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# Copyright (C) 2009-2021  Alex Schroeder <alex@gnu.org>
#
# This program is free software: you can redistribute it and/or modify it under
# the terms of the GNU Affero General Public License as published by the Free
# Software Foundation, either version 3 of the License, or (at your option) any
# later version.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
# details.
#
# You should have received a copy of the GNU Affero General Public License along
# with this program. If not, see <http://www.gnu.org/licenses/>.

=encoding utf8

=head1 NAME

Game::TextMapper::Schroeder::Square - a role for square map generators

=head1 SYNOPSIS

    # create a map
    package World;
    use Modern::Perl;
    use Mojo::Base -base;
    use Role::Tiny::With;
    with 'Game::TextMapper::Schroeder::Base';
    with 'Game::TextMapper::Schroeder::Square';
    # use it
    package main;
    my $map = World->new(height => 10, width => 10);

=head1 DESCRIPTION

This role provides basic functionality for map generation with square maps: the
number of neighbours within one or two regions distance, how to pick a random
neighbour direction, how to compute the coordinates of these neighbours, how to
draw arrows towards these neighbours.

This inherits attributes and methods from L<Game::TextMapper::Schroeder::Base>,
such as C<width> and C<height>.

=cut

package Game::TextMapper::Schroeder::Square;
use Modern::Perl '2018';
use Mojo::Base -role;

=head1 METHODS

=head2 reverse

Reverses a direction.

=cut

sub reverse {
  my ($self, $i) = @_;
  return ($i + 2) % 4;
}

=head2 neighbors

The list of directions for neighbours one step away (0 to 3).

=cut

sub neighbors { 0 .. 3 }

=head2 neighbors2

The list of directions for neighbours two steps away (0 to 7).

=cut

sub neighbors2 { 0 .. 7 }

=head2 random_neighbor

A random direction for a neighbour one step away (a random integer from 0 to 3).

=cut

sub random_neighbor { int(rand(4)) }

=head2 random_neighbor2

A random direction for a neighbour two steps away (a random integer from 0 to
7).

=cut

sub random_neighbor2 { int(rand(8)) }

my $delta_square = [[-1,  0], [ 0, -1], [+1,  0], [ 0, +1]];

=head2 neighbor($square, $i)

    say join(",", $map->neighbor("0203", 1));
    # 2,2

Returns the coordinates of a neighbor in a particular direction (0 to 3), one
step away.

C<$square> is an array reference of coordinates or a string that can be turned
into one using the C<xy> method from L<Game::TextMapper::Schroeder::Base>.