<?php

/*
 *
 *  ____            _        _   __  __ _                  __  __ ____
 * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
 * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
 * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
 * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * @author PocketMine Team
 * @link http://www.pocketmine.net/
 *
 *
*/

declare(strict_types=1);

namespace pocketmine\level\generator\biome;

use pocketmine\level\biome\Biome;
use pocketmine\level\biome\UnknownBiome;
use pocketmine\level\generator\noise\Simplex;
use pocketmine\utils\Random;

abstract class BiomeSelector{
	/** @var Simplex */
	private $temperature;
	/** @var Simplex */
	private $rainfall;

	/** @var Biome[]|\SplFixedArray */
	private $map = null;

	public function __construct(Random $random){
		$this->temperature = new Simplex($random, 2, 1 / 16, 1 / 512);
		$this->rainfall = new Simplex($random, 2, 1 / 16, 1 / 512);
	}

	/**
	 * Lookup function called by recalculate() to determine the biome to use for this temperature and rainfall.
	 *
	 * @return int biome ID 0-255
	 */
	abstract protected function lookup(float $temperature, float $rainfall) : int;

	/**
	 * @return void
	 */
	public function recalculate(){
		$this->map = new \SplFixedArray(64 * 64);

		for($i = 0; $i < 64; ++$i){
			for($j = 0; $j < 64; ++$j){
				$biome = Biome::getBiome($this->lookup($i / 63, $j / 63));
				if($biome instanceof UnknownBiome){
					throw new \RuntimeException("Unknown biome returned by selector with ID " . $biome->getId());
				}
				$this->map[$i + ($j << 6)] = $biome;
			}
		}
	}

	/**
	 * @param float $x
	 * @param float $z
	 *
	 * @return float
	 */
	public function getTemperature($x, $z){
		return ($this->temperature->noise2D($x, $z, true) + 1) / 2;
	}

	/**
	 * @param float $x
	 * @param float $z
	 *
	 * @return float
	 */
	public function getRainfall($x, $z){
		return ($this->rainfall->noise2D($x, $z, true) + 1) / 2;
	}

	/**
	 * @param int $x
	 * @param int $z
	 */
	public function pickBiome($x, $z) : Biome{
		$temperature = (int) ($this->getTemperature($x, $z) * 63);
		$rainfall = (int) ($this->getRainfall($x, $z) * 63);

		return $this->map[$temperature + ($rainfall << 6)];
	}
}