From e03dabdf0f6a57937301aa2473de4633120a8d61 Mon Sep 17 00:00:00 2001
From: Mohammed Sohail <sohailsameja@gmail.com>
Date: Mon, 14 Oct 2024 09:25:18 +0300
Subject: [PATCH] feat: add token approve handler

---
 cmd/service/router.go             |  2 +
 internal/handler/token_approve.go | 78 +++++++++++++++++++++++++++++++
 2 files changed, 80 insertions(+)
 create mode 100644 internal/handler/token_approve.go

diff --git a/cmd/service/router.go b/cmd/service/router.go
index b0d7599..83eb2ec 100644
--- a/cmd/service/router.go
+++ b/cmd/service/router.go
@@ -25,6 +25,7 @@ func bootstrapEventRouter(cacheProvider cache.Cache, pubCB router.Callback) *rou
 	router.RegisterLogRoute(w3.H("0xab8530f87dc9b59234c4623bf917212bb2536d647574c8e7e5da92c2ede0c9f8"), handler.HandleTokenMintLog())
 	router.RegisterLogRoute(w3.H("0x894e56e1dac400b4475c83d8af0f0aa44de17c62764bd82f6e768a504e242461"), handler.HandleCustodialRegistrationLog())
 	router.RegisterLogRoute(w3.H("0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"), handler.HandleTokenTransferLog(handlerContainer))
+	router.RegisterLogRoute(w3.H("0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925"), handler.HandleTokenApproveLog())
 
 	router.RegisterInputDataRoute("63e4bff4", handler.HandleFaucetGiveInputData())
 	router.RegisterInputDataRoute("de82efb4", handler.HandleFaucetGiveInputData())
@@ -41,6 +42,7 @@ func bootstrapEventRouter(cacheProvider cache.Cache, pubCB router.Callback) *rou
 	router.RegisterInputDataRoute("4420e486", handler.HandleCustodialRegistrationInputData())
 	router.RegisterInputDataRoute("a9059cbb", handler.HandleTokenTransferInputData(handlerContainer))
 	router.RegisterInputDataRoute("23b872dd", handler.HandleTokenTransferInputData(handlerContainer))
+	router.RegisterInputDataRoute("095ea7b3", handler.HandleTokenApproveInputData())
 
 	return router
 }
diff --git a/internal/handler/token_approve.go b/internal/handler/token_approve.go
new file mode 100644
index 0000000..7f32925
--- /dev/null
+++ b/internal/handler/token_approve.go
@@ -0,0 +1,78 @@
+package handler
+
+import (
+	"context"
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/grassrootseconomics/eth-tracker/pkg/event"
+	"github.com/grassrootseconomics/eth-tracker/pkg/router"
+	"github.com/lmittmann/w3"
+)
+
+const approveEventName = "TOKEN_APPROVE"
+
+var (
+	tokenApproveEvent = w3.MustNewEvent("Approval(address indexed _owner, address indexed _spender, uint256 _value)")
+	tokenApproveToSig = w3.MustNewFunc("approve(address, uint256)", "bool")
+)
+
+func HandleTokenApproveLog() router.LogHandlerFunc {
+	return func(ctx context.Context, lp router.LogPayload, c router.Callback) error {
+		var (
+			owner   common.Address
+			spender common.Address
+			value   big.Int
+		)
+
+		if err := tokenApproveEvent.DecodeArgs(lp.Log, &owner, &spender, &value); err != nil {
+			return err
+		}
+
+		tokenApproveEvent := event.Event{
+			Index:           lp.Log.Index,
+			Block:           lp.Log.BlockNumber,
+			ContractAddress: lp.Log.Address.Hex(),
+			Success:         true,
+			Timestamp:       lp.Timestamp,
+			TxHash:          lp.Log.TxHash.Hex(),
+			TxType:          approveEventName,
+			Payload: map[string]any{
+				"owner":   owner.Hex(),
+				"spender": spender.Hex(),
+				"value":   value.String(),
+			},
+		}
+
+		return c(ctx, tokenApproveEvent)
+	}
+}
+
+func HandleTokenApproveInputData() router.InputDataHandlerFunc {
+	return func(ctx context.Context, idp router.InputDataPayload, c router.Callback) error {
+		var (
+			spender common.Address
+			value   big.Int
+		)
+
+		if err := tokenApproveToSig.DecodeArgs(w3.B(idp.InputData), &spender, &value); err != nil {
+			return err
+		}
+
+		tokenApproveEvent := event.Event{
+			Block:           idp.Block,
+			ContractAddress: idp.ContractAddress,
+			Success:         false,
+			Timestamp:       idp.Timestamp,
+			TxHash:          idp.TxHash,
+			TxType:          approveEventName,
+			Payload: map[string]any{
+				"owner":   idp.From,
+				"spender": spender.Hex(),
+				"value":   value.String(),
+			},
+		}
+
+		return c(ctx, tokenApproveEvent)
+	}
+}