// ===========================================
// 多班级版班级管理系统 - Go 后端
//
// 开发者: Canglan
// 联系方式: admin@sea-studio.top
// 版权归属: Sea Network Technology Studio
// 许可证: Apache License 2.0
//
// 版权所有 © Sea Network Technology Studio
// ===========================================

package repository

import (
	"fmt"
	"strings"

	"gorm.io/gorm"

	"hz-gitea.sea-studio.top/canglan/SharedClassManager/internal/model"
)

// StudentRepo 学生数据访问层
type StudentRepo struct {
	db *gorm.DB
}

// NewStudentRepo 创建学生 Repository
func NewStudentRepo(db *gorm.DB) *StudentRepo {
	return &StudentRepo{db: db}
}

// GetByID 根据ID获取学生信息（含班级名称）
func (r *StudentRepo) GetByID(studentID int) (*model.Student, error) {
	var student model.Student
	if err := r.db.Table("students s").
		Select("s.*, c.class_name").
		Joins("LEFT JOIN classes c ON s.class_id = c.class_id").
		Where("s.student_id = ?", studentID).
		First(&student).Error; err != nil {
		return nil, err
	}
	return &student, nil
}

// GetByStudentNo 根据学号获取学生（可指定班级）
func (r *StudentRepo) GetByStudentNo(studentNo string, classID int) (*model.Student, error) {
	var student model.Student
	query := r.db.Where("student_no = ?", studentNo)
	if classID > 0 {
		query = query.Where("class_id = ?", classID)
	}
	if err := query.First(&student).Error; err != nil {
		return nil, err
	}
	return &student, nil
}

// GetAll 获取指定班级的学生列表
func (r *StudentRepo) GetAll(classID int, includeDisabled bool) ([]model.Student, error) {
	var students []model.Student
	query := r.db.Where("class_id = ?", classID)
	if !includeDisabled {
		query = query.Where("status = 1")
	}
	if err := query.Order("student_no").Find(&students).Error; err != nil {
		return nil, err
	}
	return students, nil
}

// GetDormitoryList 获取班级内所有不重复的宿舍号列表
func (r *StudentRepo) GetDormitoryList(classID int) ([]string, error) {
	var dormitories []string
	err := r.db.Model(&model.Student{}).
		Where("class_id = ? AND status = 1 AND dormitory_number IS NOT NULL AND dormitory_number != ''", classID).
		Distinct("dormitory_number").
		Order("dormitory_number").
		Pluck("dormitory_number", &dormitories).Error
	if err != nil {
		return nil, err
	}
	return dormitories, nil
}

// Create 创建学生记录
func (r *StudentRepo) Create(student *model.Student) (int, error) {
	if err := r.db.Create(student).Error; err != nil {
		return 0, err
	}
	return student.StudentID, nil
}

// Update 更新学生信息（仅更新非零值字段）
func (r *StudentRepo) Update(studentID int, updates map[string]interface{}) error {
	if len(updates) == 0 {
		return nil
	}
	return r.db.Model(&model.Student{}).
		Where("student_id = ?", studentID).
		Updates(updates).Error
}

// SoftDelete 软删除学生
func (r *StudentRepo) SoftDelete(studentID int) error {
	return r.db.Model(&model.Student{}).
		Where("student_id = ?", studentID).
		Update("status", 0).Error
}

// UpdateTotalPoints 更新学生总分（增量更新，下限保护为 0）
func (r *StudentRepo) UpdateTotalPoints(studentID int, pointsChange int) error {
	return r.db.Model(&model.Student{}).
		Where("student_id = ?", studentID).
		Update("total_points", gorm.Expr("GREATEST(total_points + ?, 0)", pointsChange)).Error
}

// GetRanking 获取班级内学生排行
func (r *StudentRepo) GetRanking(classID int, limit int) ([]model.Student, error) {
	var students []model.Student
	if err := r.db.Where("status = 1 AND class_id = ?", classID).
		Order("total_points DESC, student_id ASC").
		Limit(limit).
		Find(&students).Error; err != nil {
		return nil, err
	}
	return students, nil
}

