qb: using ttl timestamp

Fixes: #40

qb/using.go

@@ -0,0 +1,92 @@
+// Copyright (C) 2017 ScyllaDB
+// Use of this source code is governed by a ALv2-style
+// license that can be found in the LICENSE file.
+
+package qb
+
+import (
+	"bytes"
+	"fmt"
+	"time"
+)
+
+// TTL converts duration to format expected in USING TTL clause.
+func TTL(d time.Duration) int64 {
+	return int64(d.Seconds())
+}
+
+// Timestamp converts time to format expected in USING TIMESTAMP clause.
+func Timestamp(t time.Time) int64 {
+	return t.UnixNano() / 1000
+}
+
+type using struct {
+	ttl           int64
+	ttlName       string
+	timestamp     int64
+	timestampName string
+}
+
+func (u *using) TTL(d time.Duration) *using {
+	u.ttl = TTL(d)
+	if u.ttl == 0 {
+		u.ttl = -1
+	}
+	u.timestampName = ""
+	return u
+}
+
+func (u *using) TTLNamed(name string) *using {
+	u.ttl = 0
+	u.ttlName = name
+	return u
+}
+
+func (u *using) Timestamp(t time.Time) *using {
+	u.timestamp = Timestamp(t)
+	u.timestampName = ""
+	return u
+}
+
+func (u *using) TimestampNamed(name string) *using {
+	u.timestamp = 0
+	u.timestampName = name
+	return u
+}
+
+func (u *using) writeCql(cql *bytes.Buffer) (names []string) {
+	hasTTL := false
+
+	if u.ttl != 0 {
+		hasTTL = true
+		if u.ttl == -1 {
+			u.ttl = 0
+		}
+		cql.WriteString("USING TTL ")
+		cql.WriteString(fmt.Sprint(u.ttl))
+		cql.WriteByte(' ')
+	} else if u.ttlName != "" {
+		hasTTL = true
+		cql.WriteString("USING TTL ? ")
+		names = append(names, u.ttlName)
+	}
+
+	if u.timestamp != 0 {
+		if hasTTL {
+			cql.WriteString("AND TIMESTAMP ")
+		} else {
+			cql.WriteString("USING TIMESTAMP ")
+		}
+		cql.WriteString(fmt.Sprint(u.timestamp))
+		cql.WriteByte(' ')
+	} else if u.timestampName != "" {
+		if hasTTL {
+			cql.WriteString("AND TIMESTAMP ? ")
+		} else {
+			cql.WriteString("USING TIMESTAMP ? ")
+		}
+		names = append(names, u.timestampName)
+	}
+
+	return
+}