Post follow and updates notifications V1 (#111)

* It is now possible to follow a post in order to receive updates about it
* Notifications are now sent when updates are published
* Post status changes are now tracked
* Update sidebar now shows the post status history
* Mark a comment as a post update using the comment form
* ... more ...

app/controllers/comments_controller.rb

@@ -68,8 +68,30 @@ class CommentsController < ApplicationController
   end
 
   def send_notifications(comment)
-    if comment.post.user.notifications_enabled?
-      UserMailer.notify_post_owner(comment: comment).deliver_later
+    if comment.is_post_update # Post update
+      UserMailer.notify_followers_of_post_update(comment: comment).deliver_later
+      return
     end
+    
+    if comment.parent_id == nil # Reply to a post
+      user = comment.post.user
+      
+      if comment.user.id != user.id and
+         user.notifications_enabled? and
+         comment.post.follows.exists?(user_id: user.id)
+        
+        UserMailer.notify_post_owner(comment: comment).deliver_later
+      end
+    else # Reply to a comment
+      parent_comment = comment.parent
+      user = parent_comment.user
+
+      if user.notifications_enabled? and
+         parent_comment.user.id != comment.user.id
+        
+        UserMailer.notify_comment_owner(comment: comment).deliver_later
+      end
+    end
+    
   end
 end

app/controllers/follows_controller.rb

@@ -0,0 +1,53 @@
+class FollowsController < ApplicationController
+  before_action :authenticate_user!, only: [:create, :destroy]
+
+  def index
+    unless user_signed_in?
+      render json: { }
+      return
+    end
+
+    follow = Follow.find_by(follow_params)
+    render json: follow
+  end
+
+  def create
+    follow = Follow.new(follow_params)
+
+    if follow.save
+      render json: {
+        id: follow.id
+      }, status: :created
+    else
+      render json: {
+        error: I18n.t('errors.follows.create', message: follow.errors.full_messages)
+      }, status: :unprocessable_entity
+    end
+  end
+
+  def destroy
+    follow = Follow.find_by(follow_params)
+    id = follow.id
+    
+    return if follow.nil?
+
+    if follow.destroy
+      render json: {
+        id: id,
+      }, status: :accepted
+    else
+      render json: {
+        error: I18n.t('errors.follow.destroy', message: follow.errors.full_messages)
+      }, status: :unprocessable_entity
+    end
+  end
+
+  private
+
+    def follow_params
+      {
+        post_id: params[:post_id],
+        user_id: current_user.id,
+      }
+    end
+end

app/controllers/post_status_changes_controller.rb

@@ -0,0 +1,16 @@
+class PostStatusChangesController < ApplicationController
+  def index
+    post_status_changes = PostStatusChange
+      .select(
+        :post_status_id,
+        :updated_at,
+        'users.full_name as user_full_name',
+        'users.email as user_email',
+      )
+      .where(post_id: params[:post_id])
+      .left_outer_joins(:user)
+      .order(updated_at: :asc)
+
+    render json: post_status_changes
+  end
+end

app/controllers/posts_controller.rb

@@ -28,6 +28,8 @@ class PostsController < ApplicationController
     post = Post.new(post_params)
 
     if post.save
+      Follow.create(post_id: post.id, user_id: current_user.id)
+      
       render json: post, status: :created
     else
       render json: {
@@ -57,9 +59,27 @@ class PostsController < ApplicationController
     end
 
     post.board_id = params[:post][:board_id] if params[:post].has_key?(:board_id)
-    post.post_status_id = params[:post][:post_status_id] if params[:post].has_key?(:post_status_id)
+    
+    post_status_changed = false
+    
+    if params[:post].has_key?(:post_status_id) and
+       params[:post][:post_status_id] != post.post_status_id
+      
+      post_status_changed = true
+      post.post_status_id = params[:post][:post_status_id]
+    end
 
     if post.save
+      if post_status_changed
+        PostStatusChange.create(
+          user_id: current_user.id,
+          post_id: post.id,
+          post_status_id: post.post_status_id
+        )
+
+        send_notifications(post)
+      end
+
       render json: post, status: :no_content
     else
       render json: {
@@ -85,4 +105,8 @@ class PostsController < ApplicationController
         .permit(:title, :description, :board_id)
         .merge(user_id: current_user.id)
     end
+
+    def send_notifications(post)
+      UserMailer.notify_followers_of_post_status_change(post: post).deliver_later
+    end
 end

app/javascript/actions/Comment/handleCommentReplies.ts

@@ -11,6 +11,12 @@ interface SetCommentReplyBodyAction {
   body: string;
 }
 
+export const TOGGLE_COMMENT_IS_POST_UPDATE_FLAG = 'TOGGLE_COMMENT_IS_POST_UPDATE_FLAG';
+interface ToggleCommentIsPostUpdateFlag {
+  type: typeof TOGGLE_COMMENT_IS_POST_UPDATE_FLAG;
+  commentId: number;
+}
+
 export const toggleCommentReply = (commentId: number): ToggleCommentReplyAction => ({
   type: TOGGLE_COMMENT_REPLY,
   commentId,
@@ -22,6 +28,12 @@ export const setCommentReplyBody = (commentId: number, body: string): SetComment
   body,
 });
 
+export const toggleCommentIsPostUpdateFlag = (commentId: number): ToggleCommentIsPostUpdateFlag => ({
+  type: TOGGLE_COMMENT_IS_POST_UPDATE_FLAG,
+  commentId,
+});
+
 export type HandleCommentRepliesType =
   ToggleCommentReplyAction |
-  SetCommentReplyBodyAction;
+  SetCommentReplyBodyAction |
+  ToggleCommentIsPostUpdateFlag;

app/javascript/actions/Comment/submitComment.ts

@@ -52,6 +52,7 @@ export const submitComment = (
   postId: number,
   body: string,
   parentId: number,
+  isPostUpdate: boolean,
   authenticityToken: string,
 ): ThunkAction<void, State, null, Action<string>> => async (dispatch) => {
   dispatch(commentSubmitStart(parentId));
@@ -64,6 +65,7 @@ export const submitComment = (
         comment: {
           body,
           parent_id: parentId,
+          is_post_update: isPostUpdate,
         },
       }),
     });

