#!/usr/bin/perl
# Autogenerate the list of packages to dpkg-divert for this .deb package

use File::stat;

# List of files that are being overriden by this package
if (! -e "diversions") { system("touch diversions"); }
open DIVERSIONS, "<diversions";
my @diversions = <DIVERSIONS>;
close DIVERSIONS;

my $begin_delim = "### BEGIN DIVERT GENERATE ###";
my $end_delim = "### END DIVERT GENERATE ###";

my $preinst_path = "DEBIAN/preinst";
my $postrm_path = "DEBIAN/postrm";
my $pkg = shift;

# Slurp in both existing files (to use as a template)
undef $/;

if(open( PREINST, "<$preinst_path")) {
  $preinst = <PREINST>;
  close PREINST;
} else {
  $preinst='#!/bin/sh

if [ install = "$1" ] || [ upgrade = "$1" ]; then
  :
'.$begin_delim."\n".$end_delim."\nfi\n";
}

if(open(POSTRM, "<$postrm_path")) {
  $postrm = <POSTRM>;
  close POSTRM;
} else {
  $postrm='#!/bin/sh
if [ remove = "$1" ]; then
  :
'.$begin_delim."\n".$end_delim."\nfi\n";
}

# Generate preinst stub
my $preinst_stub = "";
foreach my $entry (@diversions)
{
  chomp($entry);
  next if ($entry =~ /^$/);
  my @pair = split(",", $entry);
  $pair[1] =~ s/\n//;
  $preinst_stub .= "  dpkg-divert --package $pkg --add --rename --divert $pair[0].$pair[1] $pair[0]\n";
}
$preinst =~ s/$begin_delim.*$end_delim/$begin_delim\n$preinst_stub$end_delim/s;

# Write generated portion back to script file
open PREINST, ">$preinst_path";
print PREINST $preinst;
close PREINST;
chmod 0755, $preinst_path;

# Generate postrm stub
my $postrm_stub = "";
foreach my $entry (@diversions)
{
  chomp($entry);
  next if ($entry =~ /^$/);
  my @pair = split(",", $entry);
  $pair[1] =~ s/\n//;
  $postrm_stub .= "  dpkg-divert --package $pkg --remove --rename --divert $pair[0].$pair[1] $pair[0]\n";
}
$postrm =~ s/$begin_delim.*$end_delim/$begin_delim\n$postrm_stub$end_delim/s;

# Write generated portion back to script file
open POSTRM, ">$postrm_path";
print POSTRM $postrm;
close POSTRM;
chmod 0755, $postrm_path;