package learning

import (
	"context"
	"time"

	"github.com/flipped-aurora/gin-vue-admin/server/global"
	"github.com/flipped-aurora/gin-vue-admin/server/model/learning"
	learningReq "github.com/flipped-aurora/gin-vue-admin/server/model/learning/request"
)

type WrongQuestionService struct{}

// CreateWrongQuestion 创建错题记录
func (wrongQuestionService *WrongQuestionService) CreateWrongQuestion(ctx context.Context, wrongQuestion *learning.WrongQuestion) (err error) {
	// 检查是否已存在该用户对该题目的错题记录
	var existingRecord learning.WrongQuestion
	err = global.GVA_DB.WithContext(ctx).Where("user_id = ? AND question_id = ?", wrongQuestion.UserId, wrongQuestion.QuestionId).First(&existingRecord).Error
	if err == nil {
		// 如果已存在，更新错误次数和最后错误时间
		existingRecord.WrongCount++
		existingRecord.LastWrongAt = time.Now()
		existingRecord.WrongAnswer = wrongQuestion.WrongAnswer
		existingRecord.IsMastered = false // 重新答错，标记为未掌握
		existingRecord.MasteredAt = time.Time{}
		return wrongQuestionService.UpdateWrongQuestion(ctx, existingRecord)
	}

	// 设置默认值
	if wrongQuestion.LastWrongAt.IsZero() {
		wrongQuestion.LastWrongAt = time.Now()
	}
	if wrongQuestion.WrongCount == 0 {
		wrongQuestion.WrongCount = 1
	}

	err = global.GVA_DB.WithContext(ctx).Create(wrongQuestion).Error
	return err
}

// DeleteWrongQuestion 删除错题记录
func (wrongQuestionService *WrongQuestionService) DeleteWrongQuestion(ctx context.Context, ID string) (err error) {
	err = global.GVA_DB.WithContext(ctx).Delete(&learning.WrongQuestion{}, ID).Error
	return err
}

// DeleteWrongQuestionByIds 批量删除错题记录
func (wrongQuestionService *WrongQuestionService) DeleteWrongQuestionByIds(ctx context.Context, IDs []string) (err error) {
	err = global.GVA_DB.WithContext(ctx).Delete(&[]learning.WrongQuestion{}, "id in ?", IDs).Error
	return err
}

// UpdateWrongQuestion 更新错题记录
func (wrongQuestionService *WrongQuestionService) UpdateWrongQuestion(ctx context.Context, wrongQuestion learning.WrongQuestion) (err error) {
	err = global.GVA_DB.WithContext(ctx).Model(&learning.WrongQuestion{}).Where("id = ?", wrongQuestion.ID).Updates(&wrongQuestion).Error
	return err
}

// GetWrongQuestion 根据ID获取错题记录
func (wrongQuestionService *WrongQuestionService) GetWrongQuestion(ctx context.Context, ID string) (wrongQuestion learning.WrongQuestion, err error) {
	err = global.GVA_DB.WithContext(ctx).Where("id = ?", ID).First(&wrongQuestion).Error
	if err != nil {
		return
	}
	// 手动查询关联的题目信息
	wrongQuestionService.loadQuestionInfo(ctx, &wrongQuestion)
	return
}

// GetWrongQuestionInfoList 分页获取错题记录列表
func (wrongQuestionService *WrongQuestionService) GetWrongQuestionInfoList(ctx context.Context, info learningReq.WrongQuestionSearch) (list []learning.WrongQuestion, total int64, err error) {
	limit := info.PageSize
	offset := info.PageSize * (info.Page - 1)
	// 创建db
	db := global.GVA_DB.WithContext(ctx).Model(&learning.WrongQuestion{})
	var wrongQuestions []learning.WrongQuestion
	// 如果有条件搜索 下方会自动创建搜索语句
	if info.StartCreatedAt != nil && info.EndCreatedAt != nil {
		db = db.Where("created_at BETWEEN ? AND ?", info.StartCreatedAt, info.EndCreatedAt)
	}
	if info.UserId != 0 {
		db = db.Where("user_id = ?", info.UserId)
	}
	if info.QuestionId != 0 {
		db = db.Where("question_id = ?", info.QuestionId)
	}
	if info.IsMastered {
		db = db.Where("is_mastered = ?", info.IsMastered)
	}
	err = db.Count(&total).Error
	if err != nil {
		return
	}

