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 UserLearningService struct{}

// CreateUserLearning 创建用户学习记录
func (userLearningService *UserLearningService) CreateUserLearning(ctx context.Context, userLearning *learning.UserLearning) (err error) {
	// 检查是否已存在该用户对该课程的学习记录
	var existingRecord learning.UserLearning
	err = global.GVA_DB.WithContext(ctx).Where("user_id = ? AND course_id = ?", userLearning.UserId, userLearning.CourseId).First(&existingRecord).Error
	if err == nil {
		// 如果已存在，更新记录
		return userLearningService.UpdateUserLearning(ctx, *userLearning)
	}

	// 设置默认值
	if userLearning.LastStudyAt.IsZero() {
		userLearning.LastStudyAt = time.Now()
	}
	if userLearning.Status == "" {
		userLearning.Status = "learning"
	}

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

// DeleteUserLearning 删除用户学习记录
func (userLearningService *UserLearningService) DeleteUserLearning(ctx context.Context, ID string) (err error) {
	err = global.GVA_DB.WithContext(ctx).Delete(&learning.UserLearning{}, ID).Error
	return err
}

// DeleteUserLearningByIds 批量删除用户学习记录
func (userLearningService *UserLearningService) DeleteUserLearningByIds(ctx context.Context, IDs []string) (err error) {
	err = global.GVA_DB.WithContext(ctx).Delete(&[]learning.UserLearning{}, "id in ?", IDs).Error
	return err
}

// UpdateUserLearning 更新用户学习记录
func (userLearningService *UserLearningService) UpdateUserLearning(ctx context.Context, userLearning learning.UserLearning) (err error) {
	// 更新最后学习时间
	userLearning.LastStudyAt = time.Now()

	// 如果进度达到100%，设置完成状态和完成时间
	if userLearning.Progress >= 100 && userLearning.Status != "completed" {
		userLearning.Status = "completed"
		userLearning.CompletedAt = time.Now()
	}

	err = global.GVA_DB.WithContext(ctx).Model(&learning.UserLearning{}).Where("id = ?", userLearning.ID).Updates(&userLearning).Error
	return err
}

// GetUserLearning 根据ID获取用户学习记录
func (userLearningService *UserLearningService) GetUserLearning(ctx context.Context, ID string) (userLearning learning.UserLearning, err error) {
	err = global.GVA_DB.WithContext(ctx).Where("id = ?", ID).First(&userLearning).Error
	if err != nil {
		return
	}
	// 手动查询关联信息
	userLearningService.loadAssociations(ctx, &userLearning)
	return
}

// GetUserLearningInfoList 分页获取用户学习记录列表
func (userLearningService *UserLearningService) GetUserLearningInfoList(ctx context.Context, info learningReq.UserLearningSearch) (list []learning.UserLearning, total int64, err error) {
	limit := info.PageSize
	offset := info.PageSize * (info.Page - 1)
	// 创建db
	db := global.GVA_DB.WithContext(ctx).Model(&learning.UserLearning{})
	var userLearnings []learning.UserLearning
	// 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.CourseId != 0 {
		db = db.Where("course_id = ?", info.CourseId)
	}
	if info.Status != "" {
		db = db.Where("status = ?", info.Status)
	}
	err = db.Count(&total).Error
	if err != nil {
		return
	}

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

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

	// 批量加载关联信息
	for i := range userLearnings {
		userLearningService.loadAssociations(ctx, &userLearnings[i])
	}

	return userLearnings, total, err
}

// GetUserProgress 获取用户学习进度
func (userLearningService *UserLearningService) GetUserProgress(ctx context.Context, userId uint, courseId uint) (progress []learning.UserLearning, err error) {
	db := global.GVA_DB.WithContext(ctx).Where("user_id = ?", userId)
	if courseId != 0 {
		db = db.Where("course_id = ?", courseId)
	}
	err = db.Find(&progress).Error

	// 批量加载关联信息
	for i := range progress {
		userLearningService.loadAssociations(ctx, &progress[i])
	}

	return
}

// GetLearningStatistics 获取用户学习统计
func (userLearningService *UserLearningService) GetLearningStatistics(ctx context.Context, userId uint) (stats learningReq.LearningStatistics, err error) {
	// 总课程数
	var totalCourses int64
	err = global.GVA_DB.WithContext(ctx).Model(&learning.UserLearning{}).Where("user_id = ?", userId).Count(&totalCourses).Error
	if err != nil {
		return
	}
	stats.TotalCourses = int(totalCourses)

	// 已完成课程数
	var completedCourses int64
	err = global.GVA_DB.WithContext(ctx).Model(&learning.UserLearning{}).Where("user_id = ? AND status = ?", userId, "completed").Count(&completedCourses).Error
	if err != nil {
		return
	}
	stats.CompletedCourses = int(completedCourses)

	// 学习中课程数
	var inProgressCourses int64
	err = global.GVA_DB.WithContext(ctx).Model(&learning.UserLearning{}).Where("user_id = ? AND status = ?", userId, "learning").Count(&inProgressCourses).Error
	if err != nil {
		return
	}
	stats.InProgressCourses = int(inProgressCourses)

	// 总学习时长和平均分数
	var result struct {
		TotalStudyTime int
		AverageScore   int
	}
	err = global.GVA_DB.WithContext(ctx).Model(&learning.UserLearning{}).
		Select("SUM(study_time) as total_study_time, AVG(score) as average_score").
		Where("user_id = ?", userId).
		Scan(&result).Error
	if err != nil {
		return
	}

	stats.TotalStudyTime = result.TotalStudyTime
	stats.AverageScore = result.AverageScore

	return
}

// loadAssociations 加载关联信息
func (userLearningService *UserLearningService) loadAssociations(ctx context.Context, userLearning *learning.UserLearning) {
	// 加载课程信息
	if userLearning.CourseId != 0 {
		var course learning.Course
		if err := global.GVA_DB.WithContext(ctx).Where("id = ?", userLearning.CourseId).First(&course).Error; err == nil {
			userLearning.Course = course
		}
	}

	// 加载章节信息
	if userLearning.ChapterId != 0 {
		var chapter learning.Chapter
		if err := global.GVA_DB.WithContext(ctx).Where("id = ?", userLearning.ChapterId).First(&chapter).Error; err == nil {
			userLearning.Chapter = chapter
		}
	}

	// 加载知识点信息
	if userLearning.KnowledgePointId != 0 {
		var knowledgePoint learning.KnowledgePoint
		if err := global.GVA_DB.WithContext(ctx).Where("id = ?", userLearning.KnowledgePointId).First(&knowledgePoint).Error; err == nil {
			userLearning.KnowledgePoint = knowledgePoint
		}
	}
}