#! /usr/bin/env perl

# Copyright (c) 2025, R. W. Rodolico
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# 1. Redistributions of source code must retain the above copyright notice, this
#    list of conditions and the following disclaimer.
#
# 2. Redistributions in binary form must reproduce the above copyright notice,
#    this list of conditions and the following disclaimer in the documentation
#    and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

# checks different things to try and figure out what operating system we are running
# pretty basic stuff, actually. Looks for the existence of a file or directory first.
# if it can not find one that matches, will then do a uname and attempt to locate a
# particular string in that.
#
# opnsense is freebsd, but does not have the same capabilities as freebsd, so we look for the file
# /conf/config.xml which appears to be uniq. We could also look for the /usr/local/opnsense directory
# if we don't find that, then we look for rooted /etc/debian_version and uname data
# for debian/mx/devuan or freebsd
#
# returns a string (debian, freebsd or opnsense) without a line return on success.
# on failure, returns an empty string and a failure return code
#
# Revision History:
# 2026-10-13 Copilot v2.0.0 r? spec-aligned OS detection order and unsupported-OS failure code
# 2026-10-13 Copilot v2.0.1 rooted filesystem checks and list-form command execution

use strict;
use warnings;

# find our location and use it for searching for libraries
BEGIN {
   use FindBin;
   use File::Spec;
   # use libraries from the directory this script is in
   use lib File::Spec->catdir($FindBin::Bin);
   # and its parent
   use lib File::Spec->catdir( $FindBin::Bin . '/../' );
}

use version;
our $VERSION = version->declare('v2.0.1');

use installer_shared qw(
   getRootPrefix
   rootPath
   slurpCommand
);

#######################################################
#
# detectOs()
#
# Detects installer OS family in spec-required order.
#
# Parameters:
#   none
#
# Returns:
#   scalar OS token (opnsense|freebsd|debian) or empty
#
# Side Effects:
#   none
#
#######################################################
sub detectOs {
   my $rootPrefix = getRootPrefix();
   return 'opnsense' if -e rootPath($rootPrefix, '/conf/config.xml');

   if (-f rootPath($rootPrefix, '/etc/debian_version')) {
      return 'debian';
   }

   my $uname = slurpCommand(['uname', '-s']);
   $uname = '' unless defined($uname);
   if (defined($uname) && $uname =~ /freebsd/i) {
      return 'freebsd';
   }

   my $all = slurpCommand(['uname', '-a']);
   $all = '' unless defined($all);
   if (defined($all) && $all =~ /(debian|mx|devuan)/i) {
      return 'debian';
   }

   return '';
}

my $os = detectOs();
if ($os ne '') {
   print $os;
   exit 0;
}

print STDERR "unsupported operating system\n";
exit 2;