Refactor message handling to fully use convert pattern

portal.go

@@ -3,7 +3,6 @@ package main
 import (
 	"errors"
 	"fmt"
-	"html"
 	"reflect"
 	"strconv"
 	"strings"
@@ -22,7 +21,6 @@ import (
 	"maunium.net/go/mautrix/bridge/status"
 	"maunium.net/go/mautrix/crypto/attachment"
 	"maunium.net/go/mautrix/event"
-	"maunium.net/go/mautrix/format"
 	"maunium.net/go/mautrix/id"
 	"maunium.net/go/mautrix/util"
 	"maunium.net/go/mautrix/util/variationselector"
@@ -536,517 +534,7 @@ func (portal *Portal) markMessageHandled(discordID string, editIndex int, author
 	msg.MassInsert(parts)
 }
 
-func (portal *Portal) createMediaFailedMessage(bridgeErr error) *event.MessageEventContent {
-	return &event.MessageEventContent{
-		Body:    fmt.Sprintf("Failed to bridge media: %v", bridgeErr),
-		MsgType: event.MsgNotice,
-	}
-}
-
-func (portal *Portal) sendMediaFailedMessage(intent *appservice.IntentAPI, bridgeErr error) id.EventID {
-	resp, err := portal.sendMatrixMessage(intent, event.EventMessage, portal.createMediaFailedMessage(bridgeErr), nil, 0)
-	if err != nil {
-		portal.log.Warnfln("Failed to send media error message to matrix: %v", err)
-		return ""
-	}
-	return resp.EventID
-}
-
-const DiscordStickerSize = 160
-
-func (portal *Portal) handleDiscordFile(typeName string, intent *appservice.IntentAPI, id, url string, content *event.MessageEventContent, ts time.Time, threadRelation *event.RelatesTo) *database.MessagePart {
-	meta := AttachmentMeta{AttachmentID: id, MimeType: content.Info.MimeType}
-	if typeName == "sticker" && content.Info.MimeType == "application/json" {
-		meta.Converter = portal.bridge.convertLottie
-	}
-	dbFile, err := portal.bridge.copyAttachmentToMatrix(intent, url, portal.Encrypted, meta)
-	if err != nil {
-		errorEventID := portal.sendMediaFailedMessage(intent, err)
-		if errorEventID != "" {
-			return &database.MessagePart{
-				AttachmentID: id,
-				MXID:         errorEventID,
-			}
-		}
-		return nil
-	}
-	if typeName == "sticker" && content.Info.MimeType == "application/json" {
-		content.Info.MimeType = dbFile.MimeType
-	}
-	content.Info.Size = dbFile.Size
-	if content.Info.Width == 0 && content.Info.Height == 0 {
-		content.Info.Width = dbFile.Width
-		content.Info.Height = dbFile.Height
-	}
-	if content.Info.Width == 0 && content.Info.Height == 0 && typeName == "sticker" {
-		content.Info.Width = DiscordStickerSize
-		content.Info.Height = DiscordStickerSize
-	}
-	if dbFile.DecryptionInfo != nil {
-		content.File = &event.EncryptedFileInfo{
-			EncryptedFile: *dbFile.DecryptionInfo,
-			URL:           dbFile.MXC.CUString(),
-		}
-	} else {
-		content.URL = dbFile.MXC.CUString()
-	}
-
-	evtType := event.EventMessage
-	if typeName == "sticker" && (content.Info.Width > DiscordStickerSize || content.Info.Height > DiscordStickerSize) {
-		if content.Info.Width > content.Info.Height {
-			content.Info.Height /= content.Info.Width / DiscordStickerSize
-			content.Info.Width = DiscordStickerSize
-		} else if content.Info.Width < content.Info.Height {
-			content.Info.Width /= content.Info.Height / DiscordStickerSize
-			content.Info.Height = DiscordStickerSize
-		} else {
-			content.Info.Width = DiscordStickerSize
-			content.Info.Height = DiscordStickerSize
-		}
-		evtType = event.EventSticker
-	} else if typeName == "sticker" {
-		evtType = event.EventSticker
-	}
-
-	resp, err := portal.sendMatrixMessage(intent, evtType, content, nil, ts.UnixMilli())
-	if err != nil {
-		portal.log.Warnfln("Failed to send %s to Matrix: %v", typeName, err)
-		return nil
-	}
-	// Update the fallback reply event for the next attachment
-	if threadRelation != nil {
-		threadRelation.InReplyTo.EventID = resp.EventID
-	}
-	return &database.MessagePart{
-		AttachmentID: id,
-		MXID:         resp.EventID,
-	}
-}
-
-func (portal *Portal) handleDiscordSticker(intent *appservice.IntentAPI, sticker *discordgo.Sticker, ts time.Time, threadRelation *event.RelatesTo) *database.MessagePart {
-	var mime string
-	switch sticker.FormatType {
-	case discordgo.StickerFormatTypePNG:
-		mime = "image/png"
-	case discordgo.StickerFormatTypeAPNG:
-		mime = "image/apng"
-	case discordgo.StickerFormatTypeLottie:
-		mime = "application/json"
-	case discordgo.StickerFormatTypeGIF:
-		mime = "image/gif"
-	default:
-		portal.log.Warnfln("Unknown sticker format %d in %s", sticker.FormatType, sticker.ID)
-	}
-	content := &event.MessageEventContent{
-		Body: sticker.Name, // TODO find description from somewhere?
