contains

#!/usr/bin/env perl

use strict;
use warnings;
use File::Basename;

# Check if we have the correct number of arguments
if (@ARGV != 2) {
    die "Usage: $0 <file1> <file2>\n";
}

my ($file1, $file2) = @ARGV;

# Determine which file is larger and which is smaller
my $file1_size = -s $file1;
my $file2_size = -s $file2;

my ($larger_file, $smaller_file);

if ($file1_size > $file2_size) {
    $larger_file = $file1;
    $smaller_file = $file2;
} elsif ($file2_size > $file1_size) {
    $larger_file = $file2;
    $smaller_file = $file1;
} else {
    die "Error: Both files are the same size. One file must be smaller than the other.\n";
}

sub read_file {
    my ($filename) = @_;
    open my $fh, '<:raw', $filename or die "Could not open $filename: $!";
    local $/;
    my $content = <$fh>;
    close $fh;
    return $content;
}

# Read the content of both files
my $larger_content = read_file($larger_file);
my $smaller_content = read_file($smaller_file);

# Get the lengths of the contents
my $larger_length = length($larger_content);
my $smaller_length = length($smaller_content);

# Search for the smaller content within the larger content
my $offset = index($larger_content, $smaller_content);

if ($offset != -1) {
    print "Validation successful!\n";
    print "The content of '$smaller_file' (size: $smaller_length bytes) was found at offset $offset of '$larger_file' (size: $larger_length bytes).\n";

    # Extract filename components for verification
    my ($smaller_basename, $dir, $ext) = fileparse($smaller_file, qr/\.[^.]*$/);
    my ($num_bytes, $actual_length, $reported_offset) = $smaller_basename =~ m!\.(\d+)\.(\d+)\.(\d+)$!;
    if ($reported_offset) {
        if ($num_bytes == $smaller_length && $actual_length == $smaller_length && $reported_offset == $offset) {
            print "The filename components match the actual values:\n";
            print "Number of bytes: $num_bytes\n";
            print "Actual length:   $actual_length\n";
            print "Offset:          $offset\n";
        } else {
            print "Warning: Some filename components do not match the actual values:\n";
            print "Number of bytes (filename vs actual): $num_bytes vs $smaller_length\n";
            print "Length (filename vs actual): $actual_length vs $smaller_length\n";
            print "Offset (filename vs actual): $reported_offset vs $offset\n";
        }
    } else {
        print "Warning: Couldn't parse the smaller filename for additional validation.\n";
    }
} else {
    print "Validation failed: The content of the smaller file was not found in the larger file.\n";
}