discord: blocks DM channel after sending error

discord/dm.go

@@ -2,7 +2,6 @@ package discord
 
 import (
 	"errors"
-	"fmt"
 	"time"
 
 	"github.com/getsentry/raven-go"
@@ -14,17 +13,20 @@ var (
 	dmChannelExpiryError      = time.Hour * 1
 )
 
+func dmChannelKey(session *Session, userID string) string {
+	return "cacophony:discord:dm-channel:" + session.BotID + ":" + userID
+}
+
 func DMChannel(
 	redisClient *redis.Client,
 	session *Session,
 	userID string,
 ) (string, error) {
-
 	if redisClient == nil {
 		return "", errors.New("sending DMs requires redis")
 	}
 
-	key := "cacophony:discord:dm-channel:" + session.BotID + ":" + userID
+	key := dmChannelKey(session, userID)
 
 	res, err := redisClient.Get(key).Result()
 	if err != nil && err != redis.Nil {
@@ -39,18 +41,30 @@ func DMChannel(
 
 	channel, err := session.Client.UserChannelCreate(userID)
 	if err != nil {
-		fmt.Printf("setting %s to empty\n", key) // TODO: remove me
 		if err := redisClient.Set(key, "", dmChannelExpiryError).Err(); err != nil && raven.DefaultClient != nil {
 			raven.CaptureError(err, map[string]string{"key": key})
 		}
 
 		return "", err
 	}
 
-	fmt.Printf("setting %s to %s\n", key, channel.ID) // TODO: remove me
 	if err := redisClient.Set(key, channel.ID, dmChannelExpirySuccessful).Err(); err != nil && raven.DefaultClient != nil {
 		raven.CaptureError(err, map[string]string{"key": key})
 	}
 
 	return channel.ID, nil
 }
+
+func BlockDMChannel(redisClient *redis.Client, session *Session, userID string) error {
+	if redisClient == nil {
+		return errors.New("requires redis")
+	}
+
+	key := dmChannelKey(session, userID)
+
+	if err := redisClient.Set(key, "", dmChannelExpiryError).Err(); err != nil && raven.DefaultClient != nil {
+		raven.CaptureError(err, map[string]string{"key": key})
+	}
+
+	return nil
+}

events/event_discord.go

@@ -1,6 +1,8 @@
 package events
 
 import (
+	builtinErrors "errors"
+
 	"github.com/bwmarrin/discordgo"
 	"github.com/pkg/errors"
 	"gitlab.com/Cacophony/go-kit/discord"
@@ -55,12 +57,7 @@ func (e *Event) Send(channelID, message string, values ...interface{}) ([]*disco
 }
 
 func (e *Event) SendDM(userID, message string, values ...interface{}) ([]*discordgo.Message, error) {
-	channelID, err := discord.DMChannel(e.Redis(), e.Discord(), userID)
-	if err != nil {
-		return nil, err
-	}
-
-	return e.Send(channelID, message, values...)
+	return e.SendComplexDM(userID, &discordgo.MessageSend{Content: message}, values...)
 }
 
 // SendComplex sends a message to the given channel, translates it if possible
@@ -81,7 +78,17 @@ func (e *Event) SendComplexDM(userID string, message *discordgo.MessageSend, val
 		return nil, err
 	}
 
-	return e.SendComplex(channelID, message, values...)
+	messages, err := e.SendComplex(channelID, message, values...)
+	if err != nil {
+		var discordError *discordgo.RESTError
+		if builtinErrors.As(err, &discordError) &&
+			discordError.Message != nil &&
+			discordError.Message.Code == discordgo.ErrCodeCannotSendMessagesToThisUser {
+			discord.BlockDMChannel(e.Redis(), e.Discord(), userID)
+		}
+	}
+
+	return messages, err
 }
 
 // Typing starts typing in the event channel