From de8eb31abae3393a6742d837702b13f2b1e5fb01 Mon Sep 17 00:00:00 2001
From: Mohammed Sohail <sohailsameja@gmail.com>
Date: Mon, 16 Jan 2023 13:03:22 +0000
Subject: [PATCH] feat: init base logic for rpc fetcher

---
 go.mod           |  1 +
 go.sum           |  2 ++
 pkg/fetch/rpc.go | 64 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 67 insertions(+)
 create mode 100644 pkg/fetch/rpc.go

diff --git a/go.mod b/go.mod
index 2f11125..596a636 100644
--- a/go.mod
+++ b/go.mod
@@ -7,6 +7,7 @@ require (
 	github.com/alitto/pond v1.8.2
 	github.com/celo-org/celo-blockchain v1.6.1
 	github.com/goccy/go-json v0.10.0
+	github.com/grassrootseconomics/cic-celo-sdk v0.3.1
 	github.com/grassrootseconomics/w3-celo-patch v0.1.0
 	github.com/jackc/pgx/v5 v5.2.0
 	github.com/knadh/goyesql/v2 v2.2.0
diff --git a/go.sum b/go.sum
index af16632..3fe97c0 100644
--- a/go.sum
+++ b/go.sum
@@ -248,6 +248,8 @@ github.com/gorilla/mux v1.8.0/go.mod h1:DVbg23sWSpFRCP0SfiEN6jmj59UnW/n46BH5rLB7
 github.com/gorilla/websocket v1.4.2 h1:+/TMaTYc4QFitKJxsQ7Yye35DkWvkdLcvGKqM+x0Ufc=
 github.com/gorilla/websocket v1.4.2/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 github.com/graph-gophers/graphql-go v1.3.0/go.mod h1:9CQHMSxwO4MprSdzoIEobiHpoLtHm77vfxsvsIN5Vuc=
+github.com/grassrootseconomics/cic-celo-sdk v0.3.1 h1:SzmMFrqxSIdgePqwbUdoS3PNP82MFnlOecycVk2ZYWg=
+github.com/grassrootseconomics/cic-celo-sdk v0.3.1/go.mod h1:EiR6d03GYu6jlVKNL1MbTAw/bqAW2WP3J/lkrZxPMdU=
 github.com/grassrootseconomics/w3-celo-patch v0.1.0 h1:0fev2hYkGEyFX2D4oUG8yy4jXhtHv7qUtLLboXL5ycw=
 github.com/grassrootseconomics/w3-celo-patch v0.1.0/go.mod h1:JtkXc+yDUiQQJdhYTqddZI/itdYGHY7H8PNZzBo4hCk=
 github.com/grpc-ecosystem/go-grpc-prometheus v1.2.0/go.mod h1:8NvIoxWQoOIhqOTXgfV/d3M/q6VIi02HzZEHgUlZvzk=
diff --git a/pkg/fetch/rpc.go b/pkg/fetch/rpc.go
new file mode 100644
index 0000000..33e9a67
--- /dev/null
+++ b/pkg/fetch/rpc.go
@@ -0,0 +1,64 @@
+package fetch
+
+import (
+	"context"
+	"math/big"
+
+	"github.com/celo-org/celo-blockchain/core/types"
+	celo "github.com/grassrootseconomics/cic-celo-sdk"
+	"github.com/grassrootseconomics/w3-celo-patch/module/eth"
+	"github.com/grassrootseconomics/w3-celo-patch/w3types"
+)
+
+type RPCOpts struct {
+	RPCProvider *celo.Provider
+}
+
+type RPC struct {
+	provider *celo.Provider
+}
+
+func NewRPCFetcher(o RPCOpts) Fetch {
+	return &RPC{
+		provider: o.RPCProvider,
+	}
+}
+
+// This method makes 2 calls. 1 for the block and 1 batched call for txs + receipts.
+// Should work on free tier RPC services.
+func (f *RPC) Block(ctx context.Context, blockNumber uint64) (FetchResponse, error) {
+	var (
+		block types.Block
+
+		fetchResponse FetchResponse
+	)
+
+	if err := f.provider.Client.CallCtx(
+		ctx,
+		eth.BlockByNumber(big.NewInt(int64(blockNumber))).Returns(&block),
+	); err != nil {
+		return FetchResponse{}, nil
+	}
+
+	txCount := len(block.Transactions())
+	batchCalls := make([]w3types.Caller, txCount*2)
+
+	txs := make([]types.Transaction, txCount)
+	txsReceipt := make([]types.Receipt, txCount)
+
+	for i, tx := range block.Transactions() {
+		batchCalls[i] = eth.Tx(tx.Hash()).Returns(&txs[i])
+		batchCalls[txCount+i] = eth.TxReceipt(tx.Hash()).Returns(&txsReceipt[i])
+	}
+
+	if err := f.provider.Client.CallCtx(
+		ctx,
+		batchCalls...,
+	); err != nil {
+		return FetchResponse{}, nil
+	}
+
+	// TODO: Create FetchResponse
+
+	return fetchResponse, nil
+}