#
# Copyright (c) 2013-2014 by Nils Görs <weechatter@arcor.de>
# Copyright (c) 2013-2014 by Stefan Wold <ratler@stderr.eu>
# based on irssi script stalker.pl from Kaitlyn Parkhurst (SymKat) <symkat@symkat.com>
# https://github.com/symkat/Stalker
#
# Records and correlates nick!user@host information
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# History:
# version 1.4:nils_2@freenode.#weechat
# 2014-05-14: fix: perl error under some circumstances (thanks Piotrek)
#
# version 1.3:nils_2@freenode.#weechat
# 2014-04-28: fix: output when loading script twice
#
# version 1.2:nils_2@freenode.#weechat
# 2014-04-13: add: support of customise irc_join messages (weechat >= 0.4.4)
#
# version 1.1:nils_2@freenode.#weechat
# 2013-10-31: add: flood-protection on JOINs
#
# version 1.0:nils_2@freenode.#weechat
# 2013-10-28: add: option 'additional_join_info' (idea by: arch_bcn)
#             add: option 'timeout' time to wait for result of hook_process()
#             add: localvar 'drop_additional_join_info'
#             add: hook_process() to prevent blocking weechat on slower machines (like rpi)
#             add: more DEBUG informations
#
# version 0.9: Ratler@freenode.#weechat
# 2013-08-11: fix: removed trailing whitespaces
#             fix: only add index if it doesn't exist
#             fix: dynamically create or upgrade database based on missing tables or columns
#             fix: allow dynamically creating indices for future tables
#
# version 0.8: Ratler@freenode.#weechat
# 2013-08-09: add: case insensitive nick search
#             add: show "server.nickname" in search results when search_this_network_only is set to off
#             fix: type no longer needed for _ignore_guests()
#
# version 0.7: nils_2@freenode.#weechat
# 2013-08-04: add: support of colors with format "${color:xxx}" (>= WeeChat 0.4.2)
#             add: function "remove_nick_from_host" (patch by FiXato)
#
# version 0.6: nils_2@freenode.#weechat
# 2013-05-27: cleanup code
#
# version 0.5: nils_2@freenode.#weechat
# 2013-05-26: add: function 'count'
#
# version 0.4: nils_2@freenode.#weechat
# 2013-05-18: add: option 'tags'
#
# version 0.3: nils_2@freenode.#weechat
# 2013-05-05: fix: typos in help and description option (thanks FiXato)
#             add: 'ChanServ' to option 'guest_nick_regex'
#
# version 0.2: nils_2@freenode.#weechat
# 2013-05-01: fix: bug with regular expressions using /whois
#             removed: option 'allow_regex_for_search'
#             add: command option '-regex'
#
# version 0.1: nils_2@freenode.#weechat
# 2013-04-23: - initial release -
#
# thanks to firebird and mave_ for testing...
#
# Development is currently hosted at
# https://github.com/weechat/scripts
#
# Requires:
#   DBI
#   DBD::SQLite
#
# How to install DBI:
# with cpan       : install DBI
# with deb-package: sudo apt-get install libdbi-perl
#
# How to install DBD::SQLite:
# with cpan       : install DBD::SQLite
# with deb-package: sudo apt-get install libdbd-sqlite3-perl libdbd-sqlite3 sqlite3-pcre

#use strict;
use warnings;
use File::Spec;
use DBI;

my $SCRIPT_NAME         = "stalker";
my $SCRIPT_VERSION      = "1.4";
my $SCRIPT_AUTHOR       = "Nils Görs <weechatter\@arcor.de>";
my $SCRIPT_LICENCE      = "GPL3";
my $SCRIPT_DESC         = "Records and correlates nick!user\@host information";


# internal values
my $weechat_version = "";
my $ptr_hook_timer = "";
my $flood_counter = 0;   # counter to take care of JOINs, e.g. after netsplit

# default values
my %options = ('db_name'                => '%h/nicks.db',
               'debug'                  => 'off',
               'max_recursion'          => '20',
               'recursive_search'       => 'on',
               'ignore_guest_hosts'     => 'off',
               'ignore_guest_nicks'     => 'on',
               'guest_nick_regex'       => '^(guest|weebot|Floodbot|ChanServ).*',
               'guest_host_regex'       => '^webchat',
               'normalize_nicks'        => 'on',
               'search_this_network_only' => 'on',
               'use_localvar'           => 'off',
               'ignore_nickchange'      => 'off',
               'ignore_whois'           => 'off',
               'tags'                   => '',
               'additional_join_info'   => 'off',
               'timeout'                => '1',
               'flood_timer'            => '10',
               'flood_max_nicks'        => '20',
#               '' => '',
);
my %desc_options = ('db_name'           => 'file containing the SQLite database where information is recorded. This database is created on loading of ' . $SCRIPT_NAME . ' if it does not exist. ("%h" will be replaced by WeeChat home, "~/.weechat" by default) (default: %h/nicks.db)',
                    'debug'             => 'Prints debug output to core buffer so you know exactly what is going on. This is far too verbose to be enabled when not actively debugging something. (default: off)',
                    'max_recursion'     => 'For each correlation between nick <-> host that happens, one point of recursion happens. A corrupt database, general evilness, or misfortune can cause the recursion to skyrocket. This is a ceiling number that says if after this many correlation attempts we have not found all nickname and hostname correlations, stop the process and return the list to this point. Use this option with care on slower machines like raspberry pi.',
                    'recursive_search'  => 'When enabled, recursive search causes stalker to function better than a simple hostname to nickname map. Disabling the recursive search in effect turns stalker into a more standard hostname -> nickname map.',
                    'ignore_guest_hosts'=> 'See option guest_host_regex',
                    'guest_host_regex' => 'regex mask to ignore host masks',
                    'ignore_guest_nicks'=> 'See option guest_nick_regex',
                    'guest_nick_regex'  => 'Some networks set default nicknames when a user fails to identify to nickserv, other networks using relay-bots, some irc clients set default nicknames when someone connects and often these change from network to network depending on who is configuring the java irc clients. This allows a regular expression to be entered. When a nickname matches the regular expression and "ignore_guest_nicks" is enabled the nickname is dropped from the search as if it had never been seen. (default: ^(guest|weebot|Floodbot).*)',
                    'normalize_nicks' => 'this option will truncate special chars from username (like: ~) (default: on)',
                    'search_this_network_only' => 'When enabled searches are limited to within the network the window is currently set on. Turning this off is really only useful if multiple networks don\'t encode the hostmask. (default: on)',
                    'use_localvar'      => 'When enabled, only channels with a localvar \'stalker\' will be monitored. This option will not affect /NICK and /WHOIS monitoring. It\'s only for /JOIN messages. (default: off)',
                    'ignore_nickchange' => 'When enabled, /NICK changes won\'t be monitored. (default: off)',
                    'ignore_whois'      => 'When enabled, /WHOIS won\'t be monitored. (default: off)',
                    'tags'              => 'comma separated list of tags used for messages printed by stalker. See documentation for possible tags (e.g. \'no_log\', \'no_highlight\'). This option does not effect DEBUG messages.',
                    'additional_join_info' => 'add a line below the JOIN message that will display alternative nicks (tags: "irc_join", "irc_smart_filter" will be add to additional_join_info). You can use a localvar to drop additional join info for specific buffer(s) "stalker_drop_additional_join_info" (default: off)',
                    'timeout'           => 'timeout in seconds for hook_process(), used with option "additional_join_info". On slower machines, like raspberry pi, increase time. (default: 1)',
                    'flood_timer'       => 'Time in seconds for which flood protection is active. Once max_nicks is reached, joins will be ignored for the remaining duration of the timer. (default:10)',
                    'flood_max_nicks'   => 'Maximum number of joins to allow in flood_timer length of time. Once maximum number of joins is reached, joins will be ignored until the timer ends (default:20)',
);

