<?php
include ("functions.php");
function updatecoursepeople($link,$courseid)
{
    $result = $link->query("update course set nowpeople=(SELECT COUNT(*) 
                                       FROM sc
                                       where courseid='$courseid') where courseid='$courseid'"
    );
    return $result;
}
function getnowcreditnumfromusername($link,$username)
{
    //通过username获取用户已选修的积分总和
    $result = $link->query("select * 
                           FROM sc,course as c
                           where sc.username='$username' and sc.courseid=c.courseid ");
    $num=0;
    if(!$result)return 9999;
    while($row=mysqli_fetch_assoc($result))
    {
        $num+=$row['credit'];
    }
    return $num;

}
function getmajorcreditlimitfromusername($link,$username)
{
    //通过username获取用户专业的积分选修总分限制
    $result = $link->query("select * 
                           FROM accounts as a,major as m
                           where a.username='$username' and a.majorid=m.majorid ");
    $row=mysqli_fetch_assoc($result);
    return $row['creditlimit'];
}
function getcoursecredit($link,$courseid)
{
    //通过courseid获取该课程的学分
    $result = $link->query("select * 
                           FROM course
                           where courseid='$courseid' ");
    $row=mysqli_fetch_assoc($result);
    return $row['credit'];
}
function checkcourselimit($link,$username,$courseid)
{
    //判断该username的专业majorid是否有限制electivelimit不能选课

    //1通过username 找到 专业$majorid 和 年级(1/2/3/4)
    $result = $link->query("select *
                           from accounts
                           where username='$username' ");
    $row=mysqli_fetch_assoc($result);
    $majorid1=$row['majorid'];
    $grade=gettoyear()-$row['enteryear']+1;

    //2查找limit规则中是否存在满足courseid  majorid  grade 三要素的的记录 有就是没限制  没有就是限制
    $result = $link->query("select * 
                           FROM electivelimit
                           where courseid='$courseid' and (majorid='$majorid1' or majorid='0') and (grade='$grade' or grade='0')");
    while($row=mysqli_fetch_assoc($result))
    {
        return true;
    }
    return false;

}
header("Content-type:application/json");
//在发送数据到服务器前简单的进行编码
header('Access-Control-Allow-Origin:*');
if(!isset($_GET['action']))
{
    //来访若没有定义action  那么就忽略
    exit();
}
include_once ("./conn.php");
//获取操作数据
$action=$_GET['action'];//操作类型
$results="0000";
if($action=="takeapart")
{
    //添加选修课程
if(!isset($_COOKIE['username']))
{
    $results="请先登录账户！";

}   else {
    //获取课程号
    $courseid=$_GET['courseid'];
    //判断课程是否满人
    $result = $link->query("SELECT COUNT(*) 
                                       FROM course
                                       where courseid='$courseid' and nowpeople < numpeople"
    );
    if(!$result)
    {
        $results="fail";
    }else{
        list($row_num) = $result->fetch_row();
        if($row_num<=0)
        {
            $results="fail-full";
        }else{
            //是否已加入课程？
            $username=$_COOKIE['username'];

            $result2 = $link->query("SELECT COUNT(*) 
                                       FROM sc
                                       where username='$username' and courseid='$courseid'"
            );
            if(!$result2)
            {
                $results="fail";
            }else if(!checkcourselimit($link,$username,$courseid)){
                $results="由于您的专业或年级的限制，您不能选修该门课程。";

            }else{
                list($row_num2) = $result2->fetch_row();
//                $row_num2 = mysqli_num_rows($result2);
                if($row_num2>0)
                {
                    $results="fail-already";
                }else{
                    //判断用户选修积分有没有超额度
                    if(getnowcreditnumfromusername($link,$username)+getcoursecredit($link,$courseid)>getmajorcreditlimitfromusername($link,$username))
                    {
                        //学分超限
                        $results="你能选修的学分已超过每学年的限制，请退掉其他课程再选修本课程，或者等下学期再选修。";
                    }else {
                        //学分足够
                        //加入课程
                        $result = $link->query("insert into sc
                                       values('$username','$courseid','0')"
                        );
                        if(!$result)
                        {
                            $results="fail";
                        }else {
                            if(updatecoursepeople($link,$courseid))
                            {
                                $results = "ok";
                            }else{
                                $results="fail";
                            }

                        }

                    }

                }


            }
        }

        //加入课程
    }
}




}
else if($action=="savepms"){
    //用户更新个人资料
    if(isset($_COOKIE['username']))
    {
        $username=$_COOKIE['username'];
    }else exit();
    $realname=$_GET['realname'];
    $email=$_GET['email'];
    date_default_timezone_set("PRC");//消除时差
    $birthday=(int)strtotime($_GET['birthday']);
    $identity=$_GET['identity'];
    $address=$_GET['address'];
    $tel=$_GET['tel'];
    if($_GET['gender']=='男')
    {
        $gender=0;
    }
    else{
        $gender=1;
    }
    $result = $link->query("update accounts
                                   set gender='$gender', realname='$realname',email='$email',birthday='$birthday',identity='$identity',address='$address',tel='$tel' 
                                   where username='$username'"
    );
    if(!$result) {
        $results = "fail";
    }else{
        $results="ok";
    }
}
else if($action=="dropcourse"){
    //退课操作
    if(isset($_COOKIE['username']))
    {
        $username=$_COOKIE['username'];
    }else exit();
    $courseid=$_GET['courseid'];
    $result = $link->query("delete from sc
                                   where username='$username' and courseid='$courseid'"
    );
    if(!$result) {
        $results = "fail";
    }else{
        updatecoursepeople($link,$courseid);
        $results="ok";
    }


}else $results= "???";
$link->close();
echo json_encode($results);
//最后返回数据给前端
?>