-2013 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.security.config.annotation.web.configurers;

import java.util.ArrayList;
import java.util.Collection;
import java.util.LinkedHashMap;
import java.util.List;

import org.springframework.context.ApplicationContext;
import org.springframework.http.HttpMethod;
import org.springframework.security.access.AccessDecisionVoter;
import org.springframework.security.access.ConfigAttribute;
import org.springframework.security.access.PermissionEvaluator;
import org.springframework.security.access.SecurityConfig;
import org.springframework.security.access.expression.SecurityExpressionHandler;
import org.springframework.security.access.hierarchicalroles.RoleHierarchy;
import org.springframework.security.authentication.AuthenticationTrustResolver;
import org.springframework.security.config.annotation.ObjectPostProcessor;
import org.springframework.security.config.annotation.web.HttpSecurityBuilder;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.core.GrantedAuthorityDefaults;
import org.springframework.security.web.FilterInvocation;
import org.springframework.security.web.access.expression.DefaultWebSecurityExpressionHandler;
import org.springframework.security.web.access.expression.ExpressionBasedFilterInvocationSecurityMetadataSource;
import org.springframework.security.web.access.expression.WebExpressionVoter;
import org.springframework.security.web.servlet.util.matcher.MvcRequestMatcher;
import org.springframework.security.web.util.matcher.RequestMatcher;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;

/**
 * Adds URL based authorization based upon SpEL expressions to an application. At least
 * one {@link org.springframework.web.bind.annotation.RequestMapping} needs to be mapped
 * to {@link ConfigAttribute}'s for this {@link SecurityContextConfigurer} to have
 * meaning. <h2>Security Filters</h2>
 *
 * The following Filters are populated
 *
 * <ul>
 * <li>{@link org.springframework.security.web.access.intercept.FilterSecurityInterceptor}
 * </li>
 * </ul>
 *
 * <h2>Shared Objects Created</h2>
 *
 * The following shared objects are populated to allow other
 * {@link org.springframework.security.config.annotation.SecurityConfigurer}'s to
 * customize:
 * <ul>
 * <li>{@link org.springframework.security.web.access.intercept.FilterSecurityInterceptor}
 * </li>
 * </ul>
 *
 * <h2>Shared Objects Used</h2>
 *
 * <ul>
 * <li>{@link AuthenticationTrustResolver} is optionally used to populate the
 * {@link DefaultWebSecurityExpressionHandler}</li>
 * </ul>
 *
 * @param <H> the type of {@link HttpSecurityBuilder} that is being configured
 *
 * @author Rob Winch
 * @since 3.2
 * @see org.springframework.security.config.annotation.web.builders.HttpSecurity#authorizeRequests()
 */
public final class ExpressionUrlAuthorizationConfigurer<H extends HttpSecurityBuilder<H>>
		extends
		AbstractInterceptUrlConfigurer<ExpressionUrlAuthorizationConfigurer<H>, H> {
	static final String permitAll = "permitAll";
	private static final String denyAll = "denyAll";
	private static final String anonymous = "anonymous";
	private static final String authenticated = "authenticated";
	private static final String fullyAuthenticated = "fullyAuthenticated";
	private static final String rememberMe = "rememberMe";

	private final ExpressionInterceptUrlRegistry REGISTRY;

	private SecurityExpressionHandler<FilterInvocation> expressionHandler;

	/**
	 * Creates a new instance
	 * @see HttpSecurity#authorizeRequests()
	 */
	public ExpressionUrlAuthorizationConfigurer(ApplicationContext context) {
		this.REGISTRY = new ExpressionInterceptUrlRegistry(context);
	}

	public ExpressionInterceptUrlRegistry getRegistry() {
		return REGISTRY;
	}

	public class ExpressionInterceptUrlRegistry
			extends
			ExpressionUrlAuthorizationConfigurer<H>.AbstractInterceptUrlRegistry<ExpressionInterceptUrlRegistry, AuthorizedUrl> {

		/**
		 * @param context
		 */
		private ExpressionInterceptUrlRegistry(ApplicationContext context) {
			setApplicationContext(context);
		}

		@Override
		public MvcMatchersAuthorizedUrl mvcMatchers(HttpMethod method, String... mvcPatterns) {
			return new MvcMatchersAuthorizedUrl(createMvcMatchers(method, mvcPatterns));
		}