app/javascript/actions/Follow/requestFollow.ts

@@ -0,0 +1,58 @@
+import { Action } from 'redux';
+import { ThunkAction } from 'redux-thunk';
+
+import IFollowJSON from '../../interfaces/json/IFollow';
+
+import { State } from '../../reducers/rootReducer';
+
+export const FOLLOW_REQUEST_START = 'FOLLOW_REQUEST_START';
+interface FollowRequestStartAction {
+  type: typeof FOLLOW_REQUEST_START;
+}
+
+export const FOLLOW_REQUEST_SUCCESS = 'FOLLOW_REQUEST_SUCCESS';
+interface FollowRequestSuccessAction {
+  type: typeof FOLLOW_REQUEST_SUCCESS;
+  follow: IFollowJSON;
+}
+
+export const FOLLOW_REQUEST_FAILURE = 'FOLLOW_REQUEST_FAILURE';
+interface FollowRequestFailureAction {
+  type: typeof FOLLOW_REQUEST_FAILURE;
+  error: string;
+}
+
+export type FollowRequestActionTypes =
+  FollowRequestStartAction |
+  FollowRequestSuccessAction |
+  FollowRequestFailureAction;
+
+const followRequestStart = (): FollowRequestActionTypes => ({
+  type: FOLLOW_REQUEST_START,
+});
+
+const followRequestSuccess = (
+  follow: IFollowJSON,
+): FollowRequestActionTypes => ({
+  type: FOLLOW_REQUEST_SUCCESS,
+  follow,
+});
+
+const followRequestFailure = (error: string): FollowRequestActionTypes => ({
+  type: FOLLOW_REQUEST_FAILURE,
+  error,
+});
+
+export const requestFollow = (
+  postId: number,
+): ThunkAction<void, State, null, Action<string>> => async (dispatch) => {
+  dispatch(followRequestStart());
+
+  try {
+    const response = await fetch(`/posts/${postId}/follows`);
+    const json = await response.json();
+    dispatch(followRequestSuccess(json));
+  } catch (e) {
+    dispatch(followRequestFailure(e));
+  }
+};

app/javascript/actions/Follow/submitFollow.ts

@@ -0,0 +1,47 @@
+import { Action } from "redux";
+import { ThunkAction } from "redux-thunk";
+
+import { State } from "../../reducers/rootReducer";
+import buildRequestHeaders from "../../helpers/buildRequestHeaders";
+import HttpStatus from "../../constants/http_status";
+import IFollowJSON from "../../interfaces/json/IFollow";
+
+export const FOLLOW_SUBMIT_SUCCESS = 'FOLLOW_SUBMIT_SUCCESS';
+interface FollowSubmitSuccessAction {
+  type: typeof FOLLOW_SUBMIT_SUCCESS,
+  postId: number;
+  isFollow: boolean;
+  follow: IFollowJSON;
+}
+
+export type FollowActionTypes = FollowSubmitSuccessAction;
+
+const followSubmitSuccess = (
+  postId: number,
+  isFollow: boolean,
+  follow: IFollowJSON,  
+): FollowSubmitSuccessAction => ({
+  type: FOLLOW_SUBMIT_SUCCESS,
+  postId,
+  isFollow,
+  follow,
+});
+
+export const submitFollow = (
+  postId: number,
+  isFollow: boolean,
+  authenticityToken: string,
+): ThunkAction<void, State, null, Action<string>> => async (dispatch) => {
+  try {
+    const res = await fetch(`/posts/${postId}/follows`, {
+      method: isFollow ? 'POST' : 'DELETE',
+      headers: buildRequestHeaders(authenticityToken),
+    });
+    const json = await res.json();
+
+    if (res.status === HttpStatus.Created || res.status === HttpStatus.Accepted)
+      dispatch(followSubmitSuccess(postId, isFollow, json));
+  } catch (e) {
+    console.log('An error occurred while following a post');
+  }
+}

app/javascript/actions/PostStatusChange/requestPostStatusChanges.ts

@@ -0,0 +1,58 @@
+import { Action } from 'redux';
+import { ThunkAction } from 'redux-thunk';
+
+import IPostStatusChangeJSON from '../../interfaces/json/IPostStatusChange';
+
+import { State } from '../../reducers/rootReducer';
+
+export const POST_STATUS_CHANGES_REQUEST_START = 'POST_STATUS_CHANGES_REQUEST_START';
+interface PostStatusChangesRequestStartAction {
+  type: typeof POST_STATUS_CHANGES_REQUEST_START;
+}
+
+export const POST_STATUS_CHANGES_REQUEST_SUCCESS = 'POST_STATUS_CHANGES_REQUEST_SUCCESS';
+interface PostStatusChangesRequestSuccessAction {
+  type: typeof POST_STATUS_CHANGES_REQUEST_SUCCESS;
+  postStatusChanges: Array<IPostStatusChangeJSON>;
+}
+
+export const POST_STATUS_CHANGES_REQUEST_FAILURE = 'POST_STATUS_CHANGES_REQUEST_FAILURE';
+interface PostStatusChangesRequestFailureAction {
+  type: typeof POST_STATUS_CHANGES_REQUEST_FAILURE;
+  error: string;
+}
+
+export type PostStatusChangesRequestActionTypes =
+  PostStatusChangesRequestStartAction |
+  PostStatusChangesRequestSuccessAction |
+  PostStatusChangesRequestFailureAction;
+
+const postStatusChangesRequestStart = (): PostStatusChangesRequestActionTypes => ({
+  type: POST_STATUS_CHANGES_REQUEST_START,
+});
+
+const postStatusChangesRequestSuccess = (
+  postStatusChanges: Array<IPostStatusChangeJSON>,
+): PostStatusChangesRequestActionTypes => ({
+  type: POST_STATUS_CHANGES_REQUEST_SUCCESS,
+  postStatusChanges,
+});
+
+const postStatusChangesRequestFailure = (error: string): PostStatusChangesRequestActionTypes => ({
+  type: POST_STATUS_CHANGES_REQUEST_FAILURE,
+  error,
+});
+
+export const requestPostStatusChanges = (
+  postId: number,
+): ThunkAction<void, State, null, Action<string>> => async (dispatch) => {
+  dispatch(postStatusChangesRequestStart());
+
+  try {
+    const response = await fetch(`/posts/${postId}/post_status_changes`);
+    const json = await response.json();
+    dispatch(postStatusChangesRequestSuccess(json));
+  } catch (e) {
+    dispatch(postStatusChangesRequestFailure(e));
+  }
+};

app/javascript/actions/PostStatusChange/submittedPostStatusChange.ts

@@ -0,0 +1,14 @@
+import IPostStatusChange from "../../interfaces/IPostStatusChange";
+
+export const POST_STATUS_CHANGE_SUBMITTED = 'POST_STATUS_CHANGE_SUBMITTED';
+export interface PostStatusChangeSubmitted {
+  type: typeof POST_STATUS_CHANGE_SUBMITTED;
+  postStatusChange: IPostStatusChange;
+}
+
+export const postStatusChangeSubmitted = (
+  postStatusChange: IPostStatusChange
+): PostStatusChangeSubmitted => ({
+  type: POST_STATUS_CHANGE_SUBMITTED,
+  postStatusChange,
+});

app/javascript/components/Comments/Comment.tsx

@@ -7,7 +7,7 @@ import { MutedText } from '../shared/CustomTexts';
 
 import { ReplyFormState } from '../../reducers/replyFormReducer';
 
