Add function to get string state attributes for a given contract

.gitignore

@@ -2,4 +2,5 @@
 Gododir/godobin-*
 test_data_dir/
 vendor/
+contracts/*
 environments/*.toml

cmd/run/main.go

@@ -17,9 +17,9 @@ func main() {
 	environment := flag.String("environment", "", "Environment name")
 	flag.Parse()
 	config := cmd.LoadConfig(*environment)
-	fmt.Println("Client Path ", config.Client.IPCPath)
 
 	repository := repositories.NewPostgres(config.Database)
+	fmt.Printf("Creating Geth Blockchain to: %s\n", config.Client.IPCPath)
 	listener := blockchain_listener.NewBlockchainListener(
 		geth.NewGethBlockchain(config.Client.IPCPath),
 		[]core.BlockchainObserver{

pkg/core/blockchain.go

@@ -5,4 +5,5 @@ type Blockchain interface {
 	SubscribeToBlocks(blocks chan Block)
 	StartListening()
 	StopListening()
+	GetContractStateAttribute(contractHash string, attributeName string) (*string, error)
 }

pkg/fakes/blockchain.go

@@ -4,12 +4,22 @@ import "github.com/8thlight/vulcanizedb/pkg/core"
 
 type Blockchain struct {
 	blocks             map[int64]core.Block
+	contractAttributes map[string]map[string]string
 	blocksChannel      chan core.Block
 	WasToldToStop      bool
 }
 
+func (blockchain *Blockchain) GetContractStateAttribute(contractHash string, attributeName string) (*string, error) {
+	result := new(string)
+	*result = blockchain.contractAttributes[contractHash][attributeName]
+	return result, nil
+}
+
 func NewBlockchain() *Blockchain {
-	return &Blockchain{blocks: make(map[int64]core.Block)}
+	return &Blockchain{
+		blocks:             make(map[int64]core.Block),
+		contractAttributes: make(map[string]map[string]string),
+	}
 }
 
 func NewBlockchainWithBlocks(blocks []core.Block) *Blockchain {
@@ -40,3 +50,11 @@ func (*Blockchain) StartListening() {}
 func (blockchain *Blockchain) StopListening() {
 	blockchain.WasToldToStop = true
 }
+
+func (blockchain *Blockchain) SetContractStateAttribute(contractHash string, attributeName string, attributeValue string) {
+	contractStateAttributes := blockchain.contractAttributes[contractHash]
+	if contractStateAttributes == nil {
+		blockchain.contractAttributes[contractHash] = make(map[string]string)
+	}
+	blockchain.contractAttributes[contractHash][attributeName] = attributeValue
+}

pkg/geth/abi.go

@@ -0,0 +1,27 @@
+package geth
+
+import (
+	"errors"
+	"io/ioutil"
+	"strings"
+
+	"github.com/ethereum/go-ethereum/accounts/abi"
+)
+
+var (
+	ErrInvalidAbiFile = errors.New("invalid abi")
+	ErrMissingAbiFile = errors.New("missing abi")
+)
+
+func ParseAbiFile(abiFilePath string) (abi.ABI, error) {
+	filesBytes, err := ioutil.ReadFile(abiFilePath)
+	if err != nil {
+		return abi.ABI{}, ErrMissingAbiFile
+	}
+	abiString := string(filesBytes)
+	parsedAbi, err := abi.JSON(strings.NewReader(abiString))
+	if err != nil {
+		return abi.ABI{}, ErrInvalidAbiFile
+	}
+	return parsedAbi, nil
+}

