SlackBot-ListenForEvents.go

package main

import (
	"context"
	"fmt"
	"log"
	"os"
	"time"

	"github.com/joho/godotenv"
	"github.com/slack-go/slack"
	"github.com/slack-go/slack/slackevents"
	"github.com/slack-go/slack/socketmode"
)

func main() {

	// Load Env variables from .dot file
	godotenv.Load(".env")

	token := os.Getenv("SLACK_AUTH_TOKEN")
	appToken := os.Getenv("SLACK_APP_TOKEN")
	// Create a new client to slack by giving token
	// Set debug to true while developing
	// Also add a ApplicationToken option to the client
	client := slack.New(token, slack.OptionDebug(true), slack.OptionAppLevelToken(appToken))
	// go-slack comes with a SocketMode package that we need to use that accepts a Slack client and outputs a Socket mode client instead
	socketClient := socketmode.New(
		client,
		socketmode.OptionDebug(true),
		// Option to set a custom logger
		socketmode.OptionLog(log.New(os.Stdout, "socketmode: ", log.Lshortfile|log.LstdFlags)),
	)

	// Create a context that can be used to cancel goroutine
	ctx, cancel := context.WithCancel(context.Background())
	// Make this cancel called properly in a real program , graceful shutdown etc
	defer cancel()

	go func(ctx context.Context, client *slack.Client, socketClient *socketmode.Client) {
		// Create a for loop that selects either the context cancellation or the events incomming
		for {
			select {
			// inscase context cancel is called exit the goroutine
			case <-ctx.Done():
				log.Println("Shutting down socketmode listener")
				return
			case event := <-socketClient.Events:
				// We have a new Events, let's type switch the event
				// Add more use cases here if you want to listen to other events.
				switch event.Type {
				// handle EventAPI events
				case socketmode.EventTypeEventsAPI:
					// The Event sent on the channel is not the same as the EventAPI events so we need to type cast it
					eventsAPIEvent, ok := event.Data.(slackevents.EventsAPIEvent)
					if !ok {
						log.Printf("Could not type cast the event to the EventsAPIEvent: %v\n", event)
						continue
					}
					// We need to send an Acknowledge to the slack server
					socketClient.Ack(*event.Request)
					// Now we have an Events API event, but this event type can in turn be many types, so we actually need another type switch
					log.Println(eventsAPIEvent)
				}

			}
		}
	}(ctx, client, socketClient)

	socketClient.Run()
}