Parking Spot

设计一个停车场
这道题让我们实现一个停车位的数据结构，由于题目没给任何多余的信息，所>以自由度很大，比如能停放什么种类的车，或是否是多层的等等。根据书中描>述，这里我们做如下假设：

1. 停车场有多层，每层有多行停车位
2. 停车场可以停摩托车，小轿车和公交车
3. 停车场有摩托车位，紧凑型车位，和大型车位
4. 摩托车可以停在任何位置
5. 小轿车可以停在紧凑型车位和大型车位
6. 公交车只能停在同一行中连续的五个大型车位上，不能停在小位置上

• 停车位ParkingSpot类,一个停车场ParkLot由多个停车层Level组成，一个Level由多个ParkingSpot组成
• 基类Vehicle,机动车，可以被继承，具体实例化为motocycle,car,truck
  大小，需要的停车位，停车入库，是否合适这个spot
• 停车层Level类，ParkingSpot类的集合
  还剩多少停车位，停车入库function（包括判断车位是否充足，找到应该停在哪个车位，停进去三部曲）
  参考链接：https://blog.csdn.net/xjwun/article/details/43484327

<?php

class ParkingSpot {

    private $vehicle;

    private $spotSize;

    private $row;

    private $spotNum;

    private $level;

    /**
     * ParkingSpot constructor.
     * @param Level $lvl 层数
     * @param $r  第几列
     * @param $n  spot numer，一个标示
     * @param $size spot的大小
     */
    public function __construct(Level $lvl, $r, $n, $size) {
        $this->level    = $lvl;
        $this->row      = $r;
        $this->spotNum  = $n;
        $this->spotSize = $size;
        //vehicle初始为null，因为没停车
    }

    /**
     * isAvailable
     * @return bool
     * @brief 判断当前spot是否可用
     */
    public function isAvailable() {
        return $this->vehicle == null;
    }

    /**
     * canFitVehicle
     * @param Vehicle $vehicle
     * @return bool
     */
    public function canFitVehicle(Vehicle $vehicle) {
        return $this->isAvailable() && $vehicle->canFitInSpot($this);
    }

    /**
     * park
     * @param Vehicle $v
     * @return bool
     * @brief 停车入库
     */
    public function park(Vehicle $v) {
        if (!$this->canFitVehicle()) {
            return false;
        }
        $v->parkInSpot($this);
        return true;
    }

    /**
     * removeVehicle
     * @return void
     * @brief 出库
     */
    public function removeVehicle() {
        //todo
        $this->level->spotFreed();
        $this->vehicle = null;
    }

    public function getRow() {
        return $this->spotNum;
    }

    public function getSize() {
        return $this->spotSize;
    }
}


class Level {
    private $floor;


    private $spots;//parkingpot 的集合

    private $availableSpots = 0;

    const SPOTS_PER_ROW = 10;

    public function __construct($floor, $spotsnum) {
        $this->floor = $floor;
        $this->spots = [];//理论上这里的array要申明长度为spotsnum
    }


    /**
     * parkVehicle
     * @param Vehicle $vehicle
     * @return bool
     * @brief 停车入位
     */
    public function parkVehicle(Vehicle $vehicle) {

        // 车位不足
        if ($this->availableSpots < $vehicle->getSpotsNeeded()) {
            return false;
        }

        //这里的spotNum是spots这个array的索引，并不是spots类里面的spotNum
        $spotNum = $this->findAvailableSpots($vehicle);
        if ($spotNum < 0) {
            return false;
        }

        return $this->parkStartingAtSpot($spotNum, $vehicle);
    }

    /**
     * findAvailableSpots
     * @param Vehicle $vehicle
     * @return int spots的索引$i
     * @brief 查找是否有车位能符合这辆车
     *
     */
    public function findAvailableSpots(Vehicle $vehicle) {
        $spotNeeded = $vehicle->getSpotsNeeded();
        $lastRow    = -1;
        $spotsFound = 0;
        for ($i = 0; $i < count($this->spots); $i++) {
            $spot = $this->spots[$i];//spot 为一个Parking Spot

