feat: 新增 Knowledge 知识库后端服务

- 添加 Knowledge 实体定义
- 添加 Knowledge 仓储层
- 添加 Knowledge 服务层

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/internal/service/knowledge_service.go

@@ -0,0 +1,235 @@
+package service
+
+import (
+	"mime/multipart"
+	"time"
+
+	"github.com/google/uuid"
+	"x-agents/server/internal/model"
+	"x-agents/server/internal/repository"
+)
+
+type KnowledgeService struct {
+	repo          *repository.KnowledgeRepository
+	modelRepo     *repository.ModelRepository
+	uploadService *UploadService
+}
+
+func NewKnowledgeService(repo *repository.KnowledgeRepository, modelRepo *repository.ModelRepository, uploadService *UploadService) *KnowledgeService {
+	return &KnowledgeService{
+		repo:          repo,
+		modelRepo:     modelRepo,
+		uploadService: uploadService,
+	}
+}
+
+// Create 创建知识库
+func (s *KnowledgeService) Create(req model.CreateKnowledgeRequest) (*model.KnowledgeBase, error) {
+	// 验证 LLM 模型存在
+	if _, err := s.modelRepo.FindByID(req.LLMModelID); err != nil {
+		return nil, err
+	}
+	// 验证 Embedding 模型存在
+	if _, err := s.modelRepo.FindByID(req.EmbeddingModelID); err != nil {
+		return nil, err
+	}
+
+	kb := &model.KnowledgeBase{
+		ID:                uuid.New().String(),
+		Name:              req.Name,
+		Description:       req.Description,
+		LLMModelID:        req.LLMModelID,
+		EmbeddingModelID:  req.EmbeddingModelID,
+		ParsingConfig:     req.ParsingConfig,
+		Status:            "active",
+		DocumentCount:     0,
+		ChunkCount:        0,
+	}
+
+	// 设置默认值
+	if kb.ParsingConfig.EnablePDF == false && kb.ParsingConfig.EnablePDF != true {
+		kb.ParsingConfig.EnablePDF = true
+	}
+	if kb.ParsingConfig.Pandoc == false && kb.ParsingConfig.Pandoc != true {
+		kb.ParsingConfig.Pandoc = true
+	}
+
+	if err := s.repo.Create(kb); err != nil {
+		return nil, err
+	}
+	return kb, nil
+}
+
+// List 获取知识库列表
+func (s *KnowledgeService) List() ([]model.KnowledgeBase, error) {
+	return s.repo.FindAll()
+}
+
+// GetByID 获取知识库详情
+func (s *KnowledgeService) GetByID(id string) (*model.KnowledgeBase, error) {
+	return s.repo.FindByID(id)
+}
+
+// Update 更新知识库
+func (s *KnowledgeService) Update(id string, req model.UpdateKnowledgeRequest) error {
+	updates := make(map[string]interface{})
+	if req.Name != "" {
+		updates["name"] = req.Name
+	}
+	if req.Description != "" {
+		updates["description"] = req.Description
+	}
+	if req.LLMModelID != "" {
+		// 验证模型存在
+		if _, err := s.modelRepo.FindByID(req.LLMModelID); err != nil {
+			return err
+		}
+		updates["llm_model_id"] = req.LLMModelID
+	}
+	if req.EmbeddingModelID != "" {
+		// 验证模型存在
+		if _, err := s.modelRepo.FindByID(req.EmbeddingModelID); err != nil {
+			return err
+		}
+		updates["embedding_model_id"] = req.EmbeddingModelID
+	}
+	if req.ParsingConfig.Engine != "" {
+		updates["parsing_config"] = req.ParsingConfig
+	}
+	if req.Status != "" {
+		updates["status"] = req.Status
+	}
+
+	return s.repo.Update(id, updates)
+}
+
+// Delete 删除知识库
