feat(material): add material handling and routing functionality

- Introduced MaterialHandler for managing learning materials and subjects.
- Updated router to include routes for public and admin material management.
- Enhanced database initialization with material subject and file models.
- Implemented seeding logic for material subjects and files.
- Updated wire generation to include MaterialHandler and related services.

internal/service/material_service.go

@@ -0,0 +1,172 @@
+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)
+}