Relay for posting messages from a HipChat room into a Slack room

hipchat-to-slack.go

package main

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"log"
	"net/http"
	"os"
	"path"
	"strings"
	"time"

	"github.com/andybons/hipchat"
)

func messageReceiver(client hipchat.Client, room string, ci chan []hipchat.Message) {
	var lastMsg hipchat.Message
	var start int

	log.Printf("Receiver for %s started", room)

	for {
		start = 0
		messages, err := client.RoomHistory(room, "recent", "CST")
		if err != nil {
			log.Printf("Error: %v", err)
			time.Sleep(time.Second * 10)
			continue
		}

		if (lastMsg == hipchat.Message{}) {
			lastMsg = messages[len(messages)-1]
			continue
		}

		for i, msg := range messages {
			if msg == lastMsg {
				start = i + 1
				break
			}
		}

		lastMsg = messages[len(messages)-1]
		ci <- messages[start:]
	}
}

type slackMessage struct {
	Text string `json:"text"`
}

func messageSender(slackURL, message string) {
	log.Print("Relaying message(s) to Slack")

	msg := slackMessage{Text: message}
	msgJson, err := json.Marshal(msg)
	if err != nil {
		log.Printf("Error converting message to JSON: %v", err)
		return
	}

	resp, err := http.Post(slackURL, "application/json", bytes.NewReader(msgJson))
	if err != nil {
		log.Printf("Error posting to Slack: %v", err)
		return
	}

	if resp.StatusCode == 200 {
		log.Print("Message relayed successfully!")
	} else {
		log.Printf("Error posting message to slack: %v", resp.Status)
	}
}

func Usage() {
	fmt.Printf(`usage: %s [options]

Relay for posting messages from a HipChat room to a Slack room.

Options:
`, path.Base(os.Args[0]))
	flag.PrintDefaults()
	os.Exit(2)
}

func main() {
	ci := make(chan []hipchat.Message)
	ticker := time.NewTicker(30 * time.Second)

	flag.Usage = Usage

	var hipchatToken = flag.String("hipchat-token", "", "HipChat AuthToken for the source account")
	var hipchatRoom = flag.String("hipchat-room", "", "HipChat room to relay messages from")
	var slackWebhookURL = flag.String("slack-webhook-url", "", "Incoming webhook URL for Slack room. (e.g. 'https://hooks.slack.com/services/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')")
	var messagePrefix = flag.String("prefix", "", "Text to prefix each Slack message with")

	flag.Parse()

	if *hipchatToken == "" || *hipchatRoom == "" || *slackWebhookURL == "" {
		Usage()
	}

	hipchatClient := hipchat.Client{AuthToken: *hipchatToken}

	go messageReceiver(hipchatClient, *hipchatRoom, ci)

	for {
		messages := <-ci
		if len(messages) != 0 {
			log.Printf("Found %d new message(s)", len(messages))

			formattedMsg := make([]string, len(messages)+1)
			if *messagePrefix != "" {
				formattedMsg = append(formattedMsg, *messagePrefix)
			}
			for _, msg := range messages {
				formattedMsg = append(formattedMsg, fmt.Sprintf("%s: %s", msg.From.Name, msg.Message))
			}
			go messageSender(*slackWebhookURL, strings.Join(formattedMsg, "\n"))
		} else {
			log.Print("No new messages received")
		}
		<-ticker.C
	}
}