//Abre un pop-up con una tabla para la selección de fechas,
//el resultado se anexa al contenedor asociado (input)

function muestra(str_target, str_datetime) {
	var arr_months = ["Enero", "Febrero", "Marzo", "Abril", "Mayo", "Junio",
		"Julio", "Agosto", "Septiembre", "Octubre", "Noviembre", "Diciembre"];
	var week_days = ["Do", "Lu", "Ma", "Mi", "Ju", "Vi", "Sa"];
	var n_weekstart = 1;
	var dt_datetime = (str_datetime == null || str_datetime =="" ?  new Date() : cadenaafecha(str_datetime));
	var dt_prev_month = new Date(dt_datetime);
	dt_prev_month.setMonth(dt_datetime.getMonth()-1);
	var dt_next_month = new Date(dt_datetime);
	dt_next_month.setMonth(dt_datetime.getMonth()+1);
	var dt_firstday = new Date(dt_datetime);
	dt_firstday.setDate(1);
	dt_firstday.setDate(1-(7+dt_firstday.getDay()-n_weekstart)%7);
	var dt_lastday = new Date(dt_next_month);
	dt_lastday.setDate(0);
	var dt_act_month=dt_datetime.getMonth()+1;
	
    var comboyear=new String("\n<select name=\"year\" style=\"font-family:tahoma,verdana;size:8px\" onChange=\"window.opener.muestra('"+str_target+"', '"+
				   dt_datetime.getDate()+"/"+dt_act_month+"/'+this.value+document.cal.time.value);\">\n");
	for(intYear=1950;intYear<2051;intYear++){
		var str_selYear="";
		if(intYear==dt_datetime.getFullYear()) str_selYear="SELECTED";
		comboyear+="<option value=\""+intYear+"\""+str_selYear+">"+intYear+"</option>\n";
	}
	var str_buffer = new String (
		"<html>\n"+
		"<head>\n"+
		"	<title>Calendario</title>\n"+
		"</head>\n"+
		"<body bgcolor=\"White\">\n"+
		"<table class=\"clsOTable\" cellspacing=\"0\" border=\"0\" width=\"100%\">\n"+
		"<tr><td bgcolor=\"#4682B4\">\n"+
		"<table cellspacing=\"1\" cellpadding=\"3\" border=\"0\" width=\"100%\">\n"+
		"<tr>\n	<td bgcolor=\"#4682B4\"><a href=\"javascript:window.opener.muestra('"+
		str_target+"','"+fechaacadena(dt_prev_month)+"'+document.cal.time.value);\">"+
		"<img src=\"../splash/icono_atras1.gif\" width=\"16\" height=\"16\" border=\"0\""+
		" alt=\"Mes Anterior\"></a></td>\n"+
		"	<td bgcolor=\"#4682B4\" colspan=\"5\">"+
		"<font color=\"white\" face=\"tahoma, verdana\" size=\"2\">"
		+arr_months[dt_datetime.getMonth()]+" "+comboyear+"</font></td>\n"+
		"	<td bgcolor=\"#4682B4\" align=\"right\"><a href=\"javascript:window.opener.muestra('"
		+str_target+"', '"+fechaacadena(dt_next_month)+"'+document.cal.time.value);\">"+
		"<img src=\"../splash/icono_adelante1.gif\" width=\"16\" height=\"16\" border=\"0\""+
		" alt=\"Siguiente Mes\"></a></td>\n</tr>\n"
	);

