Add option for autojoining threads when opened

thread.go

@@ -1,6 +1,10 @@
 package main
 
 import (
+	"sync"
+	"time"
+
+	"github.com/bwmarrin/discordgo"
 	"maunium.net/go/mautrix/id"
 
 	"go.mau.fi/mautrix-discord/database"
@@ -9,6 +13,8 @@ import (
 type Thread struct {
 	*database.Thread
 	Parent *Portal
+
+	creationNoticeLock sync.Mutex
 }
 
 func (br *DiscordBridge) GetThreadByID(id string, root *database.Message) *Thread {
@@ -31,6 +37,19 @@ func (br *DiscordBridge) GetThreadByRootMXID(mxid id.EventID) *Thread {
 	return thread
 }
 
+func (br *DiscordBridge) GetThreadByRootOrCreationNoticeMXID(mxid id.EventID) *Thread {
+	br.threadsLock.Lock()
+	defer br.threadsLock.Unlock()
+	thread, ok := br.threadsByRootMXID[mxid]
+	if !ok {
+		thread, ok = br.threadsByCreationNoticeMXID[mxid]
+		if !ok {
+			return br.loadThread(br.DB.Thread.GetByMatrixRootOrCreationNoticeMsg(mxid), "", nil)
+		}
+	}
+	return thread
+}
+
 func (br *DiscordBridge) loadThread(dbThread *database.Thread, id string, root *database.Message) *Thread {
 	if dbThread == nil {
 		if root == nil {
@@ -49,5 +68,25 @@ func (br *DiscordBridge) loadThread(dbThread *database.Thread, id string, root *
 	thread.Parent = br.GetExistingPortalByID(database.NewPortalKey(thread.ParentID, ""))
 	br.threadsByID[thread.ID] = thread
 	br.threadsByRootMXID[thread.RootMXID] = thread
+	if thread.CreationNoticeMXID != "" {
+		br.threadsByCreationNoticeMXID[thread.CreationNoticeMXID] = thread
+	}
 	return thread
 }
+
+func (thread *Thread) Join(user *User) {
+	if user.IsInPortal(thread.ID) {
+		return
+	}
+	user.log.Debugfln("Joining thread %s@%s", thread.ID, thread.ParentID)
+	err := user.Session.ThreadJoinWithLocation(thread.ID, discordgo.ThreadJoinLocationContextMenu)
+	if err != nil {
+		user.log.Errorfln("Error joining thread %s@%s: %v", thread.ID, thread.ParentID, err)
+	} else {
+		user.MarkInPortal(database.UserPortal{
+			DiscordID: thread.ID,
+			Type:      database.UserPortalTypeThread,
+			Timestamp: time.Now(),
+		})
+	}
+}