-		Info: &event.FileInfo{
-			MimeType: mime,
-		},
-		RelatesTo: threadRelation,
-	}
-	return portal.handleDiscordFile("sticker", intent, sticker.ID, sticker.URL(), content, ts, threadRelation)
-}
-
-func (portal *Portal) handleDiscordAttachment(intent *appservice.IntentAPI, att *discordgo.MessageAttachment, ts time.Time, threadRelation *event.RelatesTo) *database.MessagePart {
-	// var captionContent *event.MessageEventContent
-
-	// if att.Description != "" {
-	// 	captionContent = &event.MessageEventContent{
-	// 		Body:    att.Description,
-	// 		MsgType: event.MsgNotice,
-	// 	}
-	// }
-	// portal.Log.Debugfln("captionContent: %#v", captionContent)
-
-	content := &event.MessageEventContent{
-		Body: att.Filename,
-		Info: &event.FileInfo{
-			Height:   att.Height,
-			MimeType: att.ContentType,
-			Width:    att.Width,
-
-			// This gets overwritten later after the file is uploaded to the homeserver
-			Size: att.Size,
-		},
-		RelatesTo: threadRelation,
-	}
-
-	switch strings.ToLower(strings.Split(att.ContentType, "/")[0]) {
-	case "audio":
-		content.MsgType = event.MsgAudio
-	case "image":
-		content.MsgType = event.MsgImage
-	case "video":
-		content.MsgType = event.MsgVideo
-	default:
-		content.MsgType = event.MsgFile
-	}
-	return portal.handleDiscordFile("attachment", intent, att.ID, att.URL, content, ts, threadRelation)
-}
-
-type ConvertedMessage struct {
-	Content *event.MessageEventContent
-	Extra   map[string]any
-}
-
-func (portal *Portal) convertDiscordVideoEmbed(intent *appservice.IntentAPI, embed *discordgo.MessageEmbed) *ConvertedMessage {
-	dbFile, err := portal.bridge.copyAttachmentToMatrix(intent, embed.Video.ProxyURL, portal.Encrypted, NoMeta)
-	if err != nil {
-		return &ConvertedMessage{Content: portal.createMediaFailedMessage(err)}
-	}
-
-	content := &event.MessageEventContent{
-		MsgType: event.MsgVideo,
-		Body:    embed.URL,
-		Info: &event.FileInfo{
-			Width:    embed.Video.Width,
-			Height:   embed.Video.Height,
-			MimeType: dbFile.MimeType,
-
-			Size: dbFile.Size,
-		},
-	}
-	if content.Info.Width == 0 && content.Info.Height == 0 {
-		content.Info.Width = dbFile.Width
-		content.Info.Height = dbFile.Height
-	}
-	if dbFile.DecryptionInfo != nil {
-		content.File = &event.EncryptedFileInfo{
-			EncryptedFile: *dbFile.DecryptionInfo,
-			URL:           dbFile.MXC.CUString(),
-		}
-	} else {
-		content.URL = dbFile.MXC.CUString()
-	}
-	extra := map[string]any{}
-	if embed.Type == discordgo.EmbedTypeGifv {
-		extra["info"] = map[string]any{
-			"fi.mau.discord.gifv":  true,
-			"fi.mau.loop":          true,
-			"fi.mau.autoplay":      true,
-			"fi.mau.hide_controls": true,
-			"fi.mau.no_audio":      true,
-		}
-	}
-	return &ConvertedMessage{Content: content, Extra: extra}
-}
-
-func (portal *Portal) handleDiscordVideoEmbed(intent *appservice.IntentAPI, embed *discordgo.MessageEmbed, msgID string, index int, ts time.Time, threadRelation *event.RelatesTo) *database.MessagePart {
-	content := portal.convertDiscordVideoEmbed(intent, embed)
-	content.Content.RelatesTo = threadRelation
-
-	resp, err := portal.sendMatrixMessage(intent, event.EventMessage, content.Content, content.Extra, ts.UnixMilli())
-	if err != nil {
-		portal.log.Warnfln("Failed to send embed #%d of message %s to Matrix: %v", index+1, msgID, err)
-		return nil
-	}
-
-	// Update the fallback reply event for the next attachment
-	if threadRelation != nil {
-		threadRelation.InReplyTo.EventID = resp.EventID
-	}
-
-	return &database.MessagePart{
-		AttachmentID: fmt.Sprintf("video_%s", embed.URL),
-		MXID:         resp.EventID,
-	}
-}
-
-const (
-	embedHTMLWrapper         = `<blockquote class="discord-embed">%s</blockquote>`
-	embedHTMLWrapperColor    = `<blockquote class="discord-embed" background-color="#%06X">%s</blockquote>`
-	embedHTMLAuthorWithImage = `<p class="discord-embed-author"><img data-mx-emoticon height="24" src="%s" title="Author icon" alt="">&nbsp;<span>%s</span></p>`
-	embedHTMLAuthorPlain     = `<p class="discord-embed-author"><span>%s</span></p>`
-	embedHTMLAuthorLink      = `<a href="%s">%s</a>`
-	embedHTMLTitleWithLink   = `<p class="discord-embed-title"><a href="%s"><strong>%s</strong></a></p>`
-	embedHTMLTitlePlain      = `<p class="discord-embed-title"><strong>%s</strong></p>`
-	embedHTMLDescription     = `<p class="discord-embed-description">%s</p>`
-	embedHTMLFieldName       = `<th>%s</th>`
-	embedHTMLFieldValue      = `<td>%s</td>`
-	embedHTMLFields          = `<table class="discord-embed-fields"><tr>%s</tr><tr>%s</tr></table>`
-	embedHTMLLinearField     = `<p class="discord-embed-field" x-inline="%s"><strong>%s</strong><br><span>%s</span></p>`
-	embedHTMLImage           = `<p class="discord-embed-image"><img src="%s" alt="" title="Embed image"></p>`
-	embedHTMLFooterWithImage = `<p class="discord-embed-footer"><sub><img data-mx-emoticon height="20" src="%s" title="Footer icon" alt="">&nbsp;<span>%s</span>%s</sub></p>`
-	embedHTMLFooterPlain     = `<p class="discord-embed-footer"><sub><span>%s</span>%s</sub></p>`
-	embedHTMLFooterOnlyDate  = `<p class="discord-embed-footer"><sub>%s</sub></p>`
-	embedHTMLDate            = `<time datetime="%s">%s</time>`
-	embedFooterDateSeparator = ` • `
-)
-
-func (portal *Portal) convertDiscordRichEmbed(intent *appservice.IntentAPI, embed *discordgo.MessageEmbed, msgID string, index int) string {
-	var htmlParts []string
-	if embed.Author != nil {
-		var authorHTML string
-		authorNameHTML := html.EscapeString(embed.Author.Name)
-		if embed.Author.URL != "" {
-			authorNameHTML = fmt.Sprintf(embedHTMLAuthorLink, embed.Author.URL, authorNameHTML)
-		}
-		authorHTML = fmt.Sprintf(embedHTMLAuthorPlain, authorNameHTML)
-		if embed.Author.ProxyIconURL != "" {
-			dbFile, err := portal.bridge.copyAttachmentToMatrix(intent, embed.Author.ProxyIconURL, false, NoMeta)
-			if err != nil {
-				portal.log.Warnfln("Failed to reupload author icon in embed #%d of message %s: %v", index+1, msgID, err)
-			} else {
-				authorHTML = fmt.Sprintf(embedHTMLAuthorWithImage, dbFile.MXC, authorNameHTML)
-			}
