#!/usr/local/bin/perl5 -w

use strict;

die "usage: $0 <directories or files with one directory per line>\n"
    unless @ARGV;

my $lighterPrefix = ".l-";
my $verbose = 0;
my $errcutoff = 2;

#< main loop, figure out what to do
my $errors=0;
foreach my $arg (@ARGV) {
    if (-d $arg) {
	$errors += &makethumbs($arg);
    } elsif ($arg eq "-" or -f $arg) {
	open(IN, $arg) or do { warn "cannot read [$arg]: $!\n"; 
			       $errors++; next;};
	while (<IN>) {
	    chomp;
	    next if /^\#/ or !/\S/;
	    next if /\b(RCS|Thumbs)\b/;
	    $errors += &makethumbs($_);
	    last if $errors > $errcutoff;
	}
	close IN;
    } else {
	warn "no such file or directory [$arg]\n";
	$errors++;
    }
    if ($errors > $errcutoff) {
	warn "stopping after $errors errors.\n";
	last;
    }
}
#>

#< make thumbs for a single directory
sub makethumbs {
    my $dir = shift;

    warn "no such directory [$dir]\n" and return unless -d $dir;
    #warn "cannot write directory [$dir]\n" and return unless -w _;

    my $tdir = qq($dir/Thumbs);
    warn "cannot make directory [$tdir]: $!\n" and return unless 
	-e $tdir or mkdir($tdir, 0777);

    opendir(TDIR, $tdir) or 
	do {warn "cannot read Thumbs directory [$tdir]: $!\n"; return;};
    my @ts = readdir TDIR;
    close TDIR;
    my %ts=();
    foreach my $t (@ts) {
	next if $t =~ /^$lighterPrefix/o or -d qq($tdir/$t);
	$ts{$t} = 0;
    }

    opendir(DIR, $dir) or 
	do {warn "cannot read directory [$dir]: $!\n"; return;};
    my @es = readdir DIR;
    close DIR;

    my @ps = grep { !/^\./ and /\S\S+\.(gif|jpg|png)$/i } @es;
    print STDERR "$dir: ".scalar(@ps)." images\n" if $verbose;

    my $cnt=0;
    return 0 unless @ps;
    foreach my $p (@ps) {
	$ts{$p} = 1;
	my $pic = qq($dir/$p);
	my $thumb = qq($tdir/$p);
	if (not -e $thumb or 
	    -M _ > -M $pic) {
	    $cnt += &convert($pic, $thumb);
	}
    }

    foreach my $t (keys %ts) {
	# these are unused pre-existing thumbnails.  remove them.
	print "removing unused thumbs for [$t]\n" unless $ts{$t};
	&remove($dir, $tdir, $t) unless $ts{$t};
    }
    return ($cnt / @ps > .1);
}
#> 

sub sh {
    my $cmd = shift;
    #print STDERR $cmd.$/;
    system $cmd and 
	do { warn "convert error [$cmd]: $!$@\n"; return undef; };
    return 1;
}

#< remove the leavings of a removed image
sub remove {
    my ($dir, $tdir, $name) = @_;
    sh qq(/bin/rm -f "$dir/$lighterPrefix$name") or return 1;
    sh qq(/bin/rm -f "$tdir/$lighterPrefix$name") or return 1;
    sh qq(/bin/rm -f "$tdir/$name") or return 1;
    return 0;
}
#> 
#< convert an image to a thumbnail
sub convert {
    my ($pic, $thumb) = @_;
    print STDERR "mkthumbs $pic\n";
    sh qq(chmod a+r "$pic") or return 1;

    sh qq(/usr/bin/convert -resize x300 "$pic" "$thumb") or return 1;

    my $lthumb = $thumb;
    $lthumb =~ s|/([^/]+)$|/$lighterPrefix$1|;
    sh qq(/usr/bin/convert -gamma 2.2 "$thumb" "$lthumb") or return 1;

    my $bytes = -s $pic;
    my $kbytes = $bytes / 1024;
    my $mbytes = $kbytes / 1024;
    my $target = 3; # megabytes
    if ($target < $mbytes) {
	my $percent = int($target * 100 / $mbytes); # roughly
	my $display_mbytes = sprintf('%3.2f',$mbytes);
	warn "    ...shrinking it to $percent% of ${display_mbytes}Mb\n";
	# shrink the original -- space is getting out of hand.
	my $b = $pic;
	$b =~ s|.*/||;
	sh qq(/usr/bin/convert -resize $percent% "$pic" "./smaller-$$-$b");
	sh qq(/bin/mv "./smaller-$$-$b" "$pic");
    }

    my $lpic = $pic;
    $lpic =~ s|/([^/]+)$|/$lighterPrefix$1|;
    sh qq(/usr/bin/convert -gamma 2.2 "$pic" "$lpic") or return 1;

    return 0;
}
#>