[MM-42192] Include deleted posts in GetPost (#20358)

* Introduced include_deleted query param on get posts endpoint

* Update the correct func name in the comment.

Co-authored-by: santoniriccardo <santoni.riccardo@gmail.com>
Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

api4/post.go

@@ -387,7 +387,13 @@ func getPost(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	post, err := c.App.GetPostIfAuthorized(c.Params.PostId, c.AppContext.Session())
+	includeDeleted, _ := strconv.ParseBool(r.URL.Query().Get("include_deleted"))
+	if includeDeleted && !c.App.SessionHasPermissionTo(*c.AppContext.Session(), model.PermissionManageSystem) {
+		c.SetPermissionError(model.PermissionManageSystem)
+		return
+	}
+
+	post, err := c.App.GetPostIfAuthorized(c.Params.PostId, c.AppContext.Session(), includeDeleted)
 	if err != nil {
 		c.Err = err
 		return
@@ -471,7 +477,7 @@ func deletePost(c *Context, w http.ResponseWriter, _ *http.Request) {
 	defer c.LogAuditRecWithLevel(auditRec, app.LevelContent)
 	auditRec.AddMeta("post_id", c.Params.PostId)
 
-	post, err := c.App.GetSinglePost(c.Params.PostId)
+	post, err := c.App.GetSinglePost(c.Params.PostId, false)
 	if err != nil {
 		c.SetPermissionError(model.PermissionDeletePost)
 		return
@@ -563,7 +569,7 @@ func getPostThread(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	if _, err = c.App.GetPostIfAuthorized(post.Id, c.AppContext.Session()); err != nil {
+	if _, err = c.App.GetPostIfAuthorized(post.Id, c.AppContext.Session(), false); err != nil {
 		c.Err = err
 		return
 	}
@@ -708,7 +714,7 @@ func updatePost(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	originalPost, err := c.App.GetSinglePost(c.Params.PostId)
+	originalPost, err := c.App.GetSinglePost(c.Params.PostId, false)
 	if err != nil {
 		c.SetPermissionError(model.PermissionEditPost)
 		return
@@ -759,7 +765,7 @@ func patchPost(c *Context, w http.ResponseWriter, r *http.Request) {
 	// Updating the file_ids of a post is not a supported operation and will be ignored
 	post.FileIds = nil
 
-	originalPost, err := c.App.GetSinglePost(c.Params.PostId)
+	originalPost, err := c.App.GetSinglePost(c.Params.PostId, false)
 	if err != nil {
 		c.SetPermissionError(model.PermissionEditPost)
 		return
@@ -834,7 +840,7 @@ func saveIsPinnedPost(c *Context, w http.ResponseWriter, isPinned bool) {
 		return
 	}
 
-	post, err := c.App.GetSinglePost(c.Params.PostId)
+	post, err := c.App.GetSinglePost(c.Params.PostId, false)
 	if err != nil {
 		c.Err = err
 		return