Add chain_reader.go with ChainReader type defs, add ChainReader() to …

…PluginProvider

pkg/types/chain_reader.go

@@ -0,0 +1,66 @@
+package types
+
+import (
+	"math/big"
+	"time"
+)
+
+type BigInt big.Int
+type String string
+
+// Union of BigInt & String
+type BlockID interface {
+	bi() *BigInt
+	s() String
+}
+
+func (b *BigInt) bi() *BigInt {
+	return b
+}
+
+func (b String) s() String {
+	return b
+}
+
+type ChainReader interface {
+	RegisterEventFilter(filterName string, filter EventFilter, startingBlock BlockID) (string, error)
+	UnregisterEventFilter(filterName string) error
+	QueryEvents(query EventQuery) ([]Event, error)
+	// The params argument of GetLatestValue() can be any object which maps a set of generic parameters into chain specific parameters defined in RelayConfig. It must be something which can be passed into
+	// json.Marshal(). Typically would be either an anonymous map such as `map[string]any{"baz": 42, "test": true}}` or something which implements the `MarshalJSON()` method (satisfying `Marshaller` interface).
+	//
+	// returnVal should satisfy Marshaller interface.
+	GetLatestValue(bc BoundContract, method string, params, returnVal any) error
+}
+
+type BoundContract struct {
+	Address string
+	Name    string
+	Pending bool
+}
+
+type Event struct {
+	ChainId           string
+	EventIndexInBlock string
+	Address           string
+	TxHash            string
+	BlockHash         string
+	BlockNumber       int64
+	BlockTimestamp    time.Time
+	CreatedAt         time.Time
+	Keys              []string
+	Data              []byte
+}
+
+type EventFilter struct {
+	AddressList []string   // contract address
+	KeysList    [][]string // 2D list of indexed search keys, outer dim = AND, inner dim = OR.  Params[0] is the name of the event (or "event type"), rest are any narrowing parameters that may help further specify the event
+	Retention   time.Duration
+}
+
+type EventQuery struct {
+	FromBlock BlockID
+	ToBlock   BlockID
+	Filter    EventFilter
+	Pending   bool
+}

pkg/types/provider.go

@@ -18,4 +18,5 @@ type Plugin = PluginProvider
 type PluginProvider interface {
 	ConfigProvider
 	ContractTransmitter() ocrtypes.ContractTransmitter
+	ChainReader() ChainReader
 }