<?php
/*
* This file is part of sebastian/comparator.
*
* (c) Sebastian Bergmann <sebastian@phpunit.de>
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/

namespace SebastianBergmann\Comparator;

/**
* Factory for comparators which compare values for equality.
*/
class Factory
{
/**
* @var Comparator[]
*/
private $customComparators = [];

/**
* @var Comparator[]
*/
private $defaultComparators = [];

/**
* @var Factory
*/
private static $instance;

/**
* @return Factory
*/
public static function getInstance()
{
if (self::$instance === null) {
self::$instance = new self;
}

return self::$instance;
}

/**
* Constructs a new factory.
*/
public function __construct()
{
$this->registerDefaultComparators();
}

/**
* Returns the correct comparator for comparing two values.
*
* @param mixed $expected The first value to compare
* @param mixed $actual The second value to compare
*
* @return Comparator
*/
public function getComparatorFor($expected, $actual)
{
foreach ($this->customComparators as $comparator) {
if ($comparator->accepts($expected, $actual)) {
return $comparator;
}
}

foreach ($this->defaultComparators as $comparator) {
if ($comparator->accepts($expected, $actual)) {
return $comparator;
}
}
}

/**
* Registers a new comparator.
*
* This comparator will be returned by getComparatorFor() if its accept() method
* returns TRUE for the compared values. It has higher priority than the
* existing comparators, meaning that its accept() method will be invoked
* before those of the other comparators.
*
* @param Comparator $comparator The comparator to be registered
*/
public function register(Comparator $comparator)
{
\array_unshift($this->customComparators, $comparator);

$comparator->setFactory($this);
}

/**
* Unregisters a comparator.
*
* This comparator will no longer be considered by getComparatorFor().
*
* @param Comparator $comparator The comparator to be unregistered
*/
public function unregister(Comparator $comparator)
{
foreach ($this->customComparators as $key => $_comparator) {
if ($comparator === $_comparator) {
unset($this->customComparators[$key]);
}
}
}

/**
* Unregisters all non-default comparators.
*/
public function reset()
{
$this->customComparators = [];
}

private function registerDefaultComparators()
{
$this->registerDefaultComparator(new TypeComparator);
$this->registerDefaultComparator(new ScalarComparator);
$this->registerDefaultComparator(new NumericComparator);
$this->registerDefaultComparator(new DoubleComparator);
$this->registerDefaultComparator(new ArrayComparator);
$this->registerDefaultComparator(new ResourceComparator);
$this->registerDefaultComparator(new ObjectComparator);
$this->registerDefaultComparator(new ExceptionComparator);
$this->registerDefaultComparator(new SplObjectStorageComparator);
$this->registerDefaultComparator(new DOMNodeComparator);
$this->registerDefaultComparator(new MockObjectComparator);
$this->registerDefaultComparator(new DateTimeComparator);
}

private function registerDefaultComparator(Comparator $comparator)
{
\array_unshift($this->defaultComparators, $comparator);

$comparator->setFactory($this);
}
}