/* 
 *  Copyright (C) 2000 - 2008 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://www.openbluedragon.org/
 */

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

import com.naryx.tagfusion.cfm.engine.cfArgStructData;
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.expression.function.functionBase;

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

	public listSetAt() {
		min = 3;
		max = 4;
		setNamedParams( new String[]{ "list","position","element","delimiter"} );
	}

	public String[] getParamInfo(){
		return new String[]{
			"list",
			"position",
			"element",
			"delimiter - default comma (,)"
		};
	}
	
	public java.util.Map getInfo(){
		return makeInfo(
				"list", 
				"Inserts the given element at the given position, returning the newly created list", 
				ReturnType.STRING );
	}

	public cfData execute(cfSession _session, cfArgStructData argStruct ) throws cfmRunTimeException {
		String list = getNamedStringParam( argStruct, "list" , "" );
		String delimiter = getNamedStringParam( argStruct, "delimiter" , "," );
		int position = getNamedIntParam( argStruct, "position" ,0 );
		String value = getNamedStringParam( argStruct, "element" , "" );

		if (delimiter.length() == 0) {
			throwException(_session, "Invalid delimiter specified. The delimiter value must contain at least one character.");
		}

		if (position <= 0) {
			throwException(_session, "Invalid list index: " + position);
		}

		// Note that we can't use java.util.StringTokenizer nor
		// com.nary.util.stringtokenizer
		// here because we need to maintain the list delimiters used in the original
		// list
		// and there may be more than one delimiter char.

		StringBuilder newList = new StringBuilder(list);

		int currPos = 0;
		int lastDelim = -1;
		int currListPos = 1;

		while (currPos < newList.length()) {
			boolean foundDelim = delimiter.indexOf(newList.charAt(currPos)) != -1;
			// if we've found a delimiter or at the end of the list
			if (foundDelim || currPos == newList.length() - 1) {

				if ((currPos == 0 && newList.length() != 1) || (currPos - 1 == lastDelim && currPos != newList.length() - 1)) { // empty
																																																												// list
																																																												// element
					lastDelim = currPos;
					currPos++;

				} else if (currListPos == position) { // this is the element that should
																							// be deleted
					newList = newList.replace(lastDelim + 1, currPos + (foundDelim ? 1 : 2), value + (foundDelim ? delimiter.substring(0, 1) : ""));
					currPos = lastDelim + 1;

					currListPos++;
					break; // don't need to edit the list any further

				} else {
					currListPos++;
					lastDelim = currPos;
					currPos++;
				}

			} else {
				currPos++;
			}
		}

		if (currListPos <= position) {
			throwException(_session, "Invalid list position specified " + position);
		}
		return new cfStringData(newList.toString());
	}
}