package org.openslx.util;

import java.io.InputStream;
import java.time.Instant;
import java.time.ZoneId;
import java.time.format.DateTimeFormatter;
import java.util.jar.Attributes;
import java.util.jar.JarInputStream;
import java.util.jar.Manifest;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

public class AppUtil
{

	private final static Logger LOGGER = LogManager.getLogger( AppUtil.class );

	private static final int PROPERTY_MAX_WIDTH = 30;

	private static final String MANIFEST_REVISION_VERSION = "Revision-Version";
	private static final String MANIFEST_REVISION_BRANCH = "Revision-Branch";
	private static final String MANIFEST_BUILD_TIMESTAMP = "Build-Timestamp";
	private static final String MANIFEST_BUILD_JDK = "Build-Jdk";

	private static final String PROPERTY_APP_NAME = "app.name";
	private static final String PROPERTY_APP_VERSION = "app.version";
	private static final String PROPERTY_APP_REVISION_VERSION = "app.revision.version";
	private static final String PROPERTY_APP_REVISION_BRANCH = "app.revision.branch";
	private static final String PROPERTY_APP_BUILD_DATE = "app.build.date";
	private static final String PROPERTY_APP_BUILD_JDK = "app.build.jdk";

	private static final String PROPERTY_JAVA_OS_NAME = "os.name";
	private static final String PROPERTY_JAVA_OS_ARCH = "os.arch";

	private static final String PROPERTY_JAVA_SPEC_VENDOR = "java.specification.vendor";
	private static final String PROPERTY_JAVA_SPEC_NAME = "java.specification.name";
	private static final String PROPERTY_JAVA_SPEC_VERSION = "java.specification.version";

	private static final String PROPERTY_JAVA_VERSION = "java.version";
	private static final String PROPERTY_JAVA_VERSION_VM = "java.vm.version";
	private static final String PROPERTY_JAVA_VERSION_RUNTIME = "java.runtime.version";
	
	private static final String PROPERTY_JAVA_MEMORY_LIMIT = "java.runtime.memory";
	
	private static final String PROPERTY_JAVA_BITNESS = "sun.arch.data.model";
	
	private static Attributes manifestAttributes = null;

	private static String getManifestValue( final String entry )
	{
		if ( manifestAttributes == null ) {
			InputStream jarFileStream = null;
			JarInputStream jarStream = null;
			// Do this so in case of failure, we won't open the jar again and again and spam exceptions to the log
			manifestAttributes = new Attributes();

			try {
				jarFileStream = AppUtil.class.getProtectionDomain().getCodeSource().getLocation().openStream();
				jarStream = new JarInputStream( jarFileStream );
				final Manifest mf = jarStream.getManifest();
				manifestAttributes = mf.getMainAttributes();
			} catch ( Exception e ) {
				LOGGER.warn( "Cannot read jar/manifest attributes", e );
			} finally {
				Util.safeClose( jarStream, jarFileStream );
			}
		}

		return manifestAttributes.getValue( entry );
	}

	public static String getRevisionVersion()
	{
		return AppUtil.getManifestValue( AppUtil.MANIFEST_REVISION_VERSION );
	}

	public static String getRevisionBranch()
	{
		return AppUtil.getManifestValue( AppUtil.MANIFEST_REVISION_BRANCH );
	}

	public static long getBuildTimestamp()
	{
		final String timestampRaw = AppUtil.getManifestValue( AppUtil.MANIFEST_BUILD_TIMESTAMP );
		long timestamp = 0;

		try {
			timestamp = Long.valueOf( timestampRaw );
			timestamp /= 1000L;
		} catch ( NumberFormatException e ) {
			timestamp = 0;
		}

		return timestamp;
	}

	public static String getBuildTime()
	{
		final long timestamp = AppUtil.getBuildTimestamp();
		final String buildTime;

		if ( timestamp > 0 ) {
			final Instant time = Instant.ofEpochSecond( timestamp );
			buildTime = DateTimeFormatter.RFC_1123_DATE_TIME.withZone( ZoneId.systemDefault() ).format( time );
		} else {
			buildTime = null;
		}

		return buildTime;
	}

	public static String getBuildJdk()
	{
		return AppUtil.getManifestValue( AppUtil.MANIFEST_BUILD_JDK );
	}

	private static String formatProperty( final String property )
	{
		return String.format( "%-" + AppUtil.PROPERTY_MAX_WIDTH + "s", property );
	}

	public static void logProperty( final Logger logger, final String propertyName, final String propertyValue )
	{
		logger.info( AppUtil.formatProperty( propertyName ) + propertyValue );
	}

	public static void logJavaProperty( Logger logger, final String javaProperty )
	{
		AppUtil.logProperty( logger, javaProperty, System.getProperty( javaProperty ) );
	}

	public static void logHeader( final Logger logger, final String appName, final String appVersion )
	{
		// Format maximum VM memory
		final String mem;
		long limit = Runtime.getRuntime().maxMemory() / ( 1024l * 1024 );
		if ( limit > 99999999 ) {
			mem = "-";
		} else if ( limit >= 2048 ) {
			mem = String.format( "%.1fG", limit / 1024f );
		} else {
			mem = limit + "M";
		}
		logger.info( "-------------------------------------------------------------------------------" );
		logger.info( appName );
		logger.info( "-------------------------------------------------------------------------------" );
		logProperty( logger, AppUtil.PROPERTY_APP_NAME, appName );
		logProperty( logger, AppUtil.PROPERTY_APP_VERSION, appVersion );
		logProperty( logger, AppUtil.PROPERTY_APP_REVISION_VERSION, AppUtil.getRevisionVersion() );
		logProperty( logger, AppUtil.PROPERTY_APP_REVISION_BRANCH, AppUtil.getRevisionBranch() );
		logProperty( logger, AppUtil.PROPERTY_APP_BUILD_DATE, AppUtil.getBuildTime() );
		logProperty( logger, AppUtil.PROPERTY_APP_BUILD_JDK, AppUtil.getBuildJdk() );
		logJavaProperty( logger, AppUtil.PROPERTY_JAVA_OS_NAME );
		logJavaProperty( logger, AppUtil.PROPERTY_JAVA_SPEC_VENDOR );
		logJavaProperty( logger, AppUtil.PROPERTY_JAVA_SPEC_NAME );
		logJavaProperty( logger, AppUtil.PROPERTY_JAVA_SPEC_VERSION );
		logJavaProperty( logger, AppUtil.PROPERTY_JAVA_VERSION );
		logJavaProperty( logger, AppUtil.PROPERTY_JAVA_VERSION_VM );
		logJavaProperty( logger, AppUtil.PROPERTY_JAVA_VERSION_RUNTIME );
		logJavaProperty( logger, AppUtil.PROPERTY_JAVA_BITNESS );
		logJavaProperty( logger, AppUtil.PROPERTY_JAVA_OS_ARCH );
		logProperty( logger, AppUtil.PROPERTY_JAVA_MEMORY_LIMIT, mem );
		logger.info( "-------------------------------------------------------------------------------" );
	}
}