+func (s *KnowledgeService) Delete(id string) error {
+	// 先删除关联的文档
+	if err := s.repo.DeleteDocumentsByKBID(id); err != nil {
+		return err
+	}
+	return s.repo.Delete(id)
+}
+
+// ListDocuments 获取知识库下的文档列表
+func (s *KnowledgeService) ListDocuments(kbID string, status string) ([]model.KnowledgeDocument, error) {
+	return s.repo.FindDocumentsByKBID(kbID, status)
+}
+
+// UploadDocument 上传文档到知识库
+func (s *KnowledgeService) UploadDocument(kbID string, file *multipart.FileHeader) (*model.KnowledgeDocument, error) {
+	// 验证知识库存在
+	_, err := s.repo.FindByID(kbID)
+	if err != nil {
+		return nil, err
+	}
+
+	// 上传文件
+	result, err := s.uploadService.Upload(file)
+	if err != nil {
+		return nil, err
+	}
+	if !result.Success {
+		return nil, nil
+	}
+
+	// 创建文档记录
+	doc := &model.KnowledgeDocument{
+		ID:               uuid.New().String(),
+		KnowledgeBaseID:  kbID,
+		Name:             file.Filename,
+		FileKey:          result.FileKey,
+		FileSize:         file.Size,
+		Status:           "parsing",
+		UploadedAt:       time.Now(),
+	}
+
+	if err := s.repo.CreateDocument(doc); err != nil {
+		return nil, err
+	}
+
+	// 更新知识库文档数
+	s.updateDocumentCount(kbID)
+
+	return doc, nil
+}
+
+// DeleteDocument 删除文档
+func (s *KnowledgeService) DeleteDocument(kbID, docID string) error {
+	// 验证文档存在
+	doc, err := s.repo.FindDocumentByID(docID)
+	if err != nil {
+		return err
+	}
+	if doc.KnowledgeBaseID != kbID {
+		return nil
+	}
+
+	// 删除文件
+	if doc.FileKey != "" {
+		s.uploadService.DeleteFile(doc.FileKey + getFileExt(doc.Name))
+	}
+
+	// 删除文档记录
+	if err := s.repo.DeleteDocument(docID); err != nil {
+		return err
+	}
+
+	// 更新知识库文档数
+	s.updateDocumentCount(kbID)
+
+	return nil
+}
+
+// ReparseDocument 重新解析文档
+func (s *KnowledgeService) ReparseDocument(kbID, docID string) error {
+	// 验证文档存在
+	doc, err := s.repo.FindDocumentByID(docID)
+	if err != nil {
+		return err
+	}
+	if doc.KnowledgeBaseID != kbID {
+		return nil
+	}
+
+	// 重置状态为 parsing
+	return s.repo.UpdateDocument(docID, map[string]interface{}{"status": "parsing"})
+}
+
+// GetDocumentPreview 获取文档预览
+func (s *KnowledgeService) GetDocumentPreview(kbID, docID string, page int) (*model.DocumentPreviewResponse, error) {
+	// 验证文档存在
+	doc, err := s.repo.FindDocumentByID(docID)
+	if err != nil {
+		return nil, err
+	}
+	if doc.KnowledgeBaseID != kbID {
+		return nil, nil
+	}
+
+	// 简单实现：返回文件 URL（实际应由 Python 服务处理）
+	fileURL, err := s.uploadService.GetFileURL(doc.FileKey + getFileExt(doc.Name))
+	if err != nil {
+		return nil, err
+	}
+
+	return &model.DocumentPreviewResponse{
+		TotalPages:  1,
+		CurrentPage: page,
+		Content:     fileURL,
+	}, nil
+}
+
+// updateDocumentCount 更新知识库文档数
+func (s *KnowledgeService) updateDocumentCount(kbID string) {
+	count, _ := s.repo.CountDocumentsByKBID(kbID)
+	s.repo.Update(kbID, map[string]interface{}{"document_count": int(count)})
+}
+
+func getFileExt(filename string) string {
+	if len(filename) > 4 {
+		return filename[len(filename)-4:]
+	}
+	return ""
+}