<?php

abstract class Model
{

    /** @var DatabazovaTrida */
    protected $db;

    /**
     * @param DatabazovaTrida
     */
    public function __construct($db)
    {
        $this->db = $db;
    }

}

class Player extends Model
{

    /** @var int */
    private $id;

    /** @var int|NULL */
    private $money = NULL;


    /**
     * @param int
     * @param DatabazovaTrida
     */
    public function __construct($id, $db)
    {
        parent::__construct($db);
        $this->id = $id;
    }


    /**
     * @return int
     */
    public function getId()
    {
        return $this->id;
    }


    /**
     * @return int
     */
    public function getMoney()
    {
        if ($this->money === NULL) {
            $this->money = $this->db->fetchColumn("
                SELECT money
                FROM player
                WHERE id = ?
                LIMIT 1
            ", $this->id);
        }

        return $this->money;
    }


    /**
     * @param int
     * @throws Exception
     */
    public function subtractMoney($num)
    {
        if ($this->getMoney() - $num < 0) {
            throw new Exception("nemáš dostatek peněz");
        }

        $this->db->query("
            UPDATE player
            SET money = money - ?
            WHERE id = ?
        ", $num, $this->id);
        $this->money -= $num;
    }


    /**
     * @param int
     */
    public function addMoney($num)
    {
        $this->db->query("
            UPDATE player
            SET money = money + ?
            WHERE id = ?
        ", $num, $this->id);
        $this->money += $num;
    }

}

class Item extends Model
{

    /** @var int */
    private $id;

    /** @var array */
    private $data = array();


    /**
     * @param int
     * @param DatabazovaTrida
     */
    public function __construct($id, $db)
    {
        parent::__construct($db);
        $this->id = $id;
    }


    /**
     * @return array
     */
    public function getData()
    {
        if (empty($this->data)) {
            $this->data = $this->db->fetch("
                SELECT ownerId, name, price
                FROM item
                WHERE id = ?
                LIMIT 1
            ", $this->id);
        }

        return $this->data;
    }


    /**
     * @param string
     * @return int|string
     */
    public function __get($key)
    {
        return $this->getData()[$key];
    }


    /**
     * @param Player
     */
    public function changeOwner(Player $owner)
    {
        $newOwnerId = $owner->getId();
        $this->db->query("
            UPDATE item
            SET ownerId = ?
            WHERE id = ? AND ownerId = ?
        ", $newOwnerId, $this->id, $this->data["ownerId"]);

        $this->data["owner"] = $newOwnerId;
    }

}

class PlayerFactory
{

    /** @var DatabazovaTrida */
    private $db;


    /**
     * @param DatabazovaTrida
     */
    public function __construct($db)
    {
        $this->db = $db;
    }


    /**
     * @param int
     */
    function create($id)
    {
        return new Player($id, $this->db);
    }

}

class ItemFactory
{

    /** @var DatabazovaTrida */
    private $db;


    /**
     * @param DatabazovaTrida
     */
    public function __construct($db)
    {
        $this->db = $db;
    }


    /**
     * @param int
     */
    public function create($id)
    {
        return new Item($id, $this->db);
    }

}

abstract class Relation
{

    /** @var array */
    private $classes = array();

    /** @var DatabazovaTrida */
    protected $db;


    /**
     * @param DatabazovaTrida
     */
    public function __construct($db)
    {
        $this->db = $db;
    }


    /**
     * @param string
     * @param mixed
     */
    function __set($k, $v)
    {
        $this->classes[$k] = $v;
    }


    /**
     * @param string
     * @return mixed
     */
    function __get($k)
    {
        return $this->classes[$k];
    }


}


class RelationPlayerItem extends Relation
{


    /**
     * Provede transakci při koupi předmětu
     */
    function buyItem()
    {
        $this->db->beginTransaction();
        $this->player->subtractMoney($item->price);  // vyhodí výjimku, pokud nemá hráč dostatek peněz
        $this->item->changeOwner($this->player);
        $this->owner->addMoney($item->price);
        $this->db->commit();
    }


}


class Presenter
{

    // objekty $playerFactory a $itemFactory umí Nette automaticky vytvořit, když je potřeba,
    // a předat jim databázové spojení podle konfiguračního souboru

    /** @var PlayerFactory */
    private $playerFactory;

    /** @var ItemFactory */
    private $itemFactory;

    /** @var Player */
    protected $player;

    // startup se zavolá jako první a slouží pro inicializaci vlastnostní
    public function startup()
    {
        // $this->user->id je v Nette ID přihlášeného uživatele
        $this->player = $this->playerFactory->create($this->user->id);
    }


    /**
     * @param string
     * @return object
     */
    private function createRelation($name)
    {
        $class = "Relation" . ucFirst($name);

        // $this->context je instance DI containeru
        // metoda getService() vrátí objekt reprezentující databázové spojení
        return new $class($this->context->getService("db"));
    }


    /**
     * @param int
     */
    public function handleBuyItem($id)
    {
        $item = $this->itemFactory->create($id);
        $ownerId = $item->getData()->ownerId;

        // relace nyní obsahuje objekty kupujícího hráče, vlastníka předmětu a samotný předmět
        $relation = $this->createRelation("playerItem");
        $relation->player = $this->player;
        $relation->item = $item;
        $relation->owner = $this->playerFactory->create($ownerId);

        try {
            $relation->buyItem();
        } catch (Exception $e) {
            $this->flashMessage($e->getMessage());  // zpráva, která se poté objeví na stránce
            $this->redirect("default");
        }
    }
}