func formatTimeDimension()

in query/common/dimval.go [146:213]
60 lines of code
19 McCabe index (conditional complexity)

func formatTimeDimension(val int64, meta TimeDimensionMeta, cache map[TimeDimensionMeta]map[int64]string) (result string) {
	// We will not process timeUnit for application/hll because if application/hll holds the raw uint32
	// value. If we convert it to milliseconds, it will overflow.
	if meta.TimeUnit != "" {
		val = utils.AdjustOffset(meta.FromOffset, meta.ToOffset,
			meta.DSTSwitchTs, val)
		switch meta.TimeUnit {
		case "day":
			val /= SecondsPerDay
		case "hour":
			val /= SecondsPerHour
		case "minute":
			val /= SecondsPerMinute
		case "millisecond":
			val *= 1000
		}
		return strconv.FormatInt(val, 10)
	}
	// skip timezone table dims
	// TODO(shz): support timezone table dims
	if !meta.IsTimezoneTable {
		if cacheMap, ok := cache[meta]; ok {
			if result, exists := cacheMap[val]; exists {
				return result
			}
		} else if cache != nil {
			cache[meta] = make(map[int64]string)
		}
	}

	switch meta.TimeBucketizer {
	case "time of day":
		t := time.Unix(val, 0)
		return t.UTC().Format("15:04")
	case "hour of day":
		t := time.Unix(val-val%3600, 0)
		return t.UTC().Format("15:04")
	case "hour of week":
		t := time.Unix(val+SecondsPer4Day, 0)
		return t.UTC().Format("Monday 15:04")
	case "day of week":
		// 1970-01-01 was a Thursday
		t := time.Unix(((val+4)%7)*SecondsPerDay, 0)
		return t.UTC().Format("Monday")
	default:
		bucket, err := ParseRegularTimeBucketizer(meta.TimeBucketizer)
		if err != nil {
			return strconv.FormatInt(val, 10)
		}
		switch bucket.Unit {
		case "m":
			t := time.Unix(val, 0)
			return t.UTC().Format("2006-01-02 15:04")
		case "h":
			t := time.Unix(val-val%3600, 0)
			return t.UTC().Format("2006-01-02 15:00")
		case "d":
			t := time.Unix(val-val%(24*60*60), 0)
			return t.UTC().Format("2006-01-02")
		}

	}

	if !meta.IsTimezoneTable {
		cache[meta][val] = result
	}
	return
}