	if limit != 0 {
		db = db.Limit(limit).Offset(offset)
	}

	err = db.Order("last_wrong_at desc").Find(&wrongQuestions).Error
	if err != nil {
		return wrongQuestions, total, err
	}

	// 批量加载关联的题目信息
	for i := range wrongQuestions {
		wrongQuestionService.loadQuestionInfo(ctx, &wrongQuestions[i])
	}

	return wrongQuestions, total, err
}

// GetUserWrongQuestions 获取用户的错题列表
func (wrongQuestionService *WrongQuestionService) GetUserWrongQuestions(ctx context.Context, userId uint, onlyUnmastered bool) (list []learning.WrongQuestion, err error) {
	db := global.GVA_DB.WithContext(ctx).Where("user_id = ?", userId)
	if onlyUnmastered {
		db = db.Where("is_mastered = ?", false)
	}
	err = db.Order("last_wrong_at desc").Find(&list).Error

	// 批量加载关联的题目信息
	for i := range list {
		wrongQuestionService.loadQuestionInfo(ctx, &list[i])
	}

	return
}

// MarkAsMastered 标记题目为已掌握
func (wrongQuestionService *WrongQuestionService) MarkAsMastered(ctx context.Context, userId uint, wrongQuestionId uint) (err error) {
	updates := map[string]interface{}{
		"is_mastered": true,
		"mastered_at": time.Now(),
	}
	err = global.GVA_DB.WithContext(ctx).Model(&learning.WrongQuestion{}).
		Where("id = ? AND user_id = ?", wrongQuestionId, userId).
		Updates(updates).Error
	return err
}

// GetWrongQuestionStatistics 获取用户错题统计
func (wrongQuestionService *WrongQuestionService) GetWrongQuestionStatistics(ctx context.Context, userId uint) (stats learningReq.WrongQuestionStatistics, err error) {
	// 总错题数
	var totalWrongQuestions int64
	err = global.GVA_DB.WithContext(ctx).Model(&learning.WrongQuestion{}).Where("user_id = ?", userId).Count(&totalWrongQuestions).Error
	if err != nil {
		return
	}
	stats.TotalWrongQuestions = int(totalWrongQuestions)

	// 已掌握题目数
	var masteredQuestions int64
	err = global.GVA_DB.WithContext(ctx).Model(&learning.WrongQuestion{}).Where("user_id = ? AND is_mastered = ?", userId, true).Count(&masteredQuestions).Error
	if err != nil {
		return
	}
	stats.MasteredQuestions = int(masteredQuestions)

	// 未掌握题目数
	stats.UnmasteredQuestions = stats.TotalWrongQuestions - stats.MasteredQuestions

	// 平均错误次数
	var result struct {
		AverageWrongCount float64
	}
	err = global.GVA_DB.WithContext(ctx).Model(&learning.WrongQuestion{}).
		Select("AVG(wrong_count) as average_wrong_count").
		Where("user_id = ?", userId).
		Scan(&result).Error
	if err != nil {
		return
	}

	stats.AverageWrongCount = int(result.AverageWrongCount)

	return
}

// loadQuestionInfo 加载题目信息
func (wrongQuestionService *WrongQuestionService) loadQuestionInfo(ctx context.Context, wrongQuestion *learning.WrongQuestion) {
	if wrongQuestion.QuestionId != 0 {
		var question learning.Question
		if err := global.GVA_DB.WithContext(ctx).Where("id = ?", wrongQuestion.QuestionId).First(&question).Error; err == nil {
			wrongQuestion.Question = question
		}
	}
}