#!/usr/bin/perl -w
#
# $Id: musicd,v 1.2 2001/03/22 02:44:26 mdb Exp $
#
# MP3 audio server. Manages playlists of mp3 files that live on a local
# filesystem. The playlsits can be manipulated by connecting to the server
# on a port and issuing simple text commands.

use strict;
use IO::Socket;
use IO::Select;
use MPEG::MP3Play;

# this is what's currently being played
my $playing;
# this is our primary playlist
my @playlist;
# this is our current index into the playlist
my $index = -1;
# this is our handle on the MP3 player object
my $mp3;

main: {
    # create the server part of things
    my $sock = new IO::Socket::INET(LocalHost => "localhost",
                                    LocalPort => 2500,
                                    Proto => "tcp",
                                    Listen => SOMAXCONN,
                                    Reuse => 1);
    $sock or die "Unable to create server socket: $!\n";

    # create our MP3 interface
    $mp3 = new MPEG::MP3Play;

    # manage our various inputs
    my $sel = new IO::Select($sock);
    my $mph = $mp3->get_command_read_pipe();
    $sel->add($mph);

    # do our main loop thang
    my (@ready, $fh);
    while (@ready = $sel->can_read()) {
        foreach $fh (@ready) {
            if ($fh == $mph) {
                $mp3->process_messages_nowait();

            } elsif ($fh == $sock) {
                $sel->add($sock->accept());

            } else {
                # if handle_client() returns false, we remove this client from
                # the select list and close the socket
                if (!handle_client($fh)) {
                    $sel->remove($fh);
                    $fh->close();
                }
            }
        }
    }
}

# handles input from a client
sub handle_client
{
    my ($cfh) = @_;

    # see what the client has to say
    my $input = <$cfh>;

    if (defined $input) {
        # remove trailing cr/nl
        $input =~ s:[\r\n]+$::g;
    } else {
        # bail out if the socket is closed
        return 0;
    }

    # parse and process the command
    if ($input =~ m/^APPEND (.*)/) {
        # append this song to the playlist
        my $path = $1;

        # make sure the file they provided exists and is readable
        if (-r $path) {
            push @playlist, $path;
            print $cfh "200 Appended '$path' to playlist.\n";
        } else {
            print $cfh "404 Unable to read playlist candidate: '$path'\n";
        }

        # if we're not playing a song, start playing now that we have a
        # playlist with songs in it
        if (!defined $playing) {
            play_next_tune();
        }

    } elsif ($input =~ m/^CLEAR/) {
        # clear out the current playlist and reset the playing index
        @playlist = ();
        $index = -1;
        print $cfh "200 Playlist cleared.\n";

    } elsif ($input =~ m/^PLAYLIST/) {
        print $cfh "200 Playlist songs: " . @playlist . " current: " .
            (defined $playing ? $playing : "<none>") . "\n";
        my $path;
        foreach $path (@playlist) {
            print $cfh "$path\n";
        }
        return 1;

    } elsif ($input =~ m/^STOP/) {
        $mp3->stop();
        print $cfh "200 Music stopped.\n";

    } elsif ($input =~ m/^PLAY/) {
        $mp3->play();
        print $cfh "200 Music started.\n";

    } elsif ($input =~ m/^PAUSE/) {
        $mp3->pause();
        print $cfh "200 Music paused (use PLAY to unpause).\n";

    } elsif ($input =~ m/^SKIP/) {
        # stop this tune and skip to the next one
        $mp3->stop();
        play_next_tune();
        print $cfh "200 Skipped current song.\n";

    } elsif ($input =~ m/^CLOSE/) {
        print $cfh "200 Bye bye.\n";
        return 0;

    } else {
        print $cfh "500 Unknown command: '$input'\n";
    }

    return 1;
}

sub play_next_tune
{
    # bail if the playlist is empty
    if (@playlist == 0) {
        $index = -1;
        undef $playing;
        return;
    }

    # advance the playlist pointer (wrapping around at the end because we
    # always loop)
    $index = ($index + 1) % @playlist;
    $playing = $playlist[$index];

    # open it
    $mp3->open($playing);

    # and play it
    $mp3->play();
}

# message handlers
package MPEG::MP3Play;

sub msg_notify_player_state
{
    my ($mp3, $msg) = @_;
    # play the next tune if we hit the end of this one
  main::play_next_tune()
      if ($msg->{state} == &XA_PLAYER_STATE_EOF);
    return 1;
}