From 5b01306c12c779b691cf500839c7f96102c6f129 Mon Sep 17 00:00:00 2001
From: Mo Lin <molin@wanchain.org>
Date: Thu, 3 Jun 2021 14:17:04 +0800
Subject: [PATCH] add api pos_getEpochGasPoolByBlock

---
 internal/web3ext/web3ext.go |  5 +++++
 pos/posapi/api.go           | 23 +++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/internal/web3ext/web3ext.go b/internal/web3ext/web3ext.go
index 3407bd96..eafbe73a 100644
--- a/internal/web3ext/web3ext.go
+++ b/internal/web3ext/web3ext.go
@@ -275,6 +275,11 @@ web3._extend({
 			call: 'pos_getEpochGasPool',
 			params: 1
 		}),
+		new web3._extend.Method({
+			name: 'getEpochGasPoolByBlock',
+			call: 'pos_getEpochGasPoolByBlock',
+			params: 2
+		}),
 		new web3._extend.Method({
 			name: 'getStakerInfo',
 			call: 'pos_getStakerInfo',
diff --git a/pos/posapi/api.go b/pos/posapi/api.go
index cd973ba1..cbaab8d7 100644
--- a/pos/posapi/api.go
+++ b/pos/posapi/api.go
@@ -596,6 +596,29 @@ func (a PosApi) GetEpochGasPool(epochID uint64) (string, error) {
 	return incentive.GetEpochGasPool(db, epochID).String(), nil
 }
 
+func (a PosApi) GetEpochGasPoolByBlock(epochId uint64, blockNr int64) (string, error) {
+	if !isPosStage() {
+		return "Not POS stage.", nil
+	}
+
+	if blockNr > a.chain.CurrentHeader().Number.Int64() {
+		blockNr = -1
+	}
+
+	epID, _ := util.CalEpSlbyTd(a.chain.CurrentHeader().Difficulty.Uint64())
+
+	if epochId > epID {
+		return "", errors.New("wrong epochId (It hasn't arrived yet.):" + convert.Uint64ToString(epochId))
+	}
+
+	state, _, err := a.backend.StateAndHeaderByNumber(context.Background(), rpc.BlockNumber(blockNr))
+	if err != nil {
+		return "", err
+	}
+
+	return incentive.GetEpochGasPool(state, epochId).String(), nil
+}
+
 func (a PosApi) GetRBAddress(epochID uint64) []common.Address {
 	if !isPosStage() {
 		return nil