+function credit_sales_invoice_allocate($invoice_no, $credit_no, $amount, $date)
+{
+
+ $sql = "SELECT ov_freight+ov_gst+ov_amount+ov_freight_tax as total, alloc FROM ".TB_PREF."debtor_trans
+ WHERE (`type`=".ST_SALESINVOICE." AND trans_no=".db_escape($invoice_no).")";
+ $result = db_query($sql, "can't retrieve invoice totals");
+ $invoice = db_fetch($result);
+ $free = $invoice['total'] - $invoice['alloc'];
+
+ if ($free < $amount) {
+ // if there is not enough unallocated amount - remove some payment allocations
+ $sql = "SELECT * FROM ".TB_PREF."cust_allocations
+ WHERE (trans_type_to=".ST_SALESINVOICE." AND trans_no_to=".db_escape($invoice_no).")
+ AND trans_type_from <> ".ST_CUSTCREDIT;
+ $result = db_query($sql, "can't retrieve invoice allocations");
+
+ while(($free < $amount) && ($alloc = db_fetch($result))) {
+ $unalloc = min($alloc['amt'], $amount-$free);
+ update_debtor_trans_allocation($alloc['trans_type_to'], $alloc['trans_no_to'],
+ -$unalloc);
+ update_debtor_trans_allocation($alloc['trans_type_from'], $alloc['trans_no_from'],
+ -$unalloc);
+
+ delete_cust_allocation($alloc['id']);
+ if ($unalloc < $alloc['amt'])
+ add_cust_allocation($alloc['amt']-$unalloc, $alloc['trans_type_from'],
+ $alloc['trans_no_from'], ST_SALESINVOICE, $invoice_no);
+
+ $free += $unalloc;
+ }
+ }
+ if ($free < $amount) {
+ // this should never happen unless sparse credit notices were allocated to
+ // the invoice, or summarized freight costs on credit notes is more than those on invoice.
+ display_error(_("Unsuspected overallocation happened due to sparse credit notes exists for this invoice.
+ Check all credit notes allocated to this invoice for summarized freight charges."));
+ return false;
+ }
+ update_debtor_trans_allocation(ST_SALESINVOICE, $invoice_no, $amount);
+ update_debtor_trans_allocation(ST_CUSTCREDIT, $credit_no, $amount);
+ add_cust_allocation($amount, ST_CUSTCREDIT, $credit_no, ST_SALESINVOICE, $invoice_no);
+
+ exchange_variation(ST_CUSTCREDIT, $credit_no, ST_SALESINVOICE, $invoice_no, $date,
+ $amount, PT_CUSTOMER);
+ return true;
+}