package luan.host;

import java.io.File;
import java.io.IOException;
import java.lang.ref.Reference;
import java.lang.ref.SoftReference;
//import java.lang.ref.WeakReference;
import java.util.Map;
import java.util.HashMap;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import luan.webserver.Handler;
import luan.webserver.Server;
import luan.webserver.Request;
import luan.webserver.Response;
import luan.webserver.handlers.IndexHandler;
import luan.webserver.handlers.ListHandler;
import luan.Luan;
import luan.LuanState;
import luan.LuanException;
import luan.LuanTable;
import luan.LuanFunction;
import luan.modules.IoLuan;
import luan.modules.JavaLuan;
import luan.modules.PackageLuan;
import luan.modules.http.LuanHandler;
import luan.modules.http.NotFound;


public class WebHandler implements Handler {
	private static final Logger logger = LoggerFactory.getLogger(WebHandler.class);

	public static String allowJavaFileName = "allow_java";  // change for security
	private static final Map<String,Reference<LuanState>> siteMap = new HashMap<String,Reference<LuanState>>();
	private static String sitesDir = null;

	private static final String HANDLER = "WebHandler.handler";
	private static final String LUAN_HANDLER = "WebHandler.luanHandler";

	public static boolean isServing() {
		return sitesDir != null;
	}

	public WebHandler(String dir) {
		if( sitesDir != null )
			throw new RuntimeException("already set");
		if( !new File(dir).exists() )
			throw new RuntimeException();
		this.sitesDir = dir;
	}

	public Response handle(Request request) {
		String host = (String)request.headers.get("host");
		int i = host.indexOf(':');
		String domain = i == -1 ? host : host.substring(0,i);
//		System.out.println("handle "+domain);
		LuanState luan = getSite(domain);
		if( luan == null )
			return null;
		Handler handler = (Handler)luan.registry().get(HANDLER);
		return handler.handle(request);
	}

	public static Object runLuan(String domain,String sourceText,String sourceName) throws LuanException {
		LuanState luan = getSite(domain);
		LuanHandler luanHandler = (LuanHandler)luan.registry().get(LUAN_HANDLER);
		return luanHandler.runLuan(sourceText,sourceName);
	}

	public static Object callSite(String domain,String fnName,Object... args) throws LuanException {
		LuanState luan = getSite(domain);
		LuanHandler luanHandler = (LuanHandler)luan.registry().get(LUAN_HANDLER);
		return luanHandler.call_rpc(fnName,args);
	}

	private static LuanState getSite(String domain) {
		synchronized(siteMap) {
			Reference<LuanState> ref = siteMap.get(domain);
			LuanState luan = ref==null ? null : ref.get();
			if( luan == null ) {
				if(ref!=null) logger.info("gc "+domain);
				if( sitesDir==null )
					throw new NullPointerException("sitesDir");
				File dir = new File(sitesDir,domain);
				if( !dir.exists() /* && !recover(dir) */ )
					return null;
				luan = newSite(dir.toString(),domain);
				siteMap.put(domain,new SoftReference<LuanState>(luan));
			}
			return luan;
		}
	}
/*
	private static boolean recover(File dir) {
		File backups = new File(dir.getParentFile().getParentFile(),"backups");
		if( !backups.exists() )
			return false;
		String name = dir.getName();
		File from = null;
		for( File backup : backups.listFiles() ) {
			File d = new File(backup,"current/"+name);
			if( d.exists() && (from==null || from.lastModified() < d.lastModified()) )
				from = d;
		}
		if( from == null )
			return false;
		if( !from.renameTo(dir) )
			throw new RuntimeException("couldn't rename "+from+" to "+dir);
		logger.info("recovered "+name+" from "+from);
		return true;
	}
*/
	static LuanTable initLuan(LuanState luan,String dir,String domain) {
		LuanTable init;
		try {
			init = (LuanTable)luan.eval(
				"local Luan = require 'luan:Luan.luan'\n"
				+"local f = Luan.load_file 'classpath:luan/host/Init.luan'\n"
				+"return f('"+dir+"','"+domain+"')\n"
			);
		} catch(LuanException e) {
			throw new RuntimeException(e);
		}
		File allowJavaFile = new File(dir,"site/private/"+allowJavaFileName);
		if( !allowJavaFile.exists() ) {
			JavaLuan.setSecurity( luan, javaSecurity );
			IoLuan.setSecurity( luan, ioSecurity(dir) );
		}
		return init;
	}

	private static LuanState newSite(String dir,String domain) {
		LuanState luan = new LuanState();
		LuanTable init = initLuan(luan,dir,domain);

		String loggerRoot = (String)init.rawGet("logger_root");
		LuanHandler luanHandler = new LuanHandler(luan,loggerRoot);
		NotFound notFoundHandler = new NotFound(luanHandler);

		Handler handler = luanHandler;
		handler = new IndexHandler(handler);
		handler = new ListHandler( handler, notFoundHandler );

		String logDir = dir + "/site/private/local/logs/web";
		new File(logDir).mkdirs();

		luan.registry().put(HANDLER,handler);
		luan.registry().put(LUAN_HANDLER,luanHandler);

		return luan;
	}

	public static void removeHandler(String domain) throws Exception {
		synchronized(siteMap) {
			Reference<LuanState> ref = siteMap.remove(domain);
			LuanState luan = ref==null ? null : ref.get();
			if( luan != null ) {
				LuanHandler luanHandler = (LuanHandler)luan.registry().get(LUAN_HANDLER);
				luanHandler.close();
			}
		}
	}

	public static void loadHandler(String domain) {
		getSite(domain);
	}

	private static final IoLuan.Security ioSecurity(String dir) {
		final String siteUri = "file:" + dir + "/site";
		return new IoLuan.Security() {
			public void check(LuanState luan,String name) throws LuanException {
				if( name.startsWith("file:") ) {
					if( name.contains("..") )
						throw new LuanException("Security violation - '"+name+"' contains '..'");
					if( !(name.equals(siteUri) || name.startsWith(siteUri+"/")) )
						throw new LuanException("Security violation - '"+name+"' outside of site dir");
				}
				else if( name.startsWith("classpath:luan/host/") ) {
					throw new LuanException("Security violation");
				}
				else if( name.startsWith("os:") || name.startsWith("bash:") ) {
					throw new LuanException("Security violation");
				}
			}
		};
	}

	private static final JavaLuan.Security javaSecurity = new JavaLuan.Security() {
		public void check(LuanState luan,String name) throws LuanException {
			if( !name.startsWith("luan:") )
				throw new LuanException("Security violation - only luan:* modules can load Java");
			if( name.equals("luan:logging/Logging") )
				throw new LuanException("Security violation - cannot reload Logging");
		}
	};
}