-import friendlyDate from '../../helpers/friendlyDate';
+import friendlyDate from '../../helpers/datetime';
 
 interface Props {
   id: number;
@@ -21,7 +21,7 @@ interface Props {
   handleToggleCommentReply(): void;
   handleCommentReplyBodyChange(e: React.FormEvent): void;
   handleToggleIsCommentUpdate(commentId: number, currentIsPostUpdate: boolean): void;
-  handleSubmitComment(body: string, parentId: number): void;
+  handleSubmitComment(body: string, parentId: number, isPostUpdate: boolean): void;
 
   isLoggedIn: boolean;
   isPowerUser: boolean;
@@ -48,7 +48,7 @@ const Comment = ({
 }: Props) => (
   <div className="comment">
     <div className="commentHeader">
-      <Gravatar email={userEmail} size={24} className="gravatar" />
+      <Gravatar email={userEmail} size={28} className="gravatar" />
       <span className="commentAuthor">{userFullName}</span>
       { isPostUpdate ? <span className="postUpdateBadge">Post update</span> : null }
     </div>
@@ -89,12 +89,15 @@ const Comment = ({
         <NewComment
           body={replyForm.body}
           parentId={id}
+          postUpdateFlagValue={replyForm.isPostUpdate}
           isSubmitting={replyForm.isSubmitting}
           error={replyForm.error}
           handleChange={handleCommentReplyBodyChange}
+          handlePostUpdateFlag={() => null}
           handleSubmit={handleSubmitComment}
 
           isLoggedIn={isLoggedIn}
+          isPowerUser={isPowerUser}
           userEmail={currentUserEmail}
         />
         :

app/javascript/components/Comments/CommentList.tsx

@@ -14,7 +14,7 @@ interface Props {
   toggleCommentReply(commentId: number): void;
   setCommentReplyBody(commentId: number, body: string): void;
   handleToggleIsCommentUpdate(commentId: number, currentIsPostUpdate: boolean): void;
-  handleSubmitComment(body: string, parentId: number): void;
+  handleSubmitComment(body: string, parentId: number, isPostUpdate: boolean): void;
 
   isLoggedIn: boolean;
   isPowerUser: boolean;

app/javascript/components/Comments/CommentsP.tsx

@@ -23,6 +23,7 @@ interface Props {
   requestComments(postId: number, page?: number): void;
   toggleCommentReply(commentId: number): void;
   setCommentReplyBody(commentId: number, body: string): void;
+  toggleCommentIsPostUpdateFlag(): void;
   toggleCommentIsPostUpdate(
     postId: number,
     commentId: number,
@@ -33,6 +34,7 @@ interface Props {
     postId: number,
     body: string,
     parentId: number,
+    isPostUpdate: boolean,
     authenticityToken: string,
   ): void;
 }
@@ -51,11 +53,12 @@ class CommentsP extends React.Component<Props> {
     );
   }
 
-  _handleSubmitComment = (body: string, parentId: number) => {
+  _handleSubmitComment = (body: string, parentId: number, isPostUpdate: boolean) => {
     this.props.submitComment(
       this.props.postId,
       body,
       parentId,
+      isPostUpdate,
       this.props.authenticityToken,
     );
   }
@@ -73,6 +76,7 @@ class CommentsP extends React.Component<Props> {
 
       toggleCommentReply,
       setCommentReplyBody,
+      toggleCommentIsPostUpdateFlag,
     } = this.props;
 
     const postReply = replyForms.find(replyForm => replyForm.commentId === null);
@@ -82,6 +86,7 @@ class CommentsP extends React.Component<Props> {
         <NewComment
           body={postReply && postReply.body}
           parentId={null}
+          postUpdateFlagValue={postReply && postReply.isPostUpdate}
           isSubmitting={postReply && postReply.isSubmitting}
           error={postReply && postReply.error}
           handleChange={
@@ -89,9 +94,11 @@ class CommentsP extends React.Component<Props> {
               setCommentReplyBody(null, (e.target as HTMLTextAreaElement).value)
             )
           }
+          handlePostUpdateFlag={toggleCommentIsPostUpdateFlag}
           handleSubmit={this._handleSubmitComment}
 
           isLoggedIn={isLoggedIn}
+          isPowerUser={isPowerUser}
           userEmail={userEmail}
         />
 
@@ -99,7 +106,7 @@ class CommentsP extends React.Component<Props> {
         { error ? <DangerText>{error}</DangerText> : null }
 
         <div className="commentsTitle">
-          activity &bull; {comments.length} comments
+          activity &bull; {comments.length} comment{comments.length === 1 ? '' : 's'}
         </div>
 
         <CommentList

app/javascript/components/Comments/NewComment.tsx

@@ -1,6 +1,8 @@
 import * as React from 'react';
 import Gravatar from 'react-gravatar';
 
+import NewCommentUpdateSection from './NewCommentUpdateSection';
+
 import Button from '../shared/Button';
 import Spinner from '../shared/Spinner';
 import { DangerText } from '../shared/CustomTexts';
@@ -8,24 +10,34 @@ import { DangerText } from '../shared/CustomTexts';
 interface Props {
   body: string;
   parentId: number;
+  postUpdateFlagValue: boolean;
   isSubmitting: boolean;
   error: string;
   handleChange(e: React.FormEvent): void;
-  handleSubmit(body: string, parentId: number): void;
+  handlePostUpdateFlag(): void;
+  handleSubmit(
+    body: string,
+    parentId: number,
+    isPostUpdate: boolean
+  ): void;
 
   isLoggedIn: boolean;
+  isPowerUser: boolean;
   userEmail: string;
 }
 
 const NewComment = ({
   body,
   parentId,
+  postUpdateFlagValue,
   isSubmitting,
   error,
   handleChange,
+  handlePostUpdateFlag,
   handleSubmit,
 
   isLoggedIn,
+  isPowerUser,
   userEmail,
 }: Props) => (
   <React.Fragment>
@@ -33,18 +45,29 @@ const NewComment = ({
       {
         isLoggedIn ?
           <React.Fragment>
-            <Gravatar email={userEmail} size={36} className="currentUserAvatar" />
-            <textarea
-              value={body}
-              onChange={handleChange}
-              placeholder="Leave a comment"
-              className="newCommentBody"
-            />
-            <Button
-              onClick={() => handleSubmit(body, parentId)}
-              className="submitCommentButton">
-              { isSubmitting ? <Spinner color="light" /> : 'Submit' }
-            </Button>
+            <div className="commentBodyForm">
+              <Gravatar email={userEmail} size={48} className="currentUserAvatar" />
+              <textarea
+                value={body}
+                onChange={handleChange}
+                placeholder="Leave a comment"
+                className="newCommentBody"
+              />
+              <Button
+                onClick={() => handleSubmit(body, parentId, postUpdateFlagValue)}
+                className="submitCommentButton">
+                { isSubmitting ? <Spinner color="light" /> : 'Submit' }
+              </Button>
+            </div>
+            {
+              isPowerUser && parentId == null ?
+                <NewCommentUpdateSection
+                  postUpdateFlagValue={postUpdateFlagValue}
+                  handlePostUpdateFlag={handlePostUpdateFlag}
+                />
+              :
+                null
+            }
           </React.Fragment>
         :
           <a href="/users/sign_in" className="loginInfo">You need to log in to post comments.</a>