my $count;
my %data;
my $str;
my $DBH;
my $DBH_child;
my $DBH_fork;
my $last_nick = "";
my $last_host = "";

# SQLite table definition
my %tables = (
    'records' => [
        { 'column' => 'nick', 'type' => 'TEXT NOT NULL' },
        { 'column' => 'user', 'type' => 'TEXT NOT NULL' },
        { 'column' => 'host', 'type' => 'TEXT NOT NULL' },
        { 'column' => 'serv', 'type' => 'TEXT NOT NULL' },
        { 'column' => 'added', 'type' => 'DATE NOT NULL DEFAULT CURRENT_TIMESTAMP' },
      ],
  );

# SQLite index definitions
my %indices = (
    'records' => [
        { 'name' => 'index1', 'column' => 'nick' },
        { 'name' => 'index2', 'column' => 'host' },
      ],
  );

# ---------------[ external routines for hook_process() ]---------------------
if ($#ARGV == 8 ) # (0-8) nine arguments given?
{
    my $db_filename = $ARGV[0];
    my ($db_user, $db_pass);
    $DBH_fork = DBI->connect(
        'dbi:SQLite:dbname='.$db_filename, $db_user, $db_pass,
        {
            RaiseError => 1,
#           AutoCommit => 1,
            sqlite_use_immediate_transaction => 1,
        }
    );

    exit if (not defined $DBH_fork);

    if ($ARGV[1] eq 'additional_join_info')
    {
        my $nick = $ARGV[2];
        my $user = $ARGV[3];
        my $host = $ARGV[4];
        my $serv = $ARGV[5];
        my $max_recursion = $ARGV[6];
        my $ignore_guest_nicks = $ARGV[7];
        my $guest_nick_regex = $ARGV[8];

        my $nicks_found = join( ", ", (get_nick_records_fork($nick, $serv, $max_recursion, $ignore_guest_nicks, $guest_nick_regex)));

        print "$nicks_found";
        $DBH_fork->disconnect();
        exit;
    }
    elsif ($ARGV[1] eq 'db_add_record')
    {
        my $nick = $ARGV[2];
        my $user = $ARGV[3];
        my $host = $ARGV[4];
        my $serv = $ARGV[5];

#        DEBUG("info", "Adding to DB: nick = $nick, user = $user, host = $host, serv = $serv" );

        # We don't have the record, add it. Test for record is done in add_record()
        $sth = $DBH_fork->prepare("INSERT INTO records (nick,user,host,serv) VALUES( ?, ?, ?, ? )" );
        eval { $sth->execute( $nick, $user, $host, $serv ) };
        $DBH_fork->disconnect();
        if ($@)
        {
            print "error Failed to process record, database said: $@";
            exit;
        }
        print "info Added record for $nick!$user\@$host to $serv";
    }
exit;
}

my $count2;
my %data_fork;
sub get_nick_records_fork
{
    my ( $nick, $serv, $max_recursion, $ignore_guest_nicks, $guest_nick_regex ) = @_;
    my $type = 'nick';
    my @return;
    $count2 = 0; %data_fork = (  );
    @return = _r_search_fork( $serv, $type, $max_recursion, $ignore_guest_nicks, $guest_nick_regex, ({ $type => $nick }) );

    # remove original nick
    @return = grep {$_ ne $nick} @return;
    # case-insensitive sort
    return sort {uc($a) cmp uc($b)} @return;
}

my @nicks_found;
sub _r_search_fork
{
    my ( $serv, $type, $max_recursion, $ignore_guest_nicks, $guest_nick_regex, @input ) = @_;
    return @nicks_found = &del_double(@nicks_found) if $count2 > $max_recursion;

    if ( $type eq 'nick' )
    {
        $count2++;
        for my $row ( @input )
        {
            my $nick = $row->{nick};
            next if exists $data_fork{$nick};

            $data_fork{$nick} = 'nick';
            my @hosts = _get_hosts_from_nick_fork( $nick, $serv, $ignore_guest_nicks, $guest_nick_regex );
            _r_search_fork ( $serv, 'host', $max_recursion, $ignore_guest_nicks, $guest_nick_regex, @hosts );
        }
    }
    elsif ( $type eq 'host' )
    {
        $count2++;
        for my $row ( @input )
        {
            my $host = $row->{host};
            next if exists $data_fork{$host};
            $data_fork{$host} = 'host';

            my @nicks = _get_nicks_from_host_fork ( $host, $serv, $ignore_guest_nicks, $guest_nick_regex );
            next if (scalar(@nicks) <= 0);
            push @nicks_found, map {  $_->{nick} } @nicks;
            # search only current network
#            $output_nicks = join( ", ", map { $_->{nick} } @nicks );

            # use regex only for host search!
            _r_search_fork( $serv, 'nick', $max_recursion, $ignore_guest_nicks, $guest_nick_regex, @nicks );
        }
    }
    return @nicks_found = &del_double(@nicks_found);
#    return %data_fork;
}

sub _get_hosts_from_nick_fork
{
    my ( $nick, $serv, $ignore_guest_nicks, $guest_nick_regex, @return ) = @_;

    my $sth = $DBH_fork->prepare( "SELECT nick, host FROM records WHERE nick = ? COLLATE NOCASE AND serv = ?" );
    $sth->execute( $nick, $serv );

    return _ignore_guests_fork( $sth, $ignore_guest_nicks, $guest_nick_regex );
}

sub _get_nicks_from_host_fork
{
    my ( $host, $serv, $ignore_guest_nicks, $guest_nick_regex, @return ) = @_;
    my $sth = $DBH_fork->prepare( "SELECT nick, host FROM records WHERE host = ? AND serv = ?" );
    $sth->execute( $host, $serv );

    return _ignore_guests_fork( $sth,$ignore_guest_nicks, $guest_nick_regex );
}

sub del_double
{
    my %all=();
    @all{@_}=1;
    return (keys %all);
}

sub _ignore_guests_fork
{
    my ( $sth, $ignore_guest_nicks, $guest_nick_regex ) = @_;
    my @return;

    while ( my $row = $sth->fetchrow_hashref )
    {
        if ( lc($ignore_guest_nicks) eq "on" )
        {
            my $regex = $guest_nick_regex;
            next if( $row->{nick} =~ m/$regex/i );
        }
        push @return, $row;
    }
    return @return;
}