	var dt_current_day = new Date(dt_firstday);
	str_buffer += "<tr>\n";
	for (var n=0; n<7; n++)
		str_buffer += "	<td bgcolor=\"#87CEFA\">"+
		"<font color=\"white\" face=\"tahoma, verdana\" size=\"2\">"+
		week_days[(n_weekstart+n)%7]+"</font></td>\n";
	str_buffer += "</tr>\n";
	while (dt_current_day.getMonth() == dt_datetime.getMonth() ||
		dt_current_day.getMonth() == dt_firstday.getMonth()) {
		str_buffer += "<tr>\n";
		for (var n_current_wday=0; n_current_wday<7; n_current_wday++) {
				if (dt_current_day.getDate() == dt_datetime.getDate() &&
					dt_current_day.getMonth() == dt_datetime.getMonth())
					str_buffer += "	<td bgcolor=\"#CCCCCC\" align=\"right\">";
				else if (dt_current_day.getDay() == 0 || dt_current_day.getDay() == 6)
					str_buffer += "	<td bgcolor=\"#DBEAF5\" align=\"right\">";
				else
					str_buffer += "	<td bgcolor=\"white\" align=\"right\">";

				if (dt_current_day.getMonth() == dt_datetime.getMonth())
					str_buffer += "<a href=\"javascript:window.opener."+str_target+
					".value='"+fechaacadena(dt_current_day)+"'+document.cal.time.value; window.opener."+str_target+".focus(); window.close();\">"+
					"<font color=\"black\" face=\"tahoma, verdana\" size=\"2\">";
				else 
					str_buffer += "<a href=\"javascript:window.opener."+str_target+
					".value='"+fechaacadena(dt_current_day)+"'+document.cal.time.value; window.opener."+str_target+".focus(); window.close();\">"+
					"<font color=\"gray\" face=\"tahoma, verdana\" size=\"2\">";
				str_buffer += dt_current_day.getDate()+"</font></a></td>\n";
				dt_current_day.setDate(dt_current_day.getDate()+1);
		}
		str_buffer += "</tr>\n";
	}
	str_buffer +=
		"<form name=\"cal\">\n<tr><td colspan=\"7\" bgcolor=\"#87CEFA\">"+
		"<font color=\"White\" face=\"tahoma, verdana\" size=\"2\">"+
		"<input type=\"hidden\" name=\"time\" size=\"8\" maxlength=\"8\">"+
		"</font></td></tr>\n</form>\n" +
		"</table>\n" +
		"</tr>\n</td>\n</table>\n" +
		"</body>\n" +
		"</html>\n";

	var vWinCal = window.open("", "Calendario", 
		"width=200,height=250,status=no,resizable=yes,top=200,left=200");
	vWinCal.opener = self;
	var calc_doc = vWinCal.document;
	calc_doc.write (str_buffer);
	calc_doc.close();
}

function cadenaafecha (str_datetime) {
	var re_date = /^(\d+)\/(\d+)\/(\d+)$/;
	if (!re_date.exec(str_datetime))
		return alert("Formato inválido (dd/mm/aaaa): "+ str_datetime);
	return (new Date (RegExp.$3, RegExp.$2-1, RegExp.$1));
}
function fechaacadena (dt_datetime) {
	var day="";
	var month="";
	if(dt_datetime.getDate()<10)day="0"+dt_datetime.getDate();
	else day=dt_datetime.getDate();
	if((dt_datetime.getMonth()+1)<10)month="0"+(dt_datetime.getMonth()+1);
	else month=dt_datetime.getMonth()+1;
	return (new String (
			day+"/"+month+"/"+dt_datetime.getFullYear()));
}
function horaacadena (dt_datetime) {
	return (new String (dt_datetime.getHours()+":"+dt_datetime.getMinutes()+":"+dt_datetime.getSeconds()));
}

function validarfecha(strfecha,strdescripcion){
	var regreso=true;
	var fecha=strfecha.split("/");
	if (fecha.length==3){
		if (Number(fecha[0])>31){
			alert("Día no válido en " + strdescripcion);
			regreso=false;		}
		if (Number(fecha[1])>12){
			alert("Mes no válido en " + strdescripcion);
			regreso=false;		}
		if (Number(fecha[2])>2099){
			alert("Año no válido en " + strdescripcion);
			regreso=false;
		}
	}
	else{
		alert("Formato inválido en " + strdescripcion);
		regreso=false;
	}
	return regreso;
}
