feat: Add PUT and PATCH datasets endpoints

internal/transport/http/dataset_handler.go

@@ -37,6 +37,8 @@ func (h *DatasetHandler) Register(r chi.Router) {
 	r.Get("/", h.list)
 	r.Post("/", h.upload)
 	r.Get("/{id}", h.get)
+	r.Put("/{id}", h.update)
+	r.Patch("/{id}", h.patch)
 	r.Get("/{id}.geojson", h.geojson)
 	r.Get("/{id}.cog", h.cog)
 	r.Get("/{id}/status", h.status)
@@ -306,6 +308,150 @@ func (h *DatasetHandler) get(w http.ResponseWriter, r *http.Request) {
 	httputil.WriteJSON(w, http.StatusOK, dataset)
 }
 
+// datasetPutRequest is the full JSON body for PUT /datasets/{id}: every
+// editable field is required. Description and Unit are pointers so an empty
+// string is distinguishable from an absent field; a blank value clears the
+// (nullable) column. File-related and lifecycle fields are not editable here.
+type datasetPutRequest struct {
+	CategoryID  string  `json:"category_id" validate:"required,uuid"`
+	Name        string  `json:"name" validate:"required,max=255"`
+	Description *string `json:"description" validate:"required"`
+	Unit        *string `json:"unit" validate:"required"`
+}
+
+// update replaces a dataset's editable metadata (category, name, description,
+// unit).
+func (h *DatasetHandler) update(w http.ResponseWriter, r *http.Request) {
+	id, ok := parseUUIDParam(w, r, "id")
+	if !ok {
+		return
+	}
+	req, err := httputil.DecodeJSON[datasetPutRequest](w, r)
+	if err != nil {
+		httputil.WriteError(w, http.StatusBadRequest, "invalid request body")
+		return
+	}
+	if err := h.validate.Struct(req); err != nil {
+		httputil.WriteValidationErrors(w, err)
+		return
+	}
+	categoryID, err := uuid.Parse(req.CategoryID)
+	if err != nil {
+		httputil.WriteError(w, http.StatusUnprocessableEntity, "category_id must be a valid UUID")
+		return
+	}
+
+	dataset, err := h.svc.Update(r.Context(), id, service.DatasetUpdateInput{
+		CategoryID:  categoryID,
+		Name:        strings.TrimSpace(req.Name),
+		Description: normalizeOptional(*req.Description),
+		Unit:        normalizeOptional(*req.Unit),
+	})
+	if err != nil {
+		respondDomainError(w, err)
+		return
+	}
+	httputil.WriteJSON(w, http.StatusOK, dataset)
+}
+
+// datasetPatchFields lists the JSON keys accepted by PATCH /datasets/{id}.
+var datasetPatchFields = map[string]struct{}{
+	"category_id": {}, "name": {}, "description": {}, "unit": {},
+}
+
+// patch applies a sparse update to a dataset's editable metadata (category,
+// name, description, unit): only fields present in the body are changed.
+// Sending an explicit null for description/unit clears that column.
+func (h *DatasetHandler) patch(w http.ResponseWriter, r *http.Request) {
+	id, ok := parseUUIDParam(w, r, "id")
+	if !ok {
+		return
+	}
+	raw, err := httputil.DecodeJSON[map[string]json.RawMessage](w, r)
+	if err != nil {
+		httputil.WriteError(w, http.StatusBadRequest, "invalid request body")
+		return
+	}
+	if len(raw) == 0 {
+		httputil.WriteError(w, http.StatusBadRequest, "request body must include at least one field")
+		return
+	}
+
+	var in service.DatasetPatchInput
+	for key, val := range raw {
+		if _, ok := datasetPatchFields[key]; !ok {
+			httputil.WriteError(w, http.StatusUnprocessableEntity, "unknown field: "+key)
+			return
+		}
+		switch key {
+		case "category_id":
+			var s string
+			if err := json.Unmarshal(val, &s); err != nil || s == "" {
+				httputil.WriteError(w, http.StatusUnprocessableEntity, "category_id must be a valid UUID")
+				return
+			}
+			cid, err := uuid.Parse(s)
+			if err != nil {
+				httputil.WriteError(w, http.StatusUnprocessableEntity, "category_id must be a valid UUID")
+				return
+			}
+			in.CategoryID = &cid
+		case "name":
+			var s string
+			if err := json.Unmarshal(val, &s); err != nil || strings.TrimSpace(s) == "" {
+				httputil.WriteError(w, http.StatusUnprocessableEntity, "name must not be blank")
+				return
+			}
+			name := strings.TrimSpace(s)
+			in.Name = &name
+		case "description":
+			desc, err := decodeOptionalPatchString(val)
+			if err != nil {
+				httputil.WriteError(w, http.StatusUnprocessableEntity, "description must be a string or null")
+				return
+			}
+			in.Description, in.DescriptionSet = desc, true
+		case "unit":
+			unit, err := decodeOptionalPatchString(val)
+			if err != nil {
+				httputil.WriteError(w, http.StatusUnprocessableEntity, "unit must be a string or null")
+				return
+			}
+			in.Unit, in.UnitSet = unit, true
+		}
+	}
+
+	dataset, err := h.svc.Patch(r.Context(), id, in)
+	if err != nil {
+		respondDomainError(w, err)
+		return
+	}
+	httputil.WriteJSON(w, http.StatusOK, dataset)
+}
+
+// normalizeOptional trims s and returns nil when blank, so an empty string
+// clears a nullable column rather than being stored verbatim.
+func normalizeOptional(s string) *string {
+	s = strings.TrimSpace(s)
+	if s == "" {
+		return nil
+	}
+	return &s
+}
+
+// decodeOptionalPatchString unmarshals a PATCH field that may be a JSON string
+// or null, returning nil (clear the column) for null or a blank string.
+func decodeOptionalPatchString(raw json.RawMessage) (*string, error) {
+	if string(raw) == "null" {
+		return nil, nil
+	}
+	var s string
+	if err := json.Unmarshal(raw, &s); err != nil {
+		return nil, err
+	}
+	return normalizeOptional(s), nil
+}
+
 // geojson returns the dataset's pre-assembled GeoJSON FeatureCollection (RFC
 // 7946), generated and stored at processing time. A vector_with_kato dataset's
 // collection joins the districts table on KATO code (one feature per KATO with