Data::Page::FlickrLike - Generates flickr-like navigation links

    use Data::Page;
    use Data::Page::FlickrLike;

    my $page = Data::Page->new();
    $page->total_entries($total_entries);
    $page->entries_per_page($entries_per_page);
    $page->current_page($current_page);

    print join (" ",
            map { $_ == 0
              ? q{<span>...</span>}
              : qq{<a href="/page/$_">$_</a>}
            } $page->navigations);  

    # 1*2 3 4 5 6 7 ... 76 77
    # 1 2 ... 10 11 12 13*14 15 16 ... 76 77
    # 1 2 ... 71 72 73 74 75 76 77*
    # Note: * means the current page

package Data::Page::FlickrLike;

use warnings;
use strict;
use 5.008_001;

use Exporter::Lite;
use Data::Page;

our $VERSION = '2.00';

our @EXPORT = qw( navigations );

our $InnerWindow = 3;
our $OuterWindow = 2;
our $MinLength   = 7;
our $GlueLength  = 2;


sub _get_min_fill {
    my ($page, $first_page, $last_page, $min) = @_;
    my $length = $last_page - $first_page + 1 < $min
               ? $last_page - $first_page + 1
               : $min;

    my $current_length = scalar @$page;
    return $length - $current_length;
}

sub Data::Page::navigations {
    my ($self, $args) = @_;
    my $nav;
    my $prev_skip = 1;
    my $next_skip = 1;

    my $inner = exists $args->{inner_window}
      ? $args->{inner_window}
      : $Data::Page::FlickrLike::InnerWindow;
    my $outer = exists $args->{outer_window}
      ? $args->{outer_window}
      : $Data::Page::FlickrLike::OuterWindow;
    my $min = exists $args->{min_length}
      ? $args->{min_length}
      : $Data::Page::FlickrLike::MinLength;
    my $glue_length = exists $args->{glue_length}
      ? $args->{glue_length}
      : $Data::Page::FlickrLike::GlueLength;

    my $current_page = $self->current_page;
    my $last_page    = $self->last_page;
    my $first_page   = $self->first_page;

    ## build the pages around current_page to begin with
    for (my $i = $current_page - $inner; $i <= $current_page + $inner ; $i++) {
        push @$nav, $i if $i >= $first_page && $i <= $last_page;
    }

    ## shortcut if we already take all the room
    if ($nav->[0] == $first_page && $nav->[-1] == $last_page) {
        return wantarray ? @$nav : $nav;
    }

    ## NOTE: there are some extra operations in there just in case $first_page != 1
    ## but, this shouldn't really be necessary...

    if ($nav->[0] == $first_page && $nav->[-1] != $last_page) {
        ## we're stuck at the beginning, check for $min_lengh
        my $min_fill = _get_min_fill($nav, $first_page, $last_page, $min);
        my $last = $nav->[-1];
        push @$nav, map { $last + $_ } (1 .. $min_fill);
    }

    ## stuck at the end: fill the beginning using $min_length
    elsif ($nav->[0] != $first_page && $nav->[-1] == $last_page) {
        my $min_fill = _get_min_fill($nav, $first_page, $last_page, $min);
        my $first = $nav->[0];
        unshift @$nav, reverse map { $first - $_ } (1 .. $min_fill);
    }

    ## now, care about extremities specifically
    my (@begin, @end);
    for (0 .. ($outer - 1)) {
        push @begin, $first_page + $_;
        push @end,   $last_page  - $_;
    }
    @end = reverse @end;

    ## we might need some glue
    if ($begin[-1] < $nav->[0] - 1) {
        my $to_glue = $nav->[0] - $begin[-1] - 1;
        if ($to_glue <= $glue_length) {
            ## we can glue!
            my $last = $begin[-1];
            push @begin, map { $last + $_ } (1 .. $to_glue);

        }
        else {
            push @begin, 0;
        }
    }
    if ($end[0] > $nav->[-1] + 1) {
        my $to_glue = $end[0] - $nav->[-1] - 1;
        if ($to_glue <= $glue_length) {
            ## we can glue!
            my $first = $end[0];
            unshift @end, reverse map { $first - $_ } (1 .. $to_glue);
        }
        else {
            unshift @end, 0;
        }
    }

    ## trim redundant items if they exist
    while (@begin && $begin[-1] >= $nav->[0]) {
        pop @begin;
    };
    while (@end && $end[0] && $end[0] <= $nav->[-1]) {
        shift @end;
    };

    $nav = [ @begin, @$nav, @end ];

    return wantarray ? @$nav : $nav;
}

1; # Magic true value required at end of module
__END__