package GLPI::Agent::Task::Deploy::P2P;

use strict;
use warnings;

use English qw(-no_match_vars);
use Net::IP;
use Net::Ping;
use Parallel::ForkManager;

use UNIVERSAL::require;

use GLPI::Agent::Logger;
use GLPI::Agent::Tools;

sub new {
    my ($class, %params) = @_;

    my $self = {
        logger        => $params{logger} ||
                         GLPI::Agent::Logger->new(),
        datastore     => $params{datastore},
        max_workers   => $params{max_workers}   || 10,
        cache_timeout => $params{cache_timeout} || 1200,
        scan_timeout  => $params{scan_timeout}  || 5,
        max_peers     => $params{max_peers}     || 512,
        max_size      => $params{max_size}      || 5000,
        p2pnet        => {}
    };

    # On windows, max_workers should not be bigger than 60 due to a perl limitation
    if ($OSNAME eq 'MSWin32' && $self->{max_workers} > 60) {
        $self->{logger}->info("Limiting workers from $self->{max_workers} to 60 on MSWin32");
        $self->{max_workers} = 60;
    }

    bless $self, $class;

    return $self;
}

sub findPeers {
    my ($self, $port) = @_;

    $self->{logger}->info("looking for a peer in the network");

    if ((!$self->{p2pnet} || !$self->{p2pnet}->{peers}) && $self->{datastore}) {
        $self->{p2pnet} = $self->{datastore}->getP2PNet() || {};
    }

    # We don't want to update the peer list if some exist and none has expired
    if ($self->{p2pnet} && $self->{p2pnet}->{peerscount}) {
        my $now = time;
        if (! any { $self->{p2pnet}->{$_}->{expires} < $now } @{$self->{p2pnet}->{peers}}) {
            return grep {
                $self->{p2pnet}->{$_}->{active}
            } @{$self->{p2pnet}->{peers}};
        }
    }

    my @interfaces;

    if ($OSNAME eq 'linux') {
        GLPI::Agent::Tools::Linux->require();
        @interfaces = GLPI::Agent::Tools::Linux::getInterfacesFromIfconfig();

    } elsif ($OSNAME eq 'MSWin32') {
        GLPI::Agent::Tools::Win32->require();
        @interfaces = GLPI::Agent::Tools::Win32::getInterfaces();
    }

    if (!@interfaces) {
        $self->{logger}->info("No network interfaces found");
        return;
    }

    my @addresses;

    foreach my $interface (@interfaces) {
        #if interface has both ip and netmask setup then push the address
        next unless $interface->{IPADDRESS};
        next unless $interface->{IPMASK};
        next unless lc($interface->{STATUS}) eq 'up';

        push @addresses, {
            ip   => $interface->{IPADDRESS},
            mask => $interface->{IPMASK}
        };
    }

    if (!@addresses) {
        $self->{logger}->info("No local address found");
        return;
    }

    my @potential_peers;

    foreach my $address (@addresses) {
        push @potential_peers, $self->_getPotentialPeers($address);
    }

    if (!@potential_peers) {
        $self->{logger}->info("No neighbour address found");
        return;
    }

    my %peers;
    # Keep previously known addresses only if still in potential peers
    foreach my $peer (@potential_peers) {
        if ($self->{p2pnet}->{$peer}) {
            $peers{$peer} = $self->{p2pnet}->{$peer};
        } else {
            $peers{$peer} = {
                expires => time + $self->{cache_timeout},
                active  => 1
            };
        }
    }

    # Only keep active peers in the list
    my @peers = grep {
        $peers{$_}->{active}
    } keys(%peers);

    # Finally filter out the list from the ones not responding
    my @active_peers = $self->_scanPeers( $port, @peers);

    my %not_active = map { $_ => 0 } @peers;
    foreach my $peer (@active_peers) {
        delete $not_active{$peer};
    }
    foreach my $peer (keys(%not_active)) {
        $peers{$peer} = {
            expires => time + $self->{cache_timeout},
            active  => 0
        };
    }

    $self->{p2pnet} = \%peers;
    $self->{p2pnet}->{peers} = \@peers;
    $self->{p2pnet}->{peerscount} = @peers;

    # Save peers list and status
    $self->{datastore}->saveP2PNet($self->{p2pnet}) if ($self->{datastore});

    return @peers;
}

sub forgetPeer {
    my ($self, $peer) = @_;

    return unless $self->{p2pnet} && $self->{p2pnet}->{$peer};

    $self->{p2pnet}->{$peer} = {
        expires => time + $self->{cache_timeout},
        active  => 0
    };

    # Update active peers list
    my @peers = grep {
        $self->{p2pnet}->{$_}->{active}
    } @{$self->{p2pnet}->{peers}};
    $self->{p2pnet}->{peers} = \@peers;
    $self->{p2pnet}->{peerscount} = @peers;

