refactor code (#11)

* change argment type

* remove unused code

* fix regex pattern

* rewrite

* remove file

* move functions

* remove purge method

discord/bot.go

@@ -3,6 +3,9 @@ package discord
 import (
 	"errors"
 	"fmt"
+	"regexp"
+	"strings"
+	"time"
 
 	"github.com/aqyuki/expand-bot/logging"
 	"github.com/bwmarrin/discordgo"
@@ -11,7 +14,7 @@ import (
 
 // Bot provides features to interact with Discord.
 type Bot struct {
-	config Config
+	token  string
 	client *discordgo.Session
 	logger *zap.SugaredLogger
 }
@@ -30,9 +33,9 @@ func WithLogger(logger *zap.SugaredLogger) Option {
 }
 
 // NewBot creates a new Bot instance.
-func NewBot(config Config, opts ...Option) Bot {
+func NewBot(token string, opts ...Option) Bot {
 	b := Bot{
-		config: config,
+		token:  token,
 		client: nil,
 		logger: logging.DefaultLogger(),
 	}
@@ -48,12 +51,12 @@ func (b *Bot) Start() error {
 		return errors.New("bot is already running")
 	}
 
-	session, err := discordgo.New("Bot " + b.config.Token)
+	session, err := discordgo.New("Bot " + b.token)
 	if err != nil {
 		return fmt.Errorf("failed to create session to discord because %w", err)
 	}
 
-	session.AddHandler(newMessageCreateHandler(b.logger))
+	session.AddHandler(b.expandMessageLink)
 	if err := session.Open(); err != nil {
 		return fmt.Errorf("failed to open session to discord because %w", err)
 	}
@@ -67,16 +70,121 @@ func (b *Bot) Stop() error {
 	if b.client == nil {
 		return errors.New("bot is not running")
 	}
-
-	defer b.purge()
 	if err := b.client.Close(); err != nil {
 		return fmt.Errorf("failed to close session to discord because %w", err)
 	}
 	b.logger.Info("bot is stopped")
 	return nil
 }
 
-// purge cleans up the bot instance.
-func (b *Bot) purge() {
-	b.client = nil
+func (b *Bot) expandMessageLink(s *discordgo.Session, m *discordgo.MessageCreate) {
+	// Ignore all messages created by the bot itself
+	if m.Author.Bot {
+		b.logger.Info("skip message because it was created by the bot itself")
+		return
+	}
+
+	// if the message contains message link, expand it
+	links := extractMessageLinks(m.Content)
+	if len(links) == 0 {
+		b.logger.Info("skip message because it does not contain message links")
+		return
+	}
+
+	var embeds []*discordgo.MessageEmbed
+
+	for _, link := range links {
+		info, err := extractMessageInfo(link)
+		if err != nil {
+			b.logger.Error("failed to extract message info", zap.Error(err))
+			continue
+		}
+
+		// if the guild is not the same as the message, ignore it
+		if info.guild != m.GuildID {
+			b.logger.Info("skip message because the guild is not the same as the message")
+			continue
+		}
+
+		// if the channel is nsfw, ignore it
+		citationChannel, err := s.Channel(info.channel)
+		if err != nil {
+			b.logger.Error("failed to get channel", zap.Error(err))
+			continue
+		}
+		if citationChannel.NSFW {
+			b.logger.Info("skip message because the channel is nsfw")
+			continue
+		}
+
+		// get the message
+		citationMsg, err := s.ChannelMessage(info.channel, info.message)
+		if err != nil {
+			b.logger.Error("failed to get message", zap.Error(err))
+			continue
+		}
+
+		// if the message has attachment(image), use it as the thumbnail of the embed
+		var image *discordgo.MessageEmbedImage
+		if len(citationMsg.Attachments) > 0 {
+			image = &discordgo.MessageEmbedImage{
+				URL: citationMsg.Attachments[0].URL,
+			}
+		}
+
+		embed := &discordgo.MessageEmbed{
+			Image: image,
+			Author: &discordgo.MessageEmbedAuthor{
+				Name:    citationMsg.Author.Username,
+				IconURL: citationMsg.Author.AvatarURL("64"),
+			},
+			Color:       0x7fffff,
+			Description: citationMsg.Content,
+			Timestamp:   citationMsg.Timestamp.Format(time.RFC3339),
+			Footer: &discordgo.MessageEmbedFooter{
+				Text: citationChannel.Name,
+			},
+		}
+
+		embeds = append(embeds, embed)
+		b.logger.Debug("expanded message", zap.Any("embed", embed))
+	}
+	// expand the message
+	replyMsg := discordgo.MessageSend{
+		Embeds:    embeds,
+		Reference: m.Reference(),
+		AllowedMentions: &discordgo.MessageAllowedMentions{
+			RepliedUser: true,
+		},
+	}
+	if _, err := s.ChannelMessageSendComplex(m.ChannelID, &replyMsg); err != nil {
+		b.logger.Error("failed to send message", zap.Error(err))
+		return
+	}
+	b.logger.Info("expanded message", zap.String("channel", m.ChannelID), zap.String("message", m.ID))
+}
+
+var rgx = regexp.MustCompile(`https://(?:ptb\.|canary\.)?discord(app)?\.com/channels/(\d+)/(\d+)/(\d+)`)
+
+func extractMessageLinks(s string) []string {
+	return rgx.FindAllString(s, -1)
+}
+
+type message struct {
+	guild   string
+	channel string
+	message string
+}
+
+// extractMessageInfo extracts the channel ID and message ID from the message link.
+func extractMessageInfo(link string) (info message, err error) {
+	segments := strings.Split(link, "/")
+	if len(segments) < 4 {
+		return message{}, errors.New("invalid message link")
+	}
+	return message{
+		guild:   segments[len(segments)-3],
+		channel: segments[len(segments)-2],
+		message: segments[len(segments)-1],
+	}, nil
 }

main.go

@@ -6,7 +6,6 @@ import (
 	"os"
 	"os/signal"
 
-	"github.com/aqyuki/expand-bot/config"
 	"github.com/aqyuki/expand-bot/discord"
 	"github.com/aqyuki/expand-bot/logging"
 )
@@ -29,9 +28,7 @@ func main() {
 
 func run(ctx context.Context) exitCode {
 	logger := logging.DefaultLogger()
-
-	store := config.NewStore()
-	bot := discord.NewBot(store.DiscordConfig(), discord.WithLogger(logger))
+	bot := discord.NewBot(loadTokenFromEnv(), discord.WithLogger(logger))
 
 	if err := bot.Start(); err != nil {
 		logger.Errorf("failed to start the bot\n\t%v\n", err)
@@ -51,3 +48,7 @@ func run(ctx context.Context) exitCode {
 func exit[T ~int](code T) {
 	os.Exit(int(code))
 }
+
+func loadTokenFromEnv() string {
+	return os.Getenv("DISCORD_TOKEN")
+}