-		}
-		htmlParts = append(htmlParts, authorHTML)
-	}
-	if embed.Title != "" {
-		var titleHTML string
-		baseTitleHTML := portal.renderDiscordMarkdownOnlyHTML(embed.Title, false)
-		if embed.URL != "" {
-			titleHTML = fmt.Sprintf(embedHTMLTitleWithLink, html.EscapeString(embed.URL), baseTitleHTML)
-		} else {
-			titleHTML = fmt.Sprintf(embedHTMLTitlePlain, baseTitleHTML)
-		}
-		htmlParts = append(htmlParts, titleHTML)
-	}
-	if embed.Description != "" {
-		htmlParts = append(htmlParts, fmt.Sprintf(embedHTMLDescription, portal.renderDiscordMarkdownOnlyHTML(embed.Description, true)))
-	}
-	for i := 0; i < len(embed.Fields); i++ {
-		item := embed.Fields[i]
-		if portal.bridge.Config.Bridge.EmbedFieldsAsTables {
-			splitItems := []*discordgo.MessageEmbedField{item}
-			if item.Inline && len(embed.Fields) > i+1 && embed.Fields[i+1].Inline {
-				splitItems = append(splitItems, embed.Fields[i+1])
-				i++
-				if len(embed.Fields) > i+1 && embed.Fields[i+1].Inline {
-					splitItems = append(splitItems, embed.Fields[i+1])
-					i++
-				}
-			}
-			headerParts := make([]string, len(splitItems))
-			contentParts := make([]string, len(splitItems))
-			for j, splitItem := range splitItems {
-				headerParts[j] = fmt.Sprintf(embedHTMLFieldName, portal.renderDiscordMarkdownOnlyHTML(splitItem.Name, false))
-				contentParts[j] = fmt.Sprintf(embedHTMLFieldValue, portal.renderDiscordMarkdownOnlyHTML(splitItem.Value, true))
-			}
-			htmlParts = append(htmlParts, fmt.Sprintf(embedHTMLFields, strings.Join(headerParts, ""), strings.Join(contentParts, "")))
-		} else {
-			htmlParts = append(htmlParts, fmt.Sprintf(embedHTMLLinearField,
-				strconv.FormatBool(item.Inline),
-				portal.renderDiscordMarkdownOnlyHTML(item.Name, false),
-				portal.renderDiscordMarkdownOnlyHTML(item.Value, true),
-			))
-		}
-	}
-	if embed.Image != nil {
-		dbFile, err := portal.bridge.copyAttachmentToMatrix(intent, embed.Image.ProxyURL, false, NoMeta)
-		if err != nil {
-			portal.log.Warnfln("Failed to reupload image in embed #%d of message %s: %v", index+1, msgID, err)
-		} else {
-			htmlParts = append(htmlParts, fmt.Sprintf(embedHTMLImage, dbFile.MXC))
-		}
-	}
-	var embedDateHTML string
-	if embed.Timestamp != "" {
-		formattedTime := embed.Timestamp
-		parsedTS, err := time.Parse(time.RFC3339, embed.Timestamp)
-		if err != nil {
-			portal.log.Warnfln("Failed to parse timestamp in embed #%d of message %s: %v", index+1, msgID, err)
-		} else {
-			formattedTime = parsedTS.Format(discordTimestampStyle('F').Format())
-		}
-		embedDateHTML = fmt.Sprintf(embedHTMLDate, embed.Timestamp, formattedTime)
-	}
-	if embed.Footer != nil {
-		var footerHTML string
-		var datePart string
-		if embedDateHTML != "" {
-			datePart = embedFooterDateSeparator + embedDateHTML
-		}
-		footerHTML = fmt.Sprintf(embedHTMLFooterPlain, html.EscapeString(embed.Footer.Text), datePart)
-		if embed.Footer.ProxyIconURL != "" {
-			dbFile, err := portal.bridge.copyAttachmentToMatrix(intent, embed.Footer.ProxyIconURL, false, NoMeta)
-			if err != nil {
-				portal.log.Warnfln("Failed to reupload footer icon in embed #%d of message %s: %v", index+1, msgID, err)
-			} else {
-				footerHTML = fmt.Sprintf(embedHTMLFooterWithImage, dbFile.MXC, html.EscapeString(embed.Footer.Text), datePart)
-			}
-		}
-		htmlParts = append(htmlParts, footerHTML)
-	} else if embed.Timestamp != "" {
-		htmlParts = append(htmlParts, fmt.Sprintf(embedHTMLFooterOnlyDate, embedDateHTML))
-	}
-
-	if len(htmlParts) == 0 {
-		return ""
-	}
-
-	compiledHTML := strings.Join(htmlParts, "")
-	if embed.Color != 0 {
-		compiledHTML = fmt.Sprintf(embedHTMLWrapperColor, embed.Color, compiledHTML)
-	} else {
-		compiledHTML = fmt.Sprintf(embedHTMLWrapper, compiledHTML)
-	}
-	return compiledHTML
-}
-
-type BeeperLinkPreview struct {
-	mautrix.RespPreviewURL
-	MatchedURL      string                   `json:"matched_url"`
-	ImageEncryption *event.EncryptedFileInfo `json:"beeper:image:encryption,omitempty"`
-}
-
-func (portal *Portal) convertDiscordLinkEmbedImage(intent *appservice.IntentAPI, url string, width, height int, preview *BeeperLinkPreview) {
-	dbFile, err := portal.bridge.copyAttachmentToMatrix(intent, url, portal.Encrypted, NoMeta)
-	if err != nil {
-		portal.log.Warnfln("Failed to copy image in URL preview: %v", err)
-	} else {
-		if width != 0 || height != 0 {
-			preview.ImageWidth = width
-			preview.ImageHeight = height
-		} else {
-			preview.ImageWidth = dbFile.Width
-			preview.ImageHeight = dbFile.Height
-		}
-		preview.ImageSize = dbFile.Size
-		preview.ImageType = dbFile.MimeType
-		if dbFile.Encrypted {
-			preview.ImageEncryption = &event.EncryptedFileInfo{
-				EncryptedFile: *dbFile.DecryptionInfo,
-				URL:           dbFile.MXC.CUString(),
-			}
-		} else {
-			preview.ImageURL = dbFile.MXC.CUString()
-		}
-	}
-}
-
-func (portal *Portal) convertDiscordLinkEmbedToBeeper(intent *appservice.IntentAPI, embed *discordgo.MessageEmbed) *BeeperLinkPreview {
-	var preview BeeperLinkPreview
-	preview.MatchedURL = embed.URL
-	preview.Title = embed.Title
-	preview.Description = embed.Description
-	if embed.Image != nil {
-		portal.convertDiscordLinkEmbedImage(intent, embed.Image.ProxyURL, embed.Image.Width, embed.Image.Height, &preview)
-	} else if embed.Thumbnail != nil {
-		portal.convertDiscordLinkEmbedImage(intent, embed.Thumbnail.ProxyURL, embed.Thumbnail.Width, embed.Thumbnail.Height, &preview)
-	}
-	return &preview
-}
-
-const msgInteractionTemplateHTML = `<blockquote>
-<a href="https://matrix.to/#/%s">%s</a> used <font color="#3771bb">/%s</font>
-</blockquote>`
-
-const msgComponentTemplateHTML = `<p>This message contains interactive elements. Use the Discord app to interact with the message.</p>`
-
-type BridgeEmbedType int
-
-const (
-	EmbedUnknown BridgeEmbedType = iota
-	EmbedRich
-	EmbedLinkPreview
-	EmbedVideo
-)
-
-func isActuallyLinkPreview(embed *discordgo.MessageEmbed) bool {
-	// Sending YouTube links creates a video embed, but we want to bridge it as a URL preview,
-	// so this is a hacky way to detect those.
