Add welcome handler

Signed-off-by: jolheiser <john.olheiser@gmail.com>

discord/discord.go

@@ -2,6 +2,7 @@ package discord
 
 import (
 	"fmt"
+	"os"
 	"strings"
 	"time"
 
@@ -100,6 +101,7 @@ func Bot(cfg *config.Config, db *database.Database) (*discordgo.Session, error)
 	}
 
 	bot.AddHandler(readyHandler())
+	bot.AddHandler(joinHandler(cfg))
 	bot.AddHandler(leaveHandler(cfg))
 	bot.AddHandler(commandHandler(cfg, db, sapi, twitterClient))
 	bot.AddHandler(messageHandler(cfg, db))
@@ -294,3 +296,32 @@ func updateStatus(s *discordgo.Session) {
 		<-ticker.C
 	}
 }
+
+func joinHandler(cfg *config.Config) func(s *discordgo.Session, m *discordgo.GuildMemberAdd) {
+	return func(s *discordgo.Session, m *discordgo.GuildMemberAdd) {
+		sendMessage(s, cfg.Welcome.Channel, os.Expand(cfg.Welcome.Message, func(s string) string {
+			switch strings.ToLower(s) {
+			case "user":
+				return m.Mention()
+			default:
+				return s
+			}
+		}), false)
+
+		if cfg.Welcome.DM != "" {
+			dm, err := s.UserChannelCreate(m.User.ID)
+			if err != nil {
+				log.Err(err).Msgf("could not create DM with %s", m.User.Username)
+				return
+			}
+			sendMessage(s, dm.ID, os.Expand(cfg.Welcome.DM, func(s string) string {
+				switch strings.ToLower(s) {
+				case "user":
+					return m.Mention()
+				default:
+					return s
+				}
+			}), false)
+		}
+	}
+}