#!/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.

# linux_system
# Linux system and operatingsystem sections: uptime, OS name, version and kernel.
#
# Revision History:
# 2026-10-18 Claude v1.0.0 new sensor, split from unix_system (bug 210)

package linux_system;

use strict;
use warnings;
use version;
our $VERSION = version->declare('v1.0.0');

use FindBin;
use File::Spec;
use lib File::Spec->catdir($FindBin::Bin), File::Spec->catdir("$FindBin::Bin/..");
use library qw(:all);

my $CATEGORY_SYSTEM = 'system';
my $CATEGORY_OS = 'operatingsystem';
#######################################################
#
# parseLinuxUptime( $uptimeText )
#
# Converts /proc/uptime content into old system uptime and
# last_boot lines.
#
# Parameters:
#   $uptimeText - text from /proc/uptime
#
# Returns:
#   array reference of output lines
#
# Side Effects:
#   none
#
#######################################################
sub parseLinuxUptime {
   my $uptimeText = shift;
   my @out;
   if (defined($uptimeText) && $uptimeText =~ /^([0-9]+(?:\.[0-9]+)?)/) {
      my $uptime = int($1);
      push @out, "$CATEGORY_SYSTEM\tlast_boot\t" . (time() - $uptime);
      push @out, "$CATEGORY_SYSTEM\tuptime\t$uptime";
   }
   return \@out;
}

#######################################################
#
# parseLinuxOsValues( $lsbText, $unameText, $procVersion )
#
# Parses linux_os_values-compatible keys from command text.
#
# Parameters:
#   $lsbText      - text from lsb_release -a
#   $unameText    - text from uname -s -r
#   $procVersion  - text from /proc/version
#
# Returns:
#   array reference of output lines
#
# Side Effects:
#   none
#
#######################################################
sub parseLinuxOsValues {
   my ($lsbText, $unameText, $procVersion) = @_;
   my @out;

   my %map = (
      'Distributor ID' => 'distribution',
      'Description' => 'description',
      'Release' => 'release',
      'Codename' => 'codename',
   );

   if (defined($lsbText)) {
      foreach my $line (split(/\n/, $lsbText)) {
         foreach my $left (keys %map) {
            if ($line =~ /^\Q$left\E\s*:\s*(.*)$/) {
               my $v = trim($1);
               push @out, "$CATEGORY_OS\t$map{$left}\t$v" if $v ne '';
            }
         }
      }
   }

   if (defined($unameText) && $unameText =~ /^(\S+)\s+(\S+)/) {
      push @out, "$CATEGORY_OS\tos_name\t$1";
      push @out, "$CATEGORY_OS\tkernel\t$2";
   }

   if (defined($procVersion)) {
      my $v = trim($procVersion);
      push @out, "$CATEGORY_OS\tos_version\t$v" if $v ne '';
   }

   return \@out;
}

#######################################################
#
# main()
#
# Emits system and operatingsystem keys.
#
# Parameters:
#   none
#
# Returns:
#   integer exit status (1 wrong OS, 2 not applicable)
#
# Side Effects:
#   runs cat, lsb_release and uname, writes STDOUT/STDERR
#
#######################################################
sub main {
   if (!checkOS({ 'linux' => undef })) {
      print STDERR "unsupported os\n";
      return 1;
   }
   unless (validCommandOnSystem({ 'uname' => undef })) {
      print STDERR "uname not found\n";
      return 2;
   }
   my @out;
   push @out, @{parseLinuxUptime(runCommand('cat', '/proc/uptime'))};
   push @out, @{parseLinuxOsValues(
      runCommand('lsb_release', '-a'),
      runCommand('uname', '-s', '-r'),
      runCommand('cat', '/proc/version'),
   )};
   print join("\n", @out), "\n" if @out;
   return 0;
}

exit main() unless caller;
1;