main.php

<?php

/**
 * Copyright (c) 2014 Fumito MIZUNO
 * License: MIT 
 * http://opensource.org/licenses/mit-license.php
 */
require_once('yoyakulist.php');

class Main
{
    protected $data;
    protected $queuelist = array();
    protected $yoyakulist;
    public function __construct()
    {
        $this->yoyakulist =  new YoyakuList();
    }
    
    /**
     * メイン処理
     * @param $data ex. 1_12345|2_12345
     * @return string
     */
    public function main($data)
    {
        $this->splitdata($data);
        $this->setupUser();
        $this->tryReserve();
        return $this->output();
    }

    /**
     * @param $data
     */
    public function splitdata($data)
    {
        $this->data = explode('|', $data);
    }

    /**
     * ユーザー情報を登録
     * @param $userid ex. 1
     * @param $days ex. 12345
     */
    protected function addUser($userid, $days)
    {
        if (is_numeric($userid) && is_numeric($days))
        {
            $this->queuelist[$userid] = $days;
        }
        else
        {
            echo 'Input Error.';
        }
    }

    /**
     * 入力を分割し、addUserする
     */
    public function setupUser()
    {
        foreach ($this->data as $val) {
            $user_days = explode('_', $val);
            $this->addUser($user_days[0], $user_days[1]);
        }
    }

    /**
     * 予約を試みる
     */
    public function tryReserve()
    {
        for ($i=0;$i<5;$i++) // 曜日が5つなので、最大5回
        {
            foreach ($this->queuelist as $key => $val)
            {
                $day = substr($val,0,1);
                // 希望が通れば、そのユーザーを削除
                // 通らなければ、第一希望を削除
                if ($this->yoyakulist->execute($key, $day))
                {
                    unset($this->queuelist[$key]);
                }
                else
                {
                    $this->queuelist[$key] = substr($val,1);
                }
            }
        }
     }

    /**
     * 出力する
     * @return string
     */
    public function output()
    {
        $output = array();
        $return = $this->yoyakulist->getYoyakulist();
        foreach ($return as $key => $val)
        {
            // 予約のあるもののみ表示
            if ($val) {
                // 並べ替えて表示
                asort($val);
                $output[] = $key . '_' . implode(':', $val);
            }
        }
        return implode('|', $output);
    }
}

main_test.php

<?php

/**
 * Copyright (c) 2014 Fumito MIZUNO
 * License: MIT 
 * http://opensource.org/licenses/mit-license.php
 */
require_once 'main.php';

class mainTest extends PHPUnit_Framework_TestCase
{

    /**
     * @dataProvider provider
     */
    public function test1($input, $expected)
    {
        $class = new Main();
        $output = $class->main($input);
        $this->assertEquals($expected, $output);
    }

    public function provider()
    {
        return array(
            array('1_12345|2_12345','1_1:2'),
            array('55_24153|91_24531|9_12543|41_34215|72_15423|44_42531|6_42351|79_15243|21_35412|31_52413|74_24135|83_31254|33_35421|84_53421|89_53241|16_32415|36_15234|92_34521|62_12345|14_23415|40_23415|88_43251|52_45213|77_32154|59_53241','1_9:36:72:79|2_14:55:74:91|3_21:33:41:83|4_6:44:52:88|5_31:59:84:89'),
            array('90_21453|58_43521|69_42351|12_51432|34_14352|23_45321|77_35421|71_24531|95_24153|49_13254|9_45231|78_21534|15_43512|54_41532|52_54321|59_24513|57_41532|75_35214|24_12435|97_52341|39_12453|53_12435|48_51234|32_51234', '1_24:34:39:49|2_71:78:90:95|3_15:54:75:77|4_9:23:58:69|5_12:48:52:97'),
            array('55_13524|64_41523|40_23451|99_25314|65_21453|69_31524|77_45231|62_51432|21_13542|81_13452|66_21534|33_41352|5_52314|90_31452|6_42135|93_42351|84_43125|54_45213|76_21453|19_52134|50_21435|61_13542|30_35421|43_25431|24_25341|31_15234|39_15243|20_51423|67_13524', '1_21:55:61:81|2_40:65:66:99|3_30:69:84:90|4_6:33:64:77|5_5:19:20:62'),
        );
    }
}

yoyakulist.php

<?php

/**
 * Copyright (c) 2014 Fumito MIZUNO
 * License: MIT 
 * http://opensource.org/licenses/mit-license.php
 */
class YoyakuList
{
    protected $yoyakulist;
    protected $max = 4;
    /**
     * 曜日(5個)を用意しておく
     */
    public function __construct()
    {
        $this->yoyakulist = array(
            1 => array(),
            2 => array(),
            3 => array(),
            4 => array(),
            5 => array(),
        );
    }

    /**
     * 予約を実行
     * @param $userid ex. 1
     * @param $day ex. 2
     * @return bool
     */
    public function execute($userid, $day)
    {
        $day = (int) $day;
        $userid = (int) $userid;

        // 空きがあれば登録する
        if ($this->check($day))
        {
            $this->accept($userid, $day);
            return true;
        }
        else
        {
            return false;
        }
    }

    /**
     * 空きがあるかをチェックする
     * @param $day ex. 2
     * @return bool
     */
    protected function check($day)
    {
        // 4未満なら空きあり
        if (count($this->yoyakulist[$day]) < $this->max)
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    /**
     * 予約を受け入れる
     * @param $day ex. 2
     * @param $userid ex. 1
     */
    protected function accept($userid, $day)
    {
        $this->yoyakulist[$day][] = $userid;
    }

    /**
     * 予約データを返す
     * @return array
     */
    public function getYoyakulist()
    {
        return $this->yoyakulist;
    }

}

yoyakulist_test.php

<?php

/**
 * Copyright (c) 2014 Fumito MIZUNO
 * License: MIT 
 * http://opensource.org/licenses/mit-license.php
 */
require_once 'yoyakulist.php';

class YoyakuTest extends PHPUnit_Framework_TestCase
{
    // もう少し細かい粒度でテストする？
    public function testExecute()
    {
        $class = new YoyakuList();
        $class->execute(1,1);
        $class->execute(2,1);
        $class->execute(3,1);
        $class->execute(4,1);
        $class->execute(5,1);
        $output = $class->getYoyakulist();
        $expected = array(
            1 => array(1,2,3,4),
            2 => array(),
            3 => array(),
            4 => array(),
            5 => array(),
        );
        $this->assertEquals($expected, $output);
    }
}