#!/usr/bin/env perl
use warnings;
use strict;
use English;
use POSIX;

sub debug(@) {
	print join ' ', POSIX::strftime('%F %T', localtime), @_, "\n";
}

sub sid_is_attached($) {
	my ($intf) = @_;
	my $re = eval {
		my $hex = qr/[a-fA-F0-9]{2}/;
		my $mac = qr/$hex : $hex : $hex : $hex : $hex : $hex/x;
		return qr/Access Point: $mac/;
	};
	grep { /$re/ and return 1 } `iwconfig $intf`;
	return 0;
}

sub sid_get_sid($) {
	my ($intf) = @_;
	my $re = eval {
		my $sid = qr/[^"]+/;
		return qr/ESSID:"($sid)"/;
	};
	grep { /$re/ and return $1 } `iwconfig $intf`;
	die 'race condition';
}

sub sid_is_available($$) {
	my ($sid, $intf) = @_;
	my $re = eval {
		my $sid = qr/[^"]+/;
		return qr/ESSID:"($sid)"/;
	};
	grep { /$re/ and return 1 } `iwlist $intf scan`;
	return 0;
}

sub sid_connect($$) {
	my ($sid,$intf) = @_;
	my $cmd = "iwconfig $intf essid $sid";
	system $cmd;
}

sub dhcp_is_running($) {
	my ($intf) = @_;
	grep { /dhcpcd $intf/ and return 1 } `ps ax`;
	return 0;
}
sub car(@) { return shift }
sub dhcp_kill($) {
	my ($intf) = @_;
	debug "having to kill -9 dhcpcd";
	map { system "echo kill -9 $_" } map { car split } grep { /dhcpcd $intf/ } `ps ax`;
}
sub dhcp_start($) {
	my ($intf) = @_;
	system "dhcpcd $intf";
}
sub dhcp_stop($) {
	my ($intf) = @_;
	my $ret = system "dhcpcd --exit $intf";
	$ret == 0 and return 1;
	dhcp_is_running $intf and dhcp_kill $intf;
	dhcp_is_running $intf and return 0;
	return 1;
}
sub dhcp_has_default_route($) {
	my ($intf) = @_;
	return grep { /^0\.0\.0\.0.*$intf/ and return 1 } ` route -n `;
	debug "no default route";
	return 0;
}

sub test_wifi($$) {
	my ($sid, $intf) = @_;
	return sid_is_attached $intf;
}
sub fix_wifi($$) {
	my ($sid, $intf) = @_;
	sid_is_available($sid, $intf) or do { sleep 1; return};
	sid_connect $sid, $intf;
}
sub test_ip($$) {
	my ($sid, $intf) = @_;
	return dhcp_is_running $intf and dhcp_has_default_route $intf;
}
sub fix_ip($$) {
	my ($sid, $intf) = @_;
	dhcp_stop $intf;
	dhcp_start $intf;
}
sub test_if($$) {
	my ($sid, $intf) = @_;
	grep { /UP/ and return 1 } `ifconfig $intf `;
	return 0;
}
sub fix_if($$) {
	my ($sid, $intf) = @_;
	system("ifconfig $intf up");
}


$EUID == 0 or die "got root?";
my ($intf) = @ARGV;
my ($sid) = `cat $ENV{HOME}/.wifi`;
$intf ne "" or die "got interface?";
dhcp_stop $intf or die "you have unkillable dhcp running?";

close STDOUT;
open STDOUT, '>' . $ENV{HOME} . '/var/wifi-minder.log';
close STDERR;
open STDERR, ">&STDOUT";
debug "forking into background";
fork and exit;
fork and exit;
POSIX::setsid();

=head1
we have the following states:
	no wifi
	wifi
	no ip network
	ip network

for each state, we have a test and an action to fix the state
=cut

my @states = (
	{ 'test' => 'test_if',   'fix' => 'fix_if'   },
	{ 'test' => 'test_wifi', 'fix' => 'fix_wifi' },
	{ 'test' => 'test_ip',   'fix' => 'fix_ip'   },
);


while (1) {
	for my $state (@states) {
		no strict qw(refs);
		$state->{'test'}($sid, $intf) and next;
	   	$state->{'fix'}($sid, $intf);
		$state->{'test'}($sid, $intf) or last;
	}
	debug "everything ok, sleeping...";
	sleep 10;
}