#!/usr/local/bin/perl
use strict;
use warnings;
use File::Temp qw(tempdir tempfile);
use List::Util qw(reduce sum);

my $tabwidth = 4;

# Open/fetch our JS file.
my $js_file = pop @ARGV;
my $doc_name;
($doc_name = $js_file ) =~ s{.+/}{};
$doc_name =~ s/\..+//;

# Fetch my JavaScript
my $js;
if ( -f $js_file ) {
        # Open my real JavaScript file.
        open my $js_fh, '<', $js_file
                or die "Can't open $js_file: $!";
        local $/;
        $js = <$js_fh>;
}
else {
        # Use the given filename as a URL instead.
        require LWP::Simple;
        $js = LWP::Simple::get( $js_file );
}

# Some *awesome* JavaScript parsing.
my @pod =
        map { unindent( $_ ) . "\n\n=cut\n\n" }
        grep { defined and /\S/ }
        $js =~ m{/(?:\*(.*?)\*/|/([^\n]))}gxs;
unshift @pod, "=cut\n\n";


# Go make a temporary pod file.
my $pod_dir = tempdir( CLEANUP => 1 );
my $pod_file = "$pod_dir/$doc_name.pod";
open my $pod_fh, '>', $pod_file
        or die "Can't create $pod_file: $!";
END { unlink $pod_file }

print {$pod_fh} @pod
        or die "Can't write to $pod_file: $!";
close $pod_fh
  or die "Can't close $pod_file: $!";

# Run our pod file under perldoc.
system 'perldoc', @ARGV, $pod_file;
exit;

sub unindent {
    local $_ = shift @_;

    # Untabify
    s/\t/' ' x $tabwidth/ge;

    # Remove trailing whitespace
    s/\s+\z//;

    # Unindent by finding the largest quantity of removeable
    # whitespace.
    my %leading_space;
    ++ $leading_space{length $1}{count}
        while m/^( +)/mg;
    return $_ unless keys %leading_space;
    
    my @indents = sort { $a <=> $b } keys %leading_space;
    
    # Compute the space removed for each indentation level.
    for my $indent_ix ( 0 .. $#indents ) {
        my $indent = $indents[$indent_ix];
        
        my $lines = 0;
        $lines
            += $leading_space{$indents[$_]}{count}
                for $indent_ix .. $#indents;
        $leading_space{$indent}{space} = $lines * $indent;
    }
    
    # Select the indentation with the most area removed.
    my $suggested_padding
        = reduce {
            my $current_space = $leading_space{$a}{space};
            my $new_space = $leading_space{$b}{space};
            
            $current_space > $new_space ? $a : $b;
        } ( @indents );
    
    # Remove that much from the start of every line.
    s/^ {0,$suggested_padding}//mg;
   
    return $_;
}