# -----------------------------[ Database ]-----------------------------------
sub open_database
{
    my $db = weechat_dir();

    stat_database( $db );
    my ($db_user, $db_pass);
    # my $db_host = '127.0.0.1';
    # my $db_port = 3306;

    $DBH = DBI->connect(
        'dbi:SQLite:dbname='.$db, $db_user, $db_pass,
        {
            RaiseError => 1,
#            AutoCommit => 1,
            sqlite_use_immediate_transaction => 1,
        }
    );

    # DBI::SQLite and fork() don't mix. Do it anyhow but keep the parent and child DBH separate?
    # Ideally the child should open its own connection.
    $DBH_child = DBI->connect(
        'dbi:SQLite:dbname='.$db, $db_user, $db_pass,
        {
            RaiseError => 1,
#            AutoCommit => 1,
            sqlite_use_immediate_transaction => 1,
        }
    );

    # async data
    my @records_to_add; # Queue of records to add
}

# Automatic Database Creation And Checking
sub stat_database {
    my ( $db_file ) = @_;

    DEBUG('info', 'Stat database');
    if ( ! -e $db_file  ) {
        open my $fh, '>', $db_file
            or die 'Cannot create database file.  Abort.';
        close $fh;
    }
    my $DBH = DBI->connect(
        'dbi:SQLite:dbname='.$db_file, "", "",
        {
            RaiseError => 1,
#            AutoCommit => 1,
            sqlite_use_immediate_transaction => 1,
        }
    );

    create_or_upgrade_database( $DBH );

    index_db( $DBH );
}

sub create_or_upgrade_database {
    my ( $DBH ) = @_;

    # This part will always add missing tables or columns defined in @tables (ie create or upgrade the database)
    DEBUG("info", "Checking database table structure");
    my %col_exists;
    for my $table (keys %tables) {
        for my $col ( @{ $DBH->selectall_arrayref ( "PRAGMA TABLE_INFO($table)" ) } ) {
            $col_exists{$table}{$col->[1]} = 1;
        }
    }
    for my $table (keys %tables) {
        my $upgrade = 0;

        # Create missing tables
        unless ( exists( $col_exists{$table} ) ) {
            create_table( $DBH, $table );
            next;
        }

        # Check for missing columns
        my @cols_not_null;
        for my $col ( @{$tables{$table}} ) {
            unless ( $col_exists{$table}{$col->{column}} ) {
                if ( ($col->{type} =~ /NOT NULL/) and ($col->{type} !~ /DEFAULT/) ) {
                    push @cols_not_null, $col->{column};
                }
                $upgrade = 1;
            }
        }

        # Due to limitations in ALTER TABLE in sqlite this cumbersome method is necessary to alter a table
        if ( $upgrade ) {
            DEBUG("info", "Upgrade required for table '$table', please wait...");
            # Save the old records
            $DBH->do( "ALTER TABLE $table RENAME TO old_$table" );

            # Preserve old column names for copying of data later
            my $old_columns = join( ", ", map { $_->[1] } @{ $DBH->selectall_arrayref( "PRAGMA TABLE_INFO(old_$table)" ) } );

            # Create the new table
            create_table( $DBH, $table );

            # Special care for NOT NULL columns, we set value 1 for all missing columns defined with NOT NULL or the copy will fail
            my $old_select;
            if ( scalar(@cols_not_null) > 0 ) {
                $old_select = $old_columns . ", " . join(", ", map { 1 } @cols_not_null );
                $old_columns .= ", " . join(", ", @cols_not_null);
            } else {
                $old_select = $old_columns;
            }

            # Copy the old records over and drop them
            my @queries = (
                "INSERT INTO $table ($old_columns) SELECT $old_select FROM old_$table",
                "DROP TABLE old_$table",
              );
            for my $query (@queries) {
                my $sth = $DBH->prepare($query) or die "Failed to prepare '$query'. " . $sth->err;
                $sth->execute() or die "Failed to execute '$query'. " . $sth->err;
            }
            DEBUG( "info", "Table '$table' has been successfully upgraded" ) unless ( $DBH->err );
        }
    }
}

# Create table
sub create_table {
    my ( $DBH, $table_name ) = @_;

    my @queries;

    DEBUG("info", "Creating table '$table_name'");
    push @queries, "DROP TABLE IF EXISTS $table_name";
    push @queries, "CREATE TABLE $table_name (" . join(", ", map { "$_->{column} $_->{type}" } @{ $tables{$table_name} }) . ")";

    for my $query (@queries) {
        my $sth = $DBH->prepare($query) or die "Failed to prepare '$query'. " . $sth->err;
        $sth->execute() or die "Failed to execute '$query'. " . $sth->err;
    }
}

# Add indices to the DB.
sub index_db {
    my ( $DBH ) = @_;

    for my $table (keys %indices) {
        my %idx_exists;
        for my $index ( @{ $DBH->selectall_arrayref( "PRAGMA INDEX_LIST($table)" ) } ) {
            $idx_exists{$index->[1]} = 1;
        }

        $DBH->{RaiseError} = 0;
        $DBH->{PrintError} = 0;
        for my $index ( @{$indices{$table}} ) {
            $DBH->do( "CREATE INDEX $index->{name} ON $table ($index->{column})" ) unless ( $idx_exists{$index->{name}} );
        }
        $DBH->{RaiseError} = 1;
        $DBH->{PrintError} = 1;
    }
}

sub normalize
{
    my ( @nicks ) = @_;
    my ( %nicks, %ret ) = map { $_, 1 } @nicks;

    for my $nick ( @nicks )
    {
        (my $base = $nick ) =~ s/[\Q-_~^`\E]//g;
        $ret{ exists $nicks{$base} ? $base : $nick }++;
    }
    return keys %ret;
}

sub add_record
{
    my ( $nick, $user, $host, $serv ) = @_;
    return unless ($nick and $user and $host and $serv);

    # Check if we already have this record, before using a hook_process()
    my $sth = $DBH_child->prepare( "SELECT nick FROM records WHERE nick = ? AND user = ? AND host = ? AND serv = ?" );
    $sth->execute( $nick, $user, $host, $serv );
    my $result = $sth->fetchrow_hashref;

    if ( defined $result->{nick} )
    {
        if ( $result->{nick} eq $nick ) {
            DEBUG( "info", "Record for $nick skipped - already exists." );
            return weechat::WEECHAT_RC_OK;
        }
    }

    my $filename = get_script_filename();
    return weechat::WEECHAT_RC_OK if ($filename eq "");

    my $db_filename = weechat_dir();
    DEBUG("info", "Start hook_process(), to add $nick $user\@$host on $serv to database");
    weechat::hook_process("perl $filename $db_filename 'db_add_record' '$nick' '$user' '$host' '$serv' 'dummy' 'dummy' 'dummy'", 1000 * $options{'timeout'},"db_add_record_cb","");
}

