Remove SQL from grpc server

common/common.go

@@ -1,10 +1,13 @@
 package common
 
 import (
+	"encoding/hex"
 	"encoding/json"
 	"strconv"
 	"strings"
 
+	"github.com/adityapk00/lightwalletd/parser"
+	"github.com/adityapk00/lightwalletd/walletrpc"
 	"github.com/btcsuite/btcd/rpcclient"
 	"github.com/pkg/errors"
 )
@@ -40,3 +43,62 @@ func GetSaplingInfo(rpcClient *rpcclient.Client) (int, string, error) {
 
 	return int(saplingHeight), chainName, nil
 }
+
+func GetBlock(rpcClient *rpcclient.Client, height int) (*parser.Block, error) {
+	params := make([]json.RawMessage, 2)
+	params[0] = json.RawMessage("\"" + strconv.Itoa(height) + "\"")
+	params[1] = json.RawMessage("0")
+	result, rpcErr := rpcClient.RawRequest("getblock", params)
+
+	var err error
+	var errCode int64
+
+	// For some reason, the error responses are not JSON
+	if rpcErr != nil {
+		errParts := strings.SplitN(rpcErr.Error(), ":", 2)
+		errCode, err = strconv.ParseInt(errParts[0], 10, 32)
+		//Check to see if we are requesting a height the zcashd doesn't have yet
+		if err == nil && errCode == -8 {
+			return nil, nil
+		}
+		return nil, errors.Wrap(rpcErr, "error requesting block")
+	}
+
+	var blockDataHex string
+	err = json.Unmarshal(result, &blockDataHex)
+	if err != nil {
+		return nil, errors.Wrap(err, "error reading JSON response")
+	}
+
+	blockData, err := hex.DecodeString(blockDataHex)
+	if err != nil {
+		return nil, errors.Wrap(err, "error decoding getblock output")
+	}
+
+	block := parser.NewBlock()
+	rest, err := block.ParseFromSlice(blockData)
+	if err != nil {
+		return nil, errors.Wrap(err, "error parsing block")
+	}
+	if len(rest) != 0 {
+		return nil, errors.New("received overlong message")
+	}
+	return block, nil
+}
+
+func GetBlockRange(rpcClient *rpcclient.Client, blockOut chan<- walletrpc.CompactBlock,
+	errOut chan<- error, start, end int) {
+
+	// Go over [start, end] inclusive
+	for i := start; i <= end; i++ {
+		block, err := GetBlock(rpcClient, i)
+		if err != nil {
+			errOut <- err
+			return
+		}
+
+		blockOut <- *block.ToCompact()
+	}
+
+	errOut <- nil
+}