irc_bot/main.go

package main

import (
	"fmt"
	"log"
	"os"
	"regexp"

	"github.com/go-chat-bot/plugins/web"
	irc "github.com/thoj/go-ircevent"
)

const channel = "#ctf"

const (
	pattern   = "(?i)\\b(cat|gato|miau|meow|garfield|lolcat)[s|z]{0,1}\\b"
	msgPrefix = "I love cats! Here's a fact: %s"
)

type catFact struct {
	Fact   string `json:"fact"`
	Length int    `json:"length"`
}

var (
	re          = regexp.MustCompile(pattern)
	catFactsURL = "http://catfact.ninja/fact"
)

func main() {
	nick := os.Getenv("CTF2021NICK")
	irccon := irc.IRC(nick, os.Getenv("CTF2021USER"))

	irccon.VerboseCallbackHandler = false
	irccon.Debug = false
	irccon.UseTLS = false

	irccon.AddCallback("001", func(e *irc.Event) {
		log.Println("Welcome message:", e.Message())

		e.Connection.Privmsg("nickserv", "identify "+os.Getenv("CTF2021PASS"))

		e.Connection.Join(channel)
		e.Connection.Privmsg(channel, `I'm a cat facts bot!`)
		e.Connection.Privmsg(channel, `Inspired from https://github.com/go-chat-bot/plugins/blob/master/catfacts/catfacts.go`)
		e.Connection.Privmsg(channel, `Try cat /etc/passwd ^_^`)
		e.Connection.Privmsg(channel, `Source code and issue tracker: https://gitea.difrex.ru/CTF2021/irc_bot`)
	})

	irccon.AddCallback("PRIVMSG", func(e *irc.Event) {
		log.Printf("Message from %s received: %s", e.Nick, e.Message())
		catFacts(e.Message(), e.Connection)
	})

	irccon.AddCallback("", func(e *irc.Event) {})
	err := irccon.Connect(os.Getenv("CTF2021URL"))
	if err != nil {
		fmt.Printf("Err %s", err)
		return
	}
	irccon.Loop()
}

func catFacts(command string, con *irc.Connection) (string, error) {
	if !re.MatchString(command) {
		return "", nil
	}
	data := &catFact{}
	err := web.GetJSON(catFactsURL, data)
	if err != nil {
		return "", err
	}

	if len(data.Fact) == 0 {
		return "", nil
	}

	con.Privmsg(channel, fmt.Sprintf(msgPrefix, data.Fact))
	return fmt.Sprintf(msgPrefix, data.Fact), nil
}