// ===========================================
// 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 (
	"time"

	"gorm.io/gorm"

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

// AssignmentRepo 作业数据访问层
type AssignmentRepo struct {
	db *gorm.DB
}

// NewAssignmentRepo 创建作业 Repository
func NewAssignmentRepo(db *gorm.DB) *AssignmentRepo {
	return &AssignmentRepo{db: db}
}

// ========== Assignment 操作 ==========

// CreateAssignment 创建作业
func (r *AssignmentRepo) CreateAssignment(assignment *model.Assignment) (int, error) {
	if err := r.db.Create(assignment).Error; err != nil {
		return 0, err
	}
	return assignment.AssignmentID, nil
}

// GetAssignmentByID 根据ID获取作业
func (r *AssignmentRepo) GetAssignmentByID(assignmentID int) (*model.Assignment, error) {
	var assignment model.Assignment
	if err := r.db.Where("assignment_id = ?", assignmentID).First(&assignment).Error; err != nil {
		return nil, err
	}
	return &assignment, nil
}

// GetAssignmentsByClass 获取班级作业列表
func (r *AssignmentRepo) GetAssignmentsByClass(classID int, subjectID int, page, pageSize int) ([]model.Assignment, int64, error) {
	var assignments []model.Assignment
	var total int64

	query := r.db.Model(&model.Assignment{}).Where("class_id = ?", classID)
	if subjectID > 0 {
		query = query.Where("subject_id = ?", subjectID)
	}

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

	offset := (page - 1) * pageSize
	if err := query.Order("created_at DESC").
		Limit(pageSize).
		Offset(offset).
		Find(&assignments).Error; err != nil {
		return nil, 0, err
	}

	return assignments, total, nil
}

// GetAssignmentsBySubject 获取科目关联的作业列表
func (r *AssignmentRepo) GetAssignmentsBySubject(subjectID int) ([]model.Assignment, error) {
	var assignments []model.Assignment
	if err := r.db.Where("subject_id = ?", subjectID).
		Order("created_at DESC").
		Find(&assignments).Error; err != nil {
		return nil, err
	}
	return assignments, nil
}

// DeleteAssignment 删除作业
func (r *AssignmentRepo) DeleteAssignment(assignmentID int) error {
	return r.db.Where("assignment_id = ?", assignmentID).Delete(&model.Assignment{}).Error
}

// GetHomeworkStatsByDateRange 通过作业截止日期范围查询学生作业提交统计
func (r *AssignmentRepo) GetHomeworkStatsByDateRange(startDate, endDate time.Time) ([]struct {
	StudentID int
	Status    string
	Count     int64
}, error) {
	var stats []struct {
		StudentID int
		Status    string
		Count     int64
	}
	err := r.db.Table("homework_submissions hs").
		Select("hs.student_id, hs.status, COUNT(*) as count").
		Joins("JOIN assignments a ON hs.assignment_id = a.assignment_id").
		Where("a.deadline BETWEEN ? AND ?", startDate, endDate).
		Group("hs.student_id, hs.status").
		Find(&stats).Error
	if err != nil {
		return nil, err
	}
	return stats, nil
}

// ========== AssignmentSubmission 操作 ==========

// CreateSubmission 创建作业提交记录
func (r *AssignmentRepo) CreateSubmission(submission *model.AssignmentSubmission) (int, error) {
	if err := r.db.Create(submission).Error; err != nil {
		return 0, err
	}
	return submission.SubmissionID, nil
}

// GetSubmissionByAssignmentAndStudent 获取指定作业和学生的提交记录
func (r *AssignmentRepo) GetSubmissionByAssignmentAndStudent(assignmentID, studentID int) (*model.AssignmentSubmission, error) {
	var submission model.AssignmentSubmission
	if err := r.db.Where("assignment_id = ? AND student_id = ?", assignmentID, studentID).
		First(&submission).Error; err != nil {
		return nil, err
	}
	return &submission, nil
}

// GetSubmissionsByAssignment 获取作业的所有提交记录
func (r *AssignmentRepo) GetSubmissionsByAssignment(assignmentID int) ([]model.AssignmentSubmission, error) {
	var submissions []model.AssignmentSubmission
	if err := r.db.Where("assignment_id = ?", assignmentID).
		Find(&submissions).Error; err != nil {
		return nil, err
	}
	return submissions, nil
}

// GetSubmissionsByStudent 获取学生的所有提交记录
func (r *AssignmentRepo) GetSubmissionsByStudent(studentID int) ([]model.AssignmentSubmission, error) {
	var submissions []model.AssignmentSubmission
	if err := r.db.Where("student_id = ?", studentID).
		Find(&submissions).Error; err != nil {
		return nil, err
	}
	return submissions, nil
}

// UpdateSubmission 更新提交记录
func (r *AssignmentRepo) UpdateSubmission(submissionID int, updates map[string]interface{}) error {
	return r.db.Model(&model.AssignmentSubmission{}).
		Where("submission_id = ?", submissionID).
		Updates(updates).Error
}

// BatchCreateSubmissions 批量创建提交记录
func (r *AssignmentRepo) BatchCreateSubmissions(submissions []model.AssignmentSubmission) error {
	if len(submissions) == 0 {
		return nil
	}
	return r.db.Create(&submissions).Error
}