minor rework and filter dimensions

cmd/cli/commands/channeliter.go

@@ -0,0 +1,55 @@
+package commands
+
+import (
+	"context"
+	"errors"
+
+	"git.loyso.art/frx/eway/internal/entity"
+)
+
+type chanIter[T any] struct {
+	in   <-chan T
+	err  error
+	next T
+}
+
+var errChannelClosed = errors.New("channel closed")
+
+func (i *chanIter[T]) Next() (ok bool) {
+	if i.err != nil {
+		return false
+	}
+
+	i.next, ok = <-i.in
+	if !ok {
+		i.err = errChannelClosed
+	}
+
+	return ok
+}
+
+func (i *chanIter[T]) Get() T {
+	return i.next
+}
+
+func (i *chanIter[T]) Err() error {
+	if errors.Is(i.err, errChannelClosed) {
+		return nil
+	}
+
+	return i.err
+}
+
+func (i *chanIter[T]) Close() {
+	for range i.in {
+	}
+}
+
+func getItemsIter(ctx context.Context, r entity.GoodsItemRepository) *chanIter[entity.GoodsItem] {
+	in, err := r.ListIter(ctx, 3)
+
+	return &chanIter[entity.GoodsItem]{
+		in:  in,
+		err: err,
+	}
+}