<?php

namespace App\Services\Students;

use App\Models\Students\StudentClass;
use App\Services\BaseService;
use Illuminate\Pagination\LengthAwarePaginator;

/**
 * 学生班级关联服务类
 */
class StudentClassService extends BaseService
{
    protected string $modelClass = StudentClass::class;

    /**
     * 获取学生班级关联列表
     */
    public function getList(array $params): LengthAwarePaginator
    {
        $query = StudentClass::query();

        // 学生ID筛选
        if (!empty($params['student_id'])) {
            $query->where('student_id', $params['student_id']);
        }

        // 学校筛选
        if (!empty($params['school_id'])) {
            $query->where('school_id', $params['school_id']);
        }

        // 班级筛选
        if (!empty($params['class_id'])) {
            $query->where('class_id', $params['class_id']);
        }

        // 包含关联信息
        $query->with([
            'school:id,name,alias',
            'schoolClass:id,name,code,campus_id,grade_id,number'
        ]);

        // 排序
        $query->orderBy('school_id', 'asc')
              ->orderBy('class_id', 'asc')
              ->orderBy('id', 'desc');

        return $query->paginate($params['page_size'] ?? 15);
    }

    /**
     * 获取学生的班级列表
     */
    public function getStudentClasses(int $studentId): array
    {
        return StudentClass::where('student_id', $studentId)
            ->with([
                'school:id,name,alias',
                'schoolClass:id,name,code,campus_id,grade_id,number'
            ])
            ->get()
            ->toArray();
    }

    /**
     * 获取班级的学生列表
     */
    public function getClassStudents(int $classId): array
    {
        return StudentClass::where('class_id', $classId)
            ->with([
                'school:id,name,alias'
            ])
            ->get()
            ->toArray();
    }

    /**
     * 获取学校的学生列表
     */
    public function getSchoolStudents(int $schoolId): array
    {
        return StudentClass::where('school_id', $schoolId)
            ->with([
                'schoolClass:id,name,code,campus_id,grade_id,number'
            ])
            ->get()
            ->toArray();
    }

    /**
     * 批量分配学生到班级
     */
    public function batchAssignStudentsToClass(array $studentIds, int $classId): array
    {
        $class = \App\Models\Schools\SchoolClass::findOrFail($classId);
        $results = [];

        foreach ($studentIds as $studentId) {
            // 检查是否已经存在关联
            $exists = StudentClass::where('student_id', $studentId)
                ->where('class_id', $classId)
                ->exists();

            if (!$exists) {
                $data = [
                    'student_id' => $studentId,
                    'school_id' => $class->school_id,
                    'class_id' => $classId,
                ];

                $result = $this->create($data);
                $results[] = $result;
            }
        }

        return $results;
    }

    /**
     * 批量移除学生班级关联
     */
    public function batchRemoveStudentsFromClass(array $studentIds, int $classId): int
    {
        return StudentClass::whereIn('student_id', $studentIds)
            ->where('class_id', $classId)
            ->delete();
    }

    /**
     * 转移学生到新班级
     */
    public function transferStudentToClass(int $studentId, int $oldClassId, int $newClassId): bool
    {
        $newClass = \App\Models\Schools\SchoolClass::findOrFail($newClassId);

        // 删除旧的关联
        StudentClass::where('student_id', $studentId)
            ->where('class_id', $oldClassId)
            ->delete();

        // 创建新的关联
        $data = [
            'student_id' => $studentId,
            'school_id' => $newClass->school_id,
            'class_id' => $newClassId,
        ];

        $this->create($data);

        return true;
    }

    /**
     * 获取学生班级统计信息
     */
    public function getStudentClassStats(int $studentId): array
    {
        $classes = StudentClass::where('student_id', $studentId)
            ->with(['school:id,name', 'schoolClass:id,name'])
            ->get();

        return [
            'total_classes' => $classes->count(),
            'schools' => $classes->pluck('school')->unique('id')->values()->toArray(),
            'classes' => $classes->pluck('schoolClass')->toArray(),
        ];
    }

    /**
     * 创建前的特殊处理
     */
    protected function beforeCreate(array &$data): void
    {
        // 验证学校是否存在
        if (!empty($data['school_id'])) {
            $school = \App\Models\Schools\School::find($data['school_id']);
            if (!$school) {
                throw new \InvalidArgumentException('指定的学校不存在');
            }
        }

        // 验证班级是否存在
        if (!empty($data['class_id'])) {
            $class = \App\Models\Schools\SchoolClass::find($data['class_id']);
            if (!$class) {
                throw new \InvalidArgumentException('指定的班级不存在');
            }

            // 验证班级是否属于指定学校
            if ($class->school_id !== $data['school_id']) {
                throw new \InvalidArgumentException('指定的班级不属于该学校');
            }
        }

        // 检查是否已经存在关联
        $exists = StudentClass::where('student_id', $data['student_id'])
            ->where('class_id', $data['class_id'])
            ->exists();

        if ($exists) {
            throw new \InvalidArgumentException('该学生已经在此班级中');
        }
    }
}