package org.openslx.taskmanager;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;

import org.apache.log4j.Logger;

/**
 * Holds the environment that tasks running a system command *should*
 * use. The environment is read from a config file.
 */
public class Environment
{

	private static final Logger log = Logger.getLogger( Environment.class );

	private static Map<String, String> env = new LinkedHashMap<>();

	public static boolean load( String fileName )
	{
		try {
			FileReader fileReader = new FileReader( fileName );
			BufferedReader bufferedReader = new BufferedReader( fileReader );

			Map<String, String> env = new LinkedHashMap<>();
			String line = null;
			while ( ( line = bufferedReader.readLine() ) != null ) {
				if ( !line.matches( "^[a-zA-Z0-9_]+=" ) )
					continue;
				String[] part = line.split( "=", 2 );
				env.put( part[0], part[1] );
			}

			bufferedReader.close();

			Environment.env = env;
			log.info( "Loaded " + env.size() + " environment lines." );
		} catch ( IOException e ) {
			log.info( "Could not load environment definition from " + fileName + ". Processes might use the same environment as this thread." );
			return false;
		}
		return true;
	}

	public static void set( Map<String, String> environment )
	{
		environment.clear();
		environment.putAll( env );
	}

	public static String[] get()
	{
		// Get reference to env so it doesn't change while in this function (load() from other thread)
		Map<String, String> env = Environment.env;
		String ret[] = new String[ env.size() ];
		int i = 0;
		for ( Entry<String, String> it : env.entrySet() ) {
			ret[i++] = it.getKey() + "=" + it.getValue();
		}
		return ret;
	}

}