var NUM_CENTYEAR = 30;
var BUL_TIMECOMPONENT = false;
var BUL_YEARSCROLL = true;

var calendars = [];
var RE_NUM = /^\-?\d+$/;

function calendar(obj_target) {

  this.gen_date = cal_gen_date;
  this.gen_time = cal_gen_time;
  this.gen_tsmp = cal_gen_tsmp;
  this.prs_date = cal_prs_date;
  this.prs_time = cal_prs_time;
  this.prs_tsmp = cal_prs_tsmp;
  this.popup    = cal_popup;
  this.clean	= cal_clean;

    if (!obj_target)
    return cal_error("Error calling the calendar: no target control specified");
  if (obj_target.value == null)
    return cal_error("Error calling the calendar: parameter specified is not valid tardet control");
  this.target = obj_target;
  this.time_comp = BUL_TIMECOMPONENT;
  this.year_scroll = BUL_YEARSCROLL;
  
    this.id = calendars.length;
  calendars[this.id] = this;
}

function cal_clean (str_datetime) {
	this.target.value = "";

}

function cal_popup (str_datetime) {
  this.dt_current = this.prs_tsmp(str_datetime ? str_datetime : this.target.value);
  if (!this.dt_current) return;

  var obj_calwindow = window.open(
    'calendar.php?datetime=' + this.dt_current.valueOf()+ '&id=' + this.id,
    'Calendar', 'width=200,height='+(this.time_comp ? 190 : 165)+
    ',status=no,resizable=no,top=200,left=200,dependent=yes,alwaysRaised=yes'
  );
  obj_calwindow.opener = window;
  obj_calwindow.focus();
}

function cal_gen_tsmp (dt_datetime) {
  return(this.gen_date(dt_datetime) + ' ' + this.gen_time(dt_datetime));
}

function cal_gen_date (dt_datetime) {
  return (
    (dt_datetime.getDate() < 10 ? '0' : '') + dt_datetime.getDate() + "/"
    + (dt_datetime.getMonth() < 9 ? '0' : '') + (dt_datetime.getMonth() + 1) + "/"
    + dt_datetime.getFullYear()
  );
}
function cal_gen_time (dt_datetime) {
  return (
    (dt_datetime.getHours() < 10 ? '0' : '') + dt_datetime.getHours() + ":"
    + (dt_datetime.getMinutes() < 10 ? '0' : '') + (dt_datetime.getMinutes()) + ":"
    + (dt_datetime.getSeconds() < 10 ? '0' : '') + (dt_datetime.getSeconds())
  );
}

function cal_prs_tsmp (str_datetime) {
    if (!str_datetime)
    return (new Date());

    if (RE_NUM.exec(str_datetime))
    return new Date(str_datetime);
    
    var arr_datetime = str_datetime.split(' ');
  return this.prs_time(arr_datetime[1], this.prs_date(arr_datetime[0]));
}

function cal_prs_date (str_date) {

  var arr_date = str_date.split('/');

  if (arr_date.length != 3) return cal_error ("Invalid date format: '" + str_date + "'.\nFormat accepted is dd/mm/yyyy.");
  if (!arr_date[0]) return cal_error ("Invalid date format: '" + str_date + "'.\nNo day of month value can be found.");
  if (!RE_NUM.exec(arr_date[0])) return cal_error ("Invalid day of month value: '" + arr_date[0] + "'.\nAllowed values are unsigned integers.");
  if (!arr_date[1]) return cal_error ("Invalid date format: '" + str_date + "'.\nNo month value can be found.");
  if (!RE_NUM.exec(arr_date[1])) return cal_error ("Invalid month value: '" + arr_date[1] + "'.\nAllowed values are unsigned integers.");
  if (!arr_date[2]) return cal_error ("Invalid date format: '" + str_date + "'.\nNo year value can be found.");
  if (!RE_NUM.exec(arr_date[2])) return cal_error ("Invalid year value: '" + arr_date[2] + "'.\nAllowed values are unsigned integers.");

  var dt_date = new Date();
  dt_date.setDate(1);

  if (arr_date[1] < 1 || arr_date[1] > 12) return cal_error ("Invalid month value: '" + arr_date[1] + "'.\nAllowed range is 01-12.");
  dt_date.setMonth(arr_date[1]-1);
   
  if (arr_date[2] < 100) arr_date[2] = Number(arr_date[2]) + (arr_date[2] < NUM_CENTYEAR ? 2000 : 1900);
  dt_date.setFullYear(arr_date[2]);

  var dt_numdays = new Date(arr_date[2], arr_date[1], 0);
  dt_date.setDate(arr_date[0]);
  if (dt_date.getMonth() != (arr_date[1]-1)) return cal_error ("Invalid day of month value: '" + arr_date[0] + "'.\nAllowed range is 01-"+dt_numdays.getDate()+".");

  return (dt_date)
}

function cal_prs_time (str_time, dt_date) {

  if (!dt_date) return null;
  var arr_time = String(str_time ? str_time : '').split(':');

  if (!arr_time[0]) dt_date.setHours(0);
  else if (RE_NUM.exec(arr_time[0])) 
    if (arr_time[0] < 24) dt_date.setHours(arr_time[0]);
    else return cal_error ("Invalid hours value: '" + arr_time[0] + "'.\nAllowed range is 00-23.");
  else return cal_error ("Invalid hours value: '" + arr_time[0] + "'.\nAllowed values are unsigned integers.");
  
  if (!arr_time[1]) dt_date.setMinutes(0);
  else if (RE_NUM.exec(arr_time[1]))
    if (arr_time[1] < 60) dt_date.setMinutes(arr_time[1]);
    else return cal_error ("Invalid minutes value: '" + arr_time[1] + "'.\nAllowed range is 00-59.");
  else return cal_error ("Invalid minutes value: '" + arr_time[1] + "'.\nAllowed values are unsigned integers.");

  if (!arr_time[2]) dt_date.setSeconds(0);
  else if (RE_NUM.exec(arr_time[2]))
    if (arr_time[2] < 60) dt_date.setSeconds(arr_time[2]);
    else return cal_error ("Invalid seconds value: '" + arr_time[2] + "'.\nAllowed range is 00-59.");
  else return cal_error ("Invalid seconds value: '" + arr_time[2] + "'.\nAllowed values are unsigned integers.");

  dt_date.setMilliseconds(0);
  return dt_date;
}

function cal_error (str_message) {
  alert (str_message);
  return null;
}