            //换行则重新计算
            if ($lastRow != $spot->getRow()) {
                $spotsFound = 0;
                $lastRow    = $spot->getRow();
            }

            //canFitVehicle 只判断size是否合适，（类似一个truck需要5个spot，所以需要循环）
            if ($spot->canFitVehicle(vehicle)) {
                $spotsFound++;
            } else {
                $spotsFound = 0;
            }

            if ($spotsFound == $spotNeeded) {
                return $i - ($spotNeeded - 1);//index of spot
            }
        }
        return -1;
    }

    /**
     * parkStartingAtSpot
     * @param $spotNum
     * @param Vehicle $vehicle
     * @return bool
     */
    private function parkStartingAtSpot($spotNum, Vehicle $vehicle) {
        $vehicle->clearSpots();
        $success = true;

        for ($i = $spotNum; $i < $spotNum + $vehicle->getSpotsNeeded(); $i++) {
            $success &= $this->spots[$i]->park($vehicle);
        }
        $this->availableSpots -= $vehicle->getSpotsNeeded();
        return $success;
    }

    public function spotFreed() {
        $this->availableSpots++;
    }

    /**
     * availableSpots
     * @return int
     * @brief 返回当前可用spot的数量
     */
    public function availableSpots() {
        return $this->availableSpots;
    }
}

class Vehicle {

    protected $size;

    protected $license;//car license id

    protected $spotNeed;

    protected $parkingSpots = [];//一个车可能停在多个spot上面，所以是array

    protected $vehicleSize = [
        "motocycle" => 1,
        "car"       => 2,
        "truck"     => 3,
    ];

    public function __construct() {

    }

    public function getSize() {
        return $this->size;
    }

    public function getSpotsNeeded() {
        return $this->spotNeed;
    }

    /**
     * parkInSpot
     * @param ParkingSpot $spot
     * @return void
     * @brief 停车入库
     */
    public function parkInSpot(ParkingSpot $spot) {
        $this->parkingSpots[] = $spot;
    }

    /**
     * clearSpots
     * @return void
     */
    public function clearSpots() {
        $this->parkingSpots = [];
    }

    public function canFitInSpot(ParkingSpot $spot) {

    }
}

class Motocycle extends Vehicle {
    public function __construct() {
        $this->spotNeed = 1;
        $this->size     = $this->vehicleSize['motocycle'];
    }

    /**
     * canFitInSpot
     * @param ParkingSpot $spot
     * @return bool|void
     */
    public function canFitInSpot(ParkingSpot $spot) {
        return true;
    }
}

class Car extends Vehicle {

    /**
     * Car constructor.
     */
    public function __construct() {
        $this->spotNeed = 1;
        $this->size     = $this->vehicleSize['car'];
    }

    /**
     * canFitInSpot
     * @param ParkingSpot $spot
     * @return bool|void
     * @brief
     */
    public function canFitInSpot(ParkingSpot $spot) {
        return ($spot->getSize() == $this->vehicleSize['car']) || ($spot->getSize() == $this->vehicleSize['truck']);
    }
}

class Truck extends Vehicle {
    public function __construct() {
        $this->spotNeed = 5;
        $this->size     = $this->vehicleSize['truck'];
    }

    /**
     * canFitInSpot
     * @param ParkingSpot $spot
     * @return bool|void
     * @biref 只判断能不能停，
     */
    public function canFitInSpot(ParkingSpot $spot) {
        return $spot->getSize() == $this->vehicleSize['truck'];
    }
}


class ParkingLot {
    private $levels;

    const NUM_LEVELS = 5;

    /**
     * ParkingLot constructor.
     *
     */
    public function __construct() {
        $this->levels = [];
        for ($i = 0; $i < self::NUM_LEVELS; $i++) {
            $this->levels[$i] = new Level($i, 30);
        }

    }

    public function parkVehicle(Vehicle $vehicle){
        for($i = 0;$i<count($this->levels);$i++){
            if($this->levels[$i]->parkVehicle[$vehicle]){
                return true;
            }
        }
        return false;
    }
}