Handle group DMs (channels) (#360)

discord/channel.go

@@ -185,6 +185,11 @@ func (u *UnmarshalChannel) UnmarshalJSON(data []byte) error {
 		err = json.Unmarshal(data, &v)
 		channel = v
 
+	case ChannelTypeGroupDM:
+		var v GroupDMChannel
+		err = json.Unmarshal(data, &v)
+		channel = v
+
 	case ChannelTypeGuildCategory:
 		var v GuildCategoryChannel
 		err = json.Unmarshal(data, &v)
@@ -423,6 +428,91 @@ func (c DMChannel) CreatedAt() time.Time {
 func (DMChannel) channel()        {}
 func (DMChannel) messageChannel() {}
 
+var (
+	_ Channel        = (*GroupDMChannel)(nil)
+	_ MessageChannel = (*GroupDMChannel)(nil)
+)
+
+type GroupDMChannel struct {
+	id               snowflake.ID
+	ownerID          *snowflake.ID
+	name             string
+	lastPinTimestamp *time.Time
+	lastMessageID    *snowflake.ID
+	icon             *string
+}
+
+func (c *GroupDMChannel) UnmarshalJSON(data []byte) error {
+	var v groupDMChannel
+	if err := json.Unmarshal(data, &v); err != nil {
+		return err
+	}
+
+	c.id = v.ID
+	c.ownerID = v.OwnerID
+	c.name = v.Name
+	c.lastPinTimestamp = v.LastPinTimestamp
+	c.lastMessageID = v.LastMessageID
+	c.icon = v.Icon
+	return nil
+}
+
+func (c GroupDMChannel) MarshalJSON() ([]byte, error) {
+	return json.Marshal(groupDMChannel{
+		ID:               c.id,
+		Type:             c.Type(),
+		OwnerID:          c.ownerID,
+		Name:             c.name,
+		LastPinTimestamp: c.lastPinTimestamp,
+		LastMessageID:    c.lastMessageID,
+		Icon:             c.icon,
+	})
+}
+
+func (c GroupDMChannel) String() string {
+	return channelString(c)
+}
+
+func (c GroupDMChannel) ID() snowflake.ID {
+	return c.id
+}
+
+func (GroupDMChannel) Type() ChannelType {
+	return ChannelTypeGroupDM
+}
+
+func (c GroupDMChannel) OwnerID() *snowflake.ID {
+	return c.ownerID
+}
+
+func (c GroupDMChannel) Name() string {
+	return c.name
+}
+
+func (c GroupDMChannel) LastPinTimestamp() *time.Time {
+	return c.lastPinTimestamp
+}
+
+func (c GroupDMChannel) LastMessageID() *snowflake.ID {
+	return c.lastMessageID
+}
+
+func (c GroupDMChannel) CreatedAt() time.Time {
+	return c.id.Time()
+}
+
+// IconURL returns the icon URL of this group DM or nil if not set
+func (c GroupDMChannel) IconURL(opts ...CDNOpt) *string {
+	if c.icon == nil {
+		return nil
+	}
+	url := formatAssetURL(ChannelIcon, opts, c.id, *c.icon)
+	return &url
+}
+
+func (GroupDMChannel) channel()        {}
+func (GroupDMChannel) messageChannel() {}
+
 var (
 	_ Channel             = (*GuildVoiceChannel)(nil)
 	_ GuildChannel        = (*GuildVoiceChannel)(nil)

discord/channels_raw.go

@@ -15,6 +15,16 @@ type dmChannel struct {
 	LastPinTimestamp *time.Time    `json:"last_pin_timestamp"`
 }
 
+type groupDMChannel struct {
+	ID               snowflake.ID  `json:"id"`
+	Type             ChannelType   `json:"type"`
+	OwnerID          *snowflake.ID `json:"owner_id"`
+	Name             string        `json:"name"`
+	LastPinTimestamp *time.Time    `json:"last_pin_timestamp"`
+	LastMessageID    *snowflake.ID `json:"last_message_id"`
+	Icon             *string       `json:"icon"`
+}
+
 type guildTextChannel struct {
 	ID                         snowflake.ID          `json:"id"`
 	Type                       ChannelType           `json:"type"`