舞台选座位

舞台选座位-Gist

问题描述

某公司要在体育馆办一场晚会，体育馆由ABCD四个区域组成，区域之间由过道分割，每个区域第一排50个座位，隔排递增2个座位，最后一排为100个座位。

/**
 * 场景：
 * 某公司要在体育馆办一场晚会，体育馆由ABCD四个区域组成，
 * 区域之间由过道分割，每个区域第一排50个座位，隔排递增2个座位，
 * 最后一排为100个座位。
 *
 * 请您帮忙设计一个系统，解决以下需求点：
 * 1. 用户一次性可购买1~5张票
 * 2. 系统随机为用户分配座位
 */

/**
 * 舞台选座位
 */
class ChoiceSeat
{
    /**
     * @var int 第一排多少个座位，默认：50
     */
    private $baseSeatNumber = 50;
    /**
     * @var int 最后一排多少个座位，默认：100
     */
    private $lastSeatNumber = 100;
    /**
     * @var array 总递增座位编号集合
     */
    private $totalSeats = [];

    /**
     * @var string 总座位编号缓存文件
     */
    private static $cacheFilename = 'total-seats.bin';

    /**
     * ChoiceSeat constructor.
     */
    public function __construct()
    {
        $cache = $this->getTotalSeatsByCache();
        if (empty($cache)) {
            /**
             * 求出总共需要多少排
             * x=需要多少排，从0开始，隔排+2个座位。
             * 设方程式：50 + (x * 2) = 100 (一元一次方程)
             * 解：
             *   2x = 100 - 50
             *    x = 50/2
             */
            $baseSeatNumber = $this->getBaseSeatNumber();
            $lastSeatNumber = $this->getLastSeatNumber();
            if (empty($baseSeatNumber) || empty($lastSeatNumber)) {
                throw new Exception('第一排和最后一排座位数不能为空');
            }
            // 还需要 $x 排，总排数 $x + 1（第一排）
            $x = ($lastSeatNumber - $baseSeatNumber) / 2;

            $areas = ['A', 'B', 'C', 'D'];
            foreach ($areas as $areaCode) {
                // 区域的总递增座位编号
                $totalCounter = 1;
                for ($row = 0; $row < $x + 1; $row++) {
                    // 每排的座位编号范围（隔排+2）
                    $endSeatNumber = $baseSeatNumber + ($row * 2);
                    for ($j = 1; $j <= $endSeatNumber; $j++) {
                        // 总体座位编号：区域编号-排的编号-区域的总递增座位数
                        $uuid = sprintf("%s%'.04d%'.06d", $areaCode, ($row + 1), $totalCounter);
                        // 商品名称
                        $name = sprintf("%s区%s排%s号", $areaCode, ($row + 1), $j);

                        $this->addSeat([
                            'uuid' => $uuid,
                            'name' => $name,
                        ]);

                        $totalCounter ++;
                    }
                }
            }
            // 缓存到文件
            $totalSeats = $this->getTotalSeats();
            if (!empty($totalSeats)) {
                $cacheValue = serialize($totalSeats);
            } else {
                $cacheValue = serialize([]);
            }
            $handle = fopen(self::$cacheFilename, 'w');
            flock($handle, LOCK_EX);
            fwrite($handle, $cacheValue);
            flock($handle, LOCK_UN);
            fclose($handle);
        } else {
            $this->setTotalSeats($cache);
        }
    }

    /**
     * @return int
     */
    public function getBaseSeatNumber()
    {
        return $this->baseSeatNumber;
    }

    /**
     * @param int $baseSeatNumber
     *
     * @return $this
     */
    public function setBaseSeatNumber($baseSeatNumber)
    {
        $this->baseSeatNumber = $baseSeatNumber;
        return $this;
    }

    /**
     * @return int
     */
    public function getLastSeatNumber()
    {
        return $this->lastSeatNumber;
    }

    /**
     * @param int $lastSeatNumber
     *
     * @return $this
     */
    public function setLastSeatNumber($lastSeatNumber)
    {
        $this->lastSeatNumber = $lastSeatNumber;
        return $this;
    }

    /**
     * @return array
     */
    public function getTotalSeats()
    {
        return $this->totalSeats;
    }

    /**
     * @param array $totalSeats
     */
    public function setTotalSeats($totalSeats)
    {
        $this->totalSeats = $totalSeats;
    }

    /**
     * @param array $uuid
     */
    public function addSeat($uuid)
    {
        $this->totalSeats[] = $uuid;
    }

    /**
     * 获取连续的座位
     *
     * @param int $needNumber 需要多少个座位
     *
     * @return array
     */
    public function getSerialSeat($needNumber = 0)
    {
        // TODO 未实现
        return [];
    }

    /**
     * 获取系统随机分配的座位
     *
     * @param int $needNumber 需要多少个座位
     *
     * @return array
     */
    public function getRandomSeat($needNumber = 0)
    {
        $totalSeats = $this->getTotalSeats();
        if (empty($totalSeats)) {
            return [];
        }

        // 随机取出几个元素的键
        $return     = [];
        $randomKeys = array_rand($totalSeats, $needNumber);
        if (!empty($randomKeys)) {
            foreach ($randomKeys as $key) {
                if (isset($totalSeats[$key])) {
                    $return[] = $totalSeats[$key];
                }
            }
        }

        return $return;
    }

    /**
     * 获取总座位编号缓存
     *
     * @return array
     */
    private function getTotalSeatsByCache()
    {
        $cachaData = [];

        $handle = @fopen(self::$cacheFilename, 'r');
        if ($handle !== false) {
            flock($handle, LOCK_EX);
            $content = '';
            while (!feof($handle)) {
                $buffer = fgets($handle, 4096);
                $content .= $buffer;
            }
            flock($handle, LOCK_UN);
            fclose($handle);

            if (!empty($content)) {
                $array = unserialize($content);
                if ($array !== false) {
                    $cachaData = $array;
                }
            }
        }

        return $cachaData;
    }
}

$service = new ChoiceSeat();
//// 随机选择5个座位
//$output = $service->getRandomSeat(5);
//foreach ($output as $item) {
//    echo sprintf('编号：%s 商品：%s', $item['uuid'], $item['name']) . PHP_EOL;
//}
//die;


// !!! 探索增加筛选条件：比如：同一区域、同一排、座位号是否需要连续


//// 总编号集合
//$output = $service->getTotalSeats();
//foreach ($output as $item) {
//    echo sprintf('编号：%s 商品：%s', $item['uuid'], $item['name']) . PHP_EOL;
//}
//die;