		@Override
		public MvcMatchersAuthorizedUrl mvcMatchers(String... patterns) {
			return mvcMatchers(null, patterns);
		}

		@Override
		protected final AuthorizedUrl chainRequestMatchersInternal(
				List<RequestMatcher> requestMatchers) {
			return new AuthorizedUrl(requestMatchers);
		}

		/**
		 * Allows customization of the {@link SecurityExpressionHandler} to be used. The
		 * default is {@link DefaultWebSecurityExpressionHandler}
		 *
		 * @param expressionHandler the {@link SecurityExpressionHandler} to be used
		 * @return the {@link ExpressionUrlAuthorizationConfigurer} for further
		 * customization.
		 */
		public ExpressionInterceptUrlRegistry expressionHandler(
				SecurityExpressionHandler<FilterInvocation> expressionHandler) {
			ExpressionUrlAuthorizationConfigurer.this.expressionHandler = expressionHandler;
			return this;
		}

		/**
		 * Adds an {@link ObjectPostProcessor} for this class.
		 *
		 * @param objectPostProcessor
		 * @return the {@link ExpressionUrlAuthorizationConfigurer} for further
		 * customizations
		 */
		public ExpressionInterceptUrlRegistry withObjectPostProcessor(
				ObjectPostProcessor<?> objectPostProcessor) {
			addObjectPostProcessor(objectPostProcessor);
			return this;
		}

		public H and() {
			return ExpressionUrlAuthorizationConfigurer.this.and();
		}

	}

	/**
	 * Allows registering multiple {@link RequestMatcher} instances to a collection of
	 * {@link ConfigAttribute} instances
	 *
	 * @param requestMatchers the {@link RequestMatcher} instances to register to the
	 * {@link ConfigAttribute} instances
	 * @param configAttributes the {@link ConfigAttribute} to be mapped by the
	 * {@link RequestMatcher} instances
	 */
	private void interceptUrl(Iterable<? extends RequestMatcher> requestMatchers,
			Collection<ConfigAttribute> configAttributes) {
		for (RequestMatcher requestMatcher : requestMatchers) {
			REGISTRY.addMapping(new AbstractConfigAttributeRequestMatcherRegistry.UrlMapping(
					requestMatcher, configAttributes));
		}
	}

	@Override
	@SuppressWarnings("rawtypes")
	final List<AccessDecisionVoter<? extends Object>> getDecisionVoters(H http) {
		List<AccessDecisionVoter<? extends Object>> decisionVoters = new ArrayList<AccessDecisionVoter<? extends Object>>();
		WebExpressionVoter expressionVoter = new WebExpressionVoter();
		expressionVoter.setExpressionHandler(getExpressionHandler(http));
		decisionVoters.add(expressionVoter);
		return decisionVoters;
	}

	@Override
	final ExpressionBasedFilterInvocationSecurityMetadataSource createMetadataSource(
			H http) {
		LinkedHashMap<RequestMatcher, Collection<ConfigAttribute>> requestMap = REGISTRY
				.createRequestMap();
		if (requestMap.isEmpty()) {
			throw new IllegalStateException(
					"At least one mapping is required (i.e. authorizeRequests().anyRequest().authenticated())");
		}
		return new ExpressionBasedFilterInvocationSecurityMetadataSource(requestMap,
				getExpressionHandler(http));
	}

	private SecurityExpressionHandler<FilterInvocation> getExpressionHandler(H http) {
		if (expressionHandler == null) {
			DefaultWebSecurityExpressionHandler defaultHandler = new DefaultWebSecurityExpressionHandler();
			AuthenticationTrustResolver trustResolver = http
					.getSharedObject(AuthenticationTrustResolver.class);
			if (trustResolver != null) {
				defaultHandler.setTrustResolver(trustResolver);
			}
			ApplicationContext context = http.getSharedObject(ApplicationContext.class);
			if(context != null) {
				String[] roleHiearchyBeanNames = context.getBeanNamesForType(RoleHierarchy.class);
				if(roleHiearchyBeanNames.length == 1) {
					defaultHandler.setRoleHierarchy(context.getBean(roleHiearchyBeanNames[0], RoleHierarchy.class));
				}
				String[] grantedAuthorityDefaultsBeanNames = context.getBeanNamesForType(GrantedAuthorityDefaults.class);
				if(grantedAuthorityDefaultsBeanNames.length == 1) {
					GrantedAuthorityDefaults grantedAuthorityDefaults = context.getBean(grantedAuthorityDefaultsBeanNames[0], GrantedAuthorityDefaults.class);
					defaultHandler.setDefaultRolePrefix(grantedAuthorityDefaults.getRolePrefix());
				}
				String[] permissionEvaluatorBeanNames = context.getBeanNamesForType(PermissionEvaluator.class);
				if(permissionEvaluatorBeanNames.length == 1) {
					PermissionEvaluator permissionEvaluator = context.getBean(permissionEvaluatorBeanNames[0], PermissionEvaluator.class);
					defaultHandler.setPermissionEvaluator(permissionEvaluator);
				}
			}

