/*
 * Copyright 2002-2019 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.web.testfixture.servlet;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.nio.file.InvalidPathException;
import java.util.Collections;
import java.util.Enumeration;
import java.util.EventListener;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;

import javax.servlet.Filter;
import javax.servlet.FilterRegistration;
import javax.servlet.RequestDispatcher;
import javax.servlet.Servlet;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRegistration;
import javax.servlet.SessionCookieConfig;
import javax.servlet.SessionTrackingMode;
import javax.servlet.descriptor.JspConfigDescriptor;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.core.io.DefaultResourceLoader;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;
import org.springframework.http.MediaType;
import org.springframework.http.MediaTypeFactory;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.MimeType;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;
import org.springframework.web.util.WebUtils;

/**
 * Mock implementation of the {@link javax.servlet.ServletContext} interface.
 *
 * <p>As of Spring 5.0, this set of mocks is designed on a Servlet 4.0 baseline.
 *
 * <p>Compatible with Servlet 3.1 but can be configured to expose a specific version
 * through {@link #setMajorVersion}/{@link #setMinorVersion}; default is 3.1.
 * Note that Servlet 3.1 support is limited: servlet, filter and listener
 * registration methods are not supported; neither is JSP configuration.
 * We generally do not recommend to unit test your ServletContainerInitializers and
 * WebApplicationInitializers which is where those registration methods would be used.
 *
 * <p>For setting up a full {@code WebApplicationContext} in a test environment, you can
 * use {@code AnnotationConfigWebApplicationContext}, {@code XmlWebApplicationContext},
 * or {@code GenericWebApplicationContext}, passing in a corresponding
 * {@code MockServletContext} instance. Consider configuring your
 * {@code MockServletContext} with a {@code FileSystemResourceLoader} in order to
 * interpret resource paths as relative filesystem locations.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @author Sam Brannen
 * @since 1.0.2
 * @see #MockServletContext(org.springframework.core.io.ResourceLoader)
 * @see org.springframework.web.context.support.AnnotationConfigWebApplicationContext
 * @see org.springframework.web.context.support.XmlWebApplicationContext
 * @see org.springframework.web.context.support.GenericWebApplicationContext
 */
public class MockServletContext implements ServletContext {

	/** Default Servlet name used by Tomcat, Jetty, JBoss, and GlassFish: {@value}. */
	private static final String COMMON_DEFAULT_SERVLET_NAME = "default";

	private static final String TEMP_DIR_SYSTEM_PROPERTY = "java.io.tmpdir";

	private static final Set<SessionTrackingMode> DEFAULT_SESSION_TRACKING_MODES = new LinkedHashSet<>(4);

	static {
		DEFAULT_SESSION_TRACKING_MODES.add(SessionTrackingMode.COOKIE);
		DEFAULT_SESSION_TRACKING_MODES.add(SessionTrackingMode.URL);
		DEFAULT_SESSION_TRACKING_MODES.add(SessionTrackingMode.SSL);
	}


	private final Log logger = LogFactory.getLog(getClass());

	private final ResourceLoader resourceLoader;

	private final String resourceBasePath;

	private String contextPath = "";

	private final Map<String, ServletContext> contexts = new HashMap<>();

	private int majorVersion = 3;

	private int minorVersion = 1;

	private int effectiveMajorVersion = 3;

	private int effectiveMinorVersion = 1;

	private final Map<String, RequestDispatcher> namedRequestDispatchers = new HashMap<>();

	private String defaultServletName = COMMON_DEFAULT_SERVLET_NAME;

	private final Map<String, String> initParameters = new LinkedHashMap<>();

	private final Map<String, Object> attributes = new LinkedHashMap<>();

	private String servletContextName = "MockServletContext";

	private final Set<String> declaredRoles = new LinkedHashSet<>();

	@Nullable
	private Set<SessionTrackingMode> sessionTrackingModes;

	private final SessionCookieConfig sessionCookieConfig = new MockSessionCookieConfig();

	private int sessionTimeout;

	@Nullable
	private String requestCharacterEncoding;

	@Nullable
	private String responseCharacterEncoding;

	private final Map<String, MediaType> mimeTypes = new LinkedHashMap<>();


	/**
	 * Create a new {@code MockServletContext}, using no base path and a
	 * {@link DefaultResourceLoader} (i.e. the classpath root as WAR root).
	 * @see org.springframework.core.io.DefaultResourceLoader
	 */
	public MockServletContext() {
		this("", null);
	}

