/* 
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
 
window.onload = changeNextPrevUrls;

var paintingsOnPaperArray;

function initializeUrlArray(){
	paintingsOnPaperArray = new Array();
	paintingsOnPaperArray[0]="/paintingsonpaper/12_2010.html";
	paintingsOnPaperArray[1]="/paintingsonpaper/14_2010.html";
	paintingsOnPaperArray[2]="/paintingsonpaper/17_2010.html";
	paintingsOnPaperArray[3]="/paintingsonpaper/21_2010.html";
	paintingsOnPaperArray[4]="/paintingsonpaper/22_2010.html";
	paintingsOnPaperArray[5]="/paintingsonpaper/23_2010.html";
	paintingsOnPaperArray[6]="/paintingsonpaper/25_2010.html";
	paintingsOnPaperArray[7]="/paintingsonpaper/26_2010.html";
	paintingsOnPaperArray[8]="/paintingsonpaper/Lav-GyP-Fl-Pk_200903.html";
	paintingsOnPaperArray[9]="/paintingsonpaper/Gn-GyP-Br-Org_200903.html";
	paintingsOnPaperArray[10]="/paintingsonpaper/Pk-TnP_Rd-Org_200903.html";
	paintingsOnPaperArray[11]="/paintingsonpaper/80_2007.html";
	paintingsOnPaperArray[12]="/paintingsonpaper/91_2008.html";
	paintingsOnPaperArray[13]="/paintingsonpaper/79_2007.html";
	paintingsOnPaperArray[14]="/paintingsonpaper/92_2008.html";
	paintingsOnPaperArray[15]="/paintingsonpaper/50_2007.html";
}

function changeNextPrevUrls(){
	initializeUrlArray();
	qs();
	var slideNo = parseInt(qs());
	var prevIdx = (slideNo == 0) ? 0 : (slideNo - 1);
	//alert("prevIdx=" + prevIdx);
	var nextIdx = (slideNo == (paintingsOnPaperArray.length - 1)) ? slideNo : (slideNo + 1);
	//alert("nextIdx=" + nextIdx);
	
	if(prevIdx == 0 && nextIdx == 1) {
		disappear("prevhref");
	} else {
		appear("prevhref", 'PREV');
		changeUrl("prevhref", paintingsOnPaperArray[prevIdx] + "?slide_no=" + prevIdx);
	}
	
	if((prevIdx == paintingsOnPaperArray.length - 2) && (nextIdx == paintingsOnPaperArray.length - 1)) {
		disappear("nexthref");
	} else {
		appear("nexthref", 'NEXT');
		changeUrl("nexthref", paintingsOnPaperArray[nextIdx] + "?slide_no=" + nextIdx);
	}	
	
	//changeUrl("prevhref", paintingsOnPaperArray[prevIdx] + "?slide_no=" + prevIdx);
	//changeUrl("nexthref", paintingsOnPaperArray[nextIdx] + "?slide_no=" + nextIdx);
}

function changeUrl(id, newUrl){
	document.getElementById(id).href = newUrl;
}

function disappear(id){
	document.getElementById(id).innerHTML = '';
}

function appear(id, text){
	document.getElementById(id).innerHTML = text;
}


function qs() {
	var query = window.location.search.substring(1);
	var parms = query.split('&');
	//alert(parms);
	var result =0;
	for (var i=0; i<parms.length; i++) {
		var pos = parms[i].indexOf('=');
		if (pos > 0) {
			var key = parms[i].substring(0,pos);
			var val = parms[i].substring(pos+1);
			//alert("key=" + key);
			//alert("val=" + val);
			if(key == "slide_no") {
				result = val;
				break;
			}
		}
	}
	//alert("result=" + result);
	return result;
}