<?php
/*
* This file is part of PHPUnit.
*
* (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 PHPUnit\Framework\Constraint;

use Countable;
use PHPUnit\Framework\ExpectationFailedException;
use PHPUnit\Framework\SelfDescribing;
use SebastianBergmann\Comparator\ComparisonFailure;
use SebastianBergmann\Exporter\Exporter;

/**
* Abstract base class for constraints which can be applied to any value.
*/
abstract class Constraint implements Countable, SelfDescribing
{
protected $exporter;

public function __construct()
{
$this->exporter = new Exporter;
}

/**
* Evaluates the constraint for parameter $other
*
* If $returnResult is set to false (the default), an exception is thrown
* in case of a failure. null is returned otherwise.
*
* If $returnResult is true, the result of the evaluation is returned as
* a boolean value instead: true in case of success, false in case of a
* failure.
*
* @param mixed $other Value or object to evaluate.
* @param string $description Additional information about the test
* @param bool $returnResult Whether to return a result or throw an exception
*
* @return mixed
*
* @throws ExpectationFailedException
*/
public function evaluate($other, $description = '', $returnResult = false)
{
$success = false;

if ($this->matches($other)) {
$success = true;
}

if ($returnResult) {
return $success;
}

if (!$success) {
$this->fail($other, $description);
}
}

/**
* Evaluates the constraint for parameter $other. Returns true if the
* constraint is met, false otherwise.
*
* This method can be overridden to implement the evaluation algorithm.
*
* @param mixed $other Value or object to evaluate.
*
* @return bool
*/
protected function matches($other)
{
return false;
}

/**
* Counts the number of constraint elements.
*
* @return int
*/
public function count()
{
return 1;
}

/**
* Throws an exception for the given compared value and test description
*
* @param mixed $other Evaluated value or object.
* @param string $description Additional information about the test
* @param ComparisonFailure $comparisonFailure
*
* @throws ExpectationFailedException
*/
protected function fail($other, $description, ComparisonFailure $comparisonFailure = null)
{
$failureDescription = \sprintf(
'Failed asserting that %s.',
$this->failureDescription($other)
);

$additionalFailureDescription = $this->additionalFailureDescription($other);

if ($additionalFailureDescription) {
$failureDescription .= "\n" . $additionalFailureDescription;
}

if (!empty($description)) {
$failureDescription = $description . "\n" . $failureDescription;
}

throw new ExpectationFailedException(
$failureDescription,
$comparisonFailure
);
}

/**
* Return additional failure description where needed
*
* The function can be overridden to provide additional failure
* information like a diff
*
* @param mixed $other Evaluated value or object.
*
* @return string
*/
protected function additionalFailureDescription($other)
{
return '';
}

/**
* Returns the description of the failure
*
* The beginning of failure messages is "Failed asserting that" in most
* cases. This method should return the second part of that sentence.
*
* To provide additional failure information additionalFailureDescription
* can be used.
*
* @param mixed $other Evaluated value or object.
*
* @return string
*/
protected function failureDescription($other)
{
return $this->exporter->export($other) . ' ' . $this->toString();
}
}