/*
 * Copyright 2012-2020 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.context;

import java.io.File;
import java.util.Locale;

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

import org.springframework.boot.system.SystemProperties;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationListener;
import org.springframework.core.log.LogMessage;
import org.springframework.util.Assert;
import org.springframework.util.FileCopyUtils;
import org.springframework.util.StringUtils;

An ApplicationListener that saves embedded server port and management port into file. This application listener will be triggered whenever the server starts, and the file name can be overridden at runtime with a System property or environment variable named "PORTFILE" or "portfile". 
Author:
David Liu, Phillip Webb, Andy Wilkinson
Since:
2.0.0/**
 * An {@link ApplicationListener} that saves embedded server port and management port into
 * file. This application listener will be triggered whenever the server starts, and the
 * file name can be overridden at runtime with a System property or environment variable
 * named "PORTFILE" or "portfile".
 *
 * @author David Liu
 * @author Phillip Webb
 * @author Andy Wilkinson
 * @since 2.0.0
 */
public class WebServerPortFileWriter implements ApplicationListener<WebServerInitializedEvent> {

	private static final String DEFAULT_FILE_NAME = "application.port";

	private static final String[] PROPERTY_VARIABLES = { "PORTFILE", "portfile" };

	private static final Log logger = LogFactory.getLog(WebServerPortFileWriter.class);

	private final File file;

	
Create a new WebServerPortFileWriter instance using the filename 'application.port'. /**
	 * Create a new {@link WebServerPortFileWriter} instance using the filename
	 * 'application.port'.
	 */
	public WebServerPortFileWriter() {
		this(new File(DEFAULT_FILE_NAME));
	}

	
Create a new WebServerPortFileWriter instance with a specified filename. 
Params:
filename – the name of file containing port/**
	 * Create a new {@link WebServerPortFileWriter} instance with a specified filename.
	 * @param filename the name of file containing port
	 */
	public WebServerPortFileWriter(String filename) {
		this(new File(filename));
	}

	
Create a new WebServerPortFileWriter instance with a specified file. 
Params:
file – the file containing port/**
	 * Create a new {@link WebServerPortFileWriter} instance with a specified file.
	 * @param file the file containing port
	 */
	public WebServerPortFileWriter(File file) {
		Assert.notNull(file, "File must not be null");
		String override = SystemProperties.get(PROPERTY_VARIABLES);
		if (override != null) {
			this.file = new File(override);
		}
		else {
			this.file = file;
		}
	}

	@Override
	public void onApplicationEvent(WebServerInitializedEvent event) {
		File portFile = getPortFile(event.getApplicationContext());
		try {
			String port = String.valueOf(event.getWebServer().getPort());
			createParentDirectory(portFile);
			FileCopyUtils.copy(port.getBytes(), portFile);
			portFile.deleteOnExit();
		}
		catch (Exception ex) {
			logger.warn(LogMessage.format("Cannot create port file %s", this.file));
		}
	}

	
Return the actual port file that should be written for the given application
context. The default implementation builds a file from the source file and the
application context namespace if available.
Params:
applicationContext – the source application context
Returns:
the file that should be written/**
	 * Return the actual port file that should be written for the given application
	 * context. The default implementation builds a file from the source file and the
	 * application context namespace if available.
	 * @param applicationContext the source application context
	 * @return the file that should be written
	 */
	protected File getPortFile(ApplicationContext applicationContext) {
		String namespace = getServerNamespace(applicationContext);
		if (!StringUtils.hasLength(namespace)) {
			return this.file;
		}
		String name = this.file.getName();
		String extension = StringUtils.getFilenameExtension(this.file.getName());
		name = name.substring(0, name.length() - extension.length() - 1);
		if (isUpperCase(name)) {
			name = name + "-" + namespace.toUpperCase(Locale.ENGLISH);
		}
		else {
			name = name + "-" + namespace.toLowerCase(Locale.ENGLISH);
		}
		if (StringUtils.hasLength(extension)) {
			name = name + "." + extension;
		}
		return new File(this.file.getParentFile(), name);
	}

	private String getServerNamespace(ApplicationContext applicationContext) {
		if (applicationContext instanceof WebServerApplicationContext) {
			return ((WebServerApplicationContext) applicationContext).getServerNamespace();
		}
		return null;
	}

	private boolean isUpperCase(String name) {
		for (int i = 0; i < name.length(); i++) {
			if (Character.isLetter(name.charAt(i)) && !Character.isUpperCase(name.charAt(i))) {
				return false;
			}
		}
		return true;
	}

	private void createParentDirectory(File file) {
		File parent = file.getParentFile();
		if (parent != null) {
			parent.mkdirs();
		}
	}

}