	/**
	 * Create a new {@code MockServletContext}, using a {@link DefaultResourceLoader}.
	 * @param resourceBasePath the root directory of the WAR (should not end with a slash)
	 * @see org.springframework.core.io.DefaultResourceLoader
	 */
	public MockServletContext(String resourceBasePath) {
		this(resourceBasePath, null);
	}

	/**
	 * Create a new {@code MockServletContext}, using the specified {@link ResourceLoader}
	 * and no base path.
	 * @param resourceLoader the ResourceLoader to use (or null for the default)
	 */
	public MockServletContext(@Nullable ResourceLoader resourceLoader) {
		this("", resourceLoader);
	}

	/**
	 * Create a new {@code MockServletContext} using the supplied resource base
	 * path and resource loader.
	 * <p>Registers a {@link MockRequestDispatcher} for the Servlet named
	 * {@literal 'default'}.
	 * @param resourceBasePath the root directory of the WAR (should not end with a slash)
	 * @param resourceLoader the ResourceLoader to use (or null for the default)
	 * @see #registerNamedDispatcher
	 */
	public MockServletContext(String resourceBasePath, @Nullable ResourceLoader resourceLoader) {
		this.resourceLoader = (resourceLoader != null ? resourceLoader : new DefaultResourceLoader());
		this.resourceBasePath = resourceBasePath;

		// Use JVM temp dir as ServletContext temp dir.
		String tempDir = System.getProperty(TEMP_DIR_SYSTEM_PROPERTY);
		if (tempDir != null) {
			this.attributes.put(WebUtils.TEMP_DIR_CONTEXT_ATTRIBUTE, new File(tempDir));
		}

		registerNamedDispatcher(this.defaultServletName, new MockRequestDispatcher(this.defaultServletName));
	}

	/**
	 * Build a full resource location for the given path, prepending the resource
	 * base path of this {@code MockServletContext}.
	 * @param path the path as specified
	 * @return the full resource path
	 */
	protected String getResourceLocation(String path) {
		if (!path.startsWith("/")) {
			path = "/" + path;
		}
		return this.resourceBasePath + path;
	}

	public void setContextPath(String contextPath) {
		this.contextPath = contextPath;
	}

	@Override
	public String getContextPath() {
		return this.contextPath;
	}

	public void registerContext(String contextPath, ServletContext context) {
		this.contexts.put(contextPath, context);
	}

	@Override
	public ServletContext getContext(String contextPath) {
		if (this.contextPath.equals(contextPath)) {
			return this;
		}
		return this.contexts.get(contextPath);
	}

	public void setMajorVersion(int majorVersion) {
		this.majorVersion = majorVersion;
	}

	@Override
	public int getMajorVersion() {
		return this.majorVersion;
	}

	public void setMinorVersion(int minorVersion) {
		this.minorVersion = minorVersion;
	}

	@Override
	public int getMinorVersion() {
		return this.minorVersion;
	}

	public void setEffectiveMajorVersion(int effectiveMajorVersion) {
		this.effectiveMajorVersion = effectiveMajorVersion;
	}

	@Override
	public int getEffectiveMajorVersion() {
		return this.effectiveMajorVersion;
	}

	public void setEffectiveMinorVersion(int effectiveMinorVersion) {
		this.effectiveMinorVersion = effectiveMinorVersion;
	}

	@Override
	public int getEffectiveMinorVersion() {
		return this.effectiveMinorVersion;
	}

	@Override
	@Nullable
	public String getMimeType(String filePath) {
		String extension = StringUtils.getFilenameExtension(filePath);
		if (this.mimeTypes.containsKey(extension)) {
			return this.mimeTypes.get(extension).toString();
		}
		else {
			return MediaTypeFactory.getMediaType(filePath).
					map(MimeType::toString)
					.orElse(null);
		}
	}

	/**
	 * Adds a mime type mapping for use by {@link #getMimeType(String)}.
	 * @param fileExtension a file extension, such as {@code txt}, {@code gif}
	 * @param mimeType the mime type
	 */
	public void addMimeType(String fileExtension, MediaType mimeType) {
		Assert.notNull(fileExtension, "'fileExtension' must not be null");
		this.mimeTypes.put(fileExtension, mimeType);
	}

