#!/usr/bin/perl

use strict;
use warnings;
use CGI qw( :standard center);
use Fcntl qw( :flock );
use XML::Parser;

unless ( param ) {
    print login_form();
    exit;
}

$::flag = 0;
open USERS, '../../xml_final/users/users.xml' or die "Could not open users.xml: $!";
flock(USERS, LOCK_SH);
    my $parser = new XML::Parser();
    $parser->setHandlers(
        Start => \&start_handler,
        Char  => \&char_handler);

    my $document = $parser->parse(\*USERS);
close USERS;

sub login_form {
    return
        header,
        start_html(
            -title => 'Login',
            -style => {
                -src => "../../xml_final/db.css"}),
            center(
                h1('Please login'),
                start_form,
                        'username:', textfield( -name => 'username'),
                        'password:', password_field( -name => 'password'),
                        submit('send'),
                        reset,
                end_form,
                a({ -href => 'newuser.pl'}, 'New User?') ),
        end_html;
}

sub start_handler {
    my $element = $_[1];
    $::flag = 1 if $::flag == 0 && $element eq 'username';
    $::flag = 2 if $::flag == 1 && $element eq 'password';
}

sub char_handler {
    return unless $::flag;

    warn '$::flag must be 0, 1, or 2 only' if $::flag > 2 or $::flag < 0;

    return unless $::flag == 2;

    my $text = $_[1];
    if ( $text eq param('password') ) {
        print redirect('http://www.domain.com/cgi-bin/xml_final/viewdb.pl?username=' . param('username'));
    } else {
        print
            header,
            start_html(
                -title => 'Not so much correct with that login',
                -style => {
                    -src => '../..//xml_final/db.css'}),

                h1('Incorrect password'),
                p({-align => 'center'},
                    a({-href => 'login.pl'}, 'Try Agian?') ),
            end_html;
    }
    exit;
}