-	return embed.Video != nil && embed.Video.ProxyURL == ""
-}
-
-func getEmbedType(embed *discordgo.MessageEmbed) BridgeEmbedType {
-	switch embed.Type {
-	case discordgo.EmbedTypeLink, discordgo.EmbedTypeArticle:
-		return EmbedLinkPreview
-	case discordgo.EmbedTypeVideo:
-		if isActuallyLinkPreview(embed) {
-			return EmbedLinkPreview
-		}
-		return EmbedVideo
-	case discordgo.EmbedTypeGifv:
-		return EmbedVideo
-	case discordgo.EmbedTypeRich, discordgo.EmbedTypeImage:
-		return EmbedRich
-	default:
-		return EmbedUnknown
-	}
-}
-
-func (portal *Portal) convertDiscordTextMessage(intent *appservice.IntentAPI, msg *discordgo.Message, relation *event.RelatesTo, isEdit bool) *ConvertedMessage {
-	if msg.Type == discordgo.MessageTypeCall {
-		return &ConvertedMessage{Content: &event.MessageEventContent{
-			MsgType: event.MsgEmote,
-			Body:    "started a call",
-		}}
-	} else if msg.Type == discordgo.MessageTypeGuildMemberJoin {
-		return &ConvertedMessage{Content: &event.MessageEventContent{
-			MsgType: event.MsgEmote,
-			Body:    "joined the server",
-		}}
-	}
-	var htmlParts []string
-	if msg.Interaction != nil {
-		puppet := portal.bridge.GetPuppetByID(msg.Interaction.User.ID)
-		puppet.UpdateInfo(nil, msg.Interaction.User)
-		htmlParts = append(htmlParts, fmt.Sprintf(msgInteractionTemplateHTML, puppet.MXID, puppet.Name, msg.Interaction.Name))
-	}
-	if msg.Content != "" && !isPlainGifMessage(msg) {
-		htmlParts = append(htmlParts, portal.renderDiscordMarkdownOnlyHTML(msg.Content, false))
-	}
-	previews := make([]*BeeperLinkPreview, 0)
-	for i, embed := range msg.Embeds {
-		switch getEmbedType(embed) {
-		case EmbedRich:
-			htmlParts = append(htmlParts, portal.convertDiscordRichEmbed(intent, embed, msg.ID, i))
-		case EmbedLinkPreview:
-			previews = append(previews, portal.convertDiscordLinkEmbedToBeeper(intent, embed))
-		case EmbedVideo:
-			// Ignore video embeds, they're handled as separate messages
-		default:
-			portal.log.Warnfln("Unknown type %s in embed #%d of message %s", embed.Type, i+1, msg.ID)
-		}
-	}
-
-	if len(msg.Components) > 0 {
-		htmlParts = append(htmlParts, msgComponentTemplateHTML)
-	}
-
-	if len(htmlParts) == 0 {
-		return nil
-	}
-
-	fullHTML := strings.Join(htmlParts, "\n")
-	if !msg.MentionEveryone {
-		fullHTML = strings.ReplaceAll(fullHTML, "@room", "@\u2063ro\u2063om")
-	}
-
-	content := format.HTMLToContent(fullHTML)
-	if relation != nil {
-		content.RelatesTo = relation.Copy()
-	}
-	extraContent := map[string]any{
-		"com.beeper.linkpreviews": previews,
-	}
-
-	if msg.MessageReference != nil && !isEdit {
-		//key := database.PortalKey{msg.MessageReference.ChannelID, user.ID}
-		replyTo := portal.bridge.DB.Message.GetByDiscordID(portal.Key, msg.MessageReference.MessageID)
-		if len(replyTo) > 0 {
-			if content.RelatesTo == nil {
-				content.RelatesTo = &event.RelatesTo{}
-			}
-			content.RelatesTo.SetReplyTo(replyTo[0].MXID)
-		}
-	}
-
-	return &ConvertedMessage{Content: &content, Extra: extraContent}
-}
-
-func isPlainGifMessage(msg *discordgo.Message) bool {
-	return len(msg.Embeds) == 1 && msg.Embeds[0].Video != nil && msg.Embeds[0].URL == msg.Content && msg.Embeds[0].Type == discordgo.EmbedTypeGifv
-}
-
 func (portal *Portal) handleDiscordMessageCreate(user *User, msg *discordgo.Message, thread *Thread) {
-	if portal.MXID == "" {
-		portal.log.Warnln("handle message called without a valid portal")
-		return
-	}
-
 	switch msg.Type {
 	case discordgo.MessageTypeChannelNameChange, discordgo.MessageTypeChannelIconChange, discordgo.MessageTypeChannelPinnedMessage:
 		// These are handled via channel updates
@@ -1055,7 +543,6 @@ func (portal *Portal) handleDiscordMessageCreate(user *User, msg *discordgo.Mess
 
 	portal.recentMessages.Push(msg.ID, msg)
 
-	// Handle normal message
 	existing := portal.bridge.DB.Message.GetByDiscordID(portal.Key, msg.ID)
 	if existing != nil {
 		portal.log.Debugln("Dropping duplicate message", msg.ID)
@@ -1072,67 +559,56 @@ func (portal *Portal) handleDiscordMessageCreate(user *User, msg *discordgo.Mess
 	puppet.UpdateInfo(user, msg.Author)
 	intent := puppet.IntentFor(portal)
 
-	var threadRelation *event.RelatesTo
-	var threadID string
+	var discordThreadID string
+	var threadRootEvent, lastThreadEvent, replyToEvent id.EventID
 	if thread != nil {
-		threadID = thread.ID
-		lastEventID := thread.RootMXID
+		discordThreadID = thread.ID
+		threadRootEvent = thread.RootMXID
+		lastThreadEvent = threadRootEvent
 		lastInThread := portal.bridge.DB.Message.GetLastInThread(portal.Key, thread.ID)
 		if lastInThread != nil {
-			lastEventID = lastInThread.MXID
+			lastThreadEvent = lastInThread.MXID
 		}
-		threadRelation = (&event.RelatesTo{}).SetThread(thread.RootMXID, lastEventID)
 	}
 
-	var parts []database.MessagePart
-	ts, _ := discordgo.SnowflakeTimestamp(msg.ID)
-	textPart := portal.convertDiscordTextMessage(intent, msg, threadRelation, false)
-	if textPart != nil {
-		resp, err := portal.sendMatrixMessage(intent, event.EventMessage, textPart.Content, textPart.Extra, ts.UnixMilli())
-		if err != nil {
-			portal.log.Warnfln("Failed to send message %s to matrix: %v", msg.ID, err)
-			return
-		}
-
-		parts = append(parts, database.MessagePart{MXID: resp.EventID})
-		// Update the fallback reply event for attachments
-		if threadRelation != nil {
-			threadRelation.InReplyTo.EventID = resp.EventID
+	if msg.MessageReference != nil {
+		// This could be used to find cross-channel replies, but Matrix doesn't support those currently.