app/javascript/components/Comments/NewCommentUpdateSection.tsx

@@ -0,0 +1,33 @@
+import * as React from 'react';
+import { MutedText } from '../shared/CustomTexts';
+
+interface Props {
+  postUpdateFlagValue: boolean;
+  handlePostUpdateFlag(): void;
+}
+
+const NewCommentUpdateSection = ({
+  postUpdateFlagValue,
+  handlePostUpdateFlag,
+}: Props) => (
+  <div className="commentIsUpdateForm">
+    <div>
+      <input
+        id="isPostUpdateFlag"
+        type="checkbox"
+        onChange={handlePostUpdateFlag}
+        checked={postUpdateFlagValue || false}
+      />
+      &nbsp;
+      <label htmlFor="isPostUpdateFlag">Mark as post update</label>
+    </div>
+    {
+      postUpdateFlagValue ?
+        <MutedText>Users that follow this post will be notified</MutedText>
+      :
+        null
+    }
+  </div>
+);
+
+export default NewCommentUpdateSection;

app/javascript/components/Post/ActionBox.tsx

@@ -0,0 +1,33 @@
+import * as React from 'react';
+import Button from '../shared/Button';
+
+import { BoxTitleText, SmallMutedText } from '../shared/CustomTexts';
+
+interface Props {
+  followed: boolean;
+  submitFollow(): void;
+
+  isLoggedIn: boolean;
+}
+
+const ActionBox = ({followed, submitFollow, isLoggedIn}: Props) => (
+  <div className="actionBoxContainer">
+    <div className="actionBoxFollow">
+      <BoxTitleText>Actions</BoxTitleText>
+      <br />
+      <Button onClick={isLoggedIn ? submitFollow : () => location.href = '/users/sign_in'} outline>
+        { followed ? 'Unfollow post' : 'Follow post' }
+      </Button>
+      <br />
+      <SmallMutedText>
+        { followed ?
+          'you\'re receiving notifications about new updates on this post'
+          :
+          'you won\'t receive notifications about this post'
+        }
+      </SmallMutedText>
+    </div>
+  </div>
+);
+
+export default ActionBox;

app/javascript/components/Post/PostP.tsx

@@ -4,7 +4,9 @@ import IPost from '../../interfaces/IPost';
 import IPostStatus from '../../interfaces/IPostStatus';
 import IBoard from '../../interfaces/IBoard';
 
+import PostUpdateList from './PostUpdateList';
 import LikeList from './LikeList';
+import ActionBox from './ActionBox';
 import LikeButton from '../../containers/LikeButton';
 import PostBoardSelect from './PostBoardSelect';
 import PostStatusSelect from './PostStatusSelect';
@@ -13,25 +15,31 @@ import PostStatusLabel from '../shared/PostStatusLabel';
 import Comments from '../../containers/Comments';
 import { MutedText } from '../shared/CustomTexts';
 
-import friendlyDate from '../../helpers/friendlyDate';
 import { LikesState } from '../../reducers/likesReducer';
 import { CommentsState } from '../../reducers/commentsReducer';
-import PostUpdateList from './PostUpdateList';
+import { PostStatusChangesState } from '../../reducers/postStatusChangesReducer';
+
+import friendlyDate, { fromRailsStringToJavascriptDate } from '../../helpers/datetime';
 
 interface Props {
   postId: number;
   post: IPost;
   likes: LikesState;
+  followed: boolean;
   comments: CommentsState;
+  postStatusChanges: PostStatusChangesState;
   boards: Array<IBoard>;
   postStatuses: Array<IPostStatus>;
   isLoggedIn: boolean;
   isPowerUser: boolean;
+  userFullName: string;
   userEmail: string;
   authenticityToken: string;
 
   requestPost(postId: number): void;
   requestLikes(postId: number): void;
+  requestFollow(postId: number): void;
+  requestPostStatusChanges(postId: number): void;
   changePostBoard(
     postId: number,
     newBoardId: number,
@@ -40,38 +48,62 @@ interface Props {
   changePostStatus(
     postId: number,
     newPostStatusId: number,
+    userFullName: string,
+    userEmail: string,
+    authenticityToken: string,
+  ): void;
+  submitFollow(
+    postId: number,
+    isFollow: boolean,
     authenticityToken: string,
   ): void;
 }
 
 class PostP extends React.Component<Props> {
   componentDidMount() {
-    this.props.requestPost(this.props.postId);
-    this.props.requestLikes(this.props.postId);
+    const {postId} = this.props;
+
+    this.props.requestPost(postId);
+    this.props.requestLikes(postId);
+    this.props.requestFollow(postId);
+    this.props.requestPostStatusChanges(postId);
   }
 
   render() {
     const {
       post,
       likes,
+      followed,
       comments,
+      postStatusChanges,
       boards,
       postStatuses,
 
       isLoggedIn,
       isPowerUser,
+      userFullName,
       userEmail,
       authenticityToken,
 
       changePostBoard,
       changePostStatus,
+      submitFollow,
     } = this.props;
 
+    const postUpdates = [
+      ...comments.items.filter(comment => comment.isPostUpdate === true),
+      ...postStatusChanges.items,
+    ].sort(
+      (a, b) =>
+      fromRailsStringToJavascriptDate(a.updatedAt) < fromRailsStringToJavascriptDate(b.updatedAt) ? 1 : -1
+    );
+
     return (
       <div className="pageContainer">
         <div className="sidebar">
           <PostUpdateList
-            postUpdates={comments.items.filter(comment => comment.isPostUpdate === true)}
+            postUpdates={postUpdates}
+            postStatuses={postStatuses}
             areLoading={comments.areLoading}
             error={comments.error}
           />
@@ -81,6 +113,13 @@ class PostP extends React.Component<Props> {
             areLoading={likes.areLoading}
             error={likes.error}
           />
+
+          <ActionBox
+            followed={followed}
+            submitFollow={() => submitFollow(post.id, !followed, authenticityToken)}
+
+            isLoggedIn={isLoggedIn}
+          />
         </div>
 
         <div className="postAndCommentsContainer">
@@ -113,7 +152,8 @@ class PostP extends React.Component<Props> {
                     postStatuses={postStatuses}
                     selectedPostStatusId={post.postStatusId}
                     handleChange={
-                      newPostStatusId => changePostStatus(post.id, newPostStatusId, authenticityToken)
+                      newPostStatusId =>
+                        changePostStatus(post.id, newPostStatusId, userFullName, userEmail, authenticityToken)
                     }
                   />
                 </div>

app/javascript/components/Post/PostUpdateList.tsx

@@ -5,17 +5,22 @@ import { BoxTitleText, DangerText, CenteredMutedText, MutedText } from '../share
 import Spinner from '../shared/Spinner';
 
 import IComment from '../../interfaces/IComment';
+import IPostStatusChange from '../../interfaces/IPostStatusChange';
+import IPostStatus from '../../interfaces/IPostStatus';
 
