(feature) New MessagesWillBeConsumed Server Plugin Hook (#23305)

* feature: implemented basic MessageWillBeConsumed hook and applied on GetSinglePost method.

* use hook in get methods

* chore: refactored hook usage and created utils functions to apply hook

* bugfix: single post not updating

* chore: adjusted hook to return post

* chore: reverted some uneeded  changes

* chore: updated hook to accept slice of posts

* bugfix: slice filled with niil values

* chore: MessageWillBeConsumed ranamed to MessagesWillBeConsumed

* Update plugin/hooks.go

Co-authored-by: Jesse Hallam <jesse@thehallams.ca>

* Add feature flag

* Update min version

* update tests to account for feature flag

* fix linting issues

---------

Co-authored-by: Matej Topolovac <>
Co-authored-by: mtopolovac <43346061+mtopolovac@users.noreply.github.com>
Co-authored-by: Jesse Hallam <jesse@thehallams.ca>
Co-authored-by: Kevin Hsieh <kevinh@qrypt.com>
Co-authored-by: Jesse Hallam <jesse.hallam@gmail.com>

server/channels/app/post.go

@@ -386,6 +386,8 @@ func (a *App) CreatePost(c request.CTX, post *model.Post, channel *model.Channel
 	// so we just return the one that was passed with post
 	rpost = a.PreparePostForClient(c, rpost, true, false, false)
 
+	a.applyPostWillBeConsumedHook(&rpost)
+
 	if rpost.RootId != "" {
 		if appErr := a.ResolvePersistentNotification(c, parentPostList.Posts[post.RootId], rpost.UserId); appErr != nil {
 			return nil, appErr
@@ -870,6 +872,8 @@ func (a *App) GetPostsPage(options model.GetPostsOptions) (*model.PostList, *mod
 		return nil, appErr
 	}
 
+	a.applyPostsWillBeConsumedHook(postList.Posts)
+
 	return postList, nil
 }
 
@@ -889,6 +893,8 @@ func (a *App) GetPosts(channelID string, offset int, limit int) (*model.PostList
 		return nil, appErr
 	}
 
+	a.applyPostsWillBeConsumedHook(postList.Posts)
+
 	return postList, nil
 }
 
@@ -906,6 +912,8 @@ func (a *App) GetPostsSince(options model.GetPostsSinceOptions) (*model.PostList
 		return nil, appErr
 	}
 
+	a.applyPostsWillBeConsumedHook(postList.Posts)
+
 	return postList, nil
 }
 
@@ -929,6 +937,8 @@ func (a *App) GetSinglePost(postID string, includeDeleted bool) (*model.Post, *m
 		return nil, model.NewAppError("GetSinglePost", "app.post.cloud.get.app_error", nil, "", http.StatusForbidden)
 	}
 
+	a.applyPostWillBeConsumedHook(&post)
+
 	return post, nil
 }
 
@@ -959,6 +969,8 @@ func (a *App) GetPostThread(postID string, opts model.GetPostsOptions, userID st
 		return nil, appErr
 	}
 
+	a.applyPostsWillBeConsumedHook(posts.Posts)
+
 	return posts, nil
 }
 
@@ -972,6 +984,8 @@ func (a *App) GetFlaggedPosts(userID string, offset int, limit int) (*model.Post
 		return nil, appErr
 	}
 
+	a.applyPostsWillBeConsumedHook(postList.Posts)
+
 	return postList, nil
 }
 
@@ -985,6 +999,8 @@ func (a *App) GetFlaggedPostsForTeam(userID, teamID string, offset int, limit in
 		return nil, appErr
 	}
 
+	a.applyPostsWillBeConsumedHook(postList.Posts)
+
 	return postList, nil
 }
 
@@ -998,6 +1014,8 @@ func (a *App) GetFlaggedPostsForChannel(userID, channelID string, offset int, li
 		return nil, appErr
 	}
 
+	a.applyPostsWillBeConsumedHook(postList.Posts)
+
 	return postList, nil
 }
 
@@ -1034,6 +1052,8 @@ func (a *App) GetPermalinkPost(c request.CTX, postID string, userID string) (*mo
 		return nil, appErr
 	}
 
+	a.applyPostsWillBeConsumedHook(list.Posts)
+
 	return list, nil
 }
 
@@ -1062,6 +1082,8 @@ func (a *App) GetPostsBeforePost(options model.GetPostsOptions) (*model.PostList
 		return nil, appErr
 	}
 
+	a.applyPostsWillBeConsumedHook(postList.Posts)
+
 	return postList, nil
 }
 
@@ -1090,6 +1112,8 @@ func (a *App) GetPostsAfterPost(options model.GetPostsOptions) (*model.PostList,
 		return nil, appErr
 	}
 
+	a.applyPostsWillBeConsumedHook(postList.Posts)
+
 	return postList, nil
 }
 
@@ -1126,6 +1150,8 @@ func (a *App) GetPostsAroundPost(before bool, options model.GetPostsOptions) (*m
 		return nil, appErr
 	}
 
+	a.applyPostsWillBeConsumedHook(postList.Posts)
+
 	return postList, nil
 }
 
@@ -1135,6 +1161,8 @@ func (a *App) GetPostAfterTime(channelID string, time int64, collapsedThreads bo
 		return nil, model.NewAppError("GetPostAfterTime", "app.post.get_post_after_time.app_error", nil, "", http.StatusInternalServerError).Wrap(err)
 	}
 
+	a.applyPostWillBeConsumedHook(&post)
+
 	return post, nil
 }
 
@@ -2249,3 +2277,37 @@ func (a *App) GetPostInfo(c request.CTX, postID string) (*model.PostInfo, *model
 	}
 	return &info, nil
 }
+
+func (a *App) applyPostsWillBeConsumedHook(posts map[string]*model.Post) {
+	if !a.Config().FeatureFlags.ConsumePostHook {
+		return
+	}
+
+	postsSlice := make([]*model.Post, 0, len(posts))
+
+	for _, post := range posts {
+		postsSlice = append(postsSlice, post.ForPlugin())
+	}
+	a.ch.RunMultiHook(func(hooks plugin.Hooks) bool {
+		postReplacements := hooks.MessagesWillBeConsumed(postsSlice)
+		for _, postReplacement := range postReplacements {
+			posts[postReplacement.Id] = postReplacement
+		}
+		return true
+	}, plugin.MessagesWillBeConsumedID)
+}
+
+func (a *App) applyPostWillBeConsumedHook(post **model.Post) {
+	if !a.Config().FeatureFlags.ConsumePostHook {
+		return
+	}
+
+	ps := []*model.Post{*post}
+	a.ch.RunMultiHook(func(hooks plugin.Hooks) bool {
+		rp := hooks.MessagesWillBeConsumed(ps)
+		if len(rp) > 0 {
+			(*post) = rp[0]
+		}
+		return true
+	}, plugin.MessagesWillBeConsumedID)
+}