# Selima Website Content Management System
# NewSN.pm: The new S/N generator.

#  Copyright (c) 2003-2018 imacat.
#
#  Licensed under the Apache License, Version 2.0 (the "License");
#  you may not use this file except in compliance with the License.
#  You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.

# Author: imacat <imacat@mail.imacat.idv.tw>
# First written: 2003-04-03

package Selima::NewSN;
use 5.008;
use strict;
use warnings;
use base qw(Exporter);
use vars qw(@EXPORT @EXPORT_OK);
BEGIN {
@EXPORT = qw(newsn newsn_hash newsn_xmltab);
@EXPORT_OK = @EXPORT;
# Prototype declaration
sub newsn($);
sub newsn_hash(%);
sub newsn_xmltab($);
}

use Selima::DataVars qw($DBH);

use constant SN_LEN => 9;

# The relevent variables
use vars qw($MIN $MAX $INT);
$MIN = 10 ** (SN_LEN - 1);     # 100000000
$MAX = (10 ** SN_LEN) - 1;     # 999999999
$INT = $MAX - $MIN + 1;

# newsn: Generate a new random serial number for a database table
sub newsn($) {
    local ($_, %_);
    my ($table, $sth, $sql);
    $table = $_[0];
    
    do {
        # Generate a random serial number
        $_ = $MIN + int rand $INT;
        # Check if this serial number exists
        $sql = "SELECT sn FROM $table WHERE sn=$_;\n";
        $sth = $DBH->prepare($sql);
        $sth->execute;
    } until $sth->rows == 0;
    
    return $_;
}

# newsn_hash: Generate a new random serial number
sub newsn_hash(%) {
    local ($_, %_);
    my %SN = @_;
    
    do {
        # Generate a random serial number
        $_ = $MIN + int rand $INT;
    } until !exists $SN{$_};
    
    return $_;
}

# newsn_xmltab: Generate a new random serial number
sub newsn_xmltab($) {
    local ($_, %_);
    my $SN = $_[0];
    
    do {
        # Generate a random serial number
        $_ = $MIN + int rand $INT;
    } until !exists ${$SN}{$_};
    
    ${$SN}{$_} = (keys %{$SN});
    
    return $_;
}

return 1;