connector: sync guild spaces via event instead of manually

pkg/connector/events_chat_resync.go

@@ -0,0 +1,179 @@
+// mautrix-discord - A Matrix-Discord puppeting bridge.
+// Copyright (C) 2026 Tulir Asokan
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package connector
+
+import (
+	"context"
+
+	"github.com/bwmarrin/discordgo"
+	"github.com/rs/zerolog"
+	"go.mau.fi/util/ptr"
+	"maunium.net/go/mautrix/bridgev2"
+	"maunium.net/go/mautrix/bridgev2/database"
+	"maunium.net/go/mautrix/bridgev2/networkid"
+
+	"go.mau.fi/mautrix-discord/pkg/discordid"
+)
+
+type DiscordChatResync struct {
+	Client    *DiscordClient
+	channel   *discordgo.Channel
+	portalKey networkid.PortalKey
+}
+
+var (
+	_ bridgev2.RemoteChatResyncWithInfo       = (*DiscordChatResync)(nil)
+	_ bridgev2.RemoteChatResyncBackfill       = (*DiscordChatResync)(nil)
+	_ bridgev2.RemoteEventThatMayCreatePortal = (*DiscordChatResync)(nil)
+)
+
+func (d *DiscordChatResync) AddLogContext(c zerolog.Context) zerolog.Context {
+	c = c.Str("channel_id", d.channel.ID).Int("channel_type", int(d.channel.Type))
+	return c
+}
+
+func (d *DiscordChatResync) GetPortalKey() networkid.PortalKey {
+	return d.portalKey
+}
+
+func (d *DiscordChatResync) GetSender() bridgev2.EventSender {
+	return bridgev2.EventSender{}
+}
+
+func (d *DiscordChatResync) GetType() bridgev2.RemoteEventType {
+	return bridgev2.RemoteEventChatResync
+}
+
+func (d *DiscordChatResync) avatar(ctx context.Context) *bridgev2.Avatar {
+	ch := d.channel
+
+	// TODO make this configurable (ala workspace_avatar_in_rooms)
+	if !d.isPrivate() {
+		guild, err := d.Client.Session.State.Guild(ch.GuildID)
+
+		if err != nil || guild == nil {
+			zerolog.Ctx(ctx).Err(err).Msg("Couldn't look up guild in cache in order to create room avatar")
+			return nil
+		}
+
+		return d.Client.makeAvatarForGuild(guild)
+	}
+
+	return &bridgev2.Avatar{
+		ID: discordid.MakeAvatarID(ch.Icon),
+		Get: func(ctx context.Context) ([]byte, error) {
+			url := discordgo.EndpointGroupIcon(ch.ID, ch.Icon)
+			return d.Client.simpleDownload(ctx, url, "group dm icon")
+		},
+		Remove: ch.Icon == "",
+	}
+}
+
+func (d *DiscordChatResync) privateChannelMemberList() bridgev2.ChatMemberList {
+	ch := d.channel
+
+	var members bridgev2.ChatMemberList
+	members.IsFull = true
+	members.MemberMap = make(bridgev2.ChatMemberMap, len(ch.Recipients))
+	if len(ch.Recipients) > 0 {
+		selfEventSender := d.Client.selfEventSender()
+
+		// Private channels' array of participants doesn't include ourselves,
+		// so inject ourselves as a member.
+		members.MemberMap[selfEventSender.Sender] = bridgev2.ChatMember{EventSender: selfEventSender}
+
+		for _, recipient := range ch.Recipients {
+			sender := d.Client.makeEventSender(recipient)
+			members.MemberMap[sender.Sender] = bridgev2.ChatMember{EventSender: sender}
+		}
+
+		members.TotalMemberCount = len(ch.Recipients)
+	}
+
+	return members
+}
+
+func (d *DiscordChatResync) memberList() bridgev2.ChatMemberList {
+	if d.isPrivate() {
+		return d.privateChannelMemberList()
+	}
+
+	// TODO we're _always_ sending partial member lists for guilds; we can probably
+	// do better
+	selfEventSender := d.Client.selfEventSender()
+
+	return bridgev2.ChatMemberList{
+		IsFull: false,
+		MemberMap: map[networkid.UserID]bridgev2.ChatMember{
+			selfEventSender.Sender: {EventSender: selfEventSender},
+		},
+	}
+}
+
+func (d *DiscordChatResync) isPrivate() bool {
+	ch := d.channel
+	return ch.Type == discordgo.ChannelTypeDM || ch.Type == discordgo.ChannelTypeGroupDM
+}
+
+func (d *DiscordChatResync) GetChatInfo(ctx context.Context, portal *bridgev2.Portal) (*bridgev2.ChatInfo, error) {
+	ch := d.channel
+
+	var roomType database.RoomType
+
+	switch ch.Type {
+	case discordgo.ChannelTypeDM:
+		roomType = database.RoomTypeDM
+	case discordgo.ChannelTypeGroupDM:
+		roomType = database.RoomTypeGroupDM
+	}
+
+	info := &bridgev2.ChatInfo{
+		Name:        &ch.Name,
+		Members:     ptr.Ptr(d.memberList()),
+		Avatar:      d.avatar(ctx),
+		Type:        &roomType,
+		CanBackfill: true,
+		ExtraUpdates: func(ctx context.Context, portal *bridgev2.Portal) (changed bool) {
+			meta := portal.Metadata.(*discordid.PortalMetadata)
+			if meta.GuildID != ch.GuildID {
+				meta.GuildID = ch.GuildID
+				changed = true
+			}
+
+			return
+		},
+	}
+
+	if !d.isPrivate() {
+		// Channel belongs to a guild; associate it with the respective space.
+		info.ParentID = ptr.Ptr(d.Client.guildPortalKeyFromID(ch.GuildID).ID)
+	}
+
+	return info, nil
+}
+
+func (d *DiscordChatResync) ShouldCreatePortal() bool {
+	return true
+}
+
+func (d *DiscordChatResync) CheckNeedsBackfill(ctx context.Context, latestBridged *database.Message) (bool, error) {
+	if latestBridged == nil {
+		zerolog.Ctx(ctx).Debug().Str("channel_id", d.channel.ID).Msg("Haven't bridged any messages at all, not forward backfilling")
+		return false, nil
+	}
+	return latestBridged.ID < discordid.MakeMessageID(d.channel.LastMessageID), nil
+}