	@Override
	@Nullable
	public Set<String> getResourcePaths(String path) {
		String actualPath = (path.endsWith("/") ? path : path + "/");
		String resourceLocation = getResourceLocation(actualPath);
		Resource resource = null;
		try {
			resource = this.resourceLoader.getResource(resourceLocation);
			File file = resource.getFile();
			String[] fileList = file.list();
			if (ObjectUtils.isEmpty(fileList)) {
				return null;
			}
			Set<String> resourcePaths = new LinkedHashSet<>(fileList.length);
			for (String fileEntry : fileList) {
				String resultPath = actualPath + fileEntry;
				if (resource.createRelative(fileEntry).getFile().isDirectory()) {
					resultPath += "/";
				}
				resourcePaths.add(resultPath);
			}
			return resourcePaths;
		}
		catch (InvalidPathException | IOException ex ) {
			if (logger.isWarnEnabled()) {
				logger.warn("Could not get resource paths for " +
						(resource != null ? resource : resourceLocation), ex);
			}
			return null;
		}
	}

	@Override
	@Nullable
	public URL getResource(String path) throws MalformedURLException {
		String resourceLocation = getResourceLocation(path);
		Resource resource = null;
		try {
			resource = this.resourceLoader.getResource(resourceLocation);
			if (!resource.exists()) {
				return null;
			}
			return resource.getURL();
		}
		catch (MalformedURLException ex) {
			throw ex;
		}
		catch (InvalidPathException | IOException ex) {
			if (logger.isWarnEnabled()) {
				logger.warn("Could not get URL for resource " +
						(resource != null ? resource : resourceLocation), ex);
			}
			return null;
		}
	}

	@Override
	@Nullable
	public InputStream getResourceAsStream(String path) {
		String resourceLocation = getResourceLocation(path);
		Resource resource = null;
		try {
			resource = this.resourceLoader.getResource(resourceLocation);
			if (!resource.exists()) {
				return null;
			}
			return resource.getInputStream();
		}
		catch (InvalidPathException | IOException ex) {
			if (logger.isWarnEnabled()) {
				logger.warn("Could not open InputStream for resource " +
						(resource != null ? resource : resourceLocation), ex);
			}
			return null;
		}
	}

	@Override
	public RequestDispatcher getRequestDispatcher(String path) {
		Assert.isTrue(path.startsWith("/"),
				() -> "RequestDispatcher path [" + path + "] at ServletContext level must start with '/'");
		return new MockRequestDispatcher(path);
	}

	@Override
	public RequestDispatcher getNamedDispatcher(String path) {
		return this.namedRequestDispatchers.get(path);
	}

	/**
	 * Register a {@link RequestDispatcher} (typically a {@link MockRequestDispatcher})
	 * that acts as a wrapper for the named Servlet.
	 * @param name the name of the wrapped Servlet
	 * @param requestDispatcher the dispatcher that wraps the named Servlet
	 * @see #getNamedDispatcher
	 * @see #unregisterNamedDispatcher
	 */
	public void registerNamedDispatcher(String name, RequestDispatcher requestDispatcher) {
		Assert.notNull(name, "RequestDispatcher name must not be null");
		Assert.notNull(requestDispatcher, "RequestDispatcher must not be null");
		this.namedRequestDispatchers.put(name, requestDispatcher);
	}

	/**
	 * Unregister the {@link RequestDispatcher} with the given name.
	 * @param name the name of the dispatcher to unregister
	 * @see #getNamedDispatcher
	 * @see #registerNamedDispatcher
	 */
	public void unregisterNamedDispatcher(String name) {
		Assert.notNull(name, "RequestDispatcher name must not be null");
		this.namedRequestDispatchers.remove(name);
	}

	/**
	 * Get the name of the <em>default</em> {@code Servlet}.
	 * <p>Defaults to {@literal 'default'}.
	 * @see #setDefaultServletName
	 */
	public String getDefaultServletName() {
		return this.defaultServletName;
	}

	/**
	 * Set the name of the <em>default</em> {@code Servlet}.
	 * <p>Also {@link #unregisterNamedDispatcher unregisters} the current default
	 * {@link RequestDispatcher} and {@link #registerNamedDispatcher replaces}
	 * it with a {@link MockRequestDispatcher} for the provided
	 * {@code defaultServletName}.
	 * @param defaultServletName the name of the <em>default</em> {@code Servlet};
	 * never {@code null} or empty
	 * @see #getDefaultServletName
	 */
	public void setDefaultServletName(String defaultServletName) {
		Assert.hasText(defaultServletName, "defaultServletName must not be null or empty");
		unregisterNamedDispatcher(this.defaultServletName);
		this.defaultServletName = defaultServletName;
		registerNamedDispatcher(this.defaultServletName, new MockRequestDispatcher(this.defaultServletName));
	}

