[MM-42191]: Include deleted posts (#19985)

* MM-42191: Include deleted posts: Add includeDeleted query parameter for getPostsForChannel

* MM-42191: Fix error typo for includeDeleted query parameter

* MM-42191: Include deleted posts: Set permission error when deleted posts are requested by non system admins

* MM-42191: Include deleted posts: Refactor replyCountSubQuery and conditions when includeDeleted is not presented, refactor getRootPosts

* MM-42191: Include deleted posts: Refactor getRootPosts function along with skipFetchThreads and includeDeleted

* MM-42191: Include deleted posts: Rename includeDeleted to include_deleted param

* MM-42191: Include deleted posts: Fix failed posts unit tests

* MM-42191: Include deleted posts: Add missing include deleted option in multiple queries

* MM-42191: Include deleted posts: Add tests for include deleted option in TestGetPostsForChannel, TestGetPostsBefore, TestGetPostsAfter

* MM-42191: include deleted posts: Add tests cases for post store test

* MM-42191: Include deleted posts: Add extra unit test to ensure not returning deleted posts when IncludeDelete is false

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

api4/post.go

@@ -183,10 +183,16 @@ func getPostsForChannel(c *Context, w http.ResponseWriter, r *http.Request) {
 	skipFetchThreads := r.URL.Query().Get("skipFetchThreads") == "true"
 	collapsedThreads := r.URL.Query().Get("collapsedThreads") == "true"
 	collapsedThreadsExtended := r.URL.Query().Get("collapsedThreadsExtended") == "true"
+	includeDeleted := r.URL.Query().Get("include_deleted") == "true"
 	channelId := c.Params.ChannelId
 	page := c.Params.Page
 	perPage := c.Params.PerPage
 
+	if !c.IsSystemAdmin() && includeDeleted {
+		c.SetPermissionError(model.PermissionReadDeletedPosts)
+		return
+	}
+
 	if !c.App.SessionHasPermissionToChannel(c.AppContext, *c.AppContext.Session(), channelId, model.PermissionReadChannel) {
 		c.SetPermissionError(model.PermissionReadChannel)
 		return
@@ -217,7 +223,7 @@ func getPostsForChannel(c *Context, w http.ResponseWriter, r *http.Request) {
 			return
 		}
 
-		list, err = c.App.GetPostsAfterPost(model.GetPostsOptions{ChannelId: channelId, PostId: afterPost, Page: page, PerPage: perPage, SkipFetchThreads: skipFetchThreads, CollapsedThreads: collapsedThreads, UserId: c.AppContext.Session().UserId})
+		list, err = c.App.GetPostsAfterPost(model.GetPostsOptions{ChannelId: channelId, PostId: afterPost, Page: page, PerPage: perPage, SkipFetchThreads: skipFetchThreads, CollapsedThreads: collapsedThreads, UserId: c.AppContext.Session().UserId, IncludeDeleted: includeDeleted})
 	} else if beforePost != "" {
 		etag = c.App.GetPostsEtag(channelId, collapsedThreads)
 
@@ -225,7 +231,7 @@ func getPostsForChannel(c *Context, w http.ResponseWriter, r *http.Request) {
 			return
 		}
 
-		list, err = c.App.GetPostsBeforePost(model.GetPostsOptions{ChannelId: channelId, PostId: beforePost, Page: page, PerPage: perPage, SkipFetchThreads: skipFetchThreads, CollapsedThreads: collapsedThreads, CollapsedThreadsExtended: collapsedThreadsExtended, UserId: c.AppContext.Session().UserId})
+		list, err = c.App.GetPostsBeforePost(model.GetPostsOptions{ChannelId: channelId, PostId: beforePost, Page: page, PerPage: perPage, SkipFetchThreads: skipFetchThreads, CollapsedThreads: collapsedThreads, CollapsedThreadsExtended: collapsedThreadsExtended, UserId: c.AppContext.Session().UserId, IncludeDeleted: includeDeleted})
 	} else {
 		etag = c.App.GetPostsEtag(channelId, collapsedThreads)
 
@@ -233,7 +239,7 @@ func getPostsForChannel(c *Context, w http.ResponseWriter, r *http.Request) {
 			return
 		}
 
-		list, err = c.App.GetPostsPage(model.GetPostsOptions{ChannelId: channelId, Page: page, PerPage: perPage, SkipFetchThreads: skipFetchThreads, CollapsedThreads: collapsedThreads, CollapsedThreadsExtended: collapsedThreadsExtended, UserId: c.AppContext.Session().UserId})
+		list, err = c.App.GetPostsPage(model.GetPostsOptions{ChannelId: channelId, Page: page, PerPage: perPage, SkipFetchThreads: skipFetchThreads, CollapsedThreads: collapsedThreads, CollapsedThreadsExtended: collapsedThreadsExtended, UserId: c.AppContext.Session().UserId, IncludeDeleted: includeDeleted})
 	}
 
 	if err != nil {