1package packets
2
3import (
4	"bytes"
5	"fmt"
6	"io"
7)
8
9//PublishPacket is an internal representation of the fields of the
10//Publish MQTT packet
11type PublishPacket struct {
12	FixedHeader
13	TopicName string
14	MessageID uint16
15	Payload   []byte
16}
17
18func (p *PublishPacket) String() string {
19	str := fmt.Sprintf("%s", p.FixedHeader)
20	str += " "
21	str += fmt.Sprintf("topicName: %s MessageID: %d", p.TopicName, p.MessageID)
22	str += " "
23	str += fmt.Sprintf("payload: %s", string(p.Payload))
24	return str
25}
26
27func (p *PublishPacket) Write(w io.Writer) error {
28	var body bytes.Buffer
29	var err error
30
31	body.Write(encodeString(p.TopicName))
32	if p.Qos > 0 {
33		body.Write(encodeUint16(p.MessageID))
34	}
35	p.FixedHeader.RemainingLength = body.Len() + len(p.Payload)
36	packet := p.FixedHeader.pack()
37	packet.Write(body.Bytes())
38	packet.Write(p.Payload)
39	_, err = w.Write(packet.Bytes())
40
41	return err
42}
43
44//Unpack decodes the details of a ControlPacket after the fixed
45//header has been read
46func (p *PublishPacket) Unpack(b io.Reader) error {
47	var payloadLength = p.FixedHeader.RemainingLength
48	p.TopicName = decodeString(b)
49	if p.Qos > 0 {
50		p.MessageID = decodeUint16(b)
51		payloadLength -= len(p.TopicName) + 4
52	} else {
53		payloadLength -= len(p.TopicName) + 2
54	}
55	if payloadLength < 0 {
56		return fmt.Errorf("Error upacking publish, payload length < 0")
57	}
58	p.Payload = make([]byte, payloadLength)
59	_, err := b.Read(p.Payload)
60
61	return err
62}
63
64//Copy creates a new PublishPacket with the same topic and payload
65//but an empty fixed header, useful for when you want to deliver
66//a message with different properties such as Qos but the same
67//content
68func (p *PublishPacket) Copy() *PublishPacket {
69	newP := NewControlPacket(Publish).(*PublishPacket)
70	newP.TopicName = p.TopicName
71	newP.Payload = p.Payload
72
73	return newP
74}
75
76//Details returns a Details struct containing the Qos and
77//MessageID of this ControlPacket
78func (p *PublishPacket) Details() Details {
79	return Details{Qos: p.Qos, MessageID: p.MessageID}
80}
81