+		//key := database.PortalKey{msg.MessageReference.ChannelID, user.ID}
+		replyToMsg := portal.bridge.DB.Message.GetByDiscordID(portal.Key, msg.MessageReference.MessageID)
+		if len(replyToMsg) > 0 {
+			replyToEvent = replyToMsg[0].MXID
 		}
-		go portal.sendDeliveryReceipt(resp.EventID)
 	}
-	for _, att := range msg.Attachments {
-		part := portal.handleDiscordAttachment(intent, att, ts, threadRelation)
-		if part != nil {
-			parts = append(parts, *part)
+
+	ts, _ := discordgo.SnowflakeTimestamp(msg.ID)
+	parts := portal.convertDiscordMessage(intent, msg)
+	dbParts := make([]database.MessagePart, 0, len(parts))
+	for i, part := range parts {
+		if (replyToEvent != "" || threadRootEvent != "") && part.Content.RelatesTo == nil {
+			part.Content.RelatesTo = &event.RelatesTo{}
 		}
-	}
-	for _, sticker := range msg.StickerItems {
-		part := portal.handleDiscordSticker(intent, sticker, ts, threadRelation)
-		if part != nil {
-			parts = append(parts, *part)
+		if threadRootEvent != "" {
+			part.Content.RelatesTo.SetThread(threadRootEvent, lastThreadEvent)
 		}
-	}
-	handledURLs := make(map[string]struct{})
-	for i, embed := range msg.Embeds {
-		// Ignore non-video embeds, they're handled in convertDiscordTextMessage
-		if getEmbedType(embed) != EmbedVideo {
-			continue
+		if replyToEvent != "" {
+			part.Content.RelatesTo.SetReplyTo(replyToEvent)
+			// Only set reply for first event
+			replyToEvent = ""
 		}
-		// Discord deduplicates embeds by URL. It makes things easier for us too.
-		if _, handled := handledURLs[embed.URL]; handled {
+		resp, err := portal.sendMatrixMessage(intent, part.Type, part.Content, part.Extra, ts.UnixMilli())
+		if err != nil {
+			portal.log.Errorfln("Failed to send part #%d (attachment ID %q) of message %s to Matrix: %v", i+1, part.AttachmentID, msg.ID)
 			continue
 		}
-		handledURLs[embed.URL] = struct{}{}
-		part := portal.handleDiscordVideoEmbed(intent, embed, msg.ID, i, ts, threadRelation)
-		if part != nil {
-			parts = append(parts, *part)
-		}
+		lastThreadEvent = resp.EventID
+		dbParts = append(dbParts, database.MessagePart{AttachmentID: part.AttachmentID, MXID: resp.EventID})
 	}
 	if len(parts) == 0 {
 		portal.log.Warnfln("Unhandled message %s (type %d)", msg.ID, msg.Type)
+	} else if len(dbParts) == 0 {
+		portal.log.Warnfln("All parts of message %s failed to send to Matrix", msg.ID)
 	} else {
-		portal.markMessageHandled(msg.ID, 0, msg.Author.ID, ts, threadID, parts)
+		portal.markMessageHandled(msg.ID, 0, msg.Author.ID, ts, discordThreadID, dbParts)
 	}
 }
 
@@ -1265,7 +741,7 @@ func (portal *Portal) handleDiscordMessageUpdate(user *User, msg *discordgo.Mess
 	if isPlainGifMessage(msg) {
 		converted = portal.convertDiscordVideoEmbed(intent, msg.Embeds[0])
 	} else {
-		converted = portal.convertDiscordTextMessage(intent, msg, nil, true)
+		converted = portal.convertDiscordTextMessage(intent, msg)
 	}
 	if converted == nil {
 		portal.log.Debugfln("Dropping non-text edit to %s (message on matrix: %t, text on discord: %t)", msg.ID, existing[0].AttachmentID == "", len(msg.Content) > 0)

portal_convert.go

@@ -0,0 +1,519 @@
+// mautrix-discord - A Matrix-Discord puppeting bridge.
+// Copyright (C) 2023 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 main
+
+import (
+	"fmt"
+	"html"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/bwmarrin/discordgo"
+
+	"maunium.net/go/mautrix"
+	"maunium.net/go/mautrix/appservice"
+	"maunium.net/go/mautrix/event"
+	"maunium.net/go/mautrix/format"
+)
+
+type ConvertedMessage struct {
+	AttachmentID string
+
+	Type    event.Type
+	Content *event.MessageEventContent
+	Extra   map[string]any
+}
+
+func (portal *Portal) createMediaFailedMessage(bridgeErr error) *event.MessageEventContent {
+	return &event.MessageEventContent{
+		Body:    fmt.Sprintf("Failed to bridge media: %v", bridgeErr),
+		MsgType: event.MsgNotice,
+	}
+}
+
+const DiscordStickerSize = 160
+
+func (portal *Portal) convertDiscordFile(typeName string, intent *appservice.IntentAPI, id, url string, content *event.MessageEventContent) *event.MessageEventContent {
+	meta := AttachmentMeta{AttachmentID: id, MimeType: content.Info.MimeType}
+	if typeName == "sticker" && content.Info.MimeType == "application/json" {
+		meta.Converter = portal.bridge.convertLottie
+	}
+	dbFile, err := portal.bridge.copyAttachmentToMatrix(intent, url, portal.Encrypted, meta)
+	if err != nil {
+		portal.log.Errorfln("Error copying attachment %s to Matrix: %v", id, err)
+		return portal.createMediaFailedMessage(err)
+	}
+	if typeName == "sticker" && content.Info.MimeType == "application/json" {
+		content.Info.MimeType = dbFile.MimeType
+	}
+	content.Info.Size = dbFile.Size
+	if content.Info.Width == 0 && content.Info.Height == 0 {
+		content.Info.Width = dbFile.Width
+		content.Info.Height = dbFile.Height
+	}
+	if content.Info.Width == 0 && content.Info.Height == 0 && typeName == "sticker" {
+		content.Info.Width = DiscordStickerSize
+		content.Info.Height = DiscordStickerSize
+	}
+	if dbFile.DecryptionInfo != nil {
+		content.File = &event.EncryptedFileInfo{
+			EncryptedFile: *dbFile.DecryptionInfo,
+			URL:           dbFile.MXC.CUString(),
+		}
+	} else {
+		content.URL = dbFile.MXC.CUString()
+	}
+
+	if typeName == "sticker" && (content.Info.Width > DiscordStickerSize || content.Info.Height > DiscordStickerSize) {
+		if content.Info.Width > content.Info.Height {
+			content.Info.Height /= content.Info.Width / DiscordStickerSize
+			content.Info.Width = DiscordStickerSize
+		} else if content.Info.Width < content.Info.Height {
+			content.Info.Width /= content.Info.Height / DiscordStickerSize
+			content.Info.Height = DiscordStickerSize
+		} else {
+			content.Info.Width = DiscordStickerSize
+			content.Info.Height = DiscordStickerSize
+		}
+	}
+	return content
+}
+
+func (portal *Portal) convertDiscordSticker(intent *appservice.IntentAPI, sticker *discordgo.Sticker) *ConvertedMessage {
+	var mime string
+	switch sticker.FormatType {
+	case discordgo.StickerFormatTypePNG:
+		mime = "image/png"
+	case discordgo.StickerFormatTypeAPNG:
+		mime = "image/apng"
+	case discordgo.StickerFormatTypeLottie:
+		mime = "application/json"
+	case discordgo.StickerFormatTypeGIF:
+		mime = "image/gif"
+	default:
+		portal.log.Warnfln("Unknown sticker format %d in %s", sticker.FormatType, sticker.ID)
+	}
+	return &ConvertedMessage{
+		Type: event.EventSticker,
+		Content: portal.convertDiscordFile("sticker", intent, sticker.ID, sticker.URL(), &event.MessageEventContent{
+			Body: sticker.Name, // TODO find description from somewhere?