			expressionHandler = postProcess(defaultHandler);
		}

		return expressionHandler;
	}

	private static String hasAnyRole(String... authorities) {
		String anyAuthorities = StringUtils.arrayToDelimitedString(authorities,
				"','ROLE_");
		return "hasAnyRole('ROLE_" + anyAuthorities + "')";
	}

	private static String hasRole(String role) {
		Assert.notNull(role, "role cannot be null");
		if (role.startsWith("ROLE_")) {
			throw new IllegalArgumentException(
					"role should not start with 'ROLE_' since it is automatically inserted. Got '"
							+ role + "'");
		}
		return "hasRole('ROLE_" + role + "')";
	}

	private static String hasAuthority(String authority) {
		return "hasAuthority('" + authority + "')";
	}

	private static String hasAnyAuthority(String... authorities) {
		String anyAuthorities = StringUtils.arrayToDelimitedString(authorities, "','");
		return "hasAnyAuthority('" + anyAuthorities + "')";
	}

	private static String hasIpAddress(String ipAddressExpression) {
		return "hasIpAddress('" + ipAddressExpression + "')";
	}

	/**
	 * An {@link AuthorizedUrl} that allows optionally configuring the
	 * {@link MvcRequestMatcher#setMethod(HttpMethod)}
	 *
	 * @author Rob Winch
	 */
	public class MvcMatchersAuthorizedUrl extends AuthorizedUrl {
		/**
		 * Creates a new instance
		 *
		 * @param requestMatchers the {@link RequestMatcher} instances to map
		 */
		private MvcMatchersAuthorizedUrl(List<MvcRequestMatcher> requestMatchers) {
			super(requestMatchers);
		}

		public AuthorizedUrl servletPath(String servletPath) {
			for (MvcRequestMatcher matcher : (List<MvcRequestMatcher>) getMatchers()) {
				matcher.setServletPath(servletPath);
			}
			return this;
		}
	}

	public class AuthorizedUrl {
		private List<? extends RequestMatcher> requestMatchers;
		private boolean not;

		/**
		 * Creates a new instance
		 *
		 * @param requestMatchers the {@link RequestMatcher} instances to map
		 */
		private AuthorizedUrl(List<? extends RequestMatcher> requestMatchers) {
			this.requestMatchers = requestMatchers;
		}

		protected List<? extends RequestMatcher> getMatchers() {
			return this.requestMatchers;
		}

		/**
		 * Negates the following expression.
		 *
		 * @return the {@link ExpressionUrlAuthorizationConfigurer} for further
		 * customization
		 */
		public AuthorizedUrl not() {
			this.not = true;
			return this;
		}

		/**
		 * Shortcut for specifying URLs require a particular role. If you do not want to
		 * have "ROLE_" automatically inserted see {@link #hasAuthority(String)}.
		 *
		 * @param role the role to require (i.e. USER, ADMIN, etc). Note, it should not
		 * start with "ROLE_" as this is automatically inserted.
		 * @return the {@link ExpressionUrlAuthorizationConfigurer} for further
		 * customization
		 */
		public ExpressionInterceptUrlRegistry hasRole(String role) {
			return access(ExpressionUrlAuthorizationConfigurer.hasRole(role));
		}

		/**
		 * Shortcut for specifying URLs require any of a number of roles. If you do not
		 * want to have "ROLE_" automatically inserted see
		 * {@link #hasAnyAuthority(String...)}
		 *
		 * @param roles the roles to require (i.e. USER, ADMIN, etc). Note, it should not
		 * start with "ROLE_" as this is automatically inserted.
		 * @return the {@link ExpressionUrlAuthorizationConfigurer} for further
		 * customization
		 */
		public ExpressionInterceptUrlRegistry hasAnyRole(String... roles) {
			return access(ExpressionUrlAuthorizationConfigurer.hasAnyRole(roles));
		}

