<?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\network\mcpe\compression;

use pocketmine\utils\SingletonTrait;
use pocketmine\utils\Utils;
use function function_exists;
use function libdeflate_deflate_compress;
use function strlen;
use function zlib_decode;
use function zlib_encode;
use const ZLIB_ENCODING_RAW;

final class ZlibCompressor implements ThresholdCompressor{
	use SingletonTrait;

	public const DEFAULT_LEVEL = 7;
	public const DEFAULT_THRESHOLD = 256;
	public const DEFAULT_MAX_DECOMPRESSION_SIZE = 2 * 1024 * 1024;

	/**
	 * @see SingletonTrait::make()
	 */
	private static function make() : self{
		return new self(self::DEFAULT_LEVEL, self::DEFAULT_THRESHOLD, self::DEFAULT_MAX_DECOMPRESSION_SIZE);
	}

	public function __construct(
		private int $level,
		private ?int $minCompressionSize,
		private int $maxDecompressionSize
	){}

	public function getCompressionThreshold() : ?int{
		return $this->minCompressionSize;
	}

	public function willCompress(string $data) : bool{
		return $this->minCompressionSize !== null && strlen($data) >= $this->minCompressionSize;
	}

	/**
	 * @throws DecompressionException
	 */
	public function decompress(string $payload) : string{
		$result = @zlib_decode($payload, $this->maxDecompressionSize);
		if($result === false){
			throw new DecompressionException("Failed to decompress data");
		}
		return $result;
	}

	private static function zlib_encode(string $data, int $level) : string{
		return Utils::assumeNotFalse(zlib_encode($data, ZLIB_ENCODING_RAW, $level), "ZLIB compression failed");
	}

	public function compress(string $payload) : string{
		if(function_exists('libdeflate_deflate_compress')){
			return $this->willCompress($payload) ?
				libdeflate_deflate_compress($payload, $this->level) :
				self::zlib_encode($payload, 0);
		}
		return self::zlib_encode($payload, $this->willCompress($payload) ? $this->level : 0);
	}
}