    # Save peers list and status
    $self->{datastore}->saveP2PNet($self->{p2pnet}) if ($self->{datastore});
}

sub _getPotentialPeers {
    my ($self, $address, $limit) = @_;

    $limit = $self->{max_peers} unless defined $limit;

    my @ip_bytes   = split(/\./, $address->{ip});
    my @mask_bytes = split(/\./, $address->{mask});
    return if $ip_bytes[0] == 127; # Ignore 127.x.x.x addresses
    return if $ip_bytes[0] == 169; # Ignore 169.x.x.x range too

    # compute range
    my @start;
    my @end;

    foreach my $idx (0..3) {
        ## no critic (ProhibitBitwise)
        push @start, $ip_bytes[$idx] & (255 & $mask_bytes[$idx]);
        push @end,   $ip_bytes[$idx] | (255 - $mask_bytes[$idx]);
    }

    # ipEnd must not be the broadcast ip
    $end[3]--;

    my $ipStart = join('.', @start);
    my $ipEnd   = join('.', @end);
    return if $ipStart eq $ipEnd;

    # ipStart is here the network address to avoid
    my $ipNetwork = $ipStart;

    # Get ip interval before this interface ip
    my $ipIntervalBefore = Net::IP->new($ipStart.' - '.$address->{ip})
        or die Net::IP::Error();
    # Get ip interval after this interface ip
    my $ipIntervalAfter = Net::IP->new($address->{ip}.' - '.$ipEnd)
        or die Net::IP::Error();

    my $beforeCount = int($limit/2);
    my $afterCount = $beforeCount ;

    my $size = $ipIntervalBefore->size() + $ipIntervalAfter->size() - 1 ;
    if ($size > $self->{max_size}) {
        $self->{logger}->debug(
            "Range too large: $size (max $self->{max_size}) from $ipStart to $ipEnd"
        );
        return;
    }

    # Handle the case ip range is bigger than expected
    if ($ipIntervalBefore->size() + $ipIntervalAfter->size() > $limit) {
        $self->{logger}->debug(
            "Have to limit ip range between ".$ipStart." and ".$ipEnd
        );
        # Update counts in the case we are too close from a range limit
        if ( $ipIntervalBefore->size() - 1 < $beforeCount ) {
            $beforeCount = $ipIntervalBefore->size() ;
            $afterCount = $limit - $beforeCount + 1;
        } elsif ( $ipIntervalAfter->size() < $afterCount ) {
            $afterCount = $ipIntervalAfter->size();
            $beforeCount  = $limit - $afterCount + 1 ;
        }
        # Forget too far before ips
        if (defined($ipIntervalBefore) && $ipIntervalBefore->size() > $beforeCount+1) {
            $ipIntervalBefore += $ipIntervalBefore->size() - $beforeCount - 1 ;
        }
    }
    $ipStart = $ipIntervalBefore->ip();
    $beforeCount = $ipIntervalBefore->size() - 1;

    # Still skip first address if it's the network address
    if ($ipStart eq $ipNetwork) {
        ++$ipIntervalBefore;
        $beforeCount--;
        $afterCount++;
        $ipStart = $ipIntervalBefore->ip() if defined($ipIntervalBefore);
    }

    # Now add ips before
    my @peers;
    while (defined($ipIntervalBefore) && $beforeCount-->0) {
        push @peers, $ipIntervalBefore->ip() ;
        ++$ipIntervalBefore ;
    }

    # Then add ips after
    while (defined(++$ipIntervalAfter) and $afterCount-->0) {
        $ipEnd = $ipIntervalAfter->ip() ;
        push @peers, $ipEnd ;
    }

    $self->{logger}->debug("Scanning from ".$ipStart." to ".$ipEnd);

    return @peers;
}

sub _scanPeers {
    my ($self, $port, @addresses) = @_;

    $self->{logger}->debug(
        "Scanning from $addresses[0] to $addresses[-1]"
    );

    _fisher_yates_shuffle(\@addresses);

    my $ping = Net::Ping->new('tcp', $self->{scan_timeout});
    $ping->{port_num} = $port;
    $ping->service_check(1);

    my @found;

    my $manager = Parallel::ForkManager->new($self->{max_workers});
    $manager->run_on_finish(sub {
        my ($pid, $exit_code, $address) = @_;
        push @found, $address if $exit_code;
    });

    foreach my $address (@addresses) {
        $manager->start($address) and next;
        $manager->finish($ping->ping($address) ? 1 : 0);
    }

    $manager->wait_all_children();

    return @found;
}

sub _fisher_yates_shuffle {
    my $deck = shift;  # $deck is a reference to an array

    return unless @$deck; # must not be empty!

    my $i = @$deck;
    while (--$i) {
        my $j = int rand ($i+1);
        @$deck[$i,$j] = @$deck[$j,$i];
    }
}

1;
