From 04e7f833504418ddb7d198f56326cfccfd0ed9f7 Mon Sep 17 00:00:00 2001
From: SpongeBoi <66492212+Shubhaankar-Sharma@users.noreply.github.com>
Date: Sat, 6 Jan 2024 22:07:01 +0530
Subject: [PATCH] make a public contract query builder method (#110)

---
 ethrpc/ethrpc.go  | 43 ++++++----------------------------------
 ethrpc/methods.go | 50 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+), 37 deletions(-)

diff --git a/ethrpc/ethrpc.go b/ethrpc/ethrpc.go
index 844506f5..2391304f 100644
--- a/ethrpc/ethrpc.go
+++ b/ethrpc/ethrpc.go
@@ -11,7 +11,6 @@ import (
 	"net/http"
 	"sync/atomic"
 
-	"github.com/0xsequence/ethkit/ethcoder"
 	"github.com/0xsequence/ethkit/go-ethereum"
 	"github.com/0xsequence/ethkit/go-ethereum/accounts/abi/bind"
 	"github.com/0xsequence/ethkit/go-ethereum/common"
@@ -435,42 +434,12 @@ func (p *Provider) ContractQuery(ctx context.Context, contractAddress string, in
 func (p *Provider) contractQuery(ctx context.Context, contractAddress string, inputAbiExpr, outputAbiExpr string, args interface{}) ([]string, error) {
 	contract := common.HexToAddress(contractAddress)
 
-	var (
-		calldata []byte
-		err      error
-	)
-
-	switch args := args.(type) {
-	case []string:
-		calldata, err = ethcoder.AbiEncodeMethodCalldataFromStringValues(inputAbiExpr, args)
-		if err != nil {
-			return nil, fmt.Errorf("abi encode failed: %w", err)
-		}
-
-	case []interface{}:
-		calldata, err = ethcoder.AbiEncodeMethodCalldata(inputAbiExpr, args)
-		if err != nil {
-			return nil, fmt.Errorf("abi encode failed: %w", err)
-		}
-	case nil:
-		calldata, err = ethcoder.AbiEncodeMethodCalldata(inputAbiExpr, nil)
-		if err != nil {
-			return nil, fmt.Errorf("abi encode failed: %w", err)
-		}
-	}
-
-	msg := ethereum.CallMsg{
-		To:   &contract,
-		Data: calldata,
-	}
-
-	output, err := p.CallContract(ctx, msg, nil)
-	if err != nil {
-		return nil, fmt.Errorf("contract call failed: %w", err)
-	}
-	resp, err := ethcoder.AbiDecodeExprAndStringify(outputAbiExpr, output)
+	contractQueryBuilder, err := ContractQuery(contract, inputAbiExpr, outputAbiExpr, args)
 	if err != nil {
-		return nil, fmt.Errorf("abi decode of response failed: %w", err)
+		return nil, err
 	}
-	return resp, nil
+
+	var result []string
+	_, err = p.Do(ctx, contractQueryBuilder.Into(&result))
+	return result, err
 }
diff --git a/ethrpc/methods.go b/ethrpc/methods.go
index bb2246aa..12ff6cb1 100644
--- a/ethrpc/methods.go
+++ b/ethrpc/methods.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"math/big"
 
+	"github.com/0xsequence/ethkit/ethcoder"
 	"github.com/0xsequence/ethkit/ethrpc/jsonrpc"
 	"github.com/0xsequence/ethkit/go-ethereum"
 	"github.com/0xsequence/ethkit/go-ethereum/common"
@@ -282,6 +283,55 @@ func PendingTransactionCount() CallBuilder[uint] {
 	}
 }
 
+func ContractQuery(contractAddress common.Address, inputAbiExpr, outputAbiExpr string, args interface{}) (CallBuilder[[]string], error) {
+	var (
+		calldata []byte
+		err      error
+	)
+
+	switch args := args.(type) {
+	case []string:
+		calldata, err = ethcoder.AbiEncodeMethodCalldataFromStringValues(inputAbiExpr, args)
+		if err != nil {
+			return CallBuilder[[]string]{}, fmt.Errorf("abi encode failed: %w", err)
+		}
+
+	case []interface{}:
+		calldata, err = ethcoder.AbiEncodeMethodCalldata(inputAbiExpr, args)
+		if err != nil {
+			return CallBuilder[[]string]{}, fmt.Errorf("abi encode failed: %w", err)
+		}
+	case nil:
+		calldata, err = ethcoder.AbiEncodeMethodCalldata(inputAbiExpr, nil)
+		if err != nil {
+			return CallBuilder[[]string]{}, fmt.Errorf("abi encode failed: %w", err)
+		}
+	}
+
+	msg := ethereum.CallMsg{
+		To:   &contractAddress,
+		Data: calldata,
+	}
+
+	return CallBuilder[[]string]{
+		method: "eth_call",
+		params: []any{toCallArg(msg), toBlockNumArg(nil)},
+		intoFn: func(message json.RawMessage, ret *[]string) error {
+			var result hexutil.Bytes
+			if err := json.Unmarshal(message, &result); err != nil {
+				return err
+			}
+
+			resp, err := ethcoder.AbiDecodeExprAndStringify(outputAbiExpr, result)
+			if err != nil {
+				return fmt.Errorf("abi decode of response failed: %w", err)
+			}
+			*ret = resp
+			return nil
+		},
+	}, nil
+}
+
 func CallContract(msg ethereum.CallMsg, blockNum *big.Int) CallBuilder[[]byte] {
 	return CallBuilder[[]byte]{
 		method: "eth_call",