<?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\world\generator;

use pocketmine\data\bedrock\BiomeIds;
use pocketmine\scheduler\AsyncTask;
use pocketmine\utils\AssumptionFailedError;
use pocketmine\world\format\BiomeArray;
use pocketmine\world\format\Chunk;
use pocketmine\world\format\io\FastChunkSerializer;
use pocketmine\world\SimpleChunkManager;
use pocketmine\world\World;
use function intdiv;

class PopulationTask extends AsyncTask{
	private const TLS_KEY_WORLD = "world";

	/** @var int */
	public $worldId;
	/** @var int */
	private $chunkX;
	/** @var int */
	private $chunkZ;

	/** @var string|null */
	public $chunk;

	/** @var string|null */
	public $chunk0;
	/** @var string|null */
	public $chunk1;
	/** @var string|null */
	public $chunk2;
	/** @var string|null */
	public $chunk3;

	//center chunk

	/** @var string|null */
	public $chunk5;
	/** @var string|null */
	public $chunk6;
	/** @var string|null */
	public $chunk7;
	/** @var string|null */
	public $chunk8;

	public function __construct(World $world, int $chunkX, int $chunkZ, ?Chunk $chunk){
		$this->worldId = $world->getId();
		$this->chunkX = $chunkX;
		$this->chunkZ = $chunkZ;
		$this->chunk = $chunk !== null ? FastChunkSerializer::serializeTerrain($chunk) : null;

		foreach($world->getAdjacentChunks($chunkX, $chunkZ) as $i => $c){
			$this->{"chunk$i"} = $c !== null ? FastChunkSerializer::serializeTerrain($c) : null;
		}

		$this->storeLocal(self::TLS_KEY_WORLD, $world);
	}

	public function onRun() : void{
		$context = ThreadLocalGeneratorContext::fetch($this->worldId);
		if($context === null){
			throw new AssumptionFailedError("Generator context should have been initialized before any PopulationTask execution");
		}
		$generator = $context->getGenerator();
		$manager = new SimpleChunkManager($context->getWorldMinY(), $context->getWorldMaxY());

		/** @var Chunk[] $chunks */
		$chunks = [];

		$chunk = $this->chunk !== null ? FastChunkSerializer::deserializeTerrain($this->chunk) : null;

		for($i = 0; $i < 9; ++$i){
			if($i === 4){
				continue;
			}
			$ck = $this->{"chunk$i"};
			if($ck === null){
				$chunks[$i] = null;
			}else{
				$chunks[$i] = FastChunkSerializer::deserializeTerrain($ck);
			}
		}

		self::setOrGenerateChunk($manager, $generator, $this->chunkX, $this->chunkZ, $chunk);

		$resultChunks = []; //this is just to keep phpstan's type inference happy
		foreach($chunks as $i => $c){
			$cX = (-1 + $i % 3) + $this->chunkX;
			$cZ = (-1 + intdiv($i, 3)) + $this->chunkZ;
			$resultChunks[$i] = self::setOrGenerateChunk($manager, $generator, $cX, $cZ, $c);
		}
		$chunks = $resultChunks;

		$generator->populateChunk($manager, $this->chunkX, $this->chunkZ);
		$chunk = $manager->getChunk($this->chunkX, $this->chunkZ);
		if($chunk === null){
			throw new AssumptionFailedError("We just generated this chunk, so it must exist");
		}
		$chunk->setPopulated();

		$this->chunk = FastChunkSerializer::serializeTerrain($chunk);

		foreach($chunks as $i => $c){
			$this->{"chunk$i"} = $c->isTerrainDirty() ? FastChunkSerializer::serializeTerrain($c) : null;
		}
	}

	private static function setOrGenerateChunk(SimpleChunkManager $manager, Generator $generator, int $chunkX, int $chunkZ, ?Chunk $chunk) : Chunk{
		$manager->setChunk($chunkX, $chunkZ, $chunk ?? new Chunk([], BiomeArray::fill(BiomeIds::OCEAN), false));
		if($chunk === null){
			$generator->generateChunk($manager, $chunkX, $chunkZ);
			$chunk = $manager->getChunk($chunkX, $chunkZ);
			if($chunk === null){
				throw new AssumptionFailedError("We just set this chunk, so it must exist");
			}
			$chunk->setTerrainDirtyFlag(Chunk::DIRTY_FLAG_TERRAIN, true);
			$chunk->setTerrainDirtyFlag(Chunk::DIRTY_FLAG_BIOMES, true);
		}
		return $chunk;
	}

	public function onCompletion() : void{
		/** @var World $world */
		$world = $this->fetchLocal(self::TLS_KEY_WORLD);
		if($world->isLoaded()){
			$chunk = $this->chunk !== null ? FastChunkSerializer::deserializeTerrain($this->chunk) : null;

			for($i = 0; $i < 9; ++$i){
				if($i === 4){
					continue;
				}
				$c = $this->{"chunk$i"};
				if($c !== null){
					$xx = -1 + $i % 3;
					$zz = -1 + intdiv($i, 3);

					$c = FastChunkSerializer::deserializeTerrain($c);
					$world->generateChunkCallback($this->chunkX + $xx, $this->chunkZ + $zz, $c);
				}
			}

			$world->generateChunkCallback($this->chunkX, $this->chunkZ, $chunk);
		}
	}
}