package DDG::Goodie::Shuffle;
# ABSTRACT: Randomly order a given list

use strict;
use warnings;
use utf8;
use DDG::Goodie;

use List::Util qw( shuffle pairs );
use Data::Record;
use Regexp::Common;

zci answer_type => 'shuffle';

zci is_cached => 0;

my @start_words = ('shuffle', 'sort', 'order');
my @end_words = ('shuffled', 'sorted', 'ordered');

my @start_phrases = (
    'shuffle',
    (map { "randomly $_" } @start_words),
    (map { "random $_" } @start_words),
);

my @end_phrases = (
    'in a random order',
    (map { "randomly $_" } @end_words),
    (map { "random $_" } @start_words),
    'shuffled',
);

triggers start => @start_phrases;
triggers end => @end_phrases;

my @parens = (
    '[' => ']',
    '(' => ')',
    '{' => '}',
);

my $max_range = 30;

sub parse_range {
    my $range = shift;
    $range =~ /^(?:
         (?<numeric>(?<lower>\-?\d+)\.\.(?<upper>\d+))
        |(?<lower>[[:ascii:]])\.\.(?<upper>[[:ascii:]]))$/x or return;
    my ($lower, $upper) = ("$+{lower}", "$+{upper}");
    my ($lower_int, $upper_int) =
        $+{numeric} ? ($lower, $upper) : (ord $lower, ord $upper);
    return if abs ($upper_int - $lower_int) >= $max_range;
    my @result = $lower..$upper;
    return @result;
}

sub is_conj {
    return shift =~ qr/^$RE{list}{and}$/i;
}

sub get_separator {
    my $text = shift;
    my $comma_sep = qr/\s*,\s*/io;
    return qr/(?:\s*,?\s*and\s*|$comma_sep)/io if is_conj($text);
    return $comma_sep;
}

sub remove_parens {
    my $text = shift;
    foreach (pairs @parens) {
        my ($opening, $closing) = map { quotemeta $_ } @$_;
        next unless $text =~ /^$RE{balanced}{-parens=>"$opening$closing"}$/;
        $text =~ s/^$opening(.+?)$closing$/$1/;
        return $text;
    }
    return $text if is_conj($text);
    return;
}

sub trim_whitespace {
    my $to_trim = shift;
    $to_trim =~ s/^\s+//ro =~ s/\s+$//ro;
}

sub parse_list {
    my $list_text = shift;
    $list_text = remove_parens($list_text)
        // return parse_range($list_text);
    if (my @items = parse_range($list_text)) {
        return @items;
    }
    my $sep = get_separator($list_text);
    my $record = Data::Record->new({
        split => $sep,
        unless => $RE{quoted},
    });
    my @items = map { trim_whitespace $_ } $record->records($list_text);
    return @items;
}

sub display_list {
    my @items = @_;
    return "[@{[join ', ', @items]}]";
}

handle remainder => sub {

    my $remainder = $_;
    return if $remainder eq '';

    my @items = parse_list($remainder) or return;
    return unless $#items;
    srand;
    my @shuffled = shuffle @items;
    my $shuffled_display = display_list @shuffled;
    my $original_display = display_list @items;
    return "$original_display",
        structured_answer => {

            data => {
                title    => "$shuffled_display",
                subtitle => "Shuffle: $original_display",
                # Useful for API
                items    => \@shuffled,
            },

            templates => {
                group => "text",
            }
        };
};

1;