From 1cc6a87d2077c52b951ea18ed55edd9ddccf7a14 Mon Sep 17 00:00:00 2001
From: reesporte <reesedporter@gmail.com>
Date: Tue, 16 Nov 2021 14:53:30 -0600
Subject: [PATCH] refactor and add test

---
 server/pg.go |  2 +-
 util.go      | 11 +++++++++--
 util_test.go | 18 ++++++++++++++++++
 3 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/server/pg.go b/server/pg.go
index da6dfd633..169f2e747 100644
--- a/server/pg.go
+++ b/server/pg.go
@@ -332,7 +332,7 @@ func pgWriteGroupCount(w pg.QueryResultWriter, counts *pilosa.GroupCounts) error
 			switch {
 			case g.Value != nil:
 				if g.FieldOptions.Type == pilosa.FieldTypeTimestamp {
-					v = time.Unix(0, (int64(*g.Value)+int64(g.FieldOptions.Base))*pilosa.TimeUnitNanos(g.FieldOptions.TimeUnit)).UTC().Format(time.RFC3339Nano)
+					v = pilosa.FormatTimestampNano(int64(*g.Value), g.FieldOptions.Base, g.FieldOptions.TimeUnit)
 				} else {
 					v = strconv.FormatInt(*g.Value, 10)
 				}
diff --git a/util.go b/util.go
index 6d4b8e09e..1db0c74fc 100644
--- a/util.go
+++ b/util.go
@@ -115,8 +115,9 @@ func roaringFragmentHasData(path string, index, field, view string, shard uint64
 	return
 }
 
-// GetLoopProgress returns the estimated remaining time to iterate through some items
-// as well as the loop completion percentage with the following parameters:
+// GetLoopProgress returns the estimated remaining time to iterate through some
+// items as well as the loop completion percentage with the following
+// parameters:
 // the start time, the current time, the iteration, and the number of items
 func GetLoopProgress(start time.Time, now time.Time, iteration uint, total uint) (remaining time.Duration, pctDone float64) {
 	itemsLeft := total - (iteration + 1)
@@ -124,3 +125,9 @@ func GetLoopProgress(start time.Time, now time.Time, iteration uint, total uint)
 	pctDone = (float64(iteration+1) / float64(total)) * 100
 	return time.Duration(avgItemTime * float64(itemsLeft)), pctDone
 }
+
+// FormatTimestampNano returns the string representation of a timestamp given:
+// an epoch value, base, and time unit
+func FormatTimestampNano(value, base int64, timeUnit string) string {
+	return time.Unix(0, (value+base)*TimeUnitNanos(timeUnit)).UTC().Format(time.RFC3339Nano)
+}
diff --git a/util_test.go b/util_test.go
index c659053c5..14ed78c36 100644
--- a/util_test.go
+++ b/util_test.go
@@ -85,3 +85,21 @@ func TestGetLoopProgress(t *testing.T) {
 		})
 	}
 }
+
+func TestFormatTimestampNano(t *testing.T) {
+	if FormatTimestampNano(0, 69, "s") != "1970-01-01T00:01:09Z" {
+		t.Fatal("Timestamp not formatted properly")
+	}
+	if FormatTimestampNano(0, 420, "ms") != "1970-01-01T00:00:00.42Z" {
+		t.Fatal("Timestamp not formatted properly")
+	}
+	if FormatTimestampNano(420, 0, "μs") != "1970-01-01T00:00:00.00000042Z" {
+		t.Fatal("Timestamp not formatted properly")
+	}
+	if FormatTimestampNano(420, 69, "us") != "1970-01-01T00:00:00.000489Z" {
+		t.Fatal("Timestamp not formatted properly")
+	}
+	if FormatTimestampNano(69, 420, "ns") != "1970-01-01T00:00:00.000000489Z" {
+		t.Fatal("Timestamp not formatted properly")
+	}
+}