feat(prometheus): initial support for prometheus

pkg/tsdb/time_range.go

@@ -0,0 +1,77 @@
+package tsdb
+
+import (
+	"fmt"
+	"strings"
+	"time"
+)
+
+func NewTimerange(from, to string) TimeRange {
+	return TimeRange{
+		From: from,
+		To:   to,
+		Now:  time.Now(),
+	}
+}
+
+type TimeRange struct {
+	From string
+	To   string
+	Now  time.Time
+}
+
+func (tr TimeRange) FromUnix() (int64, error) {
+	fromRaw := strings.Replace(tr.From, "now-", "", 1)
+
+	diff, err := time.ParseDuration("-" + fromRaw)
+	if err != nil {
+		return 0, err
+	}
+
+	return tr.Now.Add(diff).Unix(), nil
+}
+
+func (tr TimeRange) FromTime() (time.Time, error) {
+	fromRaw := strings.Replace(tr.From, "now-", "", 1)
+
+	diff, err := time.ParseDuration("-" + fromRaw)
+	if err != nil {
+		return time.Time{}, err
+	}
+
+	return tr.Now.Add(diff), nil
+}
+
+func (tr TimeRange) ToUnix() (int64, error) {
+	if tr.To == "now" {
+		return tr.Now.Unix(), nil
+	} else if strings.HasPrefix(tr.To, "now-") {
+		withoutNow := strings.Replace(tr.To, "now-", "", 1)
+
+		diff, err := time.ParseDuration("-" + withoutNow)
+		if err != nil {
+			return 0, nil
+		}
+
+		return tr.Now.Add(diff).Unix(), nil
+	}
+
+	return 0, fmt.Errorf("cannot parse to value %s", tr.To)
+}
+
+func (tr TimeRange) ToTime() (time.Time, error) {
+	if tr.To == "now" {
+		return tr.Now, nil
+	} else if strings.HasPrefix(tr.To, "now-") {
+		withoutNow := strings.Replace(tr.To, "now-", "", 1)
+
+		diff, err := time.ParseDuration("-" + withoutNow)
+		if err != nil {
+			return time.Time{}, nil
+		}
+
+		return tr.Now.Add(diff), nil
+	}
+
+	return time.Time{}, fmt.Errorf("cannot parse to value %s", tr.To)
+}