+			Info: &event.FileInfo{
+				MimeType: mime,
+			},
+		}),
+	}
+}
+
+func (portal *Portal) convertDiscordAttachment(intent *appservice.IntentAPI, att *discordgo.MessageAttachment) *ConvertedMessage {
+	content := &event.MessageEventContent{
+		Body: att.Filename,
+		Info: &event.FileInfo{
+			Height:   att.Height,
+			MimeType: att.ContentType,
+			Width:    att.Width,
+
+			// This gets overwritten later after the file is uploaded to the homeserver
+			Size: att.Size,
+		},
+	}
+	if att.Description != "" {
+		content.Body = att.Description
+		content.FileName = att.Filename
+	}
+
+	switch strings.ToLower(strings.Split(att.ContentType, "/")[0]) {
+	case "audio":
+		content.MsgType = event.MsgAudio
+	case "image":
+		content.MsgType = event.MsgImage
+	case "video":
+		content.MsgType = event.MsgVideo
+	default:
+		content.MsgType = event.MsgFile
+	}
+	content = portal.convertDiscordFile("attachment", intent, att.ID, att.URL, content)
+	return &ConvertedMessage{
+		Type:    event.EventMessage,
+		Content: content,
+	}
+}
+
+func (portal *Portal) convertDiscordVideoEmbed(intent *appservice.IntentAPI, embed *discordgo.MessageEmbed) *ConvertedMessage {
+	attachmentID := fmt.Sprintf("video_%s", embed.URL)
+	dbFile, err := portal.bridge.copyAttachmentToMatrix(intent, embed.Video.ProxyURL, portal.Encrypted, NoMeta)
+	if err != nil {
+		return &ConvertedMessage{
+			AttachmentID: attachmentID,
+			Type:         event.EventMessage,
+			Content:      portal.createMediaFailedMessage(err),
+		}
+	}
+
+	content := &event.MessageEventContent{
+		MsgType: event.MsgVideo,
+		Body:    embed.URL,
+		Info: &event.FileInfo{
+			Width:    embed.Video.Width,
+			Height:   embed.Video.Height,
+			MimeType: dbFile.MimeType,
+
+			Size: dbFile.Size,
+		},
+	}
+	if content.Info.Width == 0 && content.Info.Height == 0 {
+		content.Info.Width = dbFile.Width
+		content.Info.Height = dbFile.Height
+	}
+	if dbFile.DecryptionInfo != nil {
+		content.File = &event.EncryptedFileInfo{
+			EncryptedFile: *dbFile.DecryptionInfo,
+			URL:           dbFile.MXC.CUString(),
+		}
+	} else {
+		content.URL = dbFile.MXC.CUString()
+	}
+	extra := map[string]any{}
+	if embed.Type == discordgo.EmbedTypeGifv {
+		extra["info"] = map[string]any{
+			"fi.mau.discord.gifv":  true,
+			"fi.mau.loop":          true,
+			"fi.mau.autoplay":      true,
+			"fi.mau.hide_controls": true,
+			"fi.mau.no_audio":      true,
+		}
+	}
+	return &ConvertedMessage{
+		AttachmentID: attachmentID,
+		Type:         event.EventMessage,
+		Content:      content,
+		Extra:        extra,
+	}
+}
+
+func (portal *Portal) convertDiscordMessage(intent *appservice.IntentAPI, msg *discordgo.Message) []*ConvertedMessage {
+	predictedLength := len(msg.Attachments) + len(msg.StickerItems)
+	if msg.Content != "" {
+		predictedLength++
+	}
+	parts := make([]*ConvertedMessage, 0, predictedLength)
+	if textPart := portal.convertDiscordTextMessage(intent, msg); textPart != nil {
+		parts = append(parts, textPart)
+	}
+	for _, att := range msg.Attachments {
+		if part := portal.convertDiscordAttachment(intent, att); part != nil {
+			parts = append(parts, part)
+		}
+	}
+	for _, sticker := range msg.StickerItems {
+		if part := portal.convertDiscordSticker(intent, sticker); part != nil {
+			parts = append(parts, part)
+		}
+	}
+	handledURLs := make(map[string]struct{})
+	for _, embed := range msg.Embeds {
+		// Ignore non-video embeds, they're handled in convertDiscordTextMessage
+		if getEmbedType(embed) != EmbedVideo {
+			continue
+		}
+		// Discord deduplicates embeds by URL. It makes things easier for us too.
