/* 
 *  Copyright (C) 2000 - 2011 TagServlet Ltd
 *
 *  This file is part of Open BlueDragon (OpenBD) CFML Server Engine.
 *  
 *  OpenBD is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  Free Software Foundation,version 3.
 *  
 *  OpenBD 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 OpenBD.  If not, see http://www.gnu.org/licenses/
 *  
 *  Additional permission under GNU GPL version 3 section 7
 *  
 *  If you modify this Program, or any covered work, by linking or combining 
 *  it with any of the JARS listed in the README.txt (or a modified version of 
 *  (that library), containing parts covered by the terms of that JAR, the 
 *  licensors of this Program grant you additional permission to convey the 
 *  resulting work. 
 *  README.txt @ http://www.openbluedragon.org/license/README.txt
 *  
 *  http://openbd.org/
 *  
 *  $Id: FileReadLine.java 1690 2011-09-26 09:38:42Z alan $
 */


package com.naryx.tagfusion.expression.function.file;

import java.io.IOException;
import java.util.List;

import com.naryx.tagfusion.cfm.engine.cfData;
import com.naryx.tagfusion.cfm.engine.cfSession;
import com.naryx.tagfusion.cfm.engine.cfStringData;
import com.naryx.tagfusion.cfm.engine.cfmRunTimeException;
import com.naryx.tagfusion.cfm.file.vfs.cfVFSData;
import com.naryx.tagfusion.expression.function.functionBase;

public class FileReadLine extends functionBase {
  private static final long serialVersionUID = 1L;

  public FileReadLine(){ min = max = 1; }
  
	public String[] getParamInfo(){
		return new String[]{
			"file object"
		};
	}
	
	public java.util.Map getInfo(){
		return makeInfo(
				"file", 
				"For an existing open file, reads and returns the next line of text", 
				ReturnType.STRING );
	}
  
  
  
  public cfData execute( cfSession _session, List<cfData> parameters )throws cfmRunTimeException{
  	if ( !(parameters.get(0) instanceof cfVFSData) ){
  		throwException( _session, "please pass in a file object from FileOpen(.)" );
  	}
  	
  	cfVFSData vfsData = (cfVFSData)parameters.get(0);
  	if ( !vfsData.isReadable() ){
  		throwException( _session, "this file object is not opened in read mode" );
  	}
  	
  	try {
  		String line = vfsData.getReader().readLine();
  		if ( line == null )
  			vfsData.setEOF();
  		
			return new cfStringData( line );
		} catch (IOException e) {
			throwException( _session, "an error has occurred: " + e.getMessage() );
			return null;
		}
  }
}