From 563cb2d624598efdd3819daef00c64079d8a20e1 Mon Sep 17 00:00:00 2001
From: Bohdan Horbeshko <bodqhrohro@gmail.com>
Date: Sun, 16 Jul 2023 08:19:11 -0400
Subject: [PATCH] Avoid webpage preview updates being sent as message edits

---
 telegram/client.go   |  3 +++
 telegram/handlers.go | 20 ++++++++++++++++++++
 telegram/utils.go    | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 56 insertions(+)

diff --git a/telegram/client.go b/telegram/client.go
index 61d46aa..5cc15a4 100644
--- a/telegram/client.go
+++ b/telegram/client.go
@@ -53,6 +53,7 @@ type Client struct {
 	Session   *persistence.Session
 	resources map[string]bool
 	outbox    map[string]string
+	editQueue map[ChatMessageId]bool
 	content   *config.TelegramContentConfig
 	cache     *cache.Cache
 	online    bool
@@ -69,6 +70,7 @@ type clientLocks struct {
 	chatMessageLocks   map[int64]*sync.Mutex
 	resourcesLock      sync.Mutex
 	outboxLock         sync.Mutex
+	editQueueLock      sync.Mutex
 }
 
 // NewClient instantiates a Telegram App
@@ -125,6 +127,7 @@ func NewClient(conf config.TelegramConfig, jid string, component *xmpp.Component
 		Session:         session,
 		resources:       make(map[string]bool),
 		outbox:          make(map[string]string),
+		editQueue:       make(map[ChatMessageId]bool),
 		content:         &conf.Content,
 		cache:           cache.NewCache(),
 		options:         options,
diff --git a/telegram/handlers.go b/telegram/handlers.go
index abc1f5d..93ac284 100644
--- a/telegram/handlers.go
+++ b/telegram/handlers.go
@@ -104,6 +104,13 @@ func (c *Client) updateHandler() {
 				}
 				c.updateNewMessage(typedUpdate)
 				log.Debugf("%#v", typedUpdate.Message)
+			case client.TypeUpdateMessageEdited:
+				typedUpdate, ok := update.(*client.UpdateMessageEdited)
+				if !ok {
+					uhOh()
+				}
+				c.updateMessageEdited(typedUpdate)
+				log.Debugf("%#v", typedUpdate)
 			case client.TypeUpdateMessageContent:
 				typedUpdate, ok := update.(*client.UpdateMessageContent)
 				if !ok {
@@ -229,6 +236,11 @@ func (c *Client) updateNewMessage(update *client.UpdateNewMessage) {
 	}()
 }
 
+// message content edited
+func (c *Client) updateMessageEdited(update *client.UpdateMessageEdited) {
+	c.addToEditQueue(update.ChatId, update.MessageId)
+}
+
 // message content updated
 func (c *Client) updateMessageContent(update *client.UpdateMessageContent) {
 	markupFunction := formatter.EntityToXEP0393
@@ -244,6 +256,14 @@ func (c *Client) updateMessageContent(update *client.UpdateMessageContent) {
 	}
 	log.Infof("ignoredResource: %v", ignoredResource)
 
+	if !c.deleteFromEditQueue(update.ChatId, update.MessageId) {
+		log.WithFields(log.Fields{
+			"chatId":    update.ChatId,
+			"messageId": update.MessageId,
+		}).Infof("Content update with no preceding message edit, ignoring")
+		return
+	}
+
 	jids := c.getCarbonFullJids(true, ignoredResource)
 	if len(jids) == 0 {
 		log.Info("The only resource is ignored, aborting")
diff --git a/telegram/utils.go b/telegram/utils.go
index 9486349..da66189 100644
--- a/telegram/utils.go
+++ b/telegram/utils.go
@@ -24,6 +24,7 @@ import (
 	"github.com/zelenin/go-tdlib/client"
 )
 
+// VCardInfo contains intermediate data to produce a vCard
 type VCardInfo struct {
 	Fn       string
 	Photo    *client.File
@@ -34,6 +35,12 @@ type VCardInfo struct {
 	Info     string
 }
 
+// ChatMessageId uniquely identifies a Telegram message
+type ChatMessageId struct {
+	ChatId int64
+	MessageId int64
+}
+
 var errOffline = errors.New("TDlib instance is offline")
 
 var spaceRegex = regexp.MustCompile(`\s+`)
@@ -1384,3 +1391,29 @@ func (c *Client) getCarbonFullJids(isOutgoing bool, ignoredResource string) []st
 	}
 	return jids
 }
+
+func (c *Client) addToEditQueue(chatId, messageId int64) {
+	c.locks.editQueueLock.Lock()
+	defer c.locks.editQueueLock.Unlock()
+
+	c.editQueue[ChatMessageId{
+		ChatId:    chatId,
+		MessageId: messageId,
+	}] = true
+}
+
+func (c *Client) deleteFromEditQueue(chatId, messageId int64) bool {
+	c.locks.editQueueLock.Lock()
+	defer c.locks.editQueueLock.Unlock()
+
+	key := ChatMessageId{
+		ChatId:    chatId,
+		MessageId: messageId,
+	}
+	_, ok := c.editQueue[key]
+	if ok {
+		delete(c.editQueue, key)
+	}
+
+	return ok
+}