+		if _, handled := handledURLs[embed.URL]; handled {
+			continue
+		}
+		handledURLs[embed.URL] = struct{}{}
+		part := portal.convertDiscordVideoEmbed(intent, embed)
+		if part != nil {
+			parts = append(parts, part)
+		}
+	}
+	return parts
+}
+
+const (
+	embedHTMLWrapper         = `<blockquote class="discord-embed">%s</blockquote>`
+	embedHTMLWrapperColor    = `<blockquote class="discord-embed" background-color="#%06X">%s</blockquote>`
+	embedHTMLAuthorWithImage = `<p class="discord-embed-author"><img data-mx-emoticon height="24" src="%s" title="Author icon" alt="">&nbsp;<span>%s</span></p>`
+	embedHTMLAuthorPlain     = `<p class="discord-embed-author"><span>%s</span></p>`
+	embedHTMLAuthorLink      = `<a href="%s">%s</a>`
+	embedHTMLTitleWithLink   = `<p class="discord-embed-title"><a href="%s"><strong>%s</strong></a></p>`
+	embedHTMLTitlePlain      = `<p class="discord-embed-title"><strong>%s</strong></p>`
+	embedHTMLDescription     = `<p class="discord-embed-description">%s</p>`
+	embedHTMLFieldName       = `<th>%s</th>`
+	embedHTMLFieldValue      = `<td>%s</td>`
+	embedHTMLFields          = `<table class="discord-embed-fields"><tr>%s</tr><tr>%s</tr></table>`
+	embedHTMLLinearField     = `<p class="discord-embed-field" x-inline="%s"><strong>%s</strong><br><span>%s</span></p>`
+	embedHTMLImage           = `<p class="discord-embed-image"><img src="%s" alt="" title="Embed image"></p>`
+	embedHTMLFooterWithImage = `<p class="discord-embed-footer"><sub><img data-mx-emoticon height="20" src="%s" title="Footer icon" alt="">&nbsp;<span>%s</span>%s</sub></p>`
+	embedHTMLFooterPlain     = `<p class="discord-embed-footer"><sub><span>%s</span>%s</sub></p>`
+	embedHTMLFooterOnlyDate  = `<p class="discord-embed-footer"><sub>%s</sub></p>`
+	embedHTMLDate            = `<time datetime="%s">%s</time>`
+	embedFooterDateSeparator = ` • `
+)
+
+func (portal *Portal) convertDiscordRichEmbed(intent *appservice.IntentAPI, embed *discordgo.MessageEmbed, msgID string, index int) string {
+	var htmlParts []string
+	if embed.Author != nil {
+		var authorHTML string
+		authorNameHTML := html.EscapeString(embed.Author.Name)
+		if embed.Author.URL != "" {
+			authorNameHTML = fmt.Sprintf(embedHTMLAuthorLink, embed.Author.URL, authorNameHTML)
+		}
+		authorHTML = fmt.Sprintf(embedHTMLAuthorPlain, authorNameHTML)
+		if embed.Author.ProxyIconURL != "" {
+			dbFile, err := portal.bridge.copyAttachmentToMatrix(intent, embed.Author.ProxyIconURL, false, NoMeta)
+			if err != nil {
+				portal.log.Warnfln("Failed to reupload author icon in embed #%d of message %s: %v", index+1, msgID, err)
+			} else {
+				authorHTML = fmt.Sprintf(embedHTMLAuthorWithImage, dbFile.MXC, authorNameHTML)
+			}
+		}
+		htmlParts = append(htmlParts, authorHTML)
+	}
+	if embed.Title != "" {
+		var titleHTML string
+		baseTitleHTML := portal.renderDiscordMarkdownOnlyHTML(embed.Title, false)
+		if embed.URL != "" {
+			titleHTML = fmt.Sprintf(embedHTMLTitleWithLink, html.EscapeString(embed.URL), baseTitleHTML)
+		} else {
+			titleHTML = fmt.Sprintf(embedHTMLTitlePlain, baseTitleHTML)
+		}
+		htmlParts = append(htmlParts, titleHTML)
+	}
+	if embed.Description != "" {
+		htmlParts = append(htmlParts, fmt.Sprintf(embedHTMLDescription, portal.renderDiscordMarkdownOnlyHTML(embed.Description, true)))
+	}
+	for i := 0; i < len(embed.Fields); i++ {
+		item := embed.Fields[i]
+		if portal.bridge.Config.Bridge.EmbedFieldsAsTables {
+			splitItems := []*discordgo.MessageEmbedField{item}
+			if item.Inline && len(embed.Fields) > i+1 && embed.Fields[i+1].Inline {
+				splitItems = append(splitItems, embed.Fields[i+1])
+				i++
+				if len(embed.Fields) > i+1 && embed.Fields[i+1].Inline {
+					splitItems = append(splitItems, embed.Fields[i+1])
+					i++
+				}
+			}
+			headerParts := make([]string, len(splitItems))
+			contentParts := make([]string, len(splitItems))
+			for j, splitItem := range splitItems {
+				headerParts[j] = fmt.Sprintf(embedHTMLFieldName, portal.renderDiscordMarkdownOnlyHTML(splitItem.Name, false))
+				contentParts[j] = fmt.Sprintf(embedHTMLFieldValue, portal.renderDiscordMarkdownOnlyHTML(splitItem.Value, true))
+			}
+			htmlParts = append(htmlParts, fmt.Sprintf(embedHTMLFields, strings.Join(headerParts, ""), strings.Join(contentParts, "")))
+		} else {
+			htmlParts = append(htmlParts, fmt.Sprintf(embedHTMLLinearField,
+				strconv.FormatBool(item.Inline),
+				portal.renderDiscordMarkdownOnlyHTML(item.Name, false),
+				portal.renderDiscordMarkdownOnlyHTML(item.Value, true),
+			))
+		}
+	}
+	if embed.Image != nil {
+		dbFile, err := portal.bridge.copyAttachmentToMatrix(intent, embed.Image.ProxyURL, false, NoMeta)
+		if err != nil {
+			portal.log.Warnfln("Failed to reupload image in embed #%d of message %s: %v", index+1, msgID, err)
+		} else {
+			htmlParts = append(htmlParts, fmt.Sprintf(embedHTMLImage, dbFile.MXC))
+		}
+	}
+	var embedDateHTML string
+	if embed.Timestamp != "" {
+		formattedTime := embed.Timestamp
+		parsedTS, err := time.Parse(time.RFC3339, embed.Timestamp)
+		if err != nil {
+			portal.log.Warnfln("Failed to parse timestamp in embed #%d of message %s: %v", index+1, msgID, err)
+		} else {
+			formattedTime = parsedTS.Format(discordTimestampStyle('F').Format())
+		}
+		embedDateHTML = fmt.Sprintf(embedHTMLDate, embed.Timestamp, formattedTime)
+	}
+	if embed.Footer != nil {
+		var footerHTML string
+		var datePart string
+		if embedDateHTML != "" {
+			datePart = embedFooterDateSeparator + embedDateHTML
+		}
+		footerHTML = fmt.Sprintf(embedHTMLFooterPlain, html.EscapeString(embed.Footer.Text), datePart)
+		if embed.Footer.ProxyIconURL != "" {
+			dbFile, err := portal.bridge.copyAttachmentToMatrix(intent, embed.Footer.ProxyIconURL, false, NoMeta)
+			if err != nil {
