Start-End date parsing

date_utils.go

func handleRequest(w http.ResponseWriter, r *http.Request) {
	args := r.URL.Query()
	startDateStr := args.Get("start") // &start=2021-10-15
	endDateStr := args.Get("end")     // &end=2021-10-15
  startDate := parseDate(startDateStr, "today")
	endDate := parseDate(endDateStr, "tomorrow")
}

func atMidnight(startDate time.Time) time.Time {
	return startDate.Truncate(24 * time.Hour).In(time.UTC)
}

func parseDate(dateStr, defaultDate string) time.Time {
	if dateStr == "" {
		dateStr = defaultDate
	}
	today := atMidnight(time.Now())
	var parsedDate time.Time
	if dateStr == "" || dateStr == "today" {
		parsedDate = today
	} else if dateStr == "yesterday" {
		parsedDate = today.AddDate(0, 0, -1)
	} else if dateStr == "tomorrow" {
		parsedDate = today.AddDate(0, 0, 1)
	} else {
		// has time...
		if strings.Contains(dateStr, "T") {
			parsedDate, _ = time.Parse(time.RFC3339, dateStr)
		} else {
			parsedDate, _ = time.Parse("2006-01-02", dateStr)
		}
	}
	return parsedDate
}