#!/usr/bin/env perl 

# mp3buff - ram-buffered MP3 file playback
# $Id: mp3buff,v 1.10 2001/12/15 12:45:49 kw Exp $
# 
# Copyright (c) 1999, 2000, 2001 Klaus Weidner <kw@w-m-p.com>
#
# Distributable under the terms of the GNU Public License (GPL)
# NO WARRANTY OF ANY KIND!
#
# I know this script is an ugly hack. It could badly use a rewrite.
# Much tearing of hair resulted from discovering that the kernel
# doesn't support nonblocking reads from a disk file.

# How many bytes of RAM to use for buffering?
#$cachesize = 3 *1024*1024;
$cachesize = 24 *1024*1024;
#
# (Note that due to to some side effects due
# to forking and copy-on-write, the kernel will
# actually allocate twice that.)

# Max data rate to be used for reading input MP3s
# (if I/O bandwidth used is excessive, playback will skip)
#$max_rate = 150 *1024; # bytes/sec
$max_rate = 2*1024*1024; # bytes/sec

# Backend player and command line options
#$player = "madplay";
#@playeropts = qw(-Q >/dev/null 2>&1);
$player = "amp";
@playeropts = qw(-q -b 64);

use Fcntl;
use POSIX ":sys_wait_h";
use integer;
$|=1;
$^W=1;

$blksize = 4096;

$nlow     = 20000 * 9 / $blksize;
$precache = 20000 * 5 / $blksize;

$nblocks = $cachesize / $blksize;

system("killall $player 2>/dev/null");

foreach $f (@ARGV) {
	if ($f =~ /(.*\/)?(.*\.m3u)/i) {
		$dir = defined $1 ? $1 : "";
		open(I, $f) || die "$f: $!\n";
		while (<I>) {
			chomp;
			$o = $dir . $_;
			$o =~ s/\/[^\/]*\/\.\.//g;
			push @tracks, $o;
		}
		close I;
	} else {
		push @tracks, $f;
	}
}

sub basename {
	my ($n) = shift;
	$n =~ s|.*/||;
	$n;
}

$readblk = 0;
$playblk = 0;
$buffered = 0;

$partial = 0;
$all_read = 0;
$songs_read = 0;
$songs_played = 0;

$playing_new_song=1;

$nprog = 40;
$progress = "-" x $nprog;
print "[$progress] ";

$kill_request = 0;
$player_running = 0;
$child_pid = 0;
$SIG{INT} = sub { $kill_request = 1 };
$SIG{PIPE} = sub { $player_running = 0 };
# $SIG{CHLD} = sub { waitpid(-1, &WNOHANG); $child_pid = 0; };
$SIG{CHLD} = sub { wait; $child_pid = 0; };

$last_time = 0;
$is_child = 0;
$read_this_sec = 0;

$curr_block = 0;
$want_block = 0;
$input_open = 0;

while(1) {
	# get new buffer
	if (!$last_song && !defined $file) {
		$file = shift @tracks;
		$last_song = 1 unless @tracks;
		#print "reading ", basename($file), "\n";
		sysopen(I, $file, O_RDONLY) || die "sysopen $file: $!\n";
		$input_open = 1;

		$cc = basename($file);
		if ($cc =~ /\d(\d)/) {
			$cc = $1;
		} elsif ($cc =~ /(\d)/) {
			$cc = $1;
		} else {
			$cc = substr($cc, 0, 1);
		}

		push @playfiles, $file;
		$songs_read ++;
	}

	# vvv !$fill &&
	if (!$fill && $buffered < $nlow+$precache && !$child_pid
		&& !$is_child && $input_open)
	{
		$child_pid = fork();
		if ($child_pid) {
			# parent: do nothing
			# print "launch child pid=$child_pid\n";
		} else {
			$is_child = 1;
			close P;
			close STDOUT;
			open (STDOUT, ">/dev/null");
			# exit 0 unless $input_open;
			$SIG{INT} = sub { kill 'INT', getppid };
			$fpos = sysseek(I, 0, 1);
			exit 0 unless $fpos;
			close I;
			sysopen(I, $file, O_RDONLY)
				|| die "sysopen $file: $!\n";
			sysseek(I, $fpos, 0);
			$fill=1;
			$player_running = 1;
		}
	}
	if ($is_child && ($buffered >= $nblocks-1 || $all_read)) {
		exit 0;
	}
	if (!$fill && $buffered < $nlow) {
		$fill = 1;
		# print "start fill\n";
		$want_block = 0;
	} 
	if ($fill && ($buffered >= $nblocks-1 || $all_read)) {
		exit 0 if $is_child;
		$fill = 0;
		# print "stop fill\n";
		$want_block = 1;
	}

