Fix SecToTime edge-cases (#20610) (#20611)

Author: Gusted

Diff for: modules/util/sec_to_time.go

@@ -16,12 +16,28 @@ import (
 // 1563418		-> 2 weeks 4 days
 // 3937125s     -> 1 month 2 weeks
 // 45677465s	-> 1 year 6 months
+//
+// Magic numbers:
+// 3600 = 60 * 60 (amount of seconds in a hour)
+// 86400 = 60 * 60 * 24 (amount of seconds in a day)
 func SecToTime(duration int64) string {
 	formattedTime := ""
-	years := duration / (3600 * 24 * 7 * 4 * 12)
-	months := (duration / (3600 * 24 * 30)) % 12
-	weeks := (duration / (3600 * 24 * 7)) % 4
-	days := (duration / (3600 * 24)) % 7
+
+	// The following four variables are calculated by taking
+	// into account the previously calculated variables, this avoids
+	// pitfalls when using remainders. As that could lead to incorrect
+	// results when the calculated number equals the quotient number.
+	remainingDays := duration / (60 * 60 * 24)
+	years := remainingDays / 365
+	remainingDays -= years * 365
+	months := remainingDays * 12 / 365
+	remainingDays -= months * 365 / 12
+	weeks := remainingDays / 7
+	remainingDays -= weeks * 7
+	days := remainingDays
+
+	// The following three variables are calculated without depending
+	// on the previous calculated variables.
 	hours := (duration / 3600) % 24
 	minutes := (duration / 60) % 60
 	seconds := duration % 60

Diff for: modules/util/sec_to_time_test.go

@@ -11,10 +11,21 @@ import (
 )
 
 func TestSecToTime(t *testing.T) {
-	assert.Equal(t, SecToTime(66), "1 minute 6 seconds")
-	assert.Equal(t, SecToTime(52410), "14 hours 33 minutes")
-	assert.Equal(t, SecToTime(563418), "6 days 12 hours")
-	assert.Equal(t, SecToTime(1563418), "2 weeks 4 days")
-	assert.Equal(t, SecToTime(3937125), "1 month 2 weeks")
-	assert.Equal(t, SecToTime(45677465), "1 year 5 months")
+	second := int64(1)
+	minute := 60 * second
+	hour := 60 * minute
+	day := 24 * hour
+	year := 365 * day
+
+	assert.Equal(t, "1 minute 6 seconds", SecToTime(minute+6*second))
+	assert.Equal(t, "1 hour", SecToTime(hour))
+	assert.Equal(t, "1 hour", SecToTime(hour+second))
+	assert.Equal(t, "14 hours 33 minutes", SecToTime(14*hour+33*minute+30*second))
+	assert.Equal(t, "6 days 12 hours", SecToTime(6*day+12*hour+30*minute+18*second))
+	assert.Equal(t, "2 weeks 4 days", SecToTime((2*7+4)*day+2*hour+16*minute+58*second))
+	assert.Equal(t, "4 weeks", SecToTime(4*7*day))
+	assert.Equal(t, "4 weeks 1 day", SecToTime((4*7+1)*day))
+	assert.Equal(t, "1 month 2 weeks", SecToTime((6*7+3)*day+13*hour+38*minute+45*second))
+	assert.Equal(t, "11 months", SecToTime(year-25*day))
+	assert.Equal(t, "1 year 5 months", SecToTime(year+163*day+10*hour+11*minute+5*second))
 }