Add ability to procure avatars from the destination bridge (#1000)

* remote_avatar: add UseLocalAvatar

* remote_avatar: make sure msg.Protocol is always set correctly

* remote_avatars: support msg.Account

* remote_avatar: add to matterbridge.toml.sample

* remote_avatar: clarify something

2 files changed, 22 insertions, 0 deletions

diff --git a/bridge/config/config.go b/bridge/config/config.go
index 84e8f75f..2d20c11f 100644
--- a/bridge/config/config.go
+++ b/bridge/config/config.go
@@ -138,6 +138,7 @@ type Protocol struct {
 	Topic                  string     // zulip
 	URL                    string     // mattermost, slack // DEPRECATED
 	UseAPI                 bool       // mattermost, slack
+	UseLocalAvatar         []string   // discord
 	UseSASL                bool       // IRC
 	UseTLS                 bool       // IRC
 	UseDiscriminator       bool       // discord
diff --git a/bridge/discord/discord.go b/bridge/discord/discord.go
index e81d0783..e37208b7 100644
--- a/bridge/discord/discord.go
+++ b/bridge/discord/discord.go
@@ -381,6 +381,19 @@ func (b *Bdiscord) webhookSend(msg *config.Message, webhookID, token string) (*d
 		err error
 	)
 
+	// If avatar is unset, check if UseLocalAvatar contains the message's
+	// account or protocol, and if so, try to find a local avatar
+	if msg.Avatar == "" {
+		for _, val := range b.GetStringSlice("UseLocalAvatar") {
+			if msg.Protocol == val || msg.Account == val {
+				if avatar := b.findAvatar(msg); avatar != "" {
+					msg.Avatar = avatar
+				}
+				break
+			}
+		}
+	}
+
 	// WebhookParams can have either `Content` or `File`.
 
 	// We can't send empty messages.
@@ -430,3 +443,11 @@ func (b *Bdiscord) webhookSend(msg *config.Message, webhookID, token string) (*d
 	}
 	return res, err
 }
+
+func (b *Bdiscord) findAvatar(m *config.Message) string {
+	member, err := b.getGuildMemberByNick(m.Username)
+	if err != nil {
+		return ""
+	}
+	return member.User.AvatarURL("")
+}