Handler Framework (#80)

* Implement base handler framework

* Add comments for the missing state transition logic components for a tx

* Fix typo

* Remove TODO checks done by anteHandler

x/evm/handler.go

@@ -1 +1,41 @@
 package evm
+
+import (
+	"fmt"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/ethermint/x/evm/types"
+)
+
+// NewHandler returns a handler for Ethermint type messages.
+func NewHandler(keeper Keeper) sdk.Handler {
+	return func(ctx sdk.Context, msg sdk.Msg) sdk.Result {
+		switch msg := msg.(type) {
+		case types.EthereumTxMsg:
+			return handleETHTxMsg(ctx, keeper, msg)
+		default:
+			errMsg := fmt.Sprintf("Unrecognized ethermint Msg type: %v", msg.Type())
+			return sdk.ErrUnknownRequest(errMsg).Result()
+		}
+	}
+}
+
+// Handle an Ethereum specific tx
+func handleETHTxMsg(ctx sdk.Context, keeper Keeper, msg types.EthereumTxMsg) sdk.Result {
+	// TODO: Implement transaction logic
+	if err := msg.ValidateBasic(); err != nil {
+		return sdk.ErrUnknownRequest("Basic validation failed").Result()
+	}
+
+	// If no to address, create contract with evm.Create(...)
+
+	// Else Call contract with evm.Call(...)
+
+	// handle errors
+
+	// Refund remaining gas from tx (Will supply keeper need to be introduced to evm Keeper to do this)
+
+	// add balance for the processor of the tx (determine who rewards are being processed to)
+
+	return sdk.Result{}
+}

x/evm/module.go

@@ -2,6 +2,7 @@ package evm
 
 import (
 	"encoding/json"
+
 	"github.com/cosmos/cosmos-sdk/client/context"
 	"github.com/cosmos/cosmos-sdk/codec"
 	sdk "github.com/cosmos/cosmos-sdk/types"
@@ -81,7 +82,7 @@ func (am AppModule) Route() string {
 }
 
 func (am AppModule) NewHandler() sdk.Handler {
-	return nil // NewHandler(am.keeper)
+	return NewHandler(am.keeper)
 }
 func (am AppModule) QuerierRoute() string {
 	return types.ModuleName