<?php

namespace App\Models\Students;

use App\Models\BaseModel;
use App\Models\Schools\School;
use App\Models\Schools\SchoolClass;
use App\Models\Students\Student;

/**
 * 学生班级关联模型
 * @package App\Models\Students
 * @property int $id 主键ID
 * @property int $student_id 学生ID
 * @property int $school_id 学校ID
 * @property int $class_id 班级ID
 * @property \Carbon\Carbon|null $join_time 入班时间
 * @property \Carbon\Carbon|null $leave_time 离班时间
 * @property int $status 状态(1正常在读2已转班3已毕业4退学)
 * @property string|null $remark 备注
 * @property \Carbon\Carbon $created_at 创建时间
 * @property \Carbon\Carbon $updated_at 更新时间
 */
class StudentClass extends BaseModel
{
    protected $table = 'student_class';

    protected $fillable = [
        'student_id',
        'school_id',
        'class_id',
        'join_time',
        'leave_time',
        'status',
        'remark',
    ];

    protected $casts = [
        'student_id' => 'integer',
        'school_id' => 'integer',
        'class_id' => 'integer',
        'join_time' => 'datetime',
        'leave_time' => 'datetime',
        'status' => 'integer',
    ];

    /**
     * 状态常量
     */
    const STATUS_NORMAL = 1;    // 正常在读
    const STATUS_TRANSFERRED = 2; // 已转班
    const STATUS_GRADUATED = 3;  // 已毕业
    const STATUS_DROPOUT = 4;    // 退学

    /**
     * 状态映射
     */
    public static $statusMap = [
        self::STATUS_NORMAL => '正常在读',
        self::STATUS_TRANSFERRED => '已转班',
        self::STATUS_GRADUATED => '已毕业',
        self::STATUS_DROPOUT => '退学',
    ];

    /**
     * 关联学生
     */
    public function student()
    {
        return $this->belongsTo(Student::class, 'student_id');
    }

    /**
     * 关联学校
     */
    public function school()
    {
        return $this->belongsTo(School::class, 'school_id');
    }

    /**
     * 关联班级
     */
    public function schoolClass()
    {
        return $this->belongsTo(SchoolClass::class, 'class_id');
    }

    /**
     * 根据学生ID查询
     */
    public function scopeByStudent($query, $studentId)
    {
        return $query->where('student_id', $studentId);
    }

    /**
     * 根据学校ID查询
     */
    public function scopeBySchool($query, $schoolId)
    {
        return $query->where('school_id', $schoolId);
    }

    /**
     * 根据班级ID查询
     */
    public function scopeByClass($query, $classId)
    {
        return $query->where('class_id', $classId);
    }

    /**
     * 根据状态查询
     */
    public function scopeByStatus($query, $status)
    {
        return $query->where('status', $status);
    }

    /**
     * 查询正常在读的学生
     */
    public function scopeNormal($query)
    {
        return $query->where('status', self::STATUS_NORMAL);
    }

    /**
     * 查询未离开的学生
     */
    public function scopeNotLeft($query)
    {
        return $query->whereNull('leave_time');
    }

    /**
     * 获取状态名称
     */
    public function getStatusNameAttribute()
    {
        return self::$statusMap[$this->status] ?? '未知状态';
    }

    /**
     * 检查是否正常在读
     */
    public function isNormal()
    {
        return $this->status === self::STATUS_NORMAL;
    }

    /**
     * 检查是否已离开
     */
    public function hasLeft()
    {
        return !is_null($this->leave_time);
    }

    /**
     * 获取在读时长（天数）
     */
    public function getStudyDays(): int
    {
        if (!$this->join_time) {
            return 0;
        }

        $endTime = $this->leave_time ?? now();
        return $this->join_time->diffInDays($endTime);
    }
}