pkg/geth/abi_test.go

@@ -0,0 +1,43 @@
+package geth_test
+
+import (
+	"path/filepath"
+
+	cfg "github.com/8thlight/vulcanizedb/pkg/config"
+	"github.com/8thlight/vulcanizedb/pkg/geth"
+	"github.com/ethereum/go-ethereum/accounts/abi"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("Reading ABI files", func() {
+
+	It("loads a valid ABI file", func() {
+		contractHash := "0xd26114cd6EE289AccF82350c8d8487fedB8A0C07"
+		path := filepath.Join(cfg.ProjectRoot(), "contracts", "public", contractHash+".json")
+
+		contractAbi, err := geth.ParseAbiFile(path)
+
+		Expect(contractAbi).NotTo(BeNil())
+		Expect(err).To(BeNil())
+	})
+
+	It("returns an error when the file does not exist", func() {
+		path := filepath.Join(cfg.ProjectRoot(), "contracts", "public", "missing_file.json")
+
+		contractAbi, err := geth.ParseAbiFile(path)
+
+		Expect(contractAbi).To(Equal(abi.ABI{}))
+		Expect(err).To(Equal(geth.ErrMissingAbiFile))
+	})
+
+	It("returns an error when the file has invalid contents", func() {
+		path := filepath.Join(cfg.ProjectRoot(), "pkg", "geth", "testing", "invalid_abi.json")
+
+		contractAbi, err := geth.ParseAbiFile(path)
+
+		Expect(contractAbi).To(Equal(abi.ABI{}))
+		Expect(err).To(Equal(geth.ErrInvalidAbiFile))
+	})
+
+})

pkg/geth/contract.go

@@ -0,0 +1,37 @@
+package geth
+
+import (
+	"errors"
+	"fmt"
+	"path/filepath"
+
+	"github.com/8thlight/vulcanizedb/pkg/config"
+	"github.com/ethereum/go-ethereum/accounts/abi/bind"
+	"github.com/ethereum/go-ethereum/common"
+)
+
+var (
+	ErrInvalidStateAttribute = errors.New("invalid state attribute")
+)
+
+func (blockchain *GethBlockchain) GetContractStateAttribute(contractHash string, attributeName string) (*string, error) {
+	boundContract, err := bindContract(common.HexToAddress(contractHash), blockchain.client, blockchain.client)
+	if err != nil {
+		return nil, err
+	}
+	result := new(string)
+	err = boundContract.Call(&bind.CallOpts{}, result, attributeName)
+	if err != nil {
+		return nil, ErrInvalidStateAttribute
+	}
+	return result, nil
+}
+
+func bindContract(address common.Address, caller bind.ContractCaller, transactor bind.ContractTransactor) (*bind.BoundContract, error) {
+	abiFilePath := filepath.Join(config.ProjectRoot(), "contracts", "public", fmt.Sprintf("%s.json", address.Hex()))
+	parsed, err := ParseAbiFile(abiFilePath)
+	if err != nil {
+		return nil, err
+	}
+	return bind.NewBoundContract(address, parsed, caller, transactor), nil
+}

pkg/geth/contract_test.go

@@ -0,0 +1,47 @@
+package geth_test
+
+//import (
+//	cfg "github.com/8thlight/vulcanizedb/pkg/config"
+//	"github.com/8thlight/vulcanizedb/pkg/geth"
+//	. "github.com/onsi/ginkgo"
+//	. "github.com/onsi/gomega"
+//)
+//
+//var _ = Describe("The Geth blockchain", func() {
+//
+//	Describe("Getting a contract attribute", func() {
+//		It("returns the correct attribute for a real contract", func() {
+//			config, _ := cfg.NewConfig("public")
+//			blockchain := geth.NewGethBlockchain(config.Client.IPCPath)
+//			contractHash := "0xd26114cd6EE289AccF82350c8d8487fedB8A0C07"
+//
+//			name, err := blockchain.GetContractStateAttribute(contractHash, "name")
+//
+//			Expect(*name).To(Equal("OMGToken"))
+//			Expect(err).To(BeNil())
+//		})
+//
+//		It("returns an error when there is no ABI for the given contract", func() {
+//			config, _ := cfg.NewConfig("public")
+//			blockchain := geth.NewGethBlockchain(config.Client.IPCPath)
+//			contractHash := "MISSINGHASH"
+//
+//			name, err := blockchain.GetContractStateAttribute(contractHash, "name")
+//
+//			Expect(name).To(BeNil())
+//			Expect(err).To(Equal(geth.ErrMissingAbiFile))
+//		})
+//
+//		It("returns an error when asking for an attribute that does not exist", func() {
+//			config, _ := cfg.NewConfig("public")
+//			blockchain := geth.NewGethBlockchain(config.Client.IPCPath)
+//			contractHash := "0xd26114cd6EE289AccF82350c8d8487fedB8A0C07"
+//
+//			name, err := blockchain.GetContractStateAttribute(contractHash, "missing_attribute")
+//
+//			Expect(err).To(Equal(geth.ErrInvalidStateAttribute))
+//			Expect(name).To(BeNil())
+//		})
+//	})
+//
+//})

