Clean up the headers to indicate a file was added/removed/modified

Also makes the file name "clickable" by removing the leading a/ and /b

diff-so-fancy

@@ -70,6 +70,10 @@ print_horizontal_rule () {
   printf "%$(tput cols)s\n"| $SED 's/ /─/g'
 }
 
+print_header_clean () {
+  "$(get_script_dir)/libs/header_clean/header_clean.pl"
+}
+
 # run it.
 # shellcheck disable=SC2002
 cat $input \
@@ -79,4 +83,5 @@ cat $input \
   | mark_empty_lines \
   | remove_first_empty_line \
   | strip_leading_symbols \
-  | strip_first_column
+  | strip_first_column \
+  | print_header_clean

libs/header_clean/header_clean.pl

@@ -0,0 +1,43 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+my $ansi_sequence_regex = qr/(\e\[([0-9]{1,3}(;[0-9]{1,3}){0,3})[mK])?/;
+
+my ($f1,$f2);
+while (my $l = <>) {
+	# Find the first file: --- a/README.md
+	if ($l =~ /^$ansi_sequence_regex--- (a\/)?(.+?)(\e|$)/) {
+		$f1 = $5;
+	# Find the second file: +++ b/README.md
+	} elsif ($l =~ /^$ansi_sequence_regex\+\+\+ (b\/)?(.+?)(\e|$)/) {
+		if ($1) {
+			print $1; # Print out whatever color we're using
+		}
+		$f2 = $5;
+
+		# If they're the same it's a modify
+		if ($f1 eq $f2) {
+			print "modified: $f1\n";
+		# If the first is /dev/null it's a new file
+		} elsif ($f1 eq "/dev/null") {
+			print "added: $f2\n";
+		# If the second is /dev/null it's a deletion
+		} elsif ($f2 eq "/dev/null") {
+			print "deleted: $f1\n";
+		# If the files aren't the same it's a rename
+		} elsif ($f1 ne $f2) {
+			print "renamed: $f1 to $f2\n";
+		# Something we haven't thought of yet
+		} else {
+			print "$f1 -> $f2\n";
+		}
+
+		# Reset the vars
+		my ($f1,$f2);
+	# Just a regular line, print it out
+	} else {
+		print $l;
+	}
+}