# function called when data from child is available, or when child has ended, arguments and return value
sub db_add_record_cb
{
    my ( $data, $command, $return_code, $out, $err ) = @_;
    return weechat::WEECHAT_RC_OK if ( $return_code > 0 or $out eq "");                              # something wrong!

    my ($DEBUG_prefix,$message) = split(/ /,$out,2);
    DEBUG($DEBUG_prefix, $message);
    return weechat::WEECHAT_RC_OK;
}

sub get_host_records {
    # suppress output? yes|no
    # type = host|nick, $query = name, $serv = server, @return = "."
    my ( $suppress, $type, $query, $serv, @return ) = @_;

    $count = 0; %data = (  );
    my %data = _r_search( $suppress, $serv, $type, $query );
    for my $k ( keys %data ) {
        DEBUG( "info", "$type query for records on $query from server $serv returned: $k" );
        push @return, $k if $data{$k} eq 'host';
    }

    # case-insensitive sort
    return sort {uc($a) cmp uc($b)} @return;
}

sub get_nick_records
{
    # type = host|nick, $query = nick, $serv = server, use_regex = 0|1, @return = "."
    my ( $suppress, $type, $query, $serv, $use_regex, @return ) = @_;

    $count = 0; %data = (  );
    my %data = _r_search( $suppress, $serv, $type, $use_regex, ({ $type => $query }) );
    for my $k ( keys %data ) {
        DEBUG( "info", "$type query for database records on $query from server $serv. returned: $k" );
        push @return, $k if $data{$k} eq 'nick';
    }

    if (lc($options{'normalize_nicks'}) eq "on" ) {
        @return = normalize(@return);
    }

    # remove original nick
    @return = grep {$_ ne $query} @return;

    # case-insensitive sort
    return sort {uc($a) cmp uc($b)} @return;
}

sub _r_search
{
    my ( $suppress, $serv, $type, $use_regex, @input ) = @_;

    return %data if $count > 1000;
    return %data if $count > $options{'max_recursion'};
    return %data if $count == 2 and ! $options{'recursive_search'};

    DEBUG( "info", "Recursion Level: $count" );

    if ( $type eq 'nick' )
    {
        $count++;
        for my $row ( @input )
        {
            my $nick = $row->{nick};
            next if exists $data{$nick};

            $data{$nick} = 'nick';
            my @hosts = _get_hosts_from_nick( $nick, $serv, $use_regex );
            # use regex only for nick search!
            $use_regex = 0 if ( $use_regex );
            _r_search( $suppress, $serv, 'host', $use_regex, @hosts );
        }
    } elsif ( $type eq 'host' )
    {
        $count++;
        for my $row ( @input )
        {
            my $host = $row->{host};
            next if exists $data{$host};
            $data{$host} = 'host';
            my @nicks = _get_nicks_from_host( $host, $serv, $use_regex );
            next if (scalar(@nicks) <= 0);

            my $output_nicks;
            if ( lc($options{'search_this_network_only'}) eq "on" )
            {
                $output_nicks = join( ", ", map { $_->{nick} } @nicks );
            }
            else {
                $output_nicks = join( ", ", map { $_->{serv} . "." . $_->{nick} } @nicks );
            }

            if ($suppress eq 'no')
            {
                my $ptr_buffer = weechat::current_buffer();

                my $output = weechat::color('chat_prefix_network').
                            weechat::prefix('network').
                            weechat::color('chat_delimiters').
                            "[".
                            weechat::color('chat_nick').
                            $SCRIPT_NAME.
                            weechat::color('chat_delimiters').
                            "] ".
                            weechat::color('reset').
                            "Found nicks: $output_nicks".
                            " from host $host";

                OUTPUT($ptr_buffer,$output);
            }

            # use regex only for host search!
            $use_regex = 0 if ( $use_regex );
            _r_search( $suppress, $serv, 'nick', $use_regex, @nicks );
        }
    }
    return %data;
}

sub _get_hosts_from_nick {
    my ( $nick, $serv, $use_regex, @return ) = @_;

    my $sth;

    if ( lc($options{'search_this_network_only'}) eq "on" )
    {
        if ( $use_regex )
        {
            $sth = $DBH->prepare( "SELECT nick, host FROM records WHERE nick REGEXP ? AND serv = ?" );
            $sth->execute( $nick, $serv );
        }
        else
        {
            $sth = $DBH->prepare( "SELECT nick, host FROM records WHERE nick = ? COLLATE NOCASE AND serv = ?" );
            $sth->execute( $nick, $serv );
        }
    }
    else
    {
        if ( $use_regex )
        {
            $sth = $DBH->prepare( "SELECT nick, host, serv FROM records WHERE nick REGEXP ?");
        }
        else
        {
            $sth = $DBH->prepare( "SELECT nick, host, serv FROM records WHERE nick = ? COLLATE NOCASE" );
        }
        $sth->execute( $nick );
    }
    # nothing found in database
#    return '' if (not defined $sth->fetchrow_hashref);
    return _ignore_guests( $sth );
}

sub _get_nicks_from_host {
    my ( $host, $serv, $use_regex, @return ) = @_;

    my $sth;
    if ( lc($options{'search_this_network_only'}) eq "on" )
    {
        if ( $use_regex )
        {
            $sth = $DBH->prepare( "SELECT nick, host FROM records WHERE host REGEXP ? AND serv = ?" );
#            $sth->execute( $host, $serv );
        }
        else
        {
            $sth = $DBH->prepare( "SELECT nick, host FROM records WHERE host = ? AND serv = ?" );
        }
        $sth->execute( $host, $serv );
    }
    else
    {
        if ( $use_regex )
        {
            $sth = $DBH->prepare( "SELECT nick, host, serv FROM records WHERE host REGEXP ?" );
        }
        else
        {
            $sth = $DBH->prepare( "SELECT nick, host, serv FROM records WHERE host = ?" );
        }
        $sth->execute( $host );
    }
    # nothing found in database
#    return '' if (not defined $sth->fetchrow_hashref);
    return _ignore_guests( $sth );
}

sub _ignore_guests
{
    my ( $sth ) = @_;
    my @return;

    while ( my $row = $sth->fetchrow_hashref )
    {
        if ( lc($options{'ignore_guest_nicks'}) eq "on" )
        {
            my $regex = $options{'guest_nick_regex'};
            next if( $row->{nick} =~ m/$regex/i );
        }
        if ( lc($options{'ignore_guest_hosts'}) eq "on" )
        {
            my $regex = $options{'guest_host_regex'};
            next if( $row->{host} =~ m/$regex/i );
        }
        push @return, $row;
    }
    return @return;
}

