<?php
// *********************************************************************
// By Dave Hale - moodtracker.com
// Version: 1.0
//
// DESCRIPTION:
// The TimezoneSelector dynamically creates a <select></select> control.
// It lets you include the current date and time in the given timezone by
// specifying a 1 in the show() method. The date and time format can be 
// indicated in the optional string parameter which follows the standard
// php date/time format string.
//
// The select list is sorted by timezone or by the current timezone's time
// if the date/time is requested.
//
// Usage Examples:
// 
// Minimum:
// $tzs = new TimezoneSelector("mySelectControlName");
// $tzs->show();
//
// Show Date (default format):
// $tzs = new TimezoneSelector("tz","class=\"mycss\" onchange=\"document.getElementById('frm').submit();\"");
// $tzs->show(1);
//
// Show Date (custom format):
// $tzs = new TimezoneSelector("tz");
// $tzs->show(1,"m-d-Y H:i:s (O)");
//
// ********************************************************************
class TimezoneSelector {
  private $name;
  private $extra;
  private $error;

  public function __construct($name, $extra = "") {
    $this->error = "";
    if (!$name) {
      $this->error = "The required 'name' parameter was not given.";
    }
    $this->name = $name;
    $this->extra = $extra;
  }

  public function show($showDateTime = 0, $dateFormat = "") {
    if ($this->error) {
      print $this->error;
      return;
    }

    printf('<select %s %s>',
      $this->name ? "name=\"" . $this->name . "\"" : "",
      $this->extra);

    $timezone_identifiers = DateTimeZone::listIdentifiers();

    if ($showDateTime) {
      foreach($timezone_identifiers as $val) {
        $atz = new DateTimeZone($val);
        $aDate = new DateTime("now", $atz);
        if ($showDateTime) {
          $timeArray["$val"] = $aDate->format("U") + $atz->getOffset($aDate) . "|" . $val;
        }
        else {
          $timeArray["$val"] = $val;
        }
      }

      asort($timeArray);

      if (!$dateFormat) $dateFormat = "j M Y (g:ia)";
      foreach($timeArray as $key => $val) {
        $nTz = new DateTimeZone($key);
        $nDate = new DateTime("now", $nTz);
        printf('<option %s value="%s">%s</option>
          ', $key == $_POST["$this->name"] ? "selected=\"selected\"" : "", $key, $nDate->format($dateFormat) . " - " . str_replace("_", " ", $key));
      }
    }
    else {
      foreach($timezone_identifiers as $val) {
        printf('<option %s value="%s">%s</option>', $val == $_POST["$this->name"] ? "selected=\"selected\"" : "", $val, str_replace("_", " ", $val));
      }
    }

    print "</select>";
  }
}

?>