		/**
		 * Specify that URLs require a particular authority.
		 *
		 * @param authority the authority to require (i.e. ROLE_USER, ROLE_ADMIN, etc).
		 * @return the {@link ExpressionUrlAuthorizationConfigurer} for further
		 * customization
		 */
		public ExpressionInterceptUrlRegistry hasAuthority(String authority) {
			return access(ExpressionUrlAuthorizationConfigurer.hasAuthority(authority));
		}

		/**
		 * Specify that URLs requires any of a number authorities.
		 *
		 * @param authorities the requests require at least one of the authorities (i.e.
		 * "ROLE_USER","ROLE_ADMIN" would mean either "ROLE_USER" or "ROLE_ADMIN" is
		 * required).
		 * @return the {@link ExpressionUrlAuthorizationConfigurer} for further
		 * customization
		 */
		public ExpressionInterceptUrlRegistry hasAnyAuthority(String... authorities) {
			return access(ExpressionUrlAuthorizationConfigurer
					.hasAnyAuthority(authorities));
		}

		/**
		 * Specify that URLs requires a specific IP Address or <a href=
		 * "http://forum.springsource.org/showthread.php?102783-How-to-use-hasIpAddress&p=343971#post343971"
		 * >subnet</a>.
		 *
		 * @param ipaddressExpression the ipaddress (i.e. 192.168.1.79) or local subnet
		 * (i.e. 192.168.0/24)
		 * @return the {@link ExpressionUrlAuthorizationConfigurer} for further
		 * customization
		 */
		public ExpressionInterceptUrlRegistry hasIpAddress(String ipaddressExpression) {
			return access(ExpressionUrlAuthorizationConfigurer
					.hasIpAddress(ipaddressExpression));
		}

		/**
		 * Specify that URLs are allowed by anyone.
		 *
		 * @return the {@link ExpressionUrlAuthorizationConfigurer} for further
		 * customization
		 */
		public ExpressionInterceptUrlRegistry permitAll() {
			return access(permitAll);
		}

		/**
		 * Specify that URLs are allowed by anonymous users.
		 *
		 * @return the {@link ExpressionUrlAuthorizationConfigurer} for further
		 * customization
		 */
		public ExpressionInterceptUrlRegistry anonymous() {
			return access(anonymous);
		}

		/**
		 * Specify that URLs are allowed by users that have been remembered.
		 *
		 * @return the {@link ExpressionUrlAuthorizationConfigurer} for further
		 * customization
		 * @see RememberMeConfigurer
		 */
		public ExpressionInterceptUrlRegistry rememberMe() {
			return access(rememberMe);
		}

		/**
		 * Specify that URLs are not allowed by anyone.
		 *
		 * @return the {@link ExpressionUrlAuthorizationConfigurer} for further
		 * customization
		 */
		public ExpressionInterceptUrlRegistry denyAll() {
			return access(denyAll);
		}

		/**
		 * Specify that URLs are allowed by any authenticated user.
		 *
		 * @return the {@link ExpressionUrlAuthorizationConfigurer} for further
		 * customization
		 */
		public ExpressionInterceptUrlRegistry authenticated() {
			return access(authenticated);
		}

		/**
		 * Specify that URLs are allowed by users who have authenticated and were not
		 * "remembered".
		 *
		 * @return the {@link ExpressionUrlAuthorizationConfigurer} for further
		 * customization
		 * @see RememberMeConfigurer
		 */
		public ExpressionInterceptUrlRegistry fullyAuthenticated() {
			return access(fullyAuthenticated);
		}

		/**
		 * Allows specifying that URLs are secured by an arbitrary expression
		 *
		 * @param attribute the expression to secure the URLs (i.e.
		 * "hasRole('ROLE_USER') and hasRole('ROLE_SUPER')")
		 * @return the {@link ExpressionUrlAuthorizationConfigurer} for further
		 * customization
		 */
		public ExpressionInterceptUrlRegistry access(String attribute) {
			if (not) {
				attribute = "!" + attribute;
			}
			interceptUrl(requestMatchers, SecurityConfig.createList(attribute));
			return ExpressionUrlAuthorizationConfigurer.this.REGISTRY;
		}
	}
}