sub _deassociate_nick_from_host
{
    my ( $nick, $host, $serv, $use_regex, @return ) = @_;

    my $sth;
    if ( lc($options{'search_this_network_only'}) eq "on" )
    {
        if ( $use_regex )
        {
            $sth = $DBH->prepare( "DELETE FROM records WHERE host REGEXP ? AND nick REGEXP ? AND serv = ?" );
        }
        else
        {
            $sth = $DBH->prepare( "DELETE FROM records WHERE host = ? AND nick = ? AND serv = ?" );
        }
        $sth->execute( $host, $nick, $serv );
    }
    else
    {
        if ( $use_regex )
        {
            $sth = $DBH->prepare( "DELETE FROM records WHERE host REGEXP ? AND nick REGEXP ?" );
        }
        else
        {
            $sth = $DBH->prepare( "DELETE FROM records WHERE host = ? AND nick = ?" );
        }
        $sth->execute( $host, $nick );
    }
    return $sth->rows;
}

# ------------------------[ OUTPUT with tags ]------------------------------
sub OUTPUT
{
    my ($ptr_buffer,$output) = @_;

    if ( $options{'tags'} ne '' )
    {
        weechat::print_date_tags($ptr_buffer,0,$options{'tags'},$output);
    }
    else
    {
        weechat::print($ptr_buffer,$output);
    }
}
# -----------------------------[ debug ]-----------------------------------
sub DEBUG
{
    my $DEBUG_prefix;
    my $color;

    return if (lc($options{debug}) eq 'off');

    if ( $_[0] eq 'info')
    {
        $DEBUG_prefix = 'info';
        $color = "default";
    }
    elsif ( $_[0] eq 'error')
    {
        $DEBUG_prefix = weechat::config_string(weechat::config_get("weechat.look.prefix_error"));
        $color  = weechat::color(weechat::config_color(weechat::config_get("weechat.color.chat_prefix_error")));
    }
    else
    {
        $DEBUG_prefix = '***';
        $color = 'default';
    }
        weechat::print('', _color_str($color, $DEBUG_prefix) . "\t$SCRIPT_NAME: $_[1]");
}

sub _color_str
{
    my ($color_name, $string) = @_;
    # use eval for colors-codes (${color:red} eg in weechat.look.prefix_error)
    $string = weechat::string_eval_expression($string, {}, {},{}) if ($weechat_version >= 0x00040200);
    weechat::color($color_name) . $string  . weechat::color('reset');
}
# -------------------------------[ subroutines ]-------------------------------------
sub weechat_dir
{
    my $dir = $options{'db_name'};
    if ( $dir =~ /%h/ )
    {
        my $weechat_dir = weechat::info_get( 'weechat_dir', '');
        $dir =~ s/%h/$weechat_dir/;
    }
    return $dir;
}
# -------------------------------[ main ]-------------------------------------
sub stalker_command_cb
{
    my ($data, $buffer, $args) = ($_[0], $_[1], $_[2]);
    my @args_array=split(/ /,$args);
    my $number = @args_array;

    return weechat::WEECHAT_RC_OK if ($number <= 0);

    if (lc($args_array[0]) eq 'count')
    {
#        my $ptr_buffer = weechat::current_buffer();
        my ($count) = $DBH->selectrow_array("SELECT count(*) FROM records");
        my $output = weechat::color('chat_prefix_network').
                     weechat::prefix('network').
                     weechat::color('chat_delimiters').
                     "[".
                     weechat::color('chat_nick').
                     $SCRIPT_NAME.
                     weechat::color('chat_delimiters').
                     "] ".
                     weechat::color('reset').
                     "number of rows: ".
                     $count;

        OUTPUT($buffer,$output);
        return weechat::WEECHAT_RC_OK;
    }
    # get localvar from current buffer
    my $name = weechat::buffer_get_string($buffer,'localvar_name');
    my $server = weechat::buffer_get_string($buffer,'localvar_server');
    my $type = weechat::buffer_get_string($buffer,'localvar_type');

    if ( weechat::buffer_get_string($buffer,'plugin') ne 'irc' and lc($args_array[0]) eq 'scan' )
    {
        command_must_be_executed_on_irc_buffer();
        return weechat::WEECHAT_RC_OK;
    }

    if (lc($args_array[0]) eq 'scan' && $type eq 'channel' && $number == 1)
    {
        channel_scan($buffer);
#        channel_scan_41(weechat::current_buffer());
        return weechat::WEECHAT_RC_OK;
    }

    # at least, we have two arguments
    return weechat::WEECHAT_RC_OK if ($number <= 1);

    my $use_regex = 0;

    if (lc($args_array[0]) eq 'scan' && $args_array[1] ne "")
    {
        $args_array[1] =~ s/\./,/;                      # info_get() needs an "," instead of "."
        my $ptr_buffer = weechat::info_get('irc_buffer',$args_array[1]);
#        channel_scan_41($ptr_buffer) if ( $ptr_buffer ne "");
        channel_scan($ptr_buffer) if ( $ptr_buffer ne "");
    }
    elsif (lc($args_array[0]) eq 'nick' or lc($args_array[0]) eq 'host')
    {
        if ( defined $args_array[2] and $args_array[2] eq "-regex" )
        {
            $use_regex = 1;
        }
        else
        {
            $server = $args_array[2] if ( defined $args_array[2] and $args_array[2] ne "" );
        }

        if ( defined $args_array[3] and $args_array[3] eq "-regex" )
        {
            $use_regex = 1;
        }

        if ( $server eq "" )
        {
            command_must_be_executed_on_irc_buffer();
            return weechat::WEECHAT_RC_OK;
        }
        # $args_array[0]: 'nick' or 'host', $args_array[1]: nick or host name
        # list will be print in subroutine!
        my $nicks_found = join( ", ", (get_nick_records('no', $args_array[0], $args_array[1], $server, $use_regex)));
    }
    elsif (lc($args_array[0]) eq 'remove_nick_from_host')
    {
      $use_regex = 1 if ( grep{ $args_array[$_] eq '-regex' }0..$#args_array );

      my $server = weechat::buffer_get_string($buffer,'localvar_server');

      if ( $server eq "" )
      {
          command_must_be_executed_on_irc_buffer();
          return weechat::WEECHAT_RC_OK;
      }
      my $affected_rows = _deassociate_nick_from_host( $args_array[1], $args_array[2], $server, $use_regex );
      my $color  = weechat::color(weechat::config_color(weechat::config_get('weechat.color.chat_prefix_error')));
      my $DEBUG_prefix = weechat::config_string(weechat::config_get('weechat.look.prefix_error'));
      weechat::print($buffer, _color_str($color, $DEBUG_prefix) . "\t$SCRIPT_NAME: $affected_rows deleted");
    }
    return weechat::WEECHAT_RC_OK;
}

