<?php

/*

 * This file is part of the Symfony package.

 *

 * (c) Fabien Potencier <fabien@symfony.com>

 *

 * For the full copyright and license information, please view the LICENSE

 * file that was distributed with this source code.

 */

namespace Symfony\Component\Translation;

/**

 * Tests if a given number belongs to a given math interval.

 *

 * An interval can represent a finite set of numbers:

 *

 *  {1,2,3,4}

 *

 * An interval can represent numbers between two numbers:

 *

 *  [1, +Inf]

 *  ]-1,2[

 *

 * The left delimiter can be [ (inclusive) or ] (exclusive).

 * The right delimiter can be [ (exclusive) or ] (inclusive).

 * Beside numbers, you can use -Inf and +Inf for the infinite.

 *

 * @see http://en.wikipedia.org/wiki/Interval_%28mathematics%29#The_ISO_notation

 *

 * @author Fabien Potencier <fabien@symfony.com>

 */

class Interval

{

    /**

     * Tests if the given number is in the math interval.

     *

     * @param integer $number   A number

     * @param string  $interval An interval

     */

    static public function test($number, $interval)

    {

        $interval = trim($interval);

        if (!preg_match('/^'.self::getIntervalRegexp().'$/x', $interval, $matches)) {

            throw new \InvalidArgumentException(sprintf('"%s" is not a valid interval.', $interval));

        }

        if ($matches[1]) {

            foreach (explode(',', $matches[2]) as $n) {

                if ($number == $n) {

                    return true;

                }

            }

        } else {

            $leftNumber = self::convertNumber($matches['left']);

            $rightNumber = self::convertNumber($matches['right']);

            return

                ('[' === $matches['left_delimiter'] ? $number >= $leftNumber : $number > $leftNumber)

                && (']' === $matches['right_delimiter'] ? $number <= $rightNumber : $number < $rightNumber)

            ;

        }

        return false;

    }

    /**

     * Returns a Regexp that matches valid intervals.

     *

     * @return string A Regexp (without the delimiters)

     */

    static public function getIntervalRegexp()

    {

        return <<<EOF

        ({\s*

            (\-?\d+[\s*,\s*\-?\d+]*)

        \s*})

            |

        (?<left_delimiter>[\[\]])

            \s*

            (?<left>-Inf|\-?\d+)

            \s*,\s*

            (?<right>\+?Inf|\-?\d+)

            \s*

        (?<right_delimiter>[\[\]])

EOF;

    }

    static private function convertNumber($number)

    {

        if ('-Inf' === $number) {

            return log(0);

        } elseif ('+Inf' === $number || 'Inf' === $number) {

            return -log(0);

        }

        return (int) $number;

    }

}