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 ExamService struct{}

// CreateExam 创建考试
func (examService *ExamService) CreateExam(ctx context.Context, exam *learning.Exam) (err error) {
	// 设置默认值
	if exam.Status == "" {
		exam.Status = "draft"
	}
	if exam.MaxAttempts == 0 {
		exam.MaxAttempts = 1
	}

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

// DeleteExam 删除考试
func (examService *ExamService) DeleteExam(ctx context.Context, ID string) (err error) {
	err = global.GVA_DB.WithContext(ctx).Delete(&learning.Exam{}, ID).Error
	return err
}

// DeleteExamByIds 批量删除考试
func (examService *ExamService) DeleteExamByIds(ctx context.Context, IDs []string) (err error) {
	err = global.GVA_DB.WithContext(ctx).Delete(&[]learning.Exam{}, "id in ?", IDs).Error
	return err
}

// UpdateExam 更新考试
func (examService *ExamService) UpdateExam(ctx context.Context, exam learning.Exam) (err error) {
	err = global.GVA_DB.WithContext(ctx).Model(&learning.Exam{}).Where("id = ?", exam.ID).Updates(&exam).Error
	return err
}

// GetExam 根据ID获取考试
func (examService *ExamService) GetExam(ctx context.Context, ID string) (exam learning.Exam, err error) {
	err = global.GVA_DB.WithContext(ctx).Where("id = ?", ID).First(&exam).Error
	if err != nil {
		return
	}
	// 手动查询关联的课程信息
	examService.loadCourseInfo(ctx, &exam)
	return
}

// GetExamInfoList 分页获取考试列表
func (examService *ExamService) GetExamInfoList(ctx context.Context, info learningReq.ExamSearch) (list []learning.Exam, total int64, err error) {
	limit := info.PageSize
	offset := info.PageSize * (info.Page - 1)
	// 创建db
	db := global.GVA_DB.WithContext(ctx).Model(&learning.Exam{})
	var exams []learning.Exam
	// 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.Title != "" {
		db = db.Where("title LIKE ?", "%"+info.Title+"%")
	}
	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("created_at desc").Find(&exams).Error
	if err != nil {
		return exams, total, err
	}

	// 批量加载关联的课程信息
	for i := range exams {
		examService.loadCourseInfo(ctx, &exams[i])
	}

	return exams, total, err
}

// GetActiveExams 获取进行中的考试列表
func (examService *ExamService) GetActiveExams(ctx context.Context) (list []learning.Exam, err error) {
	now := time.Now()
	err = global.GVA_DB.WithContext(ctx).
		Where("status = ? AND start_time <= ? AND end_time >= ?", "published", now, now).
		Order("start_time asc").
		Find(&list).Error

	// 批量加载关联的课程信息
	for i := range list {
		examService.loadCourseInfo(ctx, &list[i])
	}

	return
}

// GetExamsByCourse 根据课程获取考试列表
func (examService *ExamService) GetExamsByCourse(ctx context.Context, courseId uint) (list []learning.Exam, err error) {
	err = global.GVA_DB.WithContext(ctx).
		Where("course_id = ? AND status = ?", courseId, "published").
		Order("start_time asc").
		Find(&list).Error

	// 批量加载关联的课程信息
	for i := range list {
		examService.loadCourseInfo(ctx, &list[i])
	}

	return
}

// PublishExam 发布考试
func (examService *ExamService) PublishExam(ctx context.Context, examId uint) (err error) {
	updates := map[string]interface{}{
		"status": "published",
	}
	err = global.GVA_DB.WithContext(ctx).Model(&learning.Exam{}).
		Where("id = ?", examId).
		Updates(updates).Error
	return err
}

// GetExamStatistics 获取考试统计
func (examService *ExamService) GetExamStatistics(ctx context.Context) (stats learningReq.ExamStatistics, err error) {
	// 总考试数
	var totalExams int64
	err = global.GVA_DB.WithContext(ctx).Model(&learning.Exam{}).Count(&totalExams).Error
	if err != nil {
		return
	}
	stats.TotalExams = int(totalExams)

	// 进行中的考试数
	now := time.Now()
	var activeExams int64
	err = global.GVA_DB.WithContext(ctx).Model(&learning.Exam{}).
		Where("status = ? AND start_time <= ? AND end_time >= ?", "published", now, now).
		Count(&activeExams).Error
	if err != nil {
		return
	}
	stats.ActiveExams = int(activeExams)

	// 已结束的考试数
	var completedExams int64
	err = global.GVA_DB.WithContext(ctx).Model(&learning.Exam{}).
		Where("status = ? AND end_time < ?", "published", now).
		Count(&completedExams).Error
	if err != nil {
		return
	}
	stats.CompletedExams = int(completedExams)

	// 草稿考试数
	var draftExams int64
	err = global.GVA_DB.WithContext(ctx).Model(&learning.Exam{}).
		Where("status = ?", "draft").
		Count(&draftExams).Error
	if err != nil {
		return
	}
	stats.DraftExams = int(draftExams)

	return
}

// loadCourseInfo 加载课程信息
func (examService *ExamService) loadCourseInfo(ctx context.Context, exam *learning.Exam) {
	if exam.CourseId != 0 {
		var course learning.Course
		if err := global.GVA_DB.WithContext(ctx).Where("id = ?", exam.CourseId).First(&course).Error; err == nil {
			exam.Course = course
		}
	}
}