	@Deprecated
	@Override
	@Nullable
	public Servlet getServlet(String name) {
		return null;
	}

	@Override
	@Deprecated
	public Enumeration<Servlet> getServlets() {
		return Collections.enumeration(Collections.emptySet());
	}

	@Override
	@Deprecated
	public Enumeration<String> getServletNames() {
		return Collections.enumeration(Collections.emptySet());
	}

	@Override
	public void log(String message) {
		logger.info(message);
	}

	@Override
	@Deprecated
	public void log(Exception ex, String message) {
		logger.info(message, ex);
	}

	@Override
	public void log(String message, Throwable ex) {
		logger.info(message, ex);
	}

	@Override
	@Nullable
	public String getRealPath(String path) {
		String resourceLocation = getResourceLocation(path);
		Resource resource = null;
		try {
			resource = this.resourceLoader.getResource(resourceLocation);
			return resource.getFile().getAbsolutePath();
		}
		catch (InvalidPathException | IOException ex) {
			if (logger.isWarnEnabled()) {
				logger.warn("Could not determine real path of resource " +
						(resource != null ? resource : resourceLocation), ex);
			}
			return null;
		}
	}

	@Override
	public String getServerInfo() {
		return "MockServletContext";
	}

	@Override
	public String getInitParameter(String name) {
		Assert.notNull(name, "Parameter name must not be null");
		return this.initParameters.get(name);
	}

	@Override
	public Enumeration<String> getInitParameterNames() {
		return Collections.enumeration(this.initParameters.keySet());
	}

	@Override
	public boolean setInitParameter(String name, String value) {
		Assert.notNull(name, "Parameter name must not be null");
		if (this.initParameters.containsKey(name)) {
			return false;
		}
		this.initParameters.put(name, value);
		return true;
	}

	public void addInitParameter(String name, String value) {
		Assert.notNull(name, "Parameter name must not be null");
		this.initParameters.put(name, value);
	}

	@Override
	@Nullable
	public Object getAttribute(String name) {
		Assert.notNull(name, "Attribute name must not be null");
		return this.attributes.get(name);
	}

	@Override
	public Enumeration<String> getAttributeNames() {
		return Collections.enumeration(new LinkedHashSet<>(this.attributes.keySet()));
	}

	@Override
	public void setAttribute(String name, @Nullable Object value) {
		Assert.notNull(name, "Attribute name must not be null");
		if (value != null) {
			this.attributes.put(name, value);
		}
		else {
			this.attributes.remove(name);
		}
	}

	@Override
	public void removeAttribute(String name) {
		Assert.notNull(name, "Attribute name must not be null");
		this.attributes.remove(name);
	}

	public void setServletContextName(String servletContextName) {
		this.servletContextName = servletContextName;
	}

	@Override
	public String getServletContextName() {
		return this.servletContextName;
	}

	@Override
	@Nullable
	public ClassLoader getClassLoader() {
		return ClassUtils.getDefaultClassLoader();
	}

	@Override
	public void declareRoles(String... roleNames) {
		Assert.notNull(roleNames, "Role names array must not be null");
		for (String roleName : roleNames) {
			Assert.hasLength(roleName, "Role name must not be empty");
			this.declaredRoles.add(roleName);
		}
	}

	public Set<String> getDeclaredRoles() {
		return Collections.unmodifiableSet(this.declaredRoles);
	}

	@Override
	public void setSessionTrackingModes(Set<SessionTrackingMode> sessionTrackingModes)
			throws IllegalStateException, IllegalArgumentException {
		this.sessionTrackingModes = sessionTrackingModes;
	}

	@Override
	public Set<SessionTrackingMode> getDefaultSessionTrackingModes() {
		return DEFAULT_SESSION_TRACKING_MODES;
	}

	@Override
	public Set<SessionTrackingMode> getEffectiveSessionTrackingModes() {
		return (this.sessionTrackingModes != null ?
				Collections.unmodifiableSet(this.sessionTrackingModes) : DEFAULT_SESSION_TRACKING_MODES);
	}