sub command_must_be_executed_on_irc_buffer
{
    my $text = 'command must be executed on irc buffer (server or channel) or a server must be given';
    my $color  = weechat::color(weechat::config_color(weechat::config_get('weechat.color.chat_prefix_error')));
    my $DEBUG_prefix = weechat::config_string(weechat::config_get('weechat.look.prefix_error'));
    weechat::print('', _color_str($color, $DEBUG_prefix) . "\t$SCRIPT_NAME: $text");
}
# hdata_search()
# hdata: hdata pointer
# pointer: pointer to a WeeChat/plugin object
# search: expression to evaluate, default pointer in expression is the name of hdata (and this pointer changes for each element in list); for help on expression, see command /eval in WeeChat User’s guide
# move: number of jump(s) to execute after unsuccessful search (negative or positive integer, different from 0)

sub channel_scan_41
{
    my $ptr_buffer = $_[0];

    my $server_name = weechat::buffer_get_string($ptr_buffer, "localvar_server");
    my $channel_name = weechat::buffer_get_string($ptr_buffer, "localvar_channel");
    return if ($server_name eq "" or $channel_name eq "");

#my %hdata = { map { $_ => weechat::hdata_get( "irc_" . $_ ) } qw( server channel nick ) };
    my $hdata_server = weechat::hdata_get("irc_server");
    my $hdata_channel = weechat::hdata_get("irc_channel");
    my $hdata_nick = weechat::hdata_get("irc_nick");

    my $ptr_server = weechat::hdata_search($hdata_server, weechat::hdata_get_list($hdata_server, 'irc_servers'), '${irc_server.name} == ' . $server_name, 1);
    if ($ptr_server)
    {
        my $ptr_channel = weechat::hdata_search($hdata_channel, weechat::hdata_pointer($hdata_server, $ptr_server, 'channels'), '${irc_channel.name} == ' . $channel_name, 1);

        if ($ptr_channel)
        {
            my $nick = weechat::hdata_pointer($hdata_channel, $ptr_channel, 'nicks');
            while ( $nick )
            {
                my $nick_name = weechat::hdata_string($hdata_nick, $nick, 'name');
                my $host_name = weechat::hdata_string($hdata_nick, $nick, 'host');
                $host_name =~ /(.*)\@/;
                my $user_name = $1;

                add_record( $nick_name, $user_name, $host_name, $server_name);

                $nick = weechat::hdata_move($hdata_nick, $nick, 1);
            }
        }

    }
#    weechat::print("",$ptr_buffer);
#    weechat::print("",$server_name);

#    if ($ptr_servers)
#    {
#        my $channel = weechat::hdata_search(hdata['channel'], weechat.hdata_pointer(hdata['server'], server, 'channels'), '${irc_channel.name} == #test', 1)
#    }
}
sub channel_scan
{
    my $ptr_buffer = $_[0];
    my $infolist = weechat::infolist_get('nicklist', $ptr_buffer, '');
    # don't stalk yourself
    my $my_nick = weechat::buffer_get_string($ptr_buffer,'localvar_nick');

    my $nick_counter;

    while (weechat::infolist_next($infolist))
    {
        my $nick = weechat::infolist_string($infolist, 'name');
        if ((weechat::infolist_string($infolist, 'type') eq 'nick')
            && ($nick ne $my_nick))
        {
            my $ptr_nick = weechat::nicklist_search_nick($ptr_buffer, '', $nick);
            my $localvar_server = weechat::buffer_get_string($ptr_buffer,'localvar_server');
            my $localvar_channel = weechat::buffer_get_string($ptr_buffer,'localvar_channel');

            my $infolist_nick = weechat::infolist_get('irc_nick','',$localvar_server.','.$localvar_channel.','.$nick);
            weechat::infolist_next($infolist_nick);
            my $host = weechat::infolist_string($infolist_nick,'host');
            weechat::infolist_free($infolist_nick);

            next unless ($nick or $host or $localvar_server);
            $host =~ /(.*)\@/;
            $user = $1;

            add_record( $nick, $user, $host, $localvar_server);

#            $user=~ s/[\Q-_~^`\E]//g;
#            my $hdata = weechat::hdata_get("irc_nick");
#            my $hdata_host = weechat::hdata_string($hdata, $ptr_nick, "host");
#            next if ($host eq $name);

        }
    }
    weechat::infolist_free($infolist);
}

# simple check for last nick/host
# to prevent multiple requests (e.g. "/nick|join nick" for several channels!)
# 0 = failed
# 1 = found
sub check_last_nick_host
{
    my ($nick,$host) = @_;
    my $rc = 0;

    $rc = 1 if ($nick eq $last_nick && $host eq $last_host);

    $last_nick = $nick;
    $last_host = $host;
    return $rc;
}
# -------------------------------[ hooks ]-------------------------------------
# :old_nick!~user@host NICK :new_nick
# /NICK command called
# this is a server command
sub irc_in2_nick_cb
{
    my ($signal, $callback, $callback_data) = @_;
    my ($server,undef) = split(',',$callback);

    return weechat::WEECHAT_RC_OK if ( lc($options{'ignore_nickchange'}) eq "on" );

    DEBUG('info', 'weechat_hook_signal(): NICK change');

    my $hashtable = weechat::info_get_hashtable("irc_message_parse" => + { "message" => $callback_data });

    # $old_nick = $hashtable->{nick}
    my ($old_nick, $host) = split('!', $hashtable->{host});
    my $nick = $hashtable->{arguments};
    $nick =~ s/^.//;                            # remove leading ":"
    my ($user,undef) = split("@",$host);

    return weechat::WEECHAT_RC_OK if check_last_nick_host($nick,$host);

    add_record( $nick, $user, $host, $server);

    return weechat::WEECHAT_RC_OK;
}

sub irc_in2_whois_cb
{
    my ($signal, $callback, $callback_data) = @_;
    my ($server,undef) = split(',',$callback);

    my $ptr_buffer = '';

    my (undef, undef, undef, $nick, $user, $host, undef) = split(' ', $callback_data);
    my $msgbuffer_whois = weechat::config_string(weechat::config_get('irc.msgbuffer.whois'));


    DEBUG('info', 'weechat_hook_signal(): WHOIS');

    # check for nick_regex
    if ( lc($options{'ignore_guest_nicks'}) eq "on" )
    {
        my $regex = $options{'guest_nick_regex'};
        return weechat::WEECHAT_RC_OK if( $nick =~ m/$regex/i );
    }

    my $complete_host = $user."@".$host;

    unless ( check_last_nick_host($nick,$complete_host) or lc($options{'ignore_whois'}) eq "on" )
    {
        add_record( $nick, $user, $complete_host, $server);
    }

