<?php
/*******************************************************************************
 *                ZIP Code and Distance Claculation Class
 *******************************************************************************
 *      Author:     Micah Carrick
 *      Email:      email@micahcarrick.com
 *      Website:    http://www.micahcarrick.com
 *
 *      File:       zipcode.class.php
 *      Version:    1.2.0
 *      Copyright:  (c) 2005 - Micah Carrick 
 *                  You are free to use, distribute, and modify this software 
 *                  under the terms of the GNU General Public License.  See the
 *                  included license.txt file.
 *
 *******************************************************************************
 *  VERION HISTORY:
 *      v1.2.0 [Oct 22, 2006] - Using a completely new database based on user
                                contributions which resolves many data bugs.
                              - Added sorting to get_zips_in_range()
                              - Added ability to include/exclude the base zip
                                from get_zips_in_range()
 *      v1.1.0 [Apr 30, 2005] - Added Jeff Bearer's code to make it MUCH faster!
 *      v1.0.1 [Apr 22, 2005] - Fixed a typo :)
 *      v1.0.0 [Apr 12, 2005] - Initial Version
 *
 *******************************************************************************
 *  DESCRIPTION:
 
 *    A PHP Class and MySQL table to find the distance between zip codes and 
 *    find all zip codes within a given mileage or kilometer range.
 *      
 *******************************************************************************
*/

// constants for setting the $units data member
define('_UNIT_MILES', 'm');
define('_UNIT_KILOMETERS', 'k');

// constants for passing $sort to get_zips_in_range()
define('_ZIPS_SORT_BY_DISTANCE_ASC', 1);
define('_ZIPS_SORT_BY_DISTANCE_DESC', 2);
define('_ZIPS_SORT_BY_ZIP_ASC', 3);
define('_ZIPS_SORT_BY_ZIP_DESC', 4);

// constant for miles to kilometers conversion
define('_M2KM_FACTOR', 1.609344);

class zipcode_class {

   var $last_error = "";            // last error message set by this class
   var $last_time = 0;              // last function execution time (debug info)
   var $units = _UNIT_MILES;        // miles or kilometers
   var $decimals = 2;               // decimal places for returned distance

   function get_distance($zip1, $zip2) {

      // returns the distance between to zip codes.  If there is an error, the 
      // function will return false and set the $last_error variable.
      
      $this->chronometer();         // start the clock
      if ($zip1 == $zip2) return 0; // same zip code means 0 miles between. :)
      // get details from database about each zip and exit if there is an error
      
      $details1 = $this->get_zip_point($zip1);
      $details2 = $this->get_zip_point($zip2);
      if ($details1 == false) {
         $this->last_error = "No details found for zip code: $zip1";
         return false;
      }
      if ($details2 == false) {
         $this->last_error = "No details found for zip code: $zip2";
         return false;
      }     

      // calculate the distance between the two points based on the lattitude
      // and longitude pulled out of the database.
      
      $miles = $this->calculate_mileage($details1[0], $details2[0], $details1[1], $details2[1]);
      $this->last_time = $this->chronometer();
 
      if ($this->units == _UNIT_KILOMETERS) return round($miles * _M2KM_FACTOR, $this->decimals);
      else return round($miles, $this->decimals);       // must be miles
   }   

   function get_zip_details($zip) {
      // This function pulls the details from the database for a 
      // given zip code.
 
      $sql = "SELECT lat AS lattitude, lon AS longitude, city, county, state_prefix, 
              state_name, area_code, time_zone
              FROM zip_code 
              WHERE zip_code='$zip'";
              
      $r = mysql_query($sql);
      if (!$r) {
         $this->last_error = mysql_error();
         return false;
      } else {
         $row = mysql_fetch_array($r, MYSQL_ASSOC);
         mysql_free_result($r);
         return $row;       
      }
   }

   function get_zip_point($zip) {
      // This function pulls just the lattitude and longitude from the
      // database for a given zip code.
      
