the-farting-whale/main.go

package main

import (
	"fmt"
	"log"
	"os"
	"os/signal"
	"syscall"
	"strings"
	"regexp"
	"io"
	"net/http"

	"github.com/bwmarrin/discordgo"
	"github.com/spf13/viper"
)

func main() {
	vpr := viper.GetViper()
	vpr.SetConfigFile(".env")
	var token string = ""
	if err := vpr.ReadInConfig(); err != nil {
		if _, ok := err.(viper.ConfigFileNotFoundError); ok {
			log.Fatalln("Config file (.env) not found!")
		} else {
			log.Println("Failed to parse config!")
		}
	}

	if vpr.GetString("DISCORD_BOT_TOKEN") == "" {
		token = os.Getenv("DISCORD_BOT_TOKEN")
		if token == "" {
			log.Fatalln("Couldn't fetch bot token!")
		}
	} else {
		token = vpr.GetString("DISCORD_BOT_TOKEN")
	}

	dg, err := discordgo.New("Bot " + token)
	if err != nil {
		log.Fatalf("Error creating Discord session: %s\n", err)
	}

	dg.AddHandler(messageCreate)
	dg.Identify.Intents = discordgo.IntentsGuildMessages

	// connect to discord
	err = dg.Open()
	if err != nil {
		log.Fatalf("Couldn't connect to DIscord: %s\n", err)
	}

	// wait until ctrl+c or other term signal is received
	fmt.Println("The Farting Whale is online!")
	sc := make(chan os.Signal, 1)
	signal.Notify(sc, syscall.SIGINT, syscall.SIGTERM, os.Interrupt)
	<-sc

	// graceful shutdown
	dg.Close()
}

// incoming message handler
func messageCreate(s *discordgo.Session, m *discordgo.MessageCreate) {
	// ignore messages sent by the bot.
	if m.Author.ID == s.State.User.ID {
		return
	}

	if strings.HasPrefix(m.Content, "!fart") {
		c := strings.Fields(m.Content)
		if len(c) == 1 {
			s.ChannelMessageSend(m.ChannelID, ":whale2: :dash:")
		} else if len(c) == 2 {
			s.ChannelMessageSend(m.ChannelID, fmt.Sprintf(":whale2: :dash: %s", c[1]))
		}
		return
	} else if strings.HasPrefix(m.Content, "!weather") {
		c := strings.Fields(m.Content)
		if len(c) == 2 {
			// contact wttr.in
			url := fmt.Sprintf("https://wttr.in/%s?0QATm", c[1])
			resp, err := http.Get(url)
			if err != nil {
				fmt.Printf("ERROR while running $weather: %s", err)
				return
			}
			body, err := io.ReadAll(resp.Body)
			if err != nil {
				fmt.Printf("ERROR while running $weather: %s", err)
				return
			}
			body_string := string(body[:])
			if strings.Contains(body_string, "404 UNKNOWN") {
				s.ChannelMessageSend(m.ChannelID, fmt.Sprintf("That's not a city, silly!"))
				return
			}
			s.ChannelMessageSend(m.ChannelID, fmt.Sprintf("```%s```", body_string))
		}
		return
	}

	// check for reddit/twitter links and replace them with open source frontends
	re := regexp.MustCompile(`(?i)((([A-Za-z]{3,9}:(?:\/\/)?)(?:[-;:&=\+\$,\w]+@)?[A-Za-z0-9.-]+|(?:www.|[-;:&=\+\$,\w]+@)[A-Za-z0-9.-]+)((?:\/[\+~%\/.\w-_]*)?\??(?:[-\+=&;%@.\w_]*)#?(?:[.\!\/\\w]*))?)`)
	result := re.FindStringSubmatch(m.Content)
	// hard coded, group 2 contains the base url
	if len(result) >= 3 {
		if result[2] == "https://www.reddit.com" || result[2] == "https://reddit.com"{
			s.ChannelMessageSend(m.ChannelID, fmt.Sprintf("<https://tedd.it%s>", result[4]))
		} else if result[2] == "https://www.twitter.com" || result[2] == "https://twitter.com" {
			s.ChannelMessageSend(m.ChannelID, fmt.Sprintf("<https://nitter.lacontrevoie.fr%s>", result[4]))
		}		
	}
}