From 6fd1b9f309649696b15e123fc4c00efd5bdac4d4 Mon Sep 17 00:00:00 2001
From: Alexander Zinchuk <alx.zinchuk@gmail.com>
Date: Sat, 15 May 2021 00:53:28 +0300
Subject: [PATCH] Message List: Fixes for detecting unread messages

---
 src/api/gramjs/apiBuilders/chats.ts | 1 +
 src/modules/selectors/messages.ts   | 9 +++++----
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/api/gramjs/apiBuilders/chats.ts b/src/api/gramjs/apiBuilders/chats.ts
index fa595c368..cb0ab9de5 100644
--- a/src/api/gramjs/apiBuilders/chats.ts
+++ b/src/api/gramjs/apiBuilders/chats.ts
@@ -126,6 +126,7 @@ function buildApiChatRestrictions(peerEntity: GramJs.TypeUser | GramJs.TypeChat)
       && peerEntity.restrictionReason.some((reason) => reason.platform === 'all');
 
     return {
+      // `left` is weirdly set to `true` on all channels never joined before
       isNotJoined: peerEntity.left,
       isRestricted,
       restrictionReason: buildApiChatRestrictionReason(peerEntity.restrictionReason),
diff --git a/src/modules/selectors/messages.ts b/src/modules/selectors/messages.ts
index c08785694..0950eaeb1 100644
--- a/src/modules/selectors/messages.ts
+++ b/src/modules/selectors/messages.ts
@@ -499,8 +499,9 @@ export function selectRealLastReadId(global: GlobalState, chatId: number, thread
 }
 
 export function selectFirstUnreadId(global: GlobalState, chatId: number, threadId: number) {
+  const chat = selectChat(global, chatId);
+
   if (threadId === MAIN_THREAD_ID) {
-    const chat = selectChat(global, chatId);
     if (!chat) {
       return undefined;
     }
@@ -519,12 +520,12 @@ export function selectFirstUnreadId(global: GlobalState, chatId: number, threadI
   }
 
   const lastReadId = selectRealLastReadId(global, chatId, threadId);
-  if (!lastReadId) {
+  if (!lastReadId && chat && chat.isNotJoined) {
     return undefined;
   }
 
   if (outlyingIds) {
-    const found = outlyingIds.find((id) => {
+    const found = !lastReadId ? outlyingIds[0] : outlyingIds.find((id) => {
       return id > lastReadId && byId[id] && (!byId[id].isOutgoing || byId[id].isFromScheduled);
     });
     if (found) {
@@ -533,7 +534,7 @@ export function selectFirstUnreadId(global: GlobalState, chatId: number, threadI
   }
 
   if (listedIds) {
-    const found = listedIds.find((id) => {
+    const found = !lastReadId ? listedIds[0] : listedIds.find((id) => {
       return id > lastReadId && byId[id] && (!byId[id].isOutgoing || byId[id].isFromScheduled);
     });
     if (found) {