#! /usr/bin/perl -w

use strict;
use Cwd 'getcwd';
use File::Find;           
use File::Basename;
use File::Path;

my $debug = 0;
my $verbose = 0;

my $total_count;
my $total_saved;

my $package_name;

if ($#ARGV == 1 && $ARGV[0] eq "--raw") {
    exit (optify_raw ($ARGV[1]));
} elsif ($#ARGV >= 0) {
    my $pkg = $ARGV[0];
    my $dir;
    
    if ($#ARGV >= 1) {
        $dir = $ARGV[1];
    } else {
        $dir = "debian/" . $pkg;
    }

    optify_dir ($dir, $pkg);
} else {
    foreach (list_packages ()) {
        optify_package ($_);
    }
}

sub dbg {
    if ($debug) {
        print STDERR @_;
    }
}

sub vrb {
    if ($debug || $verbose) {
        print STDERR @_;
    }
}

sub du {
    my ($dir) = @_;

    my $size = 0;             
    find(sub { $size += -s if -f $_ }, $dir);
    return $size;
}

sub optify_entry {
    my ($entry) = @_;
    
    $entry =~ s,^\./,,;

    my $opt_entry = "opt/maemo/" . $entry;
    vrb "$entry -> $opt_entry\n";

    # mkpath seems to fail when the directory already exists, weird.
    my $dir = dirname ($opt_entry);
    if (! -d $dir) {
        mkpath ($dir) || die $!;
    }
    rename ($entry, $opt_entry) || die $!;
    symlink ("/" . $opt_entry, $entry) || die $!;
}

sub blacklisted {
    my ($entry) = @_;

    if (-f $entry) {
        # Files in /usr are always ok, but others are not.
        return ! $entry =~ /^\/usr\//;
    }
    
    if (basename ($entry) eq $package_name) {
        # Directories are OK if they are named after the package.
        # But be extra extra careful here and check some well-known names
        # that we positively never ever want to optify.
        return $package_name eq "bin"
            || $package_name eq "sbin"
            || $package_name eq "lib"
            || $package_name eq "libexec"
            || $package_name eq "var"
            || $package_name eq "share"
            || $package_name eq "X11R6"
            || $package_name eq "games"
            || $package_name eq "local"
            || $package_name eq "src"
            || $package_name eq "etc"
            || $package_name eq "boot"
            || $package_name eq "dev"
            || $package_name eq "home"
            || $package_name eq "media"
            || $package_name eq "mnt"
            || $package_name eq "opt"
            || $package_name eq "proc"
            || $package_name eq "root"
            || $package_name eq "srv"
            || $package_name eq "sys"
            || $package_name eq "syspart"
            || $package_name eq "tmp";
    } else {
        return 1;
    }
}

sub consider_entry {
    my ($entry) = @_;

    dbg "$entry: ";

    my $size = du ($entry);

    if (-l $entry) {
        dbg "link, nope\n";
    } elsif ($entry =~ /^.\/opt\//) {
        dbg "in /opt, nope\n";
    } elsif ($entry =~ /^.\/DEBIAN\//) {
        dbg "in /DEBIAN, nope\n";
    } elsif ($size >= 2048) {
        if (!blacklisted ($entry)) {
            dbg "yes, saved $size bytes\n";
            $total_count += 1;
            $total_saved += $size;
            optify_entry ($entry);
        } elsif (-d $entry) {
            dbg "not ours, recursing\n";
            local(*DIR);
            opendir(DIR, $entry);
            while ($_ = readdir (DIR)) {
                next if ($_ eq "." || $_ eq "..");
                consider_entry ($entry . "/" . $_);
            }
            closedir(DIR);
        }
    } else {
        dbg "only $size bytes, nope\n";
    }
}

sub optify_dir {
    my ($dir, $pkg) = @_;

    $package_name = $pkg;
    $total_count = 0;
    $total_saved = 0;

    dbg "package: $package_name\n";

    my $olddir = getcwd();
    chdir ($dir) || die "Cannot chdir to $dir\n";

    if (-d "opt") {
        print "$pkg: /opt exists already, not optifying further.\n";
        return 77;
    }

    consider_entry (".");

    my $total_kb_saved = int ($total_saved / 1024);
    print "$pkg: optified $total_count entries, saving about $total_kb_saved kB.\n";

    chdir ($olddir) || die "Can't chdir back to $olddir";

    return 0;
}

sub optify_raw {
     my ($dir) = @_;

     chdir ($dir) || die "Cannot chdir to $dir\n";
     
     my $pkg = basename (getcwd ());
     $pkg =~ s/_.*$//;

     optify_dir (".", $pkg);
}

sub list_packages {
    # XXX - Use some debhelper module for this maybe.
    my @packages = ();

    open IN, "<", "debian/control" or die "Can't read debian/control";
    while (<IN>) {
        if (/^Package: +(.*)\n/) {
            push (@packages, $1);
        }
    }
    close IN;
    return @packages;
}

sub optify_package {
    my ($pkg) = @_;

    optify_dir ("debian/" . $pkg, $pkg);
}