	@Override
	public SessionCookieConfig getSessionCookieConfig() {
		return this.sessionCookieConfig;
	}

	@Override  // on Servlet 4.0
	public void setSessionTimeout(int sessionTimeout) {
		this.sessionTimeout = sessionTimeout;
	}

	@Override  // on Servlet 4.0
	public int getSessionTimeout() {
		return this.sessionTimeout;
	}

	@Override  // on Servlet 4.0
	public void setRequestCharacterEncoding(@Nullable String requestCharacterEncoding) {
		this.requestCharacterEncoding = requestCharacterEncoding;
	}

	@Override  // on Servlet 4.0
	@Nullable
	public String getRequestCharacterEncoding() {
		return this.requestCharacterEncoding;
	}

	@Override  // on Servlet 4.0
	public void setResponseCharacterEncoding(@Nullable String responseCharacterEncoding) {
		this.responseCharacterEncoding = responseCharacterEncoding;
	}

	@Override  // on Servlet 4.0
	@Nullable
	public String getResponseCharacterEncoding() {
		return this.responseCharacterEncoding;
	}


	//---------------------------------------------------------------------
	// Unsupported Servlet 3.0 registration methods
	//---------------------------------------------------------------------

	@Override
	public JspConfigDescriptor getJspConfigDescriptor() {
		throw new UnsupportedOperationException();
	}

	@Override  // on Servlet 4.0
	public ServletRegistration.Dynamic addJspFile(String servletName, String jspFile) {
		throw new UnsupportedOperationException();
	}

	@Override
	public ServletRegistration.Dynamic addServlet(String servletName, String className) {
		throw new UnsupportedOperationException();
	}

	@Override
	public ServletRegistration.Dynamic addServlet(String servletName, Servlet servlet) {
		throw new UnsupportedOperationException();
	}

	@Override
	public ServletRegistration.Dynamic addServlet(String servletName, Class<? extends Servlet> servletClass) {
		throw new UnsupportedOperationException();
	}

	@Override
	public <T extends Servlet> T createServlet(Class<T> c) throws ServletException {
		throw new UnsupportedOperationException();
	}

	/**
	 * This method always returns {@code null}.
	 * @see javax.servlet.ServletContext#getServletRegistration(java.lang.String)
	 */
	@Override
	@Nullable
	public ServletRegistration getServletRegistration(String servletName) {
		return null;
	}

	/**
	 * This method always returns an {@linkplain Collections#emptyMap empty map}.
	 * @see javax.servlet.ServletContext#getServletRegistrations()
	 */
	@Override
	public Map<String, ? extends ServletRegistration> getServletRegistrations() {
		return Collections.emptyMap();
	}

	@Override
	public FilterRegistration.Dynamic addFilter(String filterName, String className) {
		throw new UnsupportedOperationException();
	}

	@Override
	public FilterRegistration.Dynamic addFilter(String filterName, Filter filter) {
		throw new UnsupportedOperationException();
	}

	@Override
	public FilterRegistration.Dynamic addFilter(String filterName, Class<? extends Filter> filterClass) {
		throw new UnsupportedOperationException();
	}

	@Override
	public <T extends Filter> T createFilter(Class<T> c) throws ServletException {
		throw new UnsupportedOperationException();
	}

	/**
	 * This method always returns {@code null}.
	 * @see javax.servlet.ServletContext#getFilterRegistration(java.lang.String)
	 */
	@Override
	@Nullable
	public FilterRegistration getFilterRegistration(String filterName) {
		return null;
	}

	/**
	 * This method always returns an {@linkplain Collections#emptyMap empty map}.
	 * @see javax.servlet.ServletContext#getFilterRegistrations()
	 */
	@Override
	public Map<String, ? extends FilterRegistration> getFilterRegistrations() {
		return Collections.emptyMap();
	}

	@Override
	public void addListener(Class<? extends EventListener> listenerClass) {
		throw new UnsupportedOperationException();
	}

	@Override
	public void addListener(String className) {
		throw new UnsupportedOperationException();
	}

	@Override
	public <T extends EventListener> void addListener(T t) {
		throw new UnsupportedOperationException();
	}

	@Override
	public <T extends EventListener> T createListener(Class<T> c) throws ServletException {
		throw new UnsupportedOperationException();
	}

	@Override
	public String getVirtualServerName() {
		throw new UnsupportedOperationException();
	}

}
