feat(workspace): implement Yjs CRDT real-time collaborative editing (resolves FLAW-01)

internal/api/server.go

@@ -3,6 +3,7 @@ package api
 import (
 	"bytes"
 	"crypto/tls"
+	"encoding/base64"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -30,6 +31,9 @@ type Server struct {
 }
 
 func NewServer(cfg *config.Config, store *storage.Store, wsHub *ws.Hub, staticFS fs.FS) *Server {
+	if wsHub != nil && store != nil {
+		wsHub.SetCRDTStore(store)
+	}
 	srv := &Server{
 		cfg:      cfg,
 		store:    store,
@@ -141,6 +145,10 @@ func (s *Server) Router() http.Handler {
 		r.Post("/api/v1/documents/{id}/lock/heartbeat", s.handleHeartbeatDocLock)
 		r.Delete("/api/v1/documents/{id}/lock", s.handleUnlockDoc)
 
+		// Document CRDT Realtime Sync
+		r.Get("/api/v1/documents/{id}/crdt", s.handleGetDocCRDT)
+		r.Put("/api/v1/documents/{id}/crdt", s.handleSaveDocCRDT)
+
 		// Shared Lists & Realtime Collaboration
 		r.Get("/api/v1/lists", s.handleGetAllLists)
 		r.Post("/api/v1/lists", s.handleCreateList)
@@ -1373,6 +1381,68 @@ func (s *Server) handleUnlockDoc(w http.ResponseWriter, r *http.Request) {
 	writeJSON(w, http.StatusOK, map[string]bool{"unlocked": released})
 }
 
+// --- DOCUMENT CRDT REALTIME SYNC ---
+
+func (s *Server) handleGetDocCRDT(w http.ResponseWriter, r *http.Request) {
+	userID := auth.GetUserID(r.Context())
+	docID := chi.URLParam(r, "id")
+	if _, err := s.store.GetDocumentByID(userID, docID); err != nil {
+		writeError(w, http.StatusNotFound, "Dokument nicht gefunden")
+		return
+	}
+	stateBlob, updates, err := s.store.GetDocumentCRDTState(docID)
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	b64State := ""
+	if len(stateBlob) > 0 {
+		b64State = base64.StdEncoding.EncodeToString(stateBlob)
+	}
+	var b64Updates []string
+	for _, u := range updates {
+		b64Updates = append(b64Updates, base64.StdEncoding.EncodeToString(u))
+	}
+	writeJSON(w, http.StatusOK, map[string]interface{}{
+		"docId":   docID,
+		"state":   b64State,
+		"updates": b64Updates,
+	})
+}
+
+func (s *Server) handleSaveDocCRDT(w http.ResponseWriter, r *http.Request) {
+	userID := auth.GetUserID(r.Context())
+	docID := chi.URLParam(r, "id")
+	doc, err := s.store.GetDocumentByID(userID, docID)
+	if err != nil {
+		writeError(w, http.StatusNotFound, "Dokument nicht gefunden")
+		return
+	}
+	if !doc.IsOwner && doc.Permission != "write" {
+		writeError(w, http.StatusForbidden, "Keine Schreibberechtigung")
+		return
+	}
+	var req struct {
+		State string `json:"state"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeError(w, http.StatusBadRequest, "Ungültiger Request-Body")
+		return
+	}
+	if req.State != "" {
+		raw, err := base64.StdEncoding.DecodeString(req.State)
+		if err != nil {
+			writeError(w, http.StatusBadRequest, "Ungültiges Base64 Format")
+			return
+		}
+		if err := s.store.SaveDocumentCRDTState(docID, raw, userID); err != nil {
+			writeError(w, http.StatusInternalServerError, err.Error())
+			return
+		}
+	}
+	writeJSON(w, http.StatusOK, map[string]bool{"success": true})
+}
+
 // --- REALTIME LISTS & SHARING ---
 
 func (s *Server) handleGetAllLists(w http.ResponseWriter, r *http.Request) {