/*******************************************************************************
 *     SDR Trunk 
 *     Copyright (C) 2014 Dennis Sheirer
 * 
 *     This program is free software: you can redistribute it and/or modify
 *     it under the terms of the GNU General Public License as published by
 *     the Free Software Foundation, either version 3 of the License, or
 *     (at your option) any later version.
 * 
 *     This program is distributed in the hope that it will be useful,
 *     but WITHOUT ANY WARRANTY; without even the implied warranty of
 *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *     GNU General Public License for more details.
 * 
 *     You should have received a copy of the GNU General Public License
 *     along with this program.  If not, see <http://www.gnu.org/licenses/>
 ******************************************************************************/
package module.log;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.nio.file.Path;

import module.Module;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import util.TimeStamp;

public abstract class EventLogger extends Module
{
	private final static Logger mLog = 
			LoggerFactory.getLogger( EventLogger.class );

	/* Illegal filename characters */
	private static final String[] mIllegalCharacters = 
		{ "#", "%", "&", "{", "}", "\\", "<", ">", "*", "?", "/", 
		  " ", "$", "!", "'", "\"", ":", "@", "+", "`", "|", "=" };
	
	private Path mLogDirectory;
	private String mFileNameSuffix;
	private String mLogFileName;
	protected Writer mLogFile;

	public EventLogger( Path logDirectory, String fileNameSuffix )
	{
		mLogDirectory = logDirectory;
		mFileNameSuffix = fileNameSuffix;
	}
	
	public String toString()
	{
		if( mLogFileName != null )
		{
			return mLogFileName;
		}
		else
		{
			return "Unknown";
		}
	}
	
	public abstract String getHeader();
	
    public void start()
    {
    	if( mLogFile == null )
    	{
        	try 
        	{
        		StringBuilder sb = new StringBuilder();
        		sb.append( mLogDirectory );
        		sb.append( File.separator );
        		sb.append( TimeStamp.getTimeStamp( "_" ) );
        		sb.append( "_" );
        		sb.append( replaceIllegalCharacters( mFileNameSuffix ) );

        		mLogFileName = sb.toString();
        		
        		mLog.info( "Creating log file:" + mLogFileName );
        		
    			mLogFile = new OutputStreamWriter(new FileOutputStream( mLogFileName ) );
    			
    			write( getHeader() );
    		} 
        	catch (FileNotFoundException e) 
        	{
        		mLog.error("Couldn't create log file in directory:" + mLogDirectory );
    		}    	
    	}
    }

    /**
     * Replaces any illegal filename characters in the proposed filename
     */
    private String replaceIllegalCharacters( String filename )
    {
    	for( String illegalCharacter: mIllegalCharacters )
    	{
    		filename = filename.replace( illegalCharacter, "_" );
    	}

    	return filename;
    }

    public void stop()
    {
    	if( mLogFile != null )
    	{
    		try
    		{
    	    	mLogFile.flush();
    	    	mLogFile.close();
    	    	mLogFile = null;
    		}
    		catch( Exception e )
    		{
    			mLog.error( "Couldn't close log file:" + mFileNameSuffix );
    		}
    	}
    }
    
    protected void write( String eventLogEntry )
    {
		try
        {
	        mLogFile.write( eventLogEntry + "\n" );
        }
        catch ( IOException e )
        {
        	mLog.error( "Error writing entry to event log file", e );
        }
    }
}