Merge pull request #69 from 8thlight/watch_contract

* Add contracts table / start building out watch contracts

pkg/core/contract.go

@@ -0,0 +1,5 @@
+package core
+
+type WatchedContract struct {
+	Hash string
+}

pkg/repositories/in_memory.go

@@ -5,7 +5,18 @@ import (
 )
 
 type InMemory struct {
-	blocks map[int64]*core.Block
+	blocks           map[int64]*core.Block
+	watchedContracts map[string]*core.WatchedContract
+}
+
+func (repository *InMemory) CreateWatchedContract(watchedContract core.WatchedContract) error {
+	repository.watchedContracts[watchedContract.Hash] = &watchedContract
+	return nil
+}
+
+func (repository *InMemory) IsWatchedContract(contractHash string) bool {
+	_, present := repository.watchedContracts[contractHash]
+	return present
 }
 
 func (repository *InMemory) MissingBlockNumbers(startingBlockNumber int64, endingBlockNumber int64) []int64 {
@@ -20,7 +31,8 @@ func (repository *InMemory) MissingBlockNumbers(startingBlockNumber int64, endin
 
 func NewInMemory() *InMemory {
 	return &InMemory{
-		blocks: make(map[int64]*core.Block),
+		blocks:           make(map[int64]*core.Block),
+		watchedContracts: make(map[string]*core.WatchedContract),
 	}
 }
 

pkg/repositories/postgres.go

@@ -18,6 +18,10 @@ type Postgres struct {
 	Db *sqlx.DB
 }
 
+var (
+	ErrDBInsertFailed = errors.New("postgres: insert failed")
+)
+
 func NewPostgres(databaseConfig config.Database) Postgres {
 	connectString := config.DbConnectionString(databaseConfig)
 	db, err := sqlx.Connect("postgres", connectString)
@@ -27,9 +31,24 @@ func NewPostgres(databaseConfig config.Database) Postgres {
 	return Postgres{Db: db}
 }
 
-var (
-	ErrDBInsertFailed = errors.New("postgres: insert failed")
-)
+func (repository Postgres) CreateWatchedContract(contract core.WatchedContract) error {
+	_, err := repository.Db.Exec(
+		`INSERT INTO watched_contracts (contract_hash) VALUES ($1)`, contract.Hash)
+	if err != nil {
+		return ErrDBInsertFailed
+	}
+	return nil
+}
+
+func (repository Postgres) IsWatchedContract(contractHash string) bool {
+	var exists bool
+	err := repository.Db.QueryRow(
+		`SELECT exists(select 1 from watched_contracts where contract_hash=$1) FROM watched_contracts`, contractHash).Scan(&exists)
+	if err != nil && err != sql.ErrNoRows {
+		log.Fatalf("error checking if row exists %v", err)
+	}
+	return exists
+}
 
 func (repository Postgres) MaxBlockNumber() int64 {
 	var highestBlockNumber int64

pkg/repositories/repository.go

@@ -8,4 +8,6 @@ type Repository interface {
 	FindBlockByNumber(blockNumber int64) *core.Block
 	MaxBlockNumber() int64
 	MissingBlockNumbers(startingBlockNumber int64, endingBlockNumber int64) []int64
+	CreateWatchedContract(contract core.WatchedContract) error
+	IsWatchedContract(contractHash string) bool
 }

pkg/repositories/repository_test.go

@@ -195,6 +195,13 @@ var _ = Describe("Repositories", func() {
 				Expect(repository.MissingBlockNumbers(1, 5)).To(Equal([]int64{1, 2, 4, 5}))
 			})
 
+			It("Adds a contract to the watched_contracts table", func() {
+				repository.CreateWatchedContract(core.WatchedContract{Hash: "x123"})
+
+				Expect(repository.IsWatchedContract("x123")).To(BeTrue())
+				Expect(repository.IsWatchedContract("x456")).To(BeFalse())
+			})
+
 		})
 
 		Describe("The max block numbers", func() {