package service

import (
	"exam_registration/internal/dao"
	"exam_registration/internal/model"
	"errors"
	"gorm.io/gorm"
)

type ScoreService struct{}

func (s *ScoreService) CreateScore(score *model.ExamScore) error {
	// 检查是否已存在成绩
	var existingScore model.ExamScore
	if err := dao.DB.Where("user_id = ? AND exam_id = ?", score.UserID, score.ExamID).First(&existingScore).Error; err == nil {
		return errors.New("该用户该考试的成绩已存在")
	}

	// 判断是否及格（假设 60 分及格）
	score.Pass = score.Score >= 60

	return dao.DB.Create(score).Error
}

func (s *ScoreService) BatchCreateScores(scores []model.ExamScore) error {
	return dao.DB.Transaction(func(tx *gorm.DB) error {
		for i := range scores {
			scores[i].Pass = scores[i].Score >= 60
			
			// 检查是否已存在
			var existing model.ExamScore
			if err := tx.Where("user_id = ? AND exam_id = ?", scores[i].UserID, scores[i].ExamID).First(&existing).Error; err == nil {
				continue // 跳过已存在的记录
			}
			
			if err := tx.Create(&scores[i]).Error; err != nil {
				return err
			}
		}
		return nil
	})
}

func (s *ScoreService) GetScoreByUserAndExam(userID, examID uint64) (*model.ExamScore, error) {
	var score model.ExamScore
	if err := dao.DB.Preload("User").Preload("Exam").Where("user_id = ? AND exam_id = ?", userID, examID).First(&score).Error; err != nil {
		return nil, errors.New("成绩不存在")
	}
	return &score, nil
}

func (s *ScoreService) GetScoreList(examID, page, pageSize int) ([]model.ExamScore, int64, error) {
	var scores []model.ExamScore
	var total int64

	offset := (page - 1) * pageSize
	query := dao.DB.Model(&model.ExamScore{}).Preload("User").Preload("Exam")

	if examID > 0 {
		query = query.Where("exam_id = ?", examID)
	}

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

	err := query.Offset(offset).Limit(pageSize).Order("score DESC").Find(&scores).Error
	
	// 计算排名
	for i := range scores {
		scores[i].Rank = offset + i + 1
	}
	
	return scores, total, err
}

func (s *ScoreService) UpdateScore(id uint64, updates map[string]interface{}) error {
	return dao.DB.Model(&model.ExamScore{}).Where("id = ?", id).Updates(updates).Error
}

func (s *ScoreService) PublishScore(id uint64) error {
	return dao.DB.Model(&model.ExamScore{}).Where("id = ?", id).Update("published", true).Error
}

func (s *ScoreService) DeleteScore(id uint64) error {
	return dao.DB.Delete(&model.ExamScore{}, id).Error
}