ensignature

#!/bin/env perl
use v5.36.0;

my $fn = $ARGV[0];
my @output;

{
  open my $fh, '<', $fn;

  my @input = <$fh>;

  LINE: while (my $line = shift @input) {
    if ($line =~ /^sub (\S+) \{$/) {
      my $sub = $1;
      my $next = shift @input;

      if ($next && $next =~ /^\s*my (\([^)]+\)) = \@_;$/) {
        my $sig = $1;
        my $new_line = "sub $sub $sig {\n";

        warn $new_line;
        push @output, $new_line;

        while (@input && $input[0] !~ /\S/) {
          shift @input;
        }

        next LINE;
      }

      unshift @input, $next;
    }

    push @output, $line;
  }
}

open my $fh, '>', $fn;
print {$fh} @output;
close $fh;