      $sql = "SELECT lat, lon from zip_code WHERE zip_code='$zip'";
      $r = mysql_query($sql);
      if (!$r) {
         $this->last_error = mysql_error();
         return false;
      } else {
         $row = mysql_fetch_array($r);
         mysql_free_result($r);
         return $row;       
      }      
   }

   function calculate_mileage($lat1, $lat2, $lon1, $lon2) {
      // used internally, this function actually performs that calculation to
      // determine the mileage between 2 points defined by lattitude and
      // longitude coordinates.  This calculation is based on the code found
      // at http://www.cryptnet.net/fsp/zipdy/
       
      // Convert lattitude/longitude (degrees) to radians for calculations
      $lat1 = deg2rad($lat1);
      $lon1 = deg2rad($lon1);
      $lat2 = deg2rad($lat2);
      $lon2 = deg2rad($lon2);
      
      // Find the deltas
      $delta_lat = $lat2 - $lat1;
      $delta_lon = $lon2 - $lon1;
	
      // Find the Great Circle distance 
      $temp = pow(sin($delta_lat/2.0),2) + cos($lat1) * cos($lat2) * pow(sin($delta_lon/2.0),2);
      $distance = 3956 * 2 * atan2(sqrt($temp),sqrt(1-$temp));

      return $distance;
   }
   
   function get_zips_in_range($zip, $range, $sort=1, $include_base) {
      // returns an array of the zip codes within $range of $zip. Returns
      // an array with keys as zip codes and values as the distance from 
      // the zipcode defined in $zip.
      
      $this->chronometer();                     // start the clock
      $details = $this->get_zip_point($zip);  // base zip details
      if ($details == false) return false;
      
      // This portion of the routine  calculates the minimum and maximum lat and
      // long within a given range.  This portion of the code was written
      // by Jeff Bearer (http://www.jeffbearer.com). This significanly decreases
      // the time it takes to execute a query.  My demo took 3.2 seconds in 
      // v1.0.0 and now executes in 0.4 seconds!  Greate job Jeff!
      
      // Find Max - Min Lat / Long for Radius and zero point and query
      // only zips in that range.
      $lat_range = $range/69.172;
      $lon_range = abs($range/(cos($details[0]) * 69.172));
      $min_lat = number_format($details[0] - $lat_range, "4", ".", "");
      $max_lat = number_format($details[0] + $lat_range, "4", ".", "");
      $min_lon = number_format($details[1] - $lon_range, "4", ".", "");
      $max_lon = number_format($details[1] + $lon_range, "4", ".", "");

      $return = array();    // declared here for scope

      $sql = "SELECT zip_code, lat, lon FROM zip_code ";
      if (!$include_base) $sql .= "WHERE zip_code <> '$zip' AND ";
      else $sql .= "WHERE "; 
      $sql .= "lat BETWEEN '$min_lat' AND '$max_lat' 
               AND lon BETWEEN '$min_lon' AND '$max_lon'";
             
      $r = mysql_query($sql);
      
      if (!$r) {    // sql error
         $this->last_error = mysql_error();
         return false;
         
      } else { 
         while ($row = mysql_fetch_row($r)) {
            // loop through all 40 some thousand zip codes and determine whether
            // or not it's within the specified range.
            
            $dist = $this->calculate_mileage($details[0],$row[1],$details[1],$row[2]);
            if ($this->units == _UNIT_KILOMETERS) $dist = $dist * _M2KM_FACTOR;
            if ($dist <= $range) {
               $return[str_pad($row[0], 5, "0", STR_PAD_LEFT)] = round($dist, $this->decimals);
            }
         }
         mysql_free_result($r);
      }
      
      // sort array
      switch($sort)
      {
         case _ZIPS_SORT_BY_DISTANCE_ASC:
            asort($return);
            break;
            
         case _ZIPS_SORT_BY_DISTANCE_DESC:
            arsort($return);
            break;
            
         case _ZIPS_SORT_BY_ZIP_ASC:
            ksort($return);
            break;
            
         case _ZIPS_SORT_BY_ZIP_DESC:
            krsort($return);
            break; 
      }
      
      $this->last_time = $this->chronometer();
      
      if (empty($return)) return false;
      return $return;
   }

   function chronometer() {
   // chronometer function taken from the php manual.  This is used primarily
   // for debugging and anlyzing the functions while developing this class.  
  
   $now = microtime(TRUE);  // float, in _seconds_
   $now = $now + time();
   $malt = 1;
   $round = 7;
  
   if ($this->last_time > 0) {
       /* Stop the chronometer : return the amount of time since it was started,
       in ms with a precision of 3 decimal places, and reset the start time.
       We could factor the multiplication by 1000 (which converts seconds
       into milliseconds) to save memory, but considering that floats can
       reach e+308 but only carry 14 decimals, this is certainly more precise */
      
       $retElapsed = round($now * $malt - $this->last_time * $malt, $round);
      
       $this->last_time = $now;
      
       return $retElapsed;
   } else {
       // Start the chronometer : save the starting time
       $this->last_time = $now;
       return 0;
   }
}

}