[#987] morph/event: Add RemoveNode event and its parser

Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>

pkg/morph/event/subnet/remove_node.go

@@ -0,0 +1,69 @@
+package subnet
+
+import (
+	"fmt"
+
+	"github.com/nspcc-dev/neo-go/pkg/rpc/response/result/subscriptions"
+	"github.com/nspcc-dev/neo-go/pkg/util"
+	"github.com/nspcc-dev/neofs-node/pkg/morph/client"
+	"github.com/nspcc-dev/neofs-node/pkg/morph/event"
+)
+
+// RemoveNode structure of subnet.RemoveNode notification from morph chain.
+type RemoveNode struct {
+	subnetID []byte
+	nodeKey  []byte
+
+	// txHash is used in notary environmental
+	// for calculating unique but same for
+	// all notification receivers values.
+	txHash util.Uint256
+}
+
+// MorphEvent implements Neo:Morph Event interface.
+func (RemoveNode) MorphEvent() {}
+
+// SubnetworkID returns a marshalled subnetID structure, defined in API.
+func (rn RemoveNode) SubnetworkID() []byte { return rn.subnetID }
+
+// Node is public key of the nodeKey that is being deleted.
+func (rn RemoveNode) Node() []byte { return rn.nodeKey }
+
+// TxHash returns hash of the TX with RemoveNode
+// notification.
+func (rn RemoveNode) TxHash() util.Uint256 { return rn.txHash }
+
+const expectedItemNumRemoveNode = 2
+
+// ParseRemoveNode parses notification into subnet event structure.
+//
+// Expects 2 stack items.
+func ParseRemoveNode(e *subscriptions.NotificationEvent) (event.Event, error) {
+	var (
+		ev  RemoveNode
+		err error
+	)
+
+	params, err := event.ParseStackArray(e)
+	if err != nil {
+		return nil, fmt.Errorf("could not parse stack items from notify event: %w", err)
+	}
+
+	if ln := len(params); ln != expectedItemNumRemoveNode {
+		return nil, event.WrongNumberOfParameters(expectedItemNumRemoveNode, ln)
+	}
+
+	ev.subnetID, err = client.BytesFromStackItem(params[0])
+	if err != nil {
+		return nil, fmt.Errorf("could not get raw subnetID: %w", err)
+	}
+
+	ev.nodeKey, err = client.BytesFromStackItem(params[1])
+	if err != nil {
+		return nil, fmt.Errorf("could not get raw public key of the node: %w", err)
+	}
+
+	ev.txHash = e.Container
+
+	return ev, nil
+}