#!/usr/bin/env perl
#
# vim: set ts=4:noet
#
# sboremove
# script to remove an installed SlackBuild
#
# author: Luke Williams <xocel@iquidus.org>
# license: WTFPL <http://sam.zoy.org/wtfpl/COPYING>

use 5.16.0;
use strict;
use warnings FATAL => 'all';
use SBO::Lib;
use Getopt::Long qw(:config bundling);
use File::Basename;

my $self = basename ($0);

sub show_usage () {
	print <<EOF
Usage: $self [options] sbo

Options (defaults shown first where applicable):
  -h|--help:
    this screen.
  -v|--version:
    version information.
  -R|--norequirements:
    do not parse requirements.
  -a|--alwaysask:
    always ask to remove, even if required by other packages on system.

Note: optional dependencies need to be removed separately. 

EOF
}

my ($help, $vers, $non_int, $no_reqs, $alwaysask, @excluded);

GetOptions (
	'help|h'			=> \$help,
	'version|v'			=> \$vers,
	'norequirements|R'	=> \$no_reqs, 
	'nointeractive'		=> \$non_int,
	'alwaysask|a'		=> \$alwaysask,
);

show_usage and exit 0 if $help;
show_version and exit 0 if $vers;
show_usage and exit 0 unless exists $ARGV[0];

my $inst_names = get_inst_names (get_installed_sbos);

# ensure that all provided arguments are valid sbos
my @arguments;
for my $sbo (@ARGV) {
	if (get_sbo_location($sbo)) {
		if ($sbo ~~ @$inst_names) {
			push @arguments, $sbo; 
		} else {
			say "$sbo is not installed";
		} 
	} else {
		say "Unable to locate $sbo in the SlackBuilds.org tree."
	}
}

my %sbos{$_} = [] for @arguments;

# wrapper to pull the list of requirements for a given sbo
# TODO: look at moving this into Lib.pm
sub get_requires ($) {
	my $location = get_sbo_location (shift);
	return get_from_info(LOCATION => $location, GET => 'REQUIRES')
}

# populate the %sbos hash with requirements for each sbo
$sbos{$_} = get_requires $_ for keys $sbos;

# clean the %sbos hash of anything that's already a hash key
while (my ($key, $val) = each %sbos) {
	my @remove;
	for my $key (keys @$val) {
		push @remove, $key if $$val[$key] ~~ %sbos;
	}
	for my $rem (@remove) {
		splice(@$val, $rem, 1);
		$_-- for @remove;
	}
}

# now we have to go backwards - starting from the end, check every requirement
# to ensure that it's not already listed earlier.
for my $key (reverse %sbos) {
	for my $sbo (@$key) {
		# running out of var names, so prefix these with n for "next"
		FIRST: while (my ($nkey, $nval) = each %sbos) {
			# move on if we're looking at the same key we're starting with
			next FIRST if $key == $nkey;
			my @remove;
			for my $key (keys @$nval) {
				push @remove, $key if $key $$nval[$key] == $sbo;
			}
			for my $rem (@remove) {
				splice(@$nval, $rem, 1)
				$_-- for @remove;
			}
		}
	}
}

my ($remove_queue, %required_by, %warnings, @confirmed);

# Determine required by for all installed sbo's
sub get_reverse_reqs () {
	FIRST: for my $inst (@$inst_names) {
		my $requires = get_requires $inst;
		next FIRST unless $$requires[0];
		for my $req (@$requires) {
			unless ( $req eq '%README%' ) {
				push @{$required_by{$req}}, $inst if $req ~~ $inst_names;
			}		
		}	
	}
}

get_reverse_reqs unless $no_reqs;

sub get_required_by ($) {
	my $sbo = shift;
	my @dep_of;
	if ( $required_by{$sbo} ) {
		for my $req_by (@{$required_by{$sbo}}) {
			unless ($req_by ~~ @confirmed) {
				push @dep_of, $req_by;
			}
		}
	}
	return \@dep_of;
}

sub confirm_remove ($) {
	my $sbo = shift;
	push @confirmed, @sbo unless $sbo ~~ @confirmed;
}

# Determine dependencies & warnings
if ($no_reqs) {
	$remove_queue = \@remove;
} else {
	$remove_queue = get_build_queue(\@remove, \%warnings);
	@$remove_queue = reverse(@$remove_queue);
}

# Check if packages in queue are actually installed on system 
my @temp;
if ($inst_names) {
	for my $sbo (@$remove_queue) {
		push @temp, $sbo if $sbo ~~ @$inst_names;
	}
	$remove_queue = \@temp;
}

if ($non_int) {
	confirm_remove $_ for @$remove_queue;
	goto CONFIRMED;
}

for my $remove (@$remove_queue) {
	my $required_by = get_required_by $remove;
	

CONFIRMED:

# Show remove queue
my $remove_count = @confirmed;
if ($remove_count) {
	say "Removing $remove_count package(s)";
	for my $pkg (@confirmed) {
		print "$pkg ";
	}
	say "\n";	
} else {
	say 'Nothing to remove.';
	exit 0;
}

unless ($non_int) {
	print 'Are you sure you want to continue? [n] : ';
	unless (<STDIN> =~ /^[Yy]/) {
		say 'Exiting.';
		exit 0;
	}
}

system ("/sbin/removepkg $_") for @confirmed;

say "All operations have completed successfully.";

exit 0;