[#74] Return ballot collection functions

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

common/ir.go

@@ -6,12 +6,28 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/interop/native/ledger"
 	"github.com/nspcc-dev/neo-go/pkg/interop/native/neo"
 	"github.com/nspcc-dev/neo-go/pkg/interop/native/roles"
+	"github.com/nspcc-dev/neo-go/pkg/interop/runtime"
 )
 
 type IRNode struct {
 	PublicKey interop.PublicKey
 }
 
+const irListMethod = "innerRingList"
+
+// InnerRingInvoker returns public key of inner ring node that invoked contract.
+// Work around for environments without notary support.
+func InnerRingInvoker(ir []IRNode) interop.PublicKey {
+	for i := 0; i < len(ir); i++ {
+		node := ir[i]
+		if runtime.CheckWitness(node.PublicKey) {
+			return node.PublicKey
+		}
+	}
+
+	return nil
+}
+
 // InnerRingNodes return list of inner ring nodes from state validator role
 // in side chain.
 func InnerRingNodes() []IRNode {
@@ -20,6 +36,13 @@ func InnerRingNodes() []IRNode {
 	return keysToNodes(list)
 }
 
+// InnerRingNodesFromNetmap gets list of inner ring through
+// calling "innerRingList" method of smart contract.
+// Work around for environments without notary support.
+func InnerRingNodesFromNetmap(sc interop.Hash160) []IRNode {
+	return contract.Call(sc, irListMethod, contract.ReadOnly).([]IRNode)
+}
+
 // AlphabetNodes return list of alphabet nodes from committee in side chain.
 func AlphabetNodes() []IRNode {
 	list := neo.GetCommittee()

common/vote.go

@@ -1,11 +1,122 @@
 package common
 
 import (
+	"github.com/nspcc-dev/neo-go/pkg/interop"
+	"github.com/nspcc-dev/neo-go/pkg/interop/native/crypto"
+	"github.com/nspcc-dev/neo-go/pkg/interop/native/ledger"
+	"github.com/nspcc-dev/neo-go/pkg/interop/native/std"
+	"github.com/nspcc-dev/neo-go/pkg/interop/storage"
 	"github.com/nspcc-dev/neo-go/pkg/interop/util"
 )
 
+type Ballot struct {
+	// ID of the voting decision.
+	ID []byte
+
+	// Public keys of already voted inner ring nodes.
+	Voters []interop.PublicKey
+
+	// Height of block with the last vote.
+	Height int
+}
+
+const voteKey = "ballots"
+
+const blockDiff = 20 // change base on performance evaluation
+
+func InitVote(ctx storage.Context) {
+	SetSerialized(ctx, voteKey, []Ballot{})
+}
+
+// Vote adds ballot for the decision with specific 'id' and returns amount
+// on unique voters for that decision.
+func Vote(ctx storage.Context, id, from []byte) int {
+	var (
+		newCandidates []Ballot
+		candidates    = getBallots(ctx)
+		found         = -1
+		blockHeight   = ledger.CurrentIndex()
+	)
+
+	for i := 0; i < len(candidates); i++ {
+		cnd := candidates[i]
+
+		if blockHeight-cnd.Height > blockDiff {
+			continue
+		}
+
+		if BytesEqual(cnd.ID, id) {
+			voters := cnd.Voters
+
+			for j := range voters {
+				if BytesEqual(voters[j], from) {
+					return len(voters)
+				}
+			}
+
+			voters = append(voters, from)
+			cnd = Ballot{ID: id, Voters: voters, Height: blockHeight}
+			found = len(voters)
+		}
+
+		newCandidates = append(newCandidates, cnd)
+	}
+
+	if found < 0 {
+		voters := []interop.PublicKey{from}
+		newCandidates = append(newCandidates, Ballot{
+			ID:     id,
+			Voters: voters,
+			Height: blockHeight})
+		found = 1
+	}
+
+	SetSerialized(ctx, voteKey, newCandidates)
+
+	return found
+}
+
+// RemoveVotes clears ballots of the decision that has been accepted by
+// inner ring nodes.
+func RemoveVotes(ctx storage.Context, id []byte) {
+	var (
+		newCandidates []Ballot
+		candidates    = getBallots(ctx)
+	)
+
+	for i := 0; i < len(candidates); i++ {
+		cnd := candidates[i]
+		if !BytesEqual(cnd.ID, id) {
+			newCandidates = append(newCandidates, cnd)
+		}
+	}
+
+	SetSerialized(ctx, voteKey, newCandidates)
+}
+
+// getBallots returns deserialized slice of vote ballots.
+func getBallots(ctx storage.Context) []Ballot {
+	data := storage.Get(ctx, voteKey)
+	if data != nil {
+		return std.Deserialize(data.([]byte)).([]Ballot)
+	}
+
+	return []Ballot{}
+}
+
 // BytesEqual compares two slice of bytes by wrapping them into strings,
 // which is necessary with new util.Equal interop behaviour, see neo-go#1176.
 func BytesEqual(a []byte, b []byte) bool {
 	return util.Equals(string(a), string(b))
 }
+
+// InvokeID returns hashed value of prefix and args concatenation. Used to
+// identify different ballots.
+func InvokeID(args []interface{}, prefix []byte) []byte {
+	for i := range args {
+		arg := args[i].([]byte)
+		prefix = append(prefix, arg...)
+	}
+
+	return crypto.Sha256(prefix)
+}