<?php

class ShoppingCart implements ArrayAccess, Iterator  {
	
	private $data = [];
		
	public function add(string $name, int $count = 1) {
		if (isset($this->data[$name])) {
			$this->data[$name] += $count;
		} else {
			$this->data[$name] = $count;
		}
	}
	
	public function remove(string $name) {
		if (!isset($this->data[$name])) {
			return;
		}
		unset($this->data[$name]);
	}
	
	public function __toString() {
		$lines = ['Content:'];
		foreach ($this->data as $name => $count) {
			$lines[] = "  $name : $count";
		}		
		$lines[] = '';
		return implode("\n", $lines);
	}
	
	// Exercise 2
		
	public function offsetExists($offset): bool {
		return isset($this->data[$offset]);
	}
	
	public function &offsetGet($offset) {
		return $this->data[$offset];
	}

	public function offsetSet($offset, $value): void {
		$this->data[$offset] = $value;
	}
	
	public function offsetUnset($offset): void {
		if (!isset($this->data[$offset])) {
			return;
		}
		unset($this->data[$offset]);
	}
	
	//

	private $position = null;

	public function current() {
		return $this->data[$this->position];
	}
	
	public function key() {
		return $this->position;
	}
	
	public function next(){
		next($this->data);
		$this->position = key($this->data);
	}
	
	public function rewind() {
		reset($this->data);		
		$this->position = key($this->data);
	}
	
	public function valid() {
		return isset($this->data[$this->position]);
	}
	
}

// Exercise 1 

$cart = new ShoppingCart();
$cart->add('milk', 1);
$cart->add('bread', 1);
$cart->add('basil', 1);
$cart->add('milk', 1);
$cart->remove('basil');
print($cart);

// Exercise 2

print("Content:\n");
$cart['apple'] = 2;
++$cart['apple'];
foreach($cart as $name => $count) {
	print( "  $name : $count\n");
}