#!/usr/bin/perl
#
# Name:    friendly_links.pl
# Version: 1.1
# Date:    2002/11/04
# Author:  Greg Zwart
# Purpose: Queries the DEC database for all ripped tracks and creates
#          "friendly" symbolic links to the "unfriendly" tracks.  This
#          does not manipulate the DEC database in any way.
#
# Disclaimer: This script is relatively non-intrusive, but has not been
# thoroughly tested with all DEC configurations.  Use at your own risk.
#
# Revision History: at end of file
#

BEGIN {
	@INC = (@INC,
		"/opt/odin/perl5/lib/site_perl/i386-linux",
		"/opt/odin/perl5/lib/site_perl");
}

use DBI;
use File::Find;
use Getopt::Std;

# Configuration variables
$db = "/content/db";
$links = "/content/exported-music/mappings";
$music = "/content/music";
$playlist = "_playlist.m3u";

# Get command line options
getopts('vtdh') or exit usage();
exit usage() if $opt_h==1;

# Verify proper configuration
abort("Invalid music directory!") if !-d $music;
abort("Invalid mapping directory!") if !-d $links;
abort("Invalid database directory!") if !-d $db;

# Skip the link creation, if the delete-only option is specified
goto DELETIONS if $opt_d==1;

# Query the database
$dbh = DBI->connect("DBI:XBase:$db") or abort("Unable to connect to database");
$sth_track = $dbh->prepare("SELECT album_id, artist_id, genre_id, title, file FROM LibraryTrack ORDER BY cd_trk_num");
$sth_album = $dbh->prepare("SELECT name FROM Album WHERE id = ?");
$sth_artist = $dbh->prepare("SELECT name FROM Artist WHERE id = ?");
$sth_genre = $dbh->prepare("SELECT genre FROM Genre WHERE id = ?");

# Query the tracks from the database and bind the columns to variables
$sth_track->execute or abort("Unable to execute SQL statement");
$sth_track->bind_columns(undef, \($album_id, $artist_id, $genre_id, $title, $file));

# Loop through all of the tracks
while( $sth_track->fetch() ) {
	# Get the track info
	$sth_album->execute($album_id); $sth_album->bind_columns(undef,\$album); $sth_album->fetch();
	$sth_artist->execute($artist_id); $sth_artist->bind_columns(undef,\$artist); $sth_artist->fetch();
	$sth_genre->execute($genre_id); $sth_genre->bind_columns(undef,\$genre); $sth_genre->fetch();

	# Format the content
	$artist =~ s/\.//g;
	$album  =~ s/\.//g;
	$artist =~ s#/#-#g;
	$album  =~ s#/#-#g;
	$genre  =~ s#/#-#g;
	$title  =~ s#/#-#g;
	
	# Determine the filepath info
	$file =~ s/^tracks/$music/;
	$link = "$links/$artist/$album/$title.mp3";

	# Create the artist/album hierarchy
	if(!-d "$links/$artist") {
		print "making $links/$artist\n" if $opt_v==1;
		mkdir "$links/$artist" unless $opt_t==1;
	}
	if(!-d "$links/$artist/$album") {
		print "making $links/$artist/$album\n" if $opt_v==1;
		mkdir "$links/$artist/$album" unless $opt_t==1;
	}

	# Create the symbolic link. Use of 'eval' is to bypass this command on
	# unsupported systems.
	if(!-f $link) {
		print "linking $link to $file\n" if $opt_v==1;
		eval{symlink($file,$link),1} unless $opt_t==1;
		open LIST,">>$links/$artist/$album/$playlist";
		print LIST "./$title.mp3\n";
		close LIST;
	}
}

# Clean up the database and statement handles
$sth_track->finish();
$sth_album->finish();
$sth_artist->finish();
$sth_genre->finish();
$dbh->disconnect();

DELETIONS:
# Finally, things need to stay in sync, so traverse the directory hierarchy
# and remove any links/artists/albums that are no longer in the database.
# This will be accomplished in a two step process:
#  
# Step 1 - Remove symbolic links.  If the -l operator indicates the file is
# a symbolic link, but the -f indicates it is not a file, this means the 
# file that the link references has been deleted, so delete the link...
# this is a hack, but it works.
finddepth({wanted=>sub{unlink $_ if -l $_ && !-f $_; }},$links) unless $opt_t==1;

# Step 2 - Remove the album/artist directories if they contain no links
finddepth({wanted=>sub{opendir(DIR,$_);@cnt=readdir(DIR)-2;closedir(DIR);rmdir $_ if -d $_ && $cnt==0;}},$links) unless $opt_t==1;

# sub: displays usage information
sub usage() {
print<<_EOF_;
usage: $0 [-vtdh]
    -v  verbose output.
    -t  test-mode.  Does not create links.
    -d  delete-only.  Only deletes out-dated links.
    -h  displays usage information.
_EOF_
}

# sub: wrapper for 'die'
sub abort($) {
	print "@_\n";
	die;
}



############################################################################
# Revision History
#
#  v1.1 - 2002/11/04
#  - modified to access database directly (eliminated a lot of module deps)
#  - added support for album playlist file creation
#  - added check for '/' characters in artist/album/track info
#
#  v1.0 - 2002/10/29
#  - initial version
#