package condorAPI;

import java.io.FileReader;
import java.io.IOException;
import java.io.LineNumberReader;
import java.util.TimerTask;
import java.util.Timer;

import condor.classad.ClassAdParser;
import condor.classad.RecordExpr;

/** 
 * Log monitor for xml formatted condor log
 */ 
class LogMonitor{
	static Timer timer = new Timer("LogMonitor", true); 
	
	Condor condor;
	String filename;
	
	LineNumberReader lnr;
	ClassAdParser parser = new ClassAdParser(ClassAdParser.XML);
	private TimerTask task = null;
	
	int counter = 0;
	int maxError = 10;
	double sleepSec = 5;
		
	LogMonitor(Condor condor, String filename, double sleepSec){
		this.condor   = condor;
		this.filename = filename;
		this.sleepSec = sleepSec;
	}
	
	synchronized void setInterval(double sleepSec){
		this.sleepSec = sleepSec;
		if (task == null)
			return;
		task.cancel();
		start();
	}
	
	void openLnr(){
		if (lnr == null) {
			try {
				FileReader reader = new FileReader(filename);
				lnr = new LineNumberReader(reader);
			} catch (IOException e){
				System.err.println("failed to open " + filename + " , retry.");
				counter++;
				return;
			}
		} 
	}
	
	StringBuffer sb = new StringBuffer();
	
	RecordExpr readExpr() throws IOException{
		String tmp;
		while (true){
			tmp = lnr.readLine();
			if (tmp == null) 
				return null;
			sb.append(tmp);
			if (tmp.trim().equals("</c>"))
				break;
		}
		String adString = sb.toString();
		sb = new StringBuffer();  // set the new string buffer for the next time;
		
		//	System.out.println(adString);
		
		
		// this line should not be required, 
		// this is here just to avoid a bug in classad library.
		parser = new ClassAdParser(ClassAdParser.XML);
		
		parser.reset(adString);
		return (RecordExpr) (parser.parse());
	}
	
	void readLog(){
		try {
			RecordExpr expr;
			while ((expr = readExpr()) != null){
				//System.out.println(expr);
				Event event = Event.getEvent(expr);
				if (condor != null)
					condor.informEvent(event);
			}
		} catch (IOException e){
			e.printStackTrace();
			counter++;
		}
	}
	
	synchronized public void start() {
		task = new TimerTask(){
			public void run(){LogMonitor.this.run();}
		};
		timer.schedule(task, 0, (long)(sleepSec * 1000));
	}
		
	synchronized public void stop(){
		if (task == null)
			return;
		task.cancel();
		task = null;
	}
	
	public void run() {
		if (counter < maxError){
			openLnr();
			if (lnr != null){
				readLog();
			}
		} else {
			stop();
			System.err.println("LogMonitor for " + filename + " exits: too many errors");
		}
	}  
	
	/**
	 * just for test
	 * @throws InterruptedException 
	 */
	public static void main(String [] args) throws InterruptedException{
		String filename = args[0];
		LogMonitor monitor = new LogMonitor(null, filename, 10);
		monitor.start();
		
		Thread.sleep(100000);
	}
}