-import friendlyDate from '../../helpers/friendlyDate';
+import friendlyDate from '../../helpers/datetime';
+import PostStatusLabel from '../shared/PostStatusLabel';
 
 interface Props {
-  postUpdates: Array<IComment>;
+  postUpdates: Array<IComment | IPostStatusChange>;
+  postStatuses: Array<IPostStatus>
   areLoading: boolean;
   error: string;
 }
 
 const PostUpdateList = ({
   postUpdates,
+  postStatuses,
   areLoading,
   error,
 }: Props) => (
@@ -33,7 +38,18 @@ const PostUpdateList = ({
               <span>{postUpdate.userFullName}</span>
             </div>
 
-            <p className="postUpdateListItemBody">{postUpdate.body}</p>
+            <p className="postUpdateListItemBody">
+              { 'body' in postUpdate ?
+                  postUpdate.body
+                :
+                  <React.Fragment>
+                    <i>changed status to</i>&nbsp;
+                    <PostStatusLabel
+                      {...postStatuses.find(postStatus => postStatus.id === postUpdate.postStatusId)}
+                    />
+                  </React.Fragment>  
+              }
+            </p>
 
             <MutedText>{friendlyDate(postUpdate.updatedAt)}</MutedText>
           </div>

app/javascript/components/Post/index.tsx

@@ -17,6 +17,7 @@ interface Props {
   postStatuses: Array<IPostStatus>;
   isLoggedIn: boolean;
   isPowerUser: boolean;
+  userFullName: string;
   userEmail: string;
   authenticityToken: string;
 }
@@ -37,6 +38,7 @@ class PostRoot extends React.Component<Props> {
       postStatuses,
       isLoggedIn,
       isPowerUser,
+      userFullName,
       userEmail,
       authenticityToken
     } = this.props;
@@ -50,6 +52,7 @@ class PostRoot extends React.Component<Props> {
 
           isLoggedIn={isLoggedIn}
           isPowerUser={isPowerUser}
+          userFullName={userFullName}
           userEmail={userEmail}
           authenticityToken={authenticityToken}
         />

app/javascript/components/shared/CustomTexts.tsx

@@ -25,6 +25,10 @@ export const CenteredMutedText = ({ children }: Props) => (
   <p className="centeredText"><span className="mutedText">{children}</span></p>
 );
 
+export const SmallMutedText = ({ children }: Props) => (
+  <p className="smallMutedText">{children}</p>
+);
+
 export const UppercaseText = ({ children }: Props) => (
   <span className="uppercaseText">{children}</span>
 );

app/javascript/components/shared/PostStatusLabel.tsx

@@ -9,8 +9,8 @@ const PostStatusLabel = ({
   name,
   color,
 }: Props) => (
-  <span className="badge" style={{backgroundColor: color, color: 'white'}}>
-    {name?.toUpperCase()}
+  <span className="badge" style={{backgroundColor: color || 'black', color: 'white'}}>
+    {(name || 'no status').toUpperCase()}
   </span>
 );
 

app/javascript/containers/Comments.tsx

@@ -4,6 +4,7 @@ import { requestComments } from '../actions/Comment/requestComments';
 import {
   toggleCommentReply,
   setCommentReplyBody,
+  toggleCommentIsPostUpdateFlag,
 } from '../actions/Comment/handleCommentReplies';
 import { toggleCommentIsUpdate } from '../actions/Comment/updateComment';
 import { submitComment } from '../actions/Comment/submitComment';
@@ -32,6 +33,10 @@ const mapDispatchToProps = (dispatch) => ({
     dispatch(setCommentReplyBody(commentId, body));
   },
 
+  toggleCommentIsPostUpdateFlag() {
+    dispatch(toggleCommentIsPostUpdateFlag(null));
+  },
+
   toggleCommentIsPostUpdate(
     postId: number,
     commentId: number,
@@ -45,9 +50,10 @@ const mapDispatchToProps = (dispatch) => ({
     postId: number,
     body: string,
     parentId: number,
+    isPostUpdate: boolean,
     authenticityToken: string,
   ) {
-    dispatch(submitComment(postId, body, parentId, authenticityToken));
+    dispatch(submitComment(postId, body, parentId, isPostUpdate, authenticityToken));
   },
 });
 

app/javascript/containers/Post.tsx

@@ -4,15 +4,23 @@ import { requestPost } from '../actions/Post/requestPost';
 import { requestLikes } from '../actions/Like/requestLikes';
 import { changePostBoard } from '../actions/Post/changePostBoard';
 import { changePostStatus } from '../actions/Post/changePostStatus';
+import { submitFollow } from '../actions/Follow/submitFollow';
+import { requestFollow } from '../actions/Follow/requestFollow';
+import { requestPostStatusChanges } from '../actions/PostStatusChange/requestPostStatusChanges';
+import { postStatusChangeSubmitted } from '../actions/PostStatusChange/submittedPostStatusChange';
 
 import { State } from '../reducers/rootReducer';
 
 import PostP from '../components/Post/PostP';
 
+import { fromJavascriptDateToRailsString } from '../helpers/datetime';
+
 const mapStateToProps = (state: State) => ({
   post: state.currentPost.item,
   likes: state.currentPost.likes,
+  followed: state.currentPost.followed,
   comments: state.currentPost.comments,
+  postStatusChanges: state.currentPost.postStatusChanges,
 });
 
 const mapDispatchToProps = (dispatch) => ({
@@ -24,14 +32,41 @@ const mapDispatchToProps = (dispatch) => ({
     dispatch(requestLikes(postId));
   },
 
+  requestFollow(postId: number) {
+    dispatch(requestFollow(postId));
+  },
+
+  requestPostStatusChanges(postId: number) {
+    dispatch(requestPostStatusChanges(postId));
+  },
+
   changePostBoard(postId: number, newBoardId: number, authenticityToken: string) {
     dispatch(changePostBoard(postId, newBoardId, authenticityToken));
   },
 
-  changePostStatus(postId: number, newPostStatusId: number, authenticityToken: string) {
+  changePostStatus(
+    postId: number,
+    newPostStatusId: number,
+    userFullName: string,
+    userEmail: string,
+    authenticityToken: string
+  ) {
     if (isNaN(newPostStatusId)) newPostStatusId = null;
 