    # output for /whois
    if ($msgbuffer_whois eq 'server')
    {
        $ptr_buffer = weechat::info_get('irc_buffer',$server);
#        $ptr_buffer = weechat::buffer_search('irc', 'server.' . $server);
    }
    elsif ($msgbuffer_whois eq 'weechat')
    {
        $ptr_buffer = weechat::buffer_search_main();
    }
    elsif  ($msgbuffer_whois eq 'current')
    {
        $ptr_buffer = weechat::current_buffer();
    }
    elsif ($msgbuffer_whois eq 'private')
    {
        $ptr_buffer = weechat::info_get('irc_buffer',$server.','.$nick);
        if ($ptr_buffer eq '')
        {
            $msgbuffer_whois = weechat::config_string(weechat::config_get('irc.look.msgbuffer_fallback'));
            $ptr_buffer = weechat::info_get('irc_buffer', $server) if ($msgbuffer_whois eq 'server');
        }
    }

    my $use_regex = 0;
    my $nicks_found = join( ", ", (get_nick_records('yes', 'nick', $nick, $server, $use_regex)));
#    my $nicks_found = join( ", ", (get_nick_records('no', 'nick', $nick, $server, $use_regex)));

    # only the given nick is returned?
    return weechat::WEECHAT_RC_OK if ($nicks_found eq $nick or $nicks_found eq "");

    # more than one nick was returned from sqlite
    my $prefix_network = weechat::prefix('network');
    my $color_chat_delimiter = weechat::color('chat_delimiters');
    my $color_chat_nick = weechat::color('chat_nick');

    my $output = weechat::color('chat_prefix_network').
                  weechat::prefix('network').
                  weechat::color('chat_delimiters').
                  "[".
                  weechat::color('chat_nick').
                  $SCRIPT_NAME.
                  weechat::color('chat_delimiters').
                  "] ".
                  $nicks_found;

    # fallback buffer..
    $ptr_buffer = weechat::buffer_search_main() unless ($ptr_buffer);

    # print /WHOIS with [stalker] line
    OUTPUT($ptr_buffer,$output);

    return weechat::WEECHAT_RC_OK;
}

sub irc_in2_join_cb
{
    my ($data, $buffer, $date, $tags, $displayed, $highlight, $prefix, $message) = @_;

    my ($nick,$user,$host);
    # get nick, user and host.
    if ($weechat_version >= 0x00040400)
    {
        # use tags to avoid problems with customised JOIN messages (v0.4.4)
        $nick = ($tags =~ m/(^|,)nick_([^,]*)/) ? $2 : "";
        ($user,$host) = ($tags =~ m/(^|,)host_(.*)\@([^,]*)/) ? ($2,$3) : ("","");
    }
    else
    {
        # message:   :nick!~user_2@host JOIN #channel
        ($nick,$user,$host) = ($message =~ /(.*) \((.*)\@(.*)\)/);
    }

    return weechat::WEECHAT_RC_OK if (not defined $nick or $nick eq ""
                                      or not defined $user or $user eq ""
                                      or not defined $host or $host eq "");

    my $my_nick = weechat::buffer_get_string($buffer,'localvar_nick');
    my $server = weechat::buffer_get_string($buffer,'localvar_server');
    my $name = weechat::buffer_get_string($buffer,'localvar_name');

    # don't stalk yourself
    return weechat::WEECHAT_RC_OK if ($nick eq $my_nick);

    return weechat::WEECHAT_RC_OK if check_last_nick_host($nick,$host);

    DEBUG('info', 'weechat_hook_signal(): JOIN');

    # check for localvar "stalker"
    if ( lc($options{'use_localvar'}) eq "on" )
    {
        return weechat::WEECHAT_RC_OK if (not weechat::config_string_to_boolean(weechat::buffer_get_string($buffer, 'localvar_stalker')) );
    }

    # check if "flood_timer" is activated
    if ( $options{'flood_timer'} > 0 )
    {
        # reset ptr_hook_timer and flood_counter if hook_timer() does not exists anymore
        if ( $ptr_hook_timer ne "" and search_hook('hook',$ptr_hook_timer) eq 0 )
        {
            $ptr_hook_timer = "";
            $flood_counter = 0;
        }
        # timer still running, add counter
        else
        {
            $flood_counter++;
        }

        if ($ptr_hook_timer eq "")
        {
            # call timer only once
            $ptr_hook_timer = weechat::hook_timer($options{'flood_timer'} * 1000, 0, 1, 'my_hook_timer_cb', '');
        }

        if ( $ptr_hook_timer ne "" and $flood_counter > $options{'flood_max_nicks'} )
        {
            DEBUG("info", "flood protection activated for: $nick with $user\@$host on $server");
            return weechat::WEECHAT_RC_OK;
        }
    }
    # end of flood protection

    add_record( $nick, $user, $host, $server);

    return weechat::WEECHAT_RC_OK if (weechat::config_string_to_boolean(weechat::buffer_get_string($buffer, 'localvar_stalker_drop_additional_join_info')) );

    if ( lc($options{'additional_join_info'}) eq "on" )
    {
        my $filename = get_script_filename();
        return weechat::WEECHAT_RC_OK if ($filename eq "");

        # get tags for stalker output
        my $my_tags = $options{'tags'};
        # add tag 'irc_smart_filter' or 'irc_join' to list of tags, if tag(s) exists in original JOIN message
        $my_tags = $my_tags . ',irc_smart_filter' if (index($tags,'irc_smart_filter') >= 0);
        $my_tags = $my_tags . ',irc_join' if (index($tags,'irc_join') >= 0);

        my $db_filename = weechat_dir();
        DEBUG("info", "Start hook_process(), get additional info from $nick with $user\@$host on $name");
        weechat::hook_process("perl $filename $db_filename 'additional_join_info' '$nick' '$user' '$host' '$server' $options{'max_recursion'} $options{'ignore_guest_nicks'} '$options{'guest_nick_regex'}'", 1000 * $options{'timeout'},"hook_process_get_nicks_records_cb","$nick $buffer $my_tags");
      }
    return weechat::WEECHAT_RC_OK;
}

# get absolute path of script
sub get_script_filename
{
    my $infolist_ptr = weechat::infolist_get("perl_script","",$SCRIPT_NAME);
    weechat::infolist_next($infolist_ptr);
    my $filename = weechat::infolist_string($infolist_ptr,"filename");
    weechat::infolist_free($infolist_ptr);
    return $filename;
}

sub hook_process_get_nicks_records_cb
{
    my ($data, $command, $return_code, $out, $err) = @_;
    DEBUG("info", "hook_process_get_nicks_records_cb: data=$data command=$command, rc=$return_code out=$out err=$err");

    return weechat::WEECHAT_RC_OK if ( $return_code > 0 or $out eq "");                              # something wrong!

