Commodity Market Lite

Main.php

<?php
/** Created By Thunder33345 **/
namespace Thunder33345\CommodityMarketLite;

use pocketmine\event\Listener;
use pocketmine\plugin\PluginBase;

class Main extends PluginBase implements Listener
{
	private $market;
	public function onLoad()
	{
	}

	public function onEnable()
	{
		//$this->getServer()->getPluginManager()->registerEvents($this, $this);
		//$this->getServer()->getPluginManager()->registerEvents(new Market($this), $this);
		$this->market = new Market($this);
	}

	public function onDisable()
	{
	}
}

Market.php

<?php
/** Created By Thunder33345 **/
namespace Thunder33345\CommodityMarketLite;

use onebone\economyapi\EconomyAPI;
use pocketmine\event\Listener;
use pocketmine\event\player\PlayerInteractEvent;
use pocketmine\item\Item;
use pocketmine\math\Vector3;
use pocketmine\tile\Sign;
use pocketmine\utils\TextFormat;

class Market implements Listener
{
	private $main, $priceHandler, $api, $tax = 100;

	public function __construct(Main $main)
	{
		$main->getServer()->getPluginManager()->registerEvents($this, $main);
		$this->main = $main;
		$this->priceHandler = new PriceHandler($main, $this);
		$this->api = EconomyAPI::getInstance();
	}

	public function updateSign()
	{
		$sp = $this->priceHandler->getPrice() - $this->tax;
		$bp = $this->priceHandler->getPrice() + $this->tax;
		$main = $this->main;
		$lv = $main->getServer()->getDefaultLevel();
		foreach ($lv->getTiles() as $tile) {
			$tile = $lv->getBlock(new Vector3($tile->getBlock()->getFloorX(), $tile->getBlock()->getFloorY(), $tile->getFloorZ()));
			if ($tile instanceof Sign) {
				$line1 = TextFormat::clean($tile->getText()[0], true);
				if ($line1 == '[Stock] Info') {
					$tile->setText('[Stock] Info','Stocks Remaining: '.'"'.$this->priceHandler->getAmount().'"','Sell Price: '.'"'.$sp.'"','Buy Price: '.'"'.$bp.'"');
				} elseif ($line1 == '[Stock] Buy') {
					$tile->setText('[Stock] Buy',"Buy Price: ".'"'.$bp.'"');
				} elseif ($line1 == '[Stock Sell]') {
					$tile->setText('[Stock] Sell',"Sell Price: ".'"'.$sp.'"');
				}
			}
		}
	}

	public function onSignClick(PlayerInteractEvent $event)
	{
		$tile = $event->getBlock()->getLevel()->getTile(new Vector3($event->getBlock()->getFloorX(), $event->getBlock()->getFloorY(), $event->getBlock()->getFloorZ()));
		if ($tile instanceof Sign) {
			$line1 = TextFormat::clean($tile->getText()[0], true);
			$p = $event->getPlayer();
			$bp = $this->priceHandler->getPrice() + $this->tax;
			$sp = $this->priceHandler->getPrice() - $this->tax;

			if ($line1 == "[Stock] Info") {
				$event->setCancelled(true);
				$p->sendMessage('Buy Price is ' . $bp . ' Sell Price is: ' . $sp . ' Stock remaining: ' . $this->priceHandler->getAmount());
			} elseif ($line1 == "[Stock] Buy") {

				$event->setCancelled(true);
				$this->priceHandler->reduceAmount();
				$this->api->reduceMoney($p->getName(), $bp);
				$p->getInventory()->addItem(Item::get(49, 0, 1));
				$p->sendMessage('You bought obsidian form the market for ' . $bp);
			} elseif ($line1 == "[Stock] Sell") {
				$event->setCancelled(true);
				if ($p->getInventory()->contains(Item::get(49, 0, 1))) {
					$p->getInventory()->remove(Item::get(49, 0, 1));
					$this->priceHandler->increaseAmount();
					$this->api->addMoney($p->getName(), $sp);
					$p->sendMessage('You sold obsidian to the market for ' . $sp);
				}
			}
		}
	}
}

PriceHandler.php

<?php
/** Created By Thunder33345 **/
namespace Thunder33345\CommodityMarketLite;
class PriceHandler
{
	private $main, $market;

	private static $equilibriumPrice = 100, $equilibriumAmount = 50;
	private static $differencesAmount = 5, $differencesPrice = 5.5;
  //i didnt learned about liquiditity and so on
	private $amount = 1, $price = 1;

	public function __construct(Main $main, Market $market, $amount = null)
	{
		$this->main = $main;
		$this->market = $market;
		if ($amount === null) {
			$this->amount = 50;
		}
		$this->recalculate();
	}

	private function recalculate()
	{
		$equilibriumPrice = $this::$equilibriumPrice;
		$equilibriumAmount = $this::$equilibriumAmount;
		$differencesAmount = $this::$differencesAmount;
		$differencesPrice = $this::$differencesPrice;
		$currentAmount = $this->amount;

		$differences = $equilibriumAmount - $currentAmount;
		$differences = $differences / $differencesAmount;
		$differences = $differences * $differencesPrice;
		$finalePrice = $equilibriumPrice + $differences;
		$this->price = $finalePrice;
		$this->market->updateSign();
	}

	public function reduceAmount($amount = 1)
	{
		$this->amount = $this->amount - $amount;
		$this->recalculate();
	}

	public function increaseAmount($amount = 1)
	{
		$this->amount = $this->amount + $amount;
		$this->recalculate();
	}

	public function setAmount($amount)
	{
		$this->amount = $amount;
		$this->recalculate();
	}

	public function getInfo()
	{
		$return = [
			"price" => $this->getPrice(),
			"amount" => $this->getAmount()
		];
		return $return;
	}

	public function getPrice()
	{
		return $this->price;
	}

	public function getAmount()
	{
		return $this->amount;
	}
}

Some old code i wrote for a dynamic market that changes price based on demand