#!/usr/bin/perl -w

#  Written and maintained by:
#  Karl Dahlke
#  eklhad@comcast.net
#  248-524-1004 (during regular business hours)
#  http://www.eklhad.net

#  Most Linux distributions include cdparanoia, for pulling songs off your cds,
#  and mpg123, for playing mp3 files.
#  My redhat distribution did not include an mp3 encoder.
#  An excellent encoder, bladeenc, is available at
#  http://www.mp3-converter.com/encoders/bladeenc.htm

#  jukebox is a program to play songs somewhat at random.
#  This can be run in the background, like a song daemon,
#  but then you'll have to kill it by hand, so to speak.
#  Or you can run it in the foreground on one of your 6 consoles.
#  If the latter, ^c skips the current song, which perhaps you don't like,
#  and moves on to the next song.
#  to see how to set up this program, check out the sample .jukerc file,
#  www.eklhad.net/linux/app/sample.jukerc

use IO::Handle;

$home = $ENV{"HOME"};
defined $home and length $home or
die '$HOME is not defined in the environment - I don\'t know how to find your .domailrc file.';
$jukerc = "$home/.jukerc";
open FH, $jukerc or
die "Cannot open config file $jukerc.";

$songdir = "";
$songext = "mp3";
#  %subdirs
$hitweight = 2;
$catweight = 2;
$player = "";

while(<FH>) {
s/^\s+//;
s/\s*#.*$//;
next if /^$/;
s/\s*$//;
if(/^([^=]+)=\s*([^=]+)/) {
my $key = $1;
my $value = $2;
$key =~ s/\s+$//;
if($key eq "songdir") {
$songdir = $value;
-d $songdir or
die "$songdir is not a directory.";
next;
}
if($key eq "hits") {
$value =~ /^\d+$/ or
die "hits value should be an integer.";
$hitweight = $value;
$catweight = $value;
next;
}
if($key eq "player") {
$player = $value;
length $player or die "missing mp3 player";
next;
}
if($key eq "songext") {
$songext = $value;
next;
}
if(length $key == 1) {
$subdirs{$key} = $value;
next;
}
die "Unrecognized keyword <$key> in config file.";
}
die "garbled line <$_> in config file.";
}
close FH;

length $songdir or
die "song directory not specified.";
%subdirs or
die "no subdirectories defined.";

$showlist = 0;
if($#ARGV == 1 && $ARGV[1] =~ /^\d+$/) {
$showlist = $ARGV[1];
pop @ARGV;
}

if($#ARGV != 0) {
print "usage:  jukebox letter[+]letter[+]letter[+]... [count]\n";
exit 1;
}

$categories = $ARGV[0];
$categories =~ s/\++/+/g;
$categories =~ s/^\+//;

@songlist = ();
@songindex = ();
$idxlevel = 0;

if($categories =~ s/^@//) {
#  categories is now the name of a group/artist
foreach my $s (glob "$songdir/*/$categories*[!-].$songext") {
next if $s =~ m,/\*/,;  # no match
next if $s =~ m,/xmas/,;  # christmas
push @songlist, $s;
push @songindex, $idxlevel;
my $increment = 1;
$increment = $hitweight if $s =~ /\+\.mp3$/;
$idxlevel += $increment;
}

} else {

for(my $i = 0; $i < length $categories; ++$i) {
my $c = substr $categories, $i, 1;
next if $c eq '+';
my $subdir = $subdirs{$c};
defined $subdir or
die "character $c is not mapped to a subdirectory in your config file.";
-d "$songdir/$subdir" or
die "$songdir/$subdir is not a directory.";
my @list = glob "$songdir/$subdir/*[!-].$songext";
next if $#list == 0 and $list[0] eq "$songdir/$subdir/*[!-].mp3";
push @songlist, @list;
}

for(my $i = 0; $i < length $categories; ++$i) {
my $c = substr $categories, $i, 1;
next if $c eq '+';
my $subdir = $subdirs{$c};
foreach my $song (@songlist) {
next unless $song =~ m,^$songdir/$subdir/[^/]*$,;
push @songindex, $idxlevel;
my $increment = 1;
$increment = $hitweight if $song =~ /\+\.mp3$/;
$increment *= $hitweight if $i < length($categories)-1 and substr($categories, $i+1, 1) eq '+';
$idxlevel += $increment;
}
}
}
push @songindex, $idxlevel;

print(($#songlist+1)." songs to choose from\n");
exit 0 if $#songlist < 0;
$memory = int $#songlist/2;

$lastsong = "";
sub randomSong()
{
my $goal;
choice: {
$goal = int rand $idxlevel;
my ($i, $l, $r);  # binary search
$l = -1, $r = $#songindex;
while($r - $l > 1) {
$i = ($l+$r+1) / 2;
if($songindex[$i] <= $goal and $songindex[$i+1] > $goal) {
redo choice if $songlist[$i] eq $lastsong and $#songlist;
return $songlist[$i]
}
if($songindex[$i] > $goal) {
$r = $i;
} else {
$l = $i;
}
}
}
die "song with index $goal not found.";
}  # randomSong

$horizon = 50;  # check against the last 50 songs
@hist = ();  # history of songs

$jukelist = "$home/.jukelist";
if(open FH, $jukelist) {
while(<FH>) {
s/\n//;
unshift @hist, $_;
}
close FH;
$#hist = $memory-1 if $#hist >= $memory;
}

sub fitness($)
{
my $song = shift;
my ($type, $artist) = $song =~ m,^(.*)/([^./-]+)[^/]*$,;
my $max = 0;
for(my $i = 0; $i <= $#hist; ++$i) {
my $song1 = $hist[$i];
return -1 if $song1 eq $song;
my $multiplier = $horizon - $i;
next if $multiplier <= 0;
my $val = 0;
my ($type1, $artist1) = $song1 =~ m,^(.*)/([^./-]+)[^/]*$,;
$val += 1 if $type eq $type1;
$val += 2 if $artist eq $artist1 and $artist ne "misc";
$val *= $multiplier;
$max = $val if $val > $max;
}
return $max;
}  # fitness

$showcount = 0;

newsong: {
my $bestfit = 10*$horizon + 1;  # big number
my $bestsong = "";
my $tries = 0;
while($tries < 4) {
my $song = randomSong();
my $fit = fitness($song);
next if $fit < 0;  # already heard this one
$bestsong = $song, $bestfit = $fit if $fit < $bestfit;
++$tries;
}
unshift @hist, $bestsong;
$lastsong = $bestsong;
$#hist = $memory-1 if $#hist >= $memory;

print "$bestsong\n";
if($showlist) {
exit if ++$showcount == $showlist;
} else {
if(open FH, ">>$jukelist") {
print FH "$bestsong\n";
close FH;
}
system "$player $bestsong";
}

redo newsong;
}  # loop selecting songs