-    dispatch(changePostStatus(postId, newPostStatusId, authenticityToken));
+    dispatch(changePostStatus(postId, newPostStatusId, authenticityToken)).then(res => {
+      if (res && res.status !== 204) return;
+
+      dispatch(postStatusChangeSubmitted({
+        postStatusId: newPostStatusId,
+        userFullName,
+        userEmail,
+        updatedAt: fromJavascriptDateToRailsString(new Date()),
+      }));
+    });
+  },
+
+  submitFollow(postId: number, isFollow: boolean, authenticityToken: string) {
+    dispatch(submitFollow(postId, isFollow, authenticityToken));
   },
 });
 

app/javascript/helpers/datetime.ts

@@ -1,4 +1,4 @@
-const friendlyDate = date => {
+export const friendlyDate = date => {
   var now = new Date();
   var timeStamp = fromRailsStringToJavascriptDate(date);
 
@@ -7,13 +7,13 @@ const friendlyDate = date => {
   if (secondsPast < 60) {
     return 'just now';
   } else if (secondsPast < 3600) {
-    let minutesPast = parseInt(secondsPast / 60);
+    let minutesPast = Math.round(secondsPast / 60);
     return minutesPast + ' ' + (minutesPast === 1 ? 'minute' : 'minutes') + ' ago';
   } else if (secondsPast <= 86400) {
-    let hoursPast = parseInt(secondsPast / 3600);
+    let hoursPast = Math.round(secondsPast / 3600);
     return hoursPast + ' ' + (hoursPast === 1 ? 'hour' : 'hours') + ' ago';
   } else {
-    let daysPast = parseInt(secondsPast / 86400);
+    let daysPast = Math.round(secondsPast / 86400);
     return daysPast + ' ' + (daysPast === 1 ? 'day' : 'days') + ' ago';
   }
 }
@@ -24,9 +24,13 @@ export default friendlyDate;
   Converts the default Rails datetime string
   format to a JavaScript Date object.
 */
-const fromRailsStringToJavascriptDate = date => {
+export const fromRailsStringToJavascriptDate = date => {
   let dateOnly = date.slice(0, 10);
   let timeOnly = date.slice(11, 19);
   
   return new Date(`${dateOnly}T${timeOnly}Z`);
+}
+
+export const fromJavascriptDateToRailsString = (date: Date) => {
+  return date.toJSON();
 }

app/javascript/interfaces/IPostStatusChange.ts

@@ -0,0 +1,8 @@
+interface IPostStatusChange {
+  postStatusId: number;
+  userFullName: string;
+  userEmail: string;
+  updatedAt: string;
+}
+
+export default IPostStatusChange;

app/javascript/interfaces/json/IFollow.ts

@@ -0,0 +1,7 @@
+interface IFollowJSON {
+  id: number;
+  user_id: number;
+  post_id: number;
+}
+
+export default IFollowJSON;

app/javascript/interfaces/json/IPostStatusChange.ts

@@ -0,0 +1,8 @@
+interface IPostStatusChangeJSON {
+  post_status_id: number;
+  user_full_name: string;
+  user_email: string;
+  updated_at: string;
+}
+
+export default IPostStatusChangeJSON;

app/javascript/reducers/commentsReducer.ts

@@ -11,6 +11,7 @@ import {
   HandleCommentRepliesType,
   TOGGLE_COMMENT_REPLY,
   SET_COMMENT_REPLY_BODY,
+  TOGGLE_COMMENT_IS_POST_UPDATE_FLAG,
 } from '../actions/Comment/handleCommentReplies';
 
 import {
@@ -82,6 +83,7 @@ const commentsReducer = (
 
     case TOGGLE_COMMENT_REPLY:
     case SET_COMMENT_REPLY_BODY:
+    case TOGGLE_COMMENT_IS_POST_UPDATE_FLAG:
       return {
         ...state,
         replyForms: replyFormsReducer(state.replyForms, action),

app/javascript/reducers/currentPostReducer.ts

@@ -38,6 +38,7 @@ import {
   HandleCommentRepliesType,
   TOGGLE_COMMENT_REPLY,
   SET_COMMENT_REPLY_BODY,
+  TOGGLE_COMMENT_IS_POST_UPDATE_FLAG,
 } from '../actions/Comment/handleCommentReplies';
 
 import {
@@ -52,21 +53,40 @@ import {
   TOGGLE_COMMENT_IS_UPDATE_SUCCESS,
 } from '../actions/Comment/updateComment';
 
+import { FollowActionTypes, FOLLOW_SUBMIT_SUCCESS } from '../actions/Follow/submitFollow';
+import { FollowRequestActionTypes, FOLLOW_REQUEST_SUCCESS } from '../actions/Follow/requestFollow';
+
+import {
+  PostStatusChangesRequestActionTypes,
+  POST_STATUS_CHANGES_REQUEST_START,
+  POST_STATUS_CHANGES_REQUEST_SUCCESS,
+  POST_STATUS_CHANGES_REQUEST_FAILURE,
+} from '../actions/PostStatusChange/requestPostStatusChanges';
+
+import {
+  PostStatusChangeSubmitted,
+  POST_STATUS_CHANGE_SUBMITTED
+} from '../actions/PostStatusChange/submittedPostStatusChange';
+
 import postReducer from './postReducer';
 import likesReducer from './likesReducer';
 import commentsReducer from './commentsReducer';
 
 import { LikesState } from './likesReducer';
 import { CommentsState } from './commentsReducer';
+import postStatusChangesReducer, { PostStatusChangesState } from './postStatusChangesReducer';
 
 import IPost from '../interfaces/IPost';
 
+
 interface CurrentPostState {
   item: IPost;
   isLoading: boolean;
   error: string;
   likes: LikesState;
+  followed: boolean;
   comments: CommentsState;
+  postStatusChanges: PostStatusChangesState,
 }
 
 const initialState: CurrentPostState = {
@@ -74,7 +94,9 @@ const initialState: CurrentPostState = {
   isLoading: false,
   error: '',
   likes: likesReducer(undefined, {} as LikesRequestActionTypes),
+  followed: false,
   comments: commentsReducer(undefined, {} as CommentsRequestActionTypes),
+  postStatusChanges: postStatusChangesReducer(undefined, {} as PostStatusChangesRequestActionTypes),
 };
 
 const currentPostReducer = (
@@ -88,7 +110,11 @@ const currentPostReducer = (
     CommentsRequestActionTypes |
     HandleCommentRepliesType |
     CommentSubmitActionTypes |
-    ToggleIsUpdateSuccessAction
+    ToggleIsUpdateSuccessAction |
+    FollowActionTypes |
+    FollowRequestActionTypes |
+    PostStatusChangesRequestActionTypes |
+    PostStatusChangeSubmitted
 ): CurrentPostState => {
   switch (action.type) {
     case POST_REQUEST_START:
@@ -137,11 +163,33 @@ const currentPostReducer = (
     case COMMENT_SUBMIT_SUCCESS:
     case COMMENT_SUBMIT_FAILURE:
     case TOGGLE_COMMENT_IS_UPDATE_SUCCESS:
+    case TOGGLE_COMMENT_IS_POST_UPDATE_FLAG:
       return {
         ...state,
         comments: commentsReducer(state.comments, action),
       };
 
