Btccheckpoint oracle schema and processing (#43)

* Btccheckpoint oracle schema

proto/babylon/btccheckpoint/btccheckpoint.proto

@@ -0,0 +1,52 @@
+syntax = "proto3";
+package babylon.btccheckpoint;
+
+import "gogoproto/gogo.proto";
+
+option go_package = "github.com/babylonchain/babylon/x/btccheckpoint/types";
+
+// Each provided OP_RETURN transaction can be idendtified by hash of block in
+// which transaction was included and transaction index in the block
+message TransactionKey {
+  uint32 index = 1;
+  bytes hash = 2 [
+    (gogoproto.customtype) = "github.com/babylonchain/babylon/types.BTCHeaderHashBytes"
+  ];
+}
+
+// Checkpoint can be composed from multiple transactions, so to identify whole
+// submission we need list of transaction keys.
+// Each submission can generally be identified by this list of (txIdx, blockHash)
+// tuples.
+// Note: this could possibly be optimized as if transactions were in one block
+// they would have the same block hash and different indexes, but each blockhash
+// is only 33 (1  byte for prefix encoding and 32 byte hash), so there should
+// be other strong arguments for this optimization
+message SubmissionKey {
+  repeated TransactionKey key = 1;
+}
+
+// TODO: Determine if we should keep any block number or depth info.
+// On one hand it may be usefull to determine if block is stable or not, on other
+// depth/block number info, without context (i.e info about chain) is pretty useless
+// and blockshash in enough to retrieve is from lightclient
+message SubmissionData {
+  // TODO: this could probably be better typed
+  // Address of submitter of given checkpoint. Required to payup the reward to
+  // submitter of given checkpoint
+  bytes submitter = 1;
+  // Required to recover address of sender of btc transction to payup the reward.
+  // TODO: Maybe it is worth recovering senders while processing the InsertProof
+  // message, and store only those. Another point is that it is not that simple
+  // to recover sender of btc tx.
+  repeated bytes btctransaction = 2;
+}
+
+// Data stored in db and indexed by epoch number
+// TODO: Add btc blockheight at epooch end, when adding hadnling of epoching callbacks
+message EpochData {
+  // List of all received checkpoints during this epoch, sorted by order of
+  // submission.
+  repeated SubmissionKey key = 1;
+}
+

x/btccheckpoint/btcutils/btcutils.go

@@ -10,7 +10,6 @@ import (
 	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/txscript"
-	"github.com/btcsuite/btcd/wire"
 )
 
 const (
@@ -20,12 +19,17 @@ const (
 
 // Parsed proof represent semantically valid:
 // - Bitcoin Header
+// - Bitcoin Header hash
 // - Bitcoin Transaction
+// - Bitcoin Transaction index in block
 // - Non-empty OpReturnData
 type ParsedProof struct {
-	BlockHeader  wire.BlockHeader
-	Transaction  *btcutil.Tx
-	OpReturnData []byte
+	// keeping header hash to avoid recomputing it everytime
+	BlockHash        types.BTCHeaderHashBytes
+	Transaction      *btcutil.Tx
+	TransactionBytes []byte
+	TransactionIdx   uint32
+	OpReturnData     []byte
 }
 
 // Concatenates and double hashes two provided inputs
@@ -147,10 +151,13 @@ func ParseProof(
 		return nil, fmt.Errorf("provided transaction should provide op return data")
 	}
 
+	bh := header.BlockHash()
 	parsedProof := &ParsedProof{
-		BlockHeader:  *header,
-		Transaction:  tx,
-		OpReturnData: opReturnData,
+		BlockHash:        types.NewBTCHeaderHashBytesFromChainhash(&bh),
+		Transaction:      tx,
+		TransactionBytes: btcTransaction,
+		TransactionIdx:   transactionIndex,
+		OpReturnData:     opReturnData,
 	}
 
 	return parsedProof, nil

x/btccheckpoint/keeper/keeper.go

@@ -3,9 +3,9 @@ package keeper
 import (
 	"fmt"
 
-	"github.com/btcsuite/btcd/wire"
 	"github.com/tendermint/tendermint/libs/log"
 
+	btypes "github.com/babylonchain/babylon/types"
 	"github.com/babylonchain/babylon/x/btccheckpoint/types"
 	"github.com/cosmos/cosmos-sdk/codec"
 	sdk "github.com/cosmos/cosmos-sdk/types"
@@ -50,26 +50,49 @@ func (k Keeper) Logger(ctx sdk.Context) log.Logger {
 	return ctx.Logger().With("module", fmt.Sprintf("x/%s", types.ModuleName))
 }
 
-func (k Keeper) GetBlockHeight(b wire.BlockHeader) (uint64, error) {
+func (k Keeper) GetBlockHeight(b btypes.BTCHeaderHashBytes) (uint64, error) {
 	return k.btcLightClientKeeper.BlockHeight(b)
 }
 
+func (k Keeper) IsAncestor(parentHash btypes.BTCHeaderHashBytes, childHash btypes.BTCHeaderHashBytes) (bool, error) {
+	return k.btcLightClientKeeper.IsAncestor(parentHash, childHash)
+}
+
 func (k Keeper) GetCheckpointEpoch(c []byte) (uint64, error) {
 	return k.checkpointingKeeper.CheckpointEpoch(c)
 }
 
-// TODO for now we jsut store raw checkpoint with epoch as key. Ultimatly
-// we should store checkpoint with some timestamp info, or even do not store
-// checkpoint itelf but its status
-func (k Keeper) StoreCheckpoint(ctx sdk.Context, e uint64, c []byte) {
+func (k Keeper) SubmissionExists(ctx sdk.Context, sk types.SubmissionKey) bool {
+	store := ctx.KVStore(k.storeKey)
+	kBytes := k.cdc.MustMarshal(&sk)
+	return store.Has(kBytes)
+}
+
+// Return epoch data for given epoch, if there is not epoch data yet returns nil
+func (k Keeper) GetEpochData(ctx sdk.Context, e uint64) *types.EpochData {
+	store := ctx.KVStore(k.storeKey)
+	bytes := store.Get(types.GetEpochIndexKey(e))
+
+	if len(bytes) == 0 {
+		return nil
+	}
+
+	ed := &types.EpochData{}
+	k.cdc.MustUnmarshal(bytes, ed)
+	return ed
+
+}
+
+func (k Keeper) SaveEpochData(ctx sdk.Context, e uint64, ed *types.EpochData) {
 	store := ctx.KVStore(k.storeKey)
-	key := sdk.Uint64ToBigEndian(e)
-	store.Set(key, c)
+	ek := types.GetEpochIndexKey(e)
+	eb := k.cdc.MustMarshal(ed)
+	store.Set(ek, eb)
 }
 
-// TODO just return checkpoint if exists
-func (k Keeper) GetCheckpoint(ctx sdk.Context, e uint64) []byte {
+func (k Keeper) SaveSubmission(ctx sdk.Context, sk types.SubmissionKey, sd types.SubmissionData) {
 	store := ctx.KVStore(k.storeKey)
-	key := sdk.Uint64ToBigEndian(e)
-	return store.Get(key)
+	kBytes := k.cdc.MustMarshal(&sk)
+	sBytes := k.cdc.MustMarshal(&sd)
+	store.Set(kBytes, sBytes)
 }