<?php
// (C) 2000 LinuxFutures.com, Inc.
// 
// Part of UPmarkets - the software behind the LinuxFutures game site
//                     visit www.LinuxFutures.com to play
//
//  We are making the software available to you under the GNU General Public License,
//  a copy of which should accompany this software in the file LICENSE.
//
// A web-based copy of the LICENSE is located at http://www.gnu.org/copyleft/gpl.txt
//
// While there is no charge for using this software, there are important restrictions.
//
// This LICENSE does not allow, in general, proprietary modifications or proprietary derivative works.
//
// This software carries ABSOLUTELY NO WARRANTY. It is offered AS-IS, and may not work at all
//  or may have harmful or hazardous side effects.
//
// 
// -------------------- what this file does ---------------------
// profides function user_holdings_array()
// from table LEDGERS, calculates total holdings of each held symbol for a single userid 
// oddity: symbols never held will be undef, symbols held but zeroed out will be zeros.
//
// If you are using these numbers for something important, 
// you should LOCK tables ledgers or they might change on you!
// Because amounts are calculated aggregates, you can't commit the
//  classic textbook problem of 2 people updating holdings and making
//  stuff appear or disappear from/to nowhere.
// BUT, if you are calling the function more than once, or using
// the data to decide elgibility for trading, debt/equity ratios,
// or even trying to aggregate pretty functions over users, watch out. 


function user_holdings_array($userid) {

  global $db_link;

  $u = (int) $userid;  // better safe than sorry
  if($u <= 0){ echo "<br>error: f_user_holdings_array called with userid <= 0 <br>"; exit(); }

  $sql  = "SELECT sum(amount) as holdings, symbol from ledgers, symbols ";
  $sql .= " WHERE ledgers.userid = '".$u."' AND symbols.symbolid = ledgers.symbolid GROUP BY symbol ORDER BY symbols.symbolid ASC;";

  $q = mysql_query($sql, $db_link);
  mysql_error_sanity("f_user_holdings_array"); // this exits on sql errors

  $n_rows = mysql_num_rows($q);
  $holdings = array();

  for($i_row = 0; $i_row < $n_rows;   $i_row++){
	$holding = mysql_fetch_object($q);
	$holdings[$holding->symbol] = $holding->holdings;
  }
  
  mysql_free_result($q);

  return($holdings);

}