<?php
/**
 * Represent the player's Inventory.
 * Implemented as a singleton in the session.
 *
 * @package inc\Inventory.inc
 * @author     Alexandre Renoux
 * @author     Pierre-Emmanuel Novac
 */
class Inventory {
	/**
	 * @var array  Arrays of array with Item object and Item's count as int
	 */
	public $items = array();

	/**
	 * Checks if the Inventory was already created in the session
	 * 
	 * @return boolean  true if Inventory was already created, false otherwise
	 */
	public static function created() {
		return !empty($_SESSION["inventory"]);
	}

	/**
	 * Returns the Inventory's content from the session.
	 * 
	 * @return array  array of Items and number
	 */
	public static function sendContent() {
		return self::get()->items;
	}

	/**
	 * Returns the Inventory from the session.
	 * Implements the singleton pattern.
	 * 
	 * @return Inventory  the Inventory object
	 */
	public static function get() {
		if(!self::created()) {
			$_SESSION["inventory"] = new Inventory();
		}
		return $_SESSION["inventory"];
	}

	/**
	 * Adds an Item object to the Inventory, incrementing the Item's count if it was already present.
	 * 
	 * @param Item $item  Item to add to the Inventory
	 * @return array  Item and Item's count
	 */
	private function _addItem($item) {
		foreach($this->items as $k => $object){
			if($object[0] == $item){
				$this->items[$k][1]++;
				return $this->items[$k];
			}
		}
		$tab = array($item,1);
		$this->items[] = $tab;
		return $tab;
	}

	/**
	 * Adds an Item object to the singleton's Inventory from session.
	 * 
	 * @param Item $item  Item to add to the Inventory
	 * @return array  Item and Item's count
	 */
	public static function addItem($item) {
		$inv = self::get();
		$tab = $inv->_addItem($item);
		return $tab;
	}

	/**
	 * Removes an Item object from the Inventory, not taking into account the Item's count.
	 * 
	 * @param Item $item  Item to remove from the Inventory
	 * @return void
	 */
	private function _removeItem($item) {
		foreach($this->items as $k => $object) {
			if($object[0] == $item) {
				unset($this->items[$k]);
				return;
			}
		}
	}

	/**
	 * Removes an Item object to the singleton's Inventory from session, not taking into account the Item's count.
	 * 
	 * @param Item $item  Item to remove from the Inventory
	 * @return void
	 */
	public static function removeItem($item) {
		$inv = self::get();
		$inv->_removeItem($item);
	}

	/**
	 * Consumes an Item object from the Inventory, decrementing the Item's count and removing it if count reaches 0.
	 * 
	 * @param Item $item  Item to consume from the Inventory
	 * @return array|false  Item and updated Item's count, false if it was not found
	 */
	private function _useItem($item) {
		foreach($this->items as $k => $object){
			if($object[0] == $item) {
				$nb = $this->items[$k][1];
				if($nb > 0) {
					$this->items[$k][0]->consume();
					$this->items[$k][1]--;
				}
				if($nb-1 <= 0) $this->_removeItem($item);
				return array($object[0], $nb-1);
			}
		}
		return false;
	}

	/**
	 * Consumes an Item object to the singleton's Inventory from session, decrementing the Item's count and removing it if count reaches 0.
	 * 
	 * @param Item $item  Item to consume from the Inventory
	 * @return array|false  Item and updated Item's count, false if it was not found
	 */
	public static function useItem($item) {
		$inv = self::get();
		$it = $inv->_useItem($item);
		return $it;
	}

	/**
	 * Generates an XML tree describing the Inventory
	 *
	 * @param SimpleXMLElement $root  root XML element to add the Inventory's Items to
	 * @return void
	 */
	public function addToXML($root) {
		foreach($this->items as $item)
			$item[0]->addToXML($root, $item[1]);
	}
}

?>