From d9f14915669737c3fd483327434a4624c74b93dc Mon Sep 17 00:00:00 2001
From: Leonard Lyubich <leonard@nspcc.ru>
Date: Tue, 23 Mar 2021 21:48:50 +0300
Subject: [PATCH] [#428] cmd/node: Implement iterator provider on local trust
 storage

Implement iterator provider on wrapper over the local trust storage.
Provided iterator passes normalized local trust values according to original
EigenTrust algorithm description. In the borderline case, normalized values
are set as 1/N, N - number of remote nodes in network map.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
---
 cmd/neofs-node/reputation.go | 90 ++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 cmd/neofs-node/reputation.go

diff --git a/cmd/neofs-node/reputation.go b/cmd/neofs-node/reputation.go
new file mode 100644
index 00000000..147b14f3
--- /dev/null
+++ b/cmd/neofs-node/reputation.go
@@ -0,0 +1,90 @@
+package main
+
+import (
+	"bytes"
+
+	netmapcore "github.com/nspcc-dev/neofs-node/pkg/core/netmap"
+	"github.com/nspcc-dev/neofs-node/pkg/services/reputation"
+	trustcontroller "github.com/nspcc-dev/neofs-node/pkg/services/reputation/local/controller"
+	truststorage "github.com/nspcc-dev/neofs-node/pkg/services/reputation/local/storage"
+	"github.com/nspcc-dev/neofs-node/pkg/util/logger"
+	"github.com/pkg/errors"
+)
+
+type localTrustStorage struct {
+	log *logger.Logger
+
+	storage *truststorage.Storage
+
+	nmSrc netmapcore.Source
+
+	localKey []byte
+}
+
+type localTrustIterator struct {
+	ctx trustcontroller.Context
+
+	storage *localTrustStorage
+
+	epochStorage *truststorage.EpochTrustValueStorage
+}
+
+func (s *localTrustStorage) InitIterator(ctx trustcontroller.Context) (trustcontroller.Iterator, error) {
+	epochStorage, err := s.storage.DataForEpoch(ctx.Epoch())
+	if err != nil && !errors.Is(err, truststorage.ErrNoPositiveTrust) {
+		return nil, err
+	}
+
+	return &localTrustIterator{
+		ctx:          ctx,
+		storage:      s,
+		epochStorage: epochStorage,
+	}, nil
+}
+
+func (it *localTrustIterator) Iterate(h reputation.TrustHandler) error {
+	if it.epochStorage != nil {
+		err := it.epochStorage.Iterate(h)
+		if !errors.Is(err, truststorage.ErrNoPositiveTrust) {
+			return err
+		}
+	}
+
+	nm, err := it.storage.nmSrc.GetNetMapByEpoch(it.ctx.Epoch())
+	if err != nil {
+		return err
+	}
+
+	// find out if local node is presented in netmap
+	localIndex := -1
+
+	for i := range nm.Nodes {
+		if bytes.Equal(nm.Nodes[i].PublicKey(), it.storage.localKey) {
+			localIndex = i
+		}
+	}
+
+	ln := len(nm.Nodes)
+	if localIndex >= 0 && ln > 0 {
+		ln--
+	}
+
+	// calculate Pj http://ilpubs.stanford.edu:8090/562/1/2002-56.pdf Chapter 4.5.
+	p := reputation.TrustOne.Div(reputation.TrustValueFromInt(ln))
+
+	for i := range nm.Nodes {
+		if i == localIndex {
+			continue
+		}
+
+		trust := reputation.Trust{}
+		trust.SetPeer(reputation.PeerIDFromBytes(nm.Nodes[i].PublicKey()))
+		trust.SetValue(p)
+
+		if err := h(trust); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}