// GetTotalCount 获取班级内活跃学生总数
func (r *StudentRepo) GetTotalCount(classID int) (int64, error) {
	var count int64
	if err := r.db.Model(&model.Student{}).
		Where("status = 1 AND class_id = ?", classID).
		Count(&count).Error; err != nil {
		return 0, err
	}
	return count, nil
}

// ListByClass 分页获取班级学生列表（支持搜索和宿舍号过滤）
func (r *StudentRepo) ListByClass(classID int, page, pageSize int, search, dormitoryNumber string) ([]model.Student, int64, error) {
	var students []model.Student
	var total int64

	query := r.db.Model(&model.Student{}).Where("status = 1 AND class_id = ?", classID)

	if search != "" {
		escaped := strings.NewReplacer("\\", "\\\\", "%", "\\%", "_", "\\_").Replace(search)
		searchPattern := fmt.Sprintf("%%%s%%", escaped)
		query = query.Where("student_no LIKE ? OR name LIKE ?", searchPattern, searchPattern)
	}

	if dormitoryNumber != "" {
		query = query.Where("dormitory_number = ?", dormitoryNumber)
	}

	// 获取总数
	if err := query.Count(&total).Error; err != nil {
		return nil, 0, err
	}

	// 分页查询
	offset := (page - 1) * pageSize
	if err := query.Order("student_no").
		Limit(pageSize).
		Offset(offset).
		Find(&students).Error; err != nil {
		return nil, 0, err
	}

	return students, total, nil
}

// BatchCreate 批量创建学生
func (r *StudentRepo) BatchCreate(students []model.Student) error {
	return r.db.Create(&students).Error
}

// GetStudentNosByClass 获取指定班级所有学生学号（用于批量导入去重）
func (r *StudentRepo) GetStudentNosByClass(classID int) ([]string, error) {
	var studentNos []string
	if err := r.db.Model(&model.Student{}).
		Where("class_id = ?", classID).
		Pluck("student_no", &studentNos).Error; err != nil {
		return nil, err
	}
	return studentNos, nil
}

// ResetPoints 重置班级内所有学生的操行分为初始值
func (r *StudentRepo) ResetPoints(classID int, initialPoints int) error {
	return r.db.Model(&model.Student{}).
		Where("class_id = ? AND status = 1", classID).
		Update("total_points", initialPoints).Error
}

// GetByParentAccount 根据家长账号查找学生
func (r *StudentRepo) GetByParentAccount(parentAccount string) (*model.Student, error) {
	var student model.Student
	if err := r.db.Where("parent_account = ? AND status = 1", parentAccount).First(&student).Error; err != nil {
		return nil, err
	}
	return &student, nil
}

// GetRankByStudentID 使用密集排名（dense rank）计算学生排名：相同分数同名次，后续名次不跳过
func (r *StudentRepo) GetRankByStudentID(classID, studentID int) (int, error) {
	var student model.Student
	if err := r.db.Select("total_points").Where("student_id = ?", studentID).First(&student).Error; err != nil {
		return 0, err
	}
	var distinctHigherCount int64
	if err := r.db.Raw("SELECT COUNT(DISTINCT total_points) FROM students WHERE status = 1 AND class_id = ? AND total_points > ?",
		classID, student.TotalPoints).Scan(&distinctHigherCount).Error; err != nil {
		return 0, err
	}
	return int(distinctHigherCount) + 1, nil
}

// GetStudentsByClassID 获取班级内所有活跃学生（用于归档等批量操作）
func (r *StudentRepo) GetStudentsByClassID(classID int) ([]model.Student, error) {
	var students []model.Student
	if err := r.db.Where("class_id = ? AND status = 1", classID).
		Order("total_points DESC, student_id ASC").
		Find(&students).Error; err != nil {
		return nil, err
	}
	return students, nil
}