	$new_time = time;
	if ($new_time != $last_time) {
		$read_this_sec = 0;
		$last_time = $new_time;
		if (!$is_child) {
			my ($tmp) = $progress;
			substr($tmp, int((($readblk+$nblocks-$nlow)%$nblocks)*$nprog/$nblocks), 1) = "#";
			substr($tmp, int($playblk*$nprog/$nblocks),1) = ">";
			print "\r[$tmp]", $fill ? "+" : " ";
			print $child_pid ? "." : " ";
			# print "buf=$buffered fill=$fill inp=$input_open\n";
		}
	}

	if (!$is_child) {
		$rin="";
		vec ($rin, fileno(STDIN), 1) = 1;
		$nfound = select ($rin, undef, undef, 0);
		if ($nfound) {
			<STDIN>;
			$kill_request = 1;
		}
	}
	if ($kill_request && !$is_child) {
		# print "skipping...\n";
		
		$kill_request = 0;
		$kill_song = 1;

		if($songs_read == $songs_played+1) {
			close I;
			$input_open = 0;
			if ($child_pid) {
				# print "kill $child_pid\n";
				kill 9, $child_pid;
			}
		}
	}
	if ($fill && !$all_read && $read_this_sec < $max_rate) {
		# print "READ $readblk buffered=$buffered\n";
		$bytes = sysread(I, $buffers[$readblk], $blksize);
		#print "READ done $bytes !=$!\n";
		if (defined $bytes && $bytes==0 || !defined $bytes) {
			undef $file;
			$last_of_file[$readblk]++;
			$all_read = 1 if $last_song;
			$input_open = 0;
		} else {
			substr($progress, int($readblk*$nprog/$nblocks),1) = $cc;
			$readblk = ($readblk+1) % $nblocks;
			$buffered++;
			$read_this_sec += $bytes;
		}
	}

	if ($read_this_sec >= $max_rate) {
		if ($is_child) {
			sleep 1;
		} else {
			$want_block = 1;
		}
	} elsif ($fill) {
		$want_block = 0;
	}

	if ($is_child) {
		next;
	}

	if (!$player_running && !$kill_song) {
		close P;
		open(P, "|$player @playeropts -")
			|| die "can't start $player: $!\n";
		fcntl(P, F_SETFL, $want_block ? 0 : O_NONBLOCK);
		$player_running = 1;
	}
	if ($playing_new_song) {
		print basename(shift @playfiles), "\n";
		$playing_new_song=0;
	}

	next unless $buffered>1 || $all_read;
	if ($kill_song) {
		$written = length($buffers[$playblk]) - $partial;
	} else {
		if ($curr_block != $want_block) {
			fcntl(P, F_SETFL, $want_block ? 0 : O_NONBLOCK);
			$curr_block = $want_block;
		}
		$written = syswrite(P, $buffers[$playblk],
				length($buffers[$playblk])-$partial, $partial);
	}
	next unless defined $written;
	$partial += $written;
	if ($partial == length($buffers[$playblk])) {
		$playblk = ($playblk+1) % $nblocks;
		$buffered--;
		$partial = 0;
		#print "    play $playblk buffered=$buffered\n";

		if ($last_of_file[$playblk]) {
			$songs_played++;
			if ($last_song && $songs_played == $songs_read) {
				print "done\n";
				exit 0;
			}
			# restart player
			close P;
			$kill_song = 0;
			$player_running = 0;
			$playing_new_song=1;
			$last_of_file[$playblk]--;
		}
	}
}