[#488] reputation/managers: Implement route builders

Add implementation of Builder interface for
intermediate trusts. Move all code associated
with managers to `common` directory in `cmd`
and `pkg/services/reputation`

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

cmd/neofs-node/reputation/common/managers.go

@@ -0,0 +1,106 @@
+package common
+
+import (
+	"bytes"
+
+	"github.com/nspcc-dev/hrw"
+	apiNetmap "github.com/nspcc-dev/neofs-api-go/pkg/netmap"
+	netmapcore "github.com/nspcc-dev/neofs-node/pkg/core/netmap"
+	"github.com/nspcc-dev/neofs-node/pkg/services/reputation"
+	"github.com/nspcc-dev/neofs-node/pkg/services/reputation/common"
+	reputationrouter "github.com/nspcc-dev/neofs-node/pkg/services/reputation/common/router"
+	"github.com/nspcc-dev/neofs-node/pkg/util/logger"
+	"go.uber.org/zap"
+)
+
+// managerBuilder is implementation of reputation ManagerBuilder interface.
+// It sorts nodes in NetMap with HRW algorithms and
+// takes the next node after the current one as the only manager.
+type managerBuilder struct {
+	log   *logger.Logger
+	nmSrc netmapcore.Source
+}
+
+// ManagersPrm groups the required parameters of the managerBuilder's constructor.
+//
+// All values must comply with the requirements imposed on them.
+// Passing incorrect parameter values will result in constructor
+// failure (error or panic depending on the implementation).
+type ManagersPrm struct {
+	NetMapSource netmapcore.Source
+}
+
+// NewManagerBuilder creates a new instance of the managerBuilder.
+//
+// Panics if at least one value of the parameters is invalid.
+//
+// The created managerBuilder does not require additional
+// initialization and is completely ready for work.
+func NewManagerBuilder(prm ManagersPrm, opts ...MngOption) common.ManagerBuilder {
+	switch {
+	case prm.NetMapSource == nil:
+		PanicOnPrmValue("NetMapSource", prm.NetMapSource)
+	}
+
+	o := defaultMngOpts()
+
+	for i := range opts {
+		opts[i](o)
+	}
+
+	return &managerBuilder{
+		log:   o.log,
+		nmSrc: prm.NetMapSource,
+	}
+}
+
+// BuildManagers sorts nodes in NetMap with HRW algorithms and
+// takes the next node after the current one as the only manager.
+func (mb *managerBuilder) BuildManagers(epoch uint64, p reputation.PeerID) ([]reputationrouter.ServerInfo, error) {
+	nm, err := mb.nmSrc.GetNetMapByEpoch(epoch)
+	if err != nil {
+		return nil, err
+	}
+
+	// make a copy to keep order consistency of the origin netmap after sorting
+	nodes := make([]*apiNetmap.Node, len(nm.Nodes))
+
+	copy(nodes, nm.Nodes)
+
+	hrw.SortSliceByValue(nodes, epoch)
+
+	for i := range nodes {
+		if bytes.Equal(nodes[i].PublicKey(), p.Bytes()) {
+			managerIndex := i + 1
+
+			if managerIndex == len(nodes) {
+				managerIndex = 0
+			}
+
+			return []reputationrouter.ServerInfo{nodes[managerIndex]}, nil
+		}
+	}
+
+	return nil, nil
+}
+
+type mngOptions struct {
+	log *logger.Logger
+}
+
+type MngOption func(*mngOptions)
+
+func defaultMngOpts() *mngOptions {
+	return &mngOptions{
+		log: zap.L(),
+	}
+}
+
+// WithLogger returns MngOption to specify logging component.
+func WithLogger(l *logger.Logger) MngOption {
+	return func(o *mngOptions) {
+		if l != nil {
+			o.log = l
+		}
+	}
+}