+    case FOLLOW_REQUEST_SUCCESS:
+      return {
+        ...state,
+        followed: action.follow.user_id ? true : false,
+      };
+      
+    case FOLLOW_SUBMIT_SUCCESS:
+      return {
+        ...state,
+        followed: action.isFollow,
+      };
+
+    case POST_STATUS_CHANGES_REQUEST_START:
+    case POST_STATUS_CHANGES_REQUEST_SUCCESS:
+    case POST_STATUS_CHANGES_REQUEST_FAILURE:
+    case POST_STATUS_CHANGE_SUBMITTED:
+      return {
+        ...state,
+        postStatusChanges: postStatusChangesReducer(state.postStatusChanges, action),
+      };
+
     default:
       return state;
   }

app/javascript/reducers/postStatusChangesReducer.ts

@@ -0,0 +1,71 @@
+import {
+  PostStatusChangesRequestActionTypes,
+  POST_STATUS_CHANGES_REQUEST_START,
+  POST_STATUS_CHANGES_REQUEST_SUCCESS,
+  POST_STATUS_CHANGES_REQUEST_FAILURE,
+} from "../actions/PostStatusChange/requestPostStatusChanges";
+
+import {
+  PostStatusChangeSubmitted,
+  POST_STATUS_CHANGE_SUBMITTED
+} from '../actions/PostStatusChange/submittedPostStatusChange';
+
+import IPostStatusChange from "../interfaces/IPostStatusChange";
+
+export interface PostStatusChangesState {
+  items: Array<IPostStatusChange>;
+  areLoading: boolean;
+  error: string;
+}
+
+const initialState: PostStatusChangesState = {
+  items: [],
+  areLoading: false,
+  error: '',
+};
+
+const postStatusChangesReducer = (
+  state = initialState,
+  action:
+    PostStatusChangesRequestActionTypes |
+    PostStatusChangeSubmitted
+) => {
+  switch (action.type) {
+    case POST_STATUS_CHANGES_REQUEST_START:
+      return {
+        ...state,
+        areLoading: true,
+      };
+
+    case POST_STATUS_CHANGES_REQUEST_SUCCESS:
+      return {
+        ...state,
+        items: action.postStatusChanges.map(postStatusChange => ({
+          postStatusId: postStatusChange.post_status_id,
+          userFullName: postStatusChange.user_full_name,
+          userEmail: postStatusChange.user_email,
+          updatedAt: postStatusChange.updated_at,
+        })),
+        areLoading: false,
+        error: '',
+      };
+
+    case POST_STATUS_CHANGES_REQUEST_FAILURE:
+      return {
+        ...state,
+        areLoading: false,
+        error: action.error,
+      };
+
+    case POST_STATUS_CHANGE_SUBMITTED:
+      return {
+        ...state,
+        items: [action.postStatusChange, ...state.items],
+      };
+
+    default:
+      return state;
+  }
+}
+
+export default postStatusChangesReducer;

app/javascript/reducers/replyFormReducer.ts

@@ -7,6 +7,7 @@ import {
   HandleCommentRepliesType,
   TOGGLE_COMMENT_REPLY,
   SET_COMMENT_REPLY_BODY,
+  TOGGLE_COMMENT_IS_POST_UPDATE_FLAG,
 } from '../actions/Comment/handleCommentReplies';
 
 import {
@@ -20,6 +21,7 @@ export interface ReplyFormState {
   commentId: number;
   isOpen: boolean;
   body: string;
+  isPostUpdate: boolean;
   isSubmitting: boolean;
   error: string;
 }
@@ -28,6 +30,7 @@ const initialState: ReplyFormState = {
   commentId: undefined,
   isOpen: false,
   body: '',
+  isPostUpdate: false,
   isSubmitting: false,
   error: '',
 }
@@ -58,6 +61,12 @@ const replyFormReducer = (
         body: action.body,
       };
 
+    case TOGGLE_COMMENT_IS_POST_UPDATE_FLAG:
+      return {
+        ...state,
+        isPostUpdate: !state.isPostUpdate,
+      };
+
     case COMMENT_SUBMIT_START:
       return {
         ...state,
@@ -69,6 +78,7 @@ const replyFormReducer = (
         ...state,
         isOpen: false,
         body: '',
+        isPostUpdate: false,
         isSubmitting: false,
         error: '',
       };

app/javascript/reducers/replyFormsReducer.ts

@@ -9,6 +9,7 @@ import {
   HandleCommentRepliesType,
   TOGGLE_COMMENT_REPLY,
   SET_COMMENT_REPLY_BODY,
+  TOGGLE_COMMENT_IS_POST_UPDATE_FLAG,
 } from '../actions/Comment/handleCommentReplies';
 
 import {
@@ -42,6 +43,7 @@ const ReplyFormsReducer = (
 
     case TOGGLE_COMMENT_REPLY:
     case SET_COMMENT_REPLY_BODY:
+    case TOGGLE_COMMENT_IS_POST_UPDATE_FLAG:
       return (
         state.map(
           replyForm => (

app/javascript/stylesheets/components/Comments.scss

@@ -1,9 +1,25 @@
 .commentsContainer {
+  @extend .my-3;
+
   .newCommentForm {
     @extend
       .d-flex,
+      .flex-column,
       .my-3;
 
+    .commentBodyForm {
+      @extend .d-flex;
+    }
+
+    .commentIsUpdateForm {
+      @extend
+        .d-flex,
+        .justify-content-between,
+        .mt-3;
+
+      margin-left: 48px;
+    }
+
     .currentUserAvatar {
       @extend
         .gravatar,

app/javascript/stylesheets/components/Post.scss

@@ -17,7 +17,9 @@
       @extend .sidebarCard;
 
       .postUpdateList {
-        @extend .w-100;
+        @extend
+          .scroll-shadows,
+          .w-100;
 
         max-height: 250px;
         overflow-y: scroll;
@@ -26,8 +28,16 @@
           @extend
             .d-flex,
             .flex-column,
-            .p-2,
-            .my-1;
+            .p-2;
+
+          &:after { // displays the little centered border under each post update
+            content: "";
+            display: block;
+            margin: 0 auto;
+            width: 25%;
+            padding-top: 16px;
+            border-bottom: 1px solid rgba(0, 0, 0, 0.1);
+          }
 
           .postUpdateListItemHeader {
             @extend .d-flex;
@@ -42,7 +52,7 @@
           }
 
           .postUpdateListItemBody {
-            @extend .m-0;
+            @extend .my-1;
 
             font-size: 15px;
           }
@@ -54,7 +64,9 @@
       @extend .sidebarCard;
 
       .likeList {
-        @extend .w-100;
+        @extend
+          .scroll-shadows,
+          .w-100;
 
         max-height: 170px;
         overflow-y: scroll;
@@ -69,7 +81,19 @@
           }
         }
       }
-    } 
+    }
+
+    .actionBoxContainer {
+      @extend
+        .sidebarCard,
+        .text-center;
+
+      .btn {
+        @extend
+          .mt-3,
+          .mb-1;
+      }
+    }
   }
 
