backend/internal/service/material_service.go

package service

import (
	"errors"
	"carrot_bbs/internal/model"
	"carrot_bbs/internal/repository"
)

// ErrSubjectHasMaterials 学科下存在资料，无法删除
var ErrSubjectHasMaterials = errors.New("学科下存在资料，无法删除")

// MaterialService 学习资料服务接口
type MaterialService interface {
	// 学科相关
	ListActiveSubjects() ([]*model.MaterialSubject, error)
	ListAllSubjects() ([]*model.MaterialSubject, error)
	GetSubjectByID(id string) (*model.MaterialSubject, error)
	GetSubjectByIDWithMaterialCount(id string) (*model.MaterialSubject, int64, error)
	CreateSubject(name, icon, color, description string, sortOrder int, isActive bool) (*model.MaterialSubject, error)
	UpdateSubject(id, name, icon, color, description string, sortOrder int, isActive bool) (*model.MaterialSubject, error)
	DeleteSubject(id string) error

	// 资料相关
	ListMaterials(params repository.MaterialFileQueryParams) ([]*model.MaterialFile, int64, error)
	GetMaterialByID(id string) (*model.MaterialFile, error)
	GetMaterialByIDWithSubject(id string) (*model.MaterialFile, error)
	GetMaterialsBySubject(subjectID string, page, pageSize int) ([]*model.MaterialFile, int64, error)
	SearchMaterials(keyword string, page, pageSize int) ([]*model.MaterialFile, int64, error)
	GetHotMaterials(limit int) ([]*model.MaterialFile, error)
	GetLatestMaterials(limit int) ([]*model.MaterialFile, error)
	CreateMaterial(file *model.MaterialFile) error
	UpdateMaterial(file *model.MaterialFile) error
	DeleteMaterial(id string) error
	IncrementDownloadCount(id string) error
}

// materialServiceImpl 学习资料服务实现
type materialServiceImpl struct {
	subjectRepo *repository.MaterialSubjectRepository
	fileRepo    *repository.MaterialFileRepository
}

// NewMaterialService 创建学习资料服务
func NewMaterialService(
	subjectRepo *repository.MaterialSubjectRepository,
	fileRepo *repository.MaterialFileRepository,
) MaterialService {
	return &materialServiceImpl{
		subjectRepo: subjectRepo,
		fileRepo:    fileRepo,
	}
}

// =====================================================
// 学科相关方法
// =====================================================

func (s *materialServiceImpl) ListActiveSubjects() ([]*model.MaterialSubject, error) {
	return s.subjectRepo.ListActive()
}

func (s *materialServiceImpl) ListAllSubjects() ([]*model.MaterialSubject, error) {
	return s.subjectRepo.ListAll()
}

func (s *materialServiceImpl) GetSubjectByID(id string) (*model.MaterialSubject, error) {
	return s.subjectRepo.GetByID(id)
}

func (s *materialServiceImpl) GetSubjectByIDWithMaterialCount(id string) (*model.MaterialSubject, int64, error) {
	subject, err := s.subjectRepo.GetByID(id)
	if err != nil {
		return nil, 0, err
	}
	count, err := s.subjectRepo.CountMaterials(id)
	if err != nil {
		return subject, 0, nil
	}
	return subject, count, nil
}

func (s *materialServiceImpl) CreateSubject(name, icon, color, description string, sortOrder int, isActive bool) (*model.MaterialSubject, error) {
	subject := &model.MaterialSubject{
		Name:        name,
		Icon:        icon,
		Color:       color,
		Description: description,
		SortOrder:   sortOrder,
		IsActive:    isActive,
	}
	if err := s.subjectRepo.Create(subject); err != nil {
		return nil, err
	}
	return subject, nil
}

func (s *materialServiceImpl) UpdateSubject(id, name, icon, color, description string, sortOrder int, isActive bool) (*model.MaterialSubject, error) {
	subject, err := s.subjectRepo.GetByID(id)
	if err != nil {
		return nil, err
	}
	subject.Name = name
	subject.Icon = icon
	subject.Color = color
	subject.Description = description
	subject.SortOrder = sortOrder
	subject.IsActive = isActive
	if err := s.subjectRepo.Update(subject); err != nil {
		return nil, err
	}
	return subject, nil
}

func (s *materialServiceImpl) DeleteSubject(id string) error {
	// 检查学科下是否有资料
	count, err := s.subjectRepo.CountMaterials(id)
	if err != nil {
		return err
	}
	if count > 0 {
		return ErrSubjectHasMaterials
	}
	return s.subjectRepo.Delete(id)
}

// =====================================================
// 资料相关方法
// =====================================================

func (s *materialServiceImpl) ListMaterials(params repository.MaterialFileQueryParams) ([]*model.MaterialFile, int64, error) {
	return s.fileRepo.List(params)
}

func (s *materialServiceImpl) GetMaterialByID(id string) (*model.MaterialFile, error) {
	return s.fileRepo.GetByID(id)
}

func (s *materialServiceImpl) GetMaterialByIDWithSubject(id string) (*model.MaterialFile, error) {
	return s.fileRepo.GetByIDWithSubject(id)
}

func (s *materialServiceImpl) GetMaterialsBySubject(subjectID string, page, pageSize int) ([]*model.MaterialFile, int64, error) {
	return s.fileRepo.GetBySubjectID(subjectID, page, pageSize)
}

func (s *materialServiceImpl) SearchMaterials(keyword string, page, pageSize int) ([]*model.MaterialFile, int64, error) {
	return s.fileRepo.Search(keyword, page, pageSize)
}

func (s *materialServiceImpl) GetHotMaterials(limit int) ([]*model.MaterialFile, error) {
	return s.fileRepo.GetHotMaterials(limit)
}

func (s *materialServiceImpl) GetLatestMaterials(limit int) ([]*model.MaterialFile, error) {
	return s.fileRepo.GetLatestMaterials(limit)
}

func (s *materialServiceImpl) CreateMaterial(file *model.MaterialFile) error {
	return s.fileRepo.Create(file)
}

func (s *materialServiceImpl) UpdateMaterial(file *model.MaterialFile) error {
	return s.fileRepo.Update(file)
}

func (s *materialServiceImpl) DeleteMaterial(id string) error {
	return s.fileRepo.Delete(id)
}

func (s *materialServiceImpl) IncrementDownloadCount(id string) error {
	return s.fileRepo.IncrementDownloadCount(id)
}