+				portal.log.Warnfln("Failed to reupload footer icon in embed #%d of message %s: %v", index+1, msgID, err)
+			} else {
+				footerHTML = fmt.Sprintf(embedHTMLFooterWithImage, dbFile.MXC, html.EscapeString(embed.Footer.Text), datePart)
+			}
+		}
+		htmlParts = append(htmlParts, footerHTML)
+	} else if embed.Timestamp != "" {
+		htmlParts = append(htmlParts, fmt.Sprintf(embedHTMLFooterOnlyDate, embedDateHTML))
+	}
+
+	if len(htmlParts) == 0 {
+		return ""
+	}
+
+	compiledHTML := strings.Join(htmlParts, "")
+	if embed.Color != 0 {
+		compiledHTML = fmt.Sprintf(embedHTMLWrapperColor, embed.Color, compiledHTML)
+	} else {
+		compiledHTML = fmt.Sprintf(embedHTMLWrapper, compiledHTML)
+	}
+	return compiledHTML
+}
+
+type BeeperLinkPreview struct {
+	mautrix.RespPreviewURL
+	MatchedURL      string                   `json:"matched_url"`
+	ImageEncryption *event.EncryptedFileInfo `json:"beeper:image:encryption,omitempty"`
+}
+
+func (portal *Portal) convertDiscordLinkEmbedImage(intent *appservice.IntentAPI, url string, width, height int, preview *BeeperLinkPreview) {
+	dbFile, err := portal.bridge.copyAttachmentToMatrix(intent, url, portal.Encrypted, NoMeta)
+	if err != nil {
+		portal.log.Warnfln("Failed to copy image in URL preview: %v", err)
+	} else {
+		if width != 0 || height != 0 {
+			preview.ImageWidth = width
+			preview.ImageHeight = height
+		} else {
+			preview.ImageWidth = dbFile.Width
+			preview.ImageHeight = dbFile.Height
+		}
+		preview.ImageSize = dbFile.Size
+		preview.ImageType = dbFile.MimeType
+		if dbFile.Encrypted {
+			preview.ImageEncryption = &event.EncryptedFileInfo{
+				EncryptedFile: *dbFile.DecryptionInfo,
+				URL:           dbFile.MXC.CUString(),
+			}
+		} else {
+			preview.ImageURL = dbFile.MXC.CUString()
+		}
+	}
+}
+
+func (portal *Portal) convertDiscordLinkEmbedToBeeper(intent *appservice.IntentAPI, embed *discordgo.MessageEmbed) *BeeperLinkPreview {
+	var preview BeeperLinkPreview
+	preview.MatchedURL = embed.URL
+	preview.Title = embed.Title
+	preview.Description = embed.Description
+	if embed.Image != nil {
+		portal.convertDiscordLinkEmbedImage(intent, embed.Image.ProxyURL, embed.Image.Width, embed.Image.Height, &preview)
+	} else if embed.Thumbnail != nil {
+		portal.convertDiscordLinkEmbedImage(intent, embed.Thumbnail.ProxyURL, embed.Thumbnail.Width, embed.Thumbnail.Height, &preview)
+	}
+	return &preview
+}
+
+const msgInteractionTemplateHTML = `<blockquote>
+<a href="https://matrix.to/#/%s">%s</a> used <font color="#3771bb">/%s</font>
+</blockquote>`
+
+const msgComponentTemplateHTML = `<p>This message contains interactive elements. Use the Discord app to interact with the message.</p>`
+
+type BridgeEmbedType int
+
+const (
+	EmbedUnknown BridgeEmbedType = iota
+	EmbedRich
+	EmbedLinkPreview
+	EmbedVideo
+)
+
+func isActuallyLinkPreview(embed *discordgo.MessageEmbed) bool {
+	// Sending YouTube links creates a video embed, but we want to bridge it as a URL preview,
+	// so this is a hacky way to detect those.
+	return embed.Video != nil && embed.Video.ProxyURL == ""
+}
+
+func getEmbedType(embed *discordgo.MessageEmbed) BridgeEmbedType {
+	switch embed.Type {
+	case discordgo.EmbedTypeLink, discordgo.EmbedTypeArticle:
+		return EmbedLinkPreview
+	case discordgo.EmbedTypeVideo:
+		if isActuallyLinkPreview(embed) {
+			return EmbedLinkPreview
+		}
+		return EmbedVideo
+	case discordgo.EmbedTypeGifv:
+		return EmbedVideo
+	case discordgo.EmbedTypeRich, discordgo.EmbedTypeImage:
+		return EmbedRich
+	default:
+		return EmbedUnknown
+	}
+}
+
+func isPlainGifMessage(msg *discordgo.Message) bool {
+	return len(msg.Embeds) == 1 && msg.Embeds[0].Video != nil && msg.Embeds[0].URL == msg.Content && msg.Embeds[0].Type == discordgo.EmbedTypeGifv
+}
+
+func (portal *Portal) convertDiscordTextMessage(intent *appservice.IntentAPI, msg *discordgo.Message) *ConvertedMessage {
+	if msg.Type == discordgo.MessageTypeCall {
+		return &ConvertedMessage{Type: event.EventMessage, Content: &event.MessageEventContent{
+			MsgType: event.MsgEmote,
+			Body:    "started a call",
+		}}
+	} else if msg.Type == discordgo.MessageTypeGuildMemberJoin {
+		return &ConvertedMessage{Type: event.EventMessage, Content: &event.MessageEventContent{
+			MsgType: event.MsgEmote,
+			Body:    "joined the server",
+		}}
+	}
+	var htmlParts []string
+	if msg.Interaction != nil {
+		puppet := portal.bridge.GetPuppetByID(msg.Interaction.User.ID)
+		puppet.UpdateInfo(nil, msg.Interaction.User)
+		htmlParts = append(htmlParts, fmt.Sprintf(msgInteractionTemplateHTML, puppet.MXID, puppet.Name, msg.Interaction.Name))
+	}
+	if msg.Content != "" && !isPlainGifMessage(msg) {
+		htmlParts = append(htmlParts, portal.renderDiscordMarkdownOnlyHTML(msg.Content, false))
+	}
+	previews := make([]*BeeperLinkPreview, 0)
+	for i, embed := range msg.Embeds {
+		switch getEmbedType(embed) {
+		case EmbedRich:
+			htmlParts = append(htmlParts, portal.convertDiscordRichEmbed(intent, embed, msg.ID, i))
+		case EmbedLinkPreview:
+			previews = append(previews, portal.convertDiscordLinkEmbedToBeeper(intent, embed))
+		case EmbedVideo:
+			// Ignore video embeds, they're handled as separate messages
+		default:
+			portal.log.Warnfln("Unknown type %s in embed #%d of message %s", embed.Type, i+1, msg.ID)
+		}
+	}
+
+	if len(msg.Components) > 0 {
+		htmlParts = append(htmlParts, msgComponentTemplateHTML)
+	}
+
+	if len(htmlParts) == 0 {
+		return nil
+	}
+
+	fullHTML := strings.Join(htmlParts, "\n")
+	if !msg.MentionEveryone {
+		fullHTML = strings.ReplaceAll(fullHTML, "@room", "@\u2063ro\u2063om")
+	}
+
+	content := format.HTMLToContent(fullHTML)
+	extraContent := map[string]any{
+		"com.beeper.linkpreviews": previews,
+	}
+
+	return &ConvertedMessage{Type: event.EventMessage, Content: &content, Extra: extraContent}
+}