From 9edf9d2168de0e1dadcd7b9829830ec3dd7e9482 Mon Sep 17 00:00:00 2001
From: laisolizq <laisolizq@gmail.com>
Date: Mon, 9 Nov 2020 17:01:35 +0100
Subject: [PATCH] API State RecommendedFee

---
 api/api.go                |  6 +++++
 api/state.go              |  7 ++++++
 api/state_test.go         |  8 +++++++
 db/historydb/historydb.go | 49 +++++++++++++++++++++++++++++++++++----
 4 files changed, 65 insertions(+), 5 deletions(-)

diff --git a/api/api.go b/api/api.go
index 98b64f7..c387408 100644
--- a/api/api.go
+++ b/api/api.go
@@ -10,6 +10,12 @@ import (
 	"github.com/hermeznetwork/hermez-node/db/statedb"
 )
 
+// TODO: Add correct values to constants
+const (
+	createAccountExtraFeePercentage         float64 = 2
+	createAccountInternalExtraFeePercentage float64 = 2.5
+)
+
 // Status define status of the network
 type Status struct {
 	Network           Network                  `json:"network"`
diff --git a/api/state.go b/api/state.go
index 3232f9b..a76b3ae 100644
--- a/api/state.go
+++ b/api/state.go
@@ -142,5 +142,12 @@ func (a *API) UpdateMetrics() error {
 
 // UpdateRecommendedFee update Status.RecommendedFee information
 func (a *API) UpdateRecommendedFee() error {
+	feeExistingAccount, err := a.h.GetAvgTxFee()
+	if err != nil {
+		return err
+	}
+	a.status.RecommendedFee.ExistingAccount = feeExistingAccount
+	a.status.RecommendedFee.CreatesAccount = createAccountExtraFeePercentage * feeExistingAccount
+	a.status.RecommendedFee.CreatesAccountAndRegister = createAccountInternalExtraFeePercentage * feeExistingAccount
 	return nil
 }
diff --git a/api/state_test.go b/api/state_test.go
index de3e3cc..6e78577 100644
--- a/api/state_test.go
+++ b/api/state_test.go
@@ -96,3 +96,11 @@ func TestUpdateMetrics(t *testing.T) {
 	assert.Greater(t, api.status.Metrics.TotalBJJs, int64(0))
 	assert.Greater(t, api.status.Metrics.AvgTransactionFee, float64(0))
 }
+
+func TestUpdateRecommendedFee(t *testing.T) {
+	err := api.UpdateRecommendedFee()
+	assert.NoError(t, err)
+	assert.Greater(t, api.status.RecommendedFee.ExistingAccount, float64(0))
+	assert.Equal(t, api.status.RecommendedFee.CreatesAccount, api.status.RecommendedFee.ExistingAccount*createAccountExtraFeePercentage)
+	assert.Equal(t, api.status.RecommendedFee.CreatesAccountAndRegister, api.status.RecommendedFee.ExistingAccount*createAccountInternalExtraFeePercentage)
+}
diff --git a/db/historydb/historydb.go b/db/historydb/historydb.go
index 4c15b47..1e537d2 100644
--- a/db/historydb/historydb.go
+++ b/db/historydb/historydb.go
@@ -1475,7 +1475,12 @@ func (hdb *HistoryDB) GetMetrics(lastBatchNum common.BatchNum) (*Metrics, error)
 	}
 
 	metrics.TransactionsPerSecond = float64(metricsTotals.TotalTransactions / (24 * 60 * 60))
-	metrics.TransactionsPerBatch = float64(int64(metricsTotals.TotalTransactions) / int64(lastBatchNum-metricsTotals.FirstBatchNum))
+	if (lastBatchNum - metricsTotals.FirstBatchNum) > 0 {
+		metrics.TransactionsPerBatch = float64(int64(metricsTotals.TotalTransactions) /
+			int64(lastBatchNum-metricsTotals.FirstBatchNum))
+	} else {
+		metrics.TransactionsPerBatch = float64(0)
+	}
 
 	err = meddler.QueryRow(
 		hdb.db, metricsTotals, `SELECT COUNT(*) AS total_batches, 
@@ -1484,10 +1489,16 @@ func (hdb *HistoryDB) GetMetrics(lastBatchNum common.BatchNum) (*Metrics, error)
 	if err != nil {
 		return nil, err
 	}
-
-	metrics.BatchFrequency = float64((24 * 60 * 60) / metricsTotals.TotalBatches)
-	metrics.AvgTransactionFee = metricsTotals.TotalFeesUSD / float64(metricsTotals.TotalTransactions)
-
+	if metricsTotals.TotalBatches > 0 {
+		metrics.BatchFrequency = float64((24 * 60 * 60) / metricsTotals.TotalBatches)
+	} else {
+		metrics.BatchFrequency = 0
+	}
+	if metricsTotals.TotalTransactions > 0 {
+		metrics.AvgTransactionFee = metricsTotals.TotalFeesUSD / float64(metricsTotals.TotalTransactions)
+	} else {
+		metrics.AvgTransactionFee = 0
+	}
 	err = meddler.QueryRow(
 		hdb.db, metrics,
 		`SELECT COUNT(*) AS total_bjjs, COUNT(DISTINCT(bjj)) AS total_accounts FROM account;`)
@@ -1497,3 +1508,31 @@ func (hdb *HistoryDB) GetMetrics(lastBatchNum common.BatchNum) (*Metrics, error)
 
 	return metrics, nil
 }
+
+// GetAvgTxFee returns average transaction fee of the last 1h
+func (hdb *HistoryDB) GetAvgTxFee() (float64, error) {
+	metricsTotals := &MetricsTotals{}
+	err := meddler.QueryRow(
+		hdb.db, metricsTotals, `SELECT COUNT(tx.*) as total_txs, MIN(tx.batch_num) as batch_num 
+		FROM tx INNER JOIN block ON tx.eth_block_num = block.eth_block_num
+		WHERE block.timestamp >= NOW() - INTERVAL '1 HOURS';`)
+	if err != nil {
+		return 0, err
+	}
+	err = meddler.QueryRow(
+		hdb.db, metricsTotals, `SELECT COUNT(*) AS total_batches, 
+		SUM(total_fees_usd) AS total_fees FROM batch 
+		WHERE batch_num > $1;`, metricsTotals.FirstBatchNum)
+	if err != nil {
+		return 0, err
+	}
+
+	var avgTransactionFee float64
+	if metricsTotals.TotalTransactions > 0 {
+		avgTransactionFee = metricsTotals.TotalFeesUSD / float64(metricsTotals.TotalTransactions)
+	} else {
+		avgTransactionFee = 0
+	}
+
+	return avgTransactionFee, nil
+}