pkg/geth/geth_blockchain.go

@@ -25,7 +25,6 @@ func (blockchain *GethBlockchain) GetBlockByNumber(blockNumber int64) core.Block
 }
 
 func NewGethBlockchain(ipcPath string) *GethBlockchain {
-	fmt.Printf("Creating Geth Blockchain to: %s\n", ipcPath)
 	blockchain := GethBlockchain{}
 	client, _ := ethclient.Dial(ipcPath)
 	blockchain.client = client

pkg/geth/testing/invalid_abi.json

@@ -0,0 +1 @@
+bad json

pkg/watched_contracts/summary.go

@@ -12,30 +12,33 @@ type ContractSummary struct {
 	ContractHash         string
 	NumberOfTransactions int
 	LastTransaction      *core.Transaction
+	blockChain           core.Blockchain
 }
 
 var NewContractNotWatchedErr = func(contractHash string) error {
 	return errors.New(fmt.Sprintf("Contract %v not being watched", contractHash))
 }
 
-func NewSummary(_ core.Blockchain, repository repositories.Repository, contractHash string) (*ContractSummary, error) {
-	contract := repository.FindWatchedContract(contractHash)
-	if contract != nil {
-		return newContractSummary(*contract), nil
+func NewSummary(blockchain core.Blockchain, repository repositories.Repository, contractHash string) (*ContractSummary, error) {
+	watchedContract := repository.FindWatchedContract(contractHash)
+	if watchedContract != nil {
+		return newContractSummary(blockchain, *watchedContract), nil
 	} else {
 		return nil, NewContractNotWatchedErr(contractHash)
 	}
 }
 
-func (ContractSummary) GetStateAttribute(attributeName string) string {
-	return "Hello world"
+func (contractSummary ContractSummary) GetStateAttribute(attributeName string) string {
+	result, _ := contractSummary.blockChain.GetContractStateAttribute(contractSummary.ContractHash, attributeName)
+	return *result
 }
 
-func newContractSummary(contract core.WatchedContract) *ContractSummary {
+func newContractSummary(blockchain core.Blockchain, watchedContract core.WatchedContract) *ContractSummary {
 	return &ContractSummary{
-		ContractHash:         contract.Hash,
-		NumberOfTransactions: len(contract.Transactions),
-		LastTransaction:      lastTransaction(contract),
+		blockChain:           blockchain,
+		ContractHash:         watchedContract.Hash,
+		NumberOfTransactions: len(watchedContract.Transactions),
+		LastTransaction:      lastTransaction(watchedContract),
 	}
 }
 

pkg/watched_contracts/summary_test.go

@@ -82,6 +82,18 @@ var _ bool = Describe("The watched contract summary", func() {
 
 			Expect(contractSummary.LastTransaction.Hash).To(Equal("TRANSACTION2"))
 		})
+
+		It("gets a state attribute for the contract from the blockchain", func() {
+			repository := repositories.NewInMemory()
+			watchedContract := core.WatchedContract{Hash: "0x123"}
+			repository.CreateWatchedContract(watchedContract)
+			blockchain := fakes.NewBlockchain()
+			blockchain.SetContractStateAttribute("0x123", "foo", "bar")
+
+			contractSummary, _ := watched_contracts.NewSummary(blockchain, repository, "0x123")
+
+			Expect(contractSummary.GetStateAttribute("foo")).To(Equal("bar"))
+		})
 	})
 
 })