package App::Beam::Command;

use strict;
use Carp;

require Exporter;
our @ISA = qw(Exporter);
our @EXPORT_OK = qw(CHAN_STDOUT CHAN_STDERR);
our %EXPORT_TAGS = (
    channels => [ qw(CHAN_STDOUT CHAN_STDERR) ]
);

use IPC::Open3;
use Symbol 'gensym';
use POSIX qw(:sys_wait_h);

sub new {
    my $class = shift;
    return bless { argv => \@_ }, $class;
}

sub add {
    my $self = shift;
    push @{$self->{argv}}, @_;
}

use constant {
    CHAN_STDOUT => 0,
    CHAN_STDERR => 1
};

sub start_log {
    my ($self, $chan, $rfd) = @_;

    if (exists($self->{log}) && defined($self->{log}[$chan])) {
	local $^F = fileno($rfd);
	my $pid = fork();
	if ($pid == 0) {
	    local $_ = $rfd;
	    &{$self->{log}[CHAN_STDERR]};
	    exit(0);
	} else {
	    push @{$self->{pids}}, $pid;
	    return undef;
	}
    }
    return $rfd;
}

sub run {
    my $self = shift;
    my $out = gensym;
    my $err = gensym;

    return $self->{status} if exists($self->{status});

    eval {
	push @{$self->{pids}},
	     open3(\*STDIN, $out, $err, @{$self->{argv}});
	$out = $self->start_log(CHAN_STDOUT, $out);
	$err = $self->start_log(CHAN_STDERR, $err);
	do {
	    my $pid = waitpid(-1, 0);
	    if ($pid > 0) {
		@{$self->{pids}} = grep { $pid != $_ } @{$self->{pids}};
	    }
	} while ($#{$self->{pids}} >= 0);
    };
    if ($@) {
	$self->{status} = $@;
    } else {
	$self->{status} = $?;
	local $/ = undef;
	$self->{channel}[CHAN_STDOUT] = defined($out) ? <$out> : undef;
	$self->{channel}[CHAN_STDERR] = defined($err) ? <$err> : undef;
    }
    return $self->{status};
}

sub set_logger {
    my ($self, $chan, $fun) = @_;
    $self->{log}[$chan] = $fun;
}

sub restart {
    my $self = shift;

    delete $self->{status};
    delete $self->{channel};
    delete $self->{pids};
    return $self->run;
}

sub status {
    my $self = shift;
    return undef unless exists $self->{status};
    return $self->{status};
}

sub channel {
    my ($self, $chan) = @_;
    return undef
	unless (exists($self->{channel}) && defined($self->{channel}[$chan]));
    open(my $fd, '<', \$self->{channel}[$chan]) or croak "can't dup: $!"; 
    return $fd;
}

sub argv {
    my ($self) = @_;
    return @{$self->{argv}};
}

sub command_line {
    my ($self) = @_;
    return join(' ', $self->argv);
}

sub command_name {
    my ($self) = @_;
    return $self->{argv}[0];
}

sub exit_code {
    my ($self) = @_;
    my $code = $self->status;
    return -1 if (!defined($code) || $code == -1 || ($code & 127));
    return $code >> 8;
}

1;