#!/usr/bin/env perl

# transportStats - Display disk usage statistics for transport drives
#
# PURPOSE:
#   Reports disk space usage for all filesystems mounted under /mnt, typically
#   used to monitor transport drives and report disks during sneakernet operations.
#
# USAGE:
#   Standalone: ./transportStats
#   From sneakernet: Executed automatically during cleanup phase
#   From Perl script: my ($results, $errors) = eval { do './transportStats' };
#
# EXECUTION CONTEXT:
#   When executed by sneakernet on the target server:
#   - Script is read from transport drive, decrypted, and executed via eval()
#   - Results returned as tuple (output, error_messages) for logging
#   - When run standalone, prints results to STDOUT
#
# BEHAVIOR:
#   1. Executes 'df -h' to get human-readable disk usage statistics
#   2. Filters output to show only mounts under /mnt/ (where transport drives are mounted)
#   3. Includes df header line for readability
#   4. Returns formatted output with any error messages
#
# OUTPUT FORMAT:
#   Filesystem      Size    Used   Avail Capacity  Mounted on
#   /dev/gpt/data1  100G     45G     55G    45%    /mnt/transport
#   /dev/gpt/data2   50G     20G     30G    40%    /mnt/reports
#
# RETURN VALUE:
#   When called from another script: ($results, $errors)
#   - $results: String containing df output
#   - $errors: String containing error messages (empty if none)

use strict;
use warnings;

my $caller = caller(); # Check if called from another script and, if not, prints updates to STDOUT
# if we are being called from sneakernet, get verbosity level, otherwise just set to 5
my $verbosityLevel = ($caller && defined $ZFS_Utils::verboseLoggingLevel) ? $ZFS_Utils::verboseLoggingLevel : 5;


# Get disk stats on anything mounted under /mnt
# This assumes that transport disks are mounted under /mnt/
# will also get the reports disk if mounted there
my $cmd = "df -h | grep -E '(^Filesystem)|(/mnt/)'";
my @results = `$cmd 2>&1`;
chomp @results;
my @errors;

# Check if command executed successfully
if ($? != 0) {
   push @errors, "Error executing df command: $!";
}

# Return or print results depending on context
if ($caller) { # called from another script
   return ( 
      join( "\n", @results ) . "\n",
      @errors ? join("\n", @errors) : ""
   );
} else { # run standalone
   print "Results Summary:\n";
   print join( "\n", @results ) . "\n";
   if (@errors) {
      print "\n=== CLEANUP SCRIPT ERRORS ===\n";
      print join("\n", @errors) . "\n";
   }
}
# End of script