    my ($nick,$buffer_ptr,$tags) = split(/ /,$data);
    my $nicks_found = $out;
    # don't print output if there is no other nick used
    return weechat::WEECHAT_RC_OK if ($nick eq $nicks_found or $nicks_found eq '');

    my $string = weechat::color('chat_prefix_network').
                weechat::prefix('network').
                weechat::color('chat_delimiters').
                "[".
                weechat::color('chat_nick').
                $SCRIPT_NAME.
                weechat::color('chat_delimiters').
                "] ".
                weechat::color('reset').
                $nick.
                " is also known as: ".
                $nicks_found;

    weechat::print_date_tags($buffer_ptr,0,$tags,$string);
    return weechat::WEECHAT_RC_OK;
}

sub search_hook
{
    my ($hook, $ptr_hook) = @_;
    my $hook_found = 0;
    my $infolist = weechat::infolist_get($hook, $ptr_hook, '');
    while ( weechat::infolist_next($infolist) )
    {
        $hook_found = 1 if ( weechat::infolist_pointer($infolist,'pointer') eq $ptr_hook );
    }
    weechat::infolist_free($infolist);

    return $hook_found;
}

sub my_hook_timer_cb
{
    # simply add the flood_counter
    $flood_counter++;
    return weechat::WEECHAT_RC_OK;
}

# -----------------------------[ config ]-----------------------------------
sub init_config
{

    foreach my $option (keys %options){
        if (!weechat::config_is_set_plugin($option)){
            weechat::config_set_plugin($option, $options{$option});
        }
        else{
            $options{$option} = weechat::config_get_plugin($option);
        }
    }
  # set help text for options
  if ( ($weechat_version ne '') && (weechat::info_get('version_number', '') >= 0x00030500) ) {    # v0.3.5
    foreach my $desc_options (keys %desc_options)
    {
      weechat::config_set_desc_plugin($desc_options,$desc_options{$desc_options});
    }
  }

}

sub toggle_config_by_set
{
    my ($pointer, $name, $value) = @_;
    $name = substr($name, length("plugins.var.perl.$SCRIPT_NAME."), length($name));
    $options{$name} = $value;
# insert a refresh here
    return weechat::WEECHAT_RC_OK;
}
# -----------------------------[ shutdown ]-----------------------------------
sub shutdown_cb
{
    # close database
    $DBH->disconnect() if ($DBH);
    $DBH_child->disconnect() if ($DBH_child);
    return weechat::WEECHAT_RC_OK;
}

# -------------------------------[ init ]-------------------------------------
# first function called by a WeeChat-script.
weechat::register($SCRIPT_NAME, $SCRIPT_AUTHOR, $SCRIPT_VERSION,
                  $SCRIPT_LICENCE, $SCRIPT_DESC, 'shutdown_cb', '')  || return;

    $weechat_version = weechat::info_get('version_number', '');

    if ( ($weechat_version ne '') && (weechat::info_get('version_number', '') <= 0x00030400) )
    {
        OUTPUT('',weechat::prefix('error') . 'You need WeeChat >= 0.3.4. Visit: www.weechat.org');
        weechat::command('',"/wait 1ms /perl unload $SCRIPT_NAME");
    }
    else
    {
        init_config();
        open_database();

        weechat::hook_command($SCRIPT_NAME, $SCRIPT_DESC, "host <host> [server] [-regex] || nick <nick> [server] [-regex] || scan [<server.channel>] || count",
                      "                host : look for hostname\n".
                      "                nick : look for nick\n".
                      "                scan : scan a channel (be careful; scanning large channels takes a while!)\n".
                      "                       you should manually /WHO #channel first or use /quote PROTOCTL UHNAMES\n".
                      "                count: display the number of rows in database\n".
                      "remove_nick_from_host: remove a nick from a given host\n".
                      "\n\n".
                      "Stalker will add nick!user\@host to database monitoring JOIN/WHOIS/NICK messages.\n\n".
                      "\n".
                      "Monitor specific channels:\n".
                      "==========================\n".
                      "Set following option:\n".
                      "    /set plugins.var.perl.".$SCRIPT_NAME.".use_localvar \"on\"  (default: off)\n".
                      "Now you'll have to set a localvar for those channels to monitor:\n".
                      "    /buffer set localvar_set_stalker [value]\n".
                      "       values: \"on\", \"true\", \"t\", \"yes\", \"y\", \"1\")\n".
                      "\n".
                      "Display additional information below join message:\n".
                      "=================================================\n".
                      "Example: [stalker] nils_2 is also known as: nils_2_\n".
                      "    /set plugins.var.perl.".$SCRIPT_NAME.".additional_join_info \"on\"  (default: off)\n".
                      "If you want to drop informations for specific channels (especially channels with lot of nicks):\n".
                      "    /buffer set localvar_set_stalker_drop_additional_join_info [value]\n".
                      "       values: \"on\", \"true\", \"t\", \"yes\", \"y\", \"1\")\n".
                      "\n".
                      "Regex:\n".
                      "======\n".
                      "$SCRIPT_NAME performs standard perl regular expression matching with option '-regex'.\n".
                      "Note that regex matching will not use SQLite indices, but will iterate over all rows, so it could be quite costly in terms of performance.\n".
                      "\n".
                      "Tags:\n".
                      "======\n".
                      $SCRIPT_NAME." can use tags to display messages. See documentation for most commonly used tags and add them in following option:\n".
                      "    /set plugins.var.perl.".$SCRIPT_NAME.".tags \"no_log\"\n".
                      "\n".
                      "Examples:\n".
                      "  search for nick 'nils_2'\n".
                      "    /".$SCRIPT_NAME." nick nils_2\n".
                      "  search for nick 'nils_2' on a different server named 'unknown'\n".
                      "    /".$SCRIPT_NAME." nick nils_2 unknown\n".
                      "  search for nicks starting with 'ni'\n".
                      "    /".$SCRIPT_NAME." nick \\bni.* -regex\n".
                      "  search all hosts located in '.de'\n".
                      "    /".$SCRIPT_NAME." host .*\\.de -regex\n".
                      "  remove nick from an association host'\n".
                      "    /".$SCRIPT_NAME." remove_nick_from_host TheNick ~the\@bad.users.host\n".
                      "",
                      "count %-||".
                      "host %% %(irc_servers)|-regex %-||".
                      "nick %(nick) %(irc_servers)|-regex -regex %-||".
                      "remove_nick_from_host %(nick) |-regex -regex %-||".
                      "scan %(buffers_names) %-", "stalker_command_cb", "");

        weechat::hook_config("plugins.var.perl.$SCRIPT_NAME.*", "toggle_config_by_set", "");
#        weechat::hook_signal('*,irc_in2_join', 'irc_in2_join_cb', '');
        weechat::hook_print('','irc_join','',1,'irc_in2_join_cb','');
        weechat::hook_signal('*,irc_in2_311', 'irc_in2_whois_cb', '');
        weechat::hook_signal('*,irc_in2_NICK', 'irc_in2_nick_cb', '');
    }