From 2dd850c9ef227d4df57be75620b7f35bfa6c2e39 Mon Sep 17 00:00:00 2001
From: Grigory Zubankov <Grigory.Zubankov@acronis.com>
Date: Wed, 24 Oct 2018 14:37:00 +0300
Subject: [PATCH] fix: incorrect parsing of UNIX nanoseconds

---
 time_parse.go      | 34 +++++++++++++++++-----------------
 time_parse_test.go | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 17 deletions(-)
 create mode 100644 time_parse_test.go

diff --git a/time_parse.go b/time_parse.go
index d0a60a1..83bca4f 100644
--- a/time_parse.go
+++ b/time_parse.go
@@ -1,7 +1,6 @@
 package humanlog
 
 import (
-	"math"
 	"time"
 )
 
@@ -24,18 +23,19 @@ var formats = []string{
 	time.StampNano,
 }
 
-func parseTimeFloat64(value float64) (time.Time, bool) {
-	if value/math.Pow10(15) > 1 { // Nanoseconds
-		secs := int64(math.Trunc(value / math.Pow10(6)))
-		nsecs := int64(math.Mod(value, math.Pow10(6)))
-		return time.Unix(secs, nsecs), true
-	} else if value/math.Pow10(12) > 1 { // Milliseconds
-		secs := int64(math.Trunc(value / math.Pow10(3)))
-		nsecs := int64(math.Mod(value, math.Pow10(3))) * int64(math.Pow10(3))
-		return time.Unix(secs, nsecs), true
-	} else {
-		return time.Unix(int64(value), 0), true
+func parseTimeFloat64(value float64) time.Time {
+	v := int64(value)
+	switch {
+	case v > 1e18:
+	case v > 1e15:
+		v *= 1e3
+	case v > 1e12:
+		v *= 1e6
+	default:
+		return time.Unix(v, 0)
 	}
+
+	return time.Unix(v/1e9, v%1e9)
 }
 
 // tries to parse time using a couple of formats before giving up
@@ -51,15 +51,15 @@ func tryParseTime(value interface{}) (time.Time, bool) {
 			}
 		}
 	case float32:
-		return parseTimeFloat64(float64(value.(float32)))
+		return parseTimeFloat64(float64(value.(float32))), true
 	case float64:
-		return parseTimeFloat64(value.(float64))
+		return parseTimeFloat64(value.(float64)), true
 	case int:
-		return parseTimeFloat64(float64(value.(int)))
+		return parseTimeFloat64(float64(value.(int))), true
 	case int32:
-		return parseTimeFloat64(float64(value.(int32)))
+		return parseTimeFloat64(float64(value.(int32))), true
 	case int64:
-		return parseTimeFloat64(float64(value.(int64)))
+		return parseTimeFloat64(float64(value.(int64))), true
 	}
 	return t, false
 }
diff --git a/time_parse_test.go b/time_parse_test.go
new file mode 100644
index 0000000..ac7ee49
--- /dev/null
+++ b/time_parse_test.go
@@ -0,0 +1,36 @@
+package humanlog
+
+import (
+	"testing"
+)
+
+func TestTimeParseFloat64(t *testing.T) {
+	t.Run("nanoseconds", func(t *testing.T) {
+		golden := float64(1540369190466951764)
+		tm := parseTimeFloat64(golden)
+		if int64(golden) != tm.UnixNano() {
+			t.Fatal(tm.UnixNano())
+		}
+	})
+	t.Run("microseconds", func(t *testing.T) {
+		golden := float64(1540369190466951)
+		tm := parseTimeFloat64(golden)
+		if int64(golden)*1e3 != tm.UnixNano() {
+			t.Fatal(tm.UnixNano())
+		}
+	})
+	t.Run("milliseconds", func(t *testing.T) {
+		golden := float64(1540369190466)
+		tm := parseTimeFloat64(golden)
+		if int64(golden)*1e6 != tm.UnixNano() {
+			t.Fatal(tm.UnixNano())
+		}
+	})
+	t.Run("seconds", func(t *testing.T) {
+		golden := float64(1540369190)
+		tm := parseTimeFloat64(golden)
+		if int64(golden)*1e9 != tm.UnixNano() {
+			t.Fatal(tm.UnixNano())
+		}
+	})
+}