Make --to relative to --from

logcat.go

@@ -23,13 +23,13 @@ import (
 )
 
 var (
-	elasticURL  = flag.String("url", "http://127.0.0.1:9200", "ES URL")
-	fromDate    = flag.String("from", "-1h", "start date")
-	toDate      = flag.String("to", "", "end date (default now)")
+	elasticURL  = flag.String("url", "http://127.0.0.1:9200", "Elasticsearch URL")
+	fromDate    = flag.String("from", "-1h", "start `date`")
+	toDate      = flag.String("to", "", "end `date` (default now, otherwise relative to --from)")
 	doDumpQuery = flag.Bool("dump-query", false, "don't do anything, just print the ES query as JSON")
-	batchSize   = flag.Int("batch-size", 10000, "ES scroll batch size")
-	indexBase   = flag.String("index", "logstash", "ES index base name")
-	objType     = flag.String("obj-type", "events", "ES index object type")
+	batchSize   = flag.Int("batch-size", 10000, "ES scroll batch `size`")
+	indexFmt    = flag.String("index-format", "logstash-2006.01.02", "ES index `format` string, as supported by Go time.Format()")
+	objType     = flag.String("obj-type", "events", "ES index object `type`")
 )
 
 var allowedTimeFormats = []string{
@@ -40,7 +40,7 @@ var allowedTimeFormats = []string{
 	"2006/1/2",
 }
 
-func parseTime(now time.Time, s string) (t time.Time, err error) {
+func parseTime(base time.Time, s string) (t time.Time, err error) {
 	var d time.Duration
 	switch {
 	case strings.HasPrefix(s, "+"):
@@ -48,13 +48,13 @@ func parseTime(now time.Time, s string) (t time.Time, err error) {
 		if err != nil {
 			return
 		}
-		t = now.Add(d)
+		t = base.Add(d)
 	case strings.HasPrefix(s, "-"):
 		d, err = time.ParseDuration(s[1:])
 		if err != nil {
 			return
 		}
-		t = now.Add(-d)
+		t = base.Add(-d)
 	default:
 		for _, f := range allowedTimeFormats {
 			t, err = time.Parse(f, s)
@@ -82,7 +82,7 @@ func parseTimeRange(fromStr, toStr string) (from time.Time, to time.Time, err er
 	if toStr == "" {
 		to = now
 	} else {
-		to, err = parseTime(now, toStr)
+		to, err = parseTime(from, toStr)
 		if err != nil {
 			err = fmt.Errorf("error in --to: %v", err)
 			return
@@ -113,9 +113,8 @@ func (m *logMessage) format() string {
 func getIndexes(from, to time.Time) []string {
 	var idxs []string
 	t := time.Date(from.Year(), from.Month(), from.Day(), 0, 0, 0, 0, time.UTC)
-	idxFmt := fmt.Sprintf("%s-2006.01.02", *indexBase)
 	for t.Before(to) {
-		idxs = append(idxs, t.Format(idxFmt))
+		idxs = append(idxs, t.Format(*indexFmt))
 		t = t.AddDate(0, 0, 1)
 	}
 	return idxs