   .postAndCommentsContainer {

app/javascript/stylesheets/general/_components.scss

@@ -72,7 +72,7 @@ a {
       .mb-3,
       .p-2;
 
-    width: 250px;
+    width: 280px;
     margin-right: 16px;
   }
 }

app/javascript/stylesheets/general/_custom_texts.scss

@@ -27,6 +27,15 @@
   color: $muted-text-color;
 }
 
+.smallMutedText {
+  @extend
+    .mutedText,
+    .m-0;
+  
+  font-size: smaller;
+  line-height: 95%;
+}
+
 .uppercaseText {
   @extend
     .text-secondary,

app/javascript/stylesheets/general/_index.scss

@@ -4,7 +4,7 @@
 */
 
 .container {
-  max-width: 920px;
+  max-width: 960px;
 }
 
 .turbolinks-progress-bar {
@@ -34,4 +34,41 @@
   color: #fff;
   background-color: #343a40;
   border-color: #343a40;
+}
+
+// Credits: https://codepen.io/chriscoyier/pen/YzXBYvL
+.scroll-shadows {
+  max-height: 200px;
+  overflow: auto;
+
+  background:
+    /* Shadow Cover TOP */
+    linear-gradient(
+      white 30%,
+      rgba(255, 255, 255, 0)
+    ) center top,
+    
+    /* Shadow Cover BOTTOM */
+    linear-gradient(
+      rgba(255, 255, 255, 0), 
+      white 70%
+    ) center bottom,
+    
+    /* Shadow TOP */
+    radial-gradient(
+      farthest-side at 50% 0,
+      rgba(0, 0, 0, 0.2),
+      rgba(0, 0, 0, 0)
+    ) center top,
+    
+    /* Shadow BOTTOM */
+    radial-gradient(
+      farthest-side at 50% 100%,
+      rgba(0, 0, 0, 0.2),
+      rgba(0, 0, 0, 0)
+    ) center bottom;
+  
+  background-repeat: no-repeat;
+  background-size: 100% 40px, 100% 40px, 100% 10px, 100% 10px;
+  background-attachment: local, local, scroll, scroll;
 }

app/mailers/application_mailer.rb

@@ -1,4 +1,4 @@
 class ApplicationMailer < ActionMailer::Base
-  default from: 'from@example.com'
+  default from: "notifications@example.com"
   layout 'mailer'
 end

app/mailers/user_mailer.rb

@@ -1,10 +1,45 @@
 class UserMailer < ApplicationMailer
-  default from: "notifications@example.com"
-
   def notify_post_owner(comment:)
     @comment = comment
     @user = comment.post.user
 
-    mail(to: @user.email, subject: "[#{ENV.fetch('APP_NAME')}] - New comment on #{comment.post.title}")
+    mail(
+      to: @user.email,
+      subject: "[#{app_name}] New comment on #{comment.post.title}"
+    )
   end
+
+  def notify_comment_owner(comment:)
+    @comment = comment
+    @user = comment.parent.user
+
+    mail(
+      to: @user.email,
+      subject: "[#{app_name}] New reply on your comment from #{comment.post.title}"
+    )
+  end
+
+  def notify_followers_of_post_update(comment:)
+    @comment = comment
+
+    mail(
+      to: comment.post.followers.pluck(:email),
+      subject: "[#{app_name}] New update on #{comment.post.title}"
+    )
+  end
+
+  def notify_followers_of_post_status_change(post:)
+    @post = post
+
+    mail(
+      to: post.followers.pluck(:email),
+      subject: "[#{app_name}] Status change on post #{post.title}"
+    )
+  end
+
+  private
+
+    def app_name
+      ENV.fetch('APP_NAME')
+    end
 end

app/models/follow.rb

@@ -0,0 +1,6 @@
+class Follow < ApplicationRecord
+  belongs_to :user
+  belongs_to :post
+
+  validates :user_id, uniqueness: { scope: :post_id }
+end

app/models/post.rb

@@ -2,8 +2,12 @@ class Post < ApplicationRecord
   belongs_to :board
   belongs_to :user
   belongs_to :post_status, optional: true
+
   has_many :likes, dependent: :destroy
+  has_many :follows, dependent: :destroy
+  has_many :followers, through: :follows, source: :user
   has_many :comments, dependent: :destroy
+  has_many :post_status_changes, dependent: :destroy
 
   validates :title, presence: true, length: { in: 4..64 }
 

app/models/post_status_change.rb

@@ -0,0 +1,5 @@
+class PostStatusChange < ApplicationRecord
+  belongs_to :user
+  belongs_to :post
+  belongs_to :post_status, optional: true
+end

app/views/devise/registrations/edit.html.erb

@@ -17,7 +17,7 @@
   </div>
 
   <div class="form-group">
-    <%= f.label :notifications_enabled %> <br />
+    <%= f.label :notifications_enabled %>&nbsp;
     <%= f.check_box :notifications_enabled, style: "transform: scale(1.5)" %>
     <small id="notificationsHelp" class="form-text text-muted">
       if disabled, you won't receive any notification

app/views/posts/show.html.erb

@@ -7,6 +7,7 @@
       postStatuses: @post_statuses,
       isLoggedIn: user_signed_in?,
       isPowerUser: user_signed_in? ? current_user.power_user? : false,
+      userFullName: user_signed_in? ? current_user.full_name : nil,
       userEmail: user_signed_in? ? current_user.email : nil,
       authenticityToken: form_authenticity_token,
     }

app/views/user_mailer/notify_comment_owner.html.erb

@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <meta content='text/html; charset=utf-8' http-equiv='content-type' />
+  </head>
+  <body>
+    <h1>Hello, <%= @user.full_name %></h1>
+    <p>
+      There is a new reply by <b><%= @comment.user.full_name %></b> on your comment from post <b><%= @comment.post.title %></b>:
+    </p>
+    <p>
+      <i><%= @comment.body %></i>
+    </p>
+    <p>
+      <%= link_to "Click here", post_url(@comment.post) %> to have your say!
+    </p>
+    <p>
+      Have a great day!
+    </p>
+  </body>
+  <footer>
+    Annoyed? You can <%= link_to("turn off notifications here", edit_user_registration_url) %>.
+  </footer>
+</html>

app/views/user_mailer/notify_followers_of_post_status_change.erb

@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <meta content='text/html; charset=utf-8' http-equiv='content-type' />
+  </head>
+  <body>
+    <h1>Hello!</h1>
+    <p>
+      The post you're following <b><%= @post.title %></b> has a new status:
+      <span style='background-color: <%= @post.post_status.color %>; color: white;'%>>
+        <%= @post.post_status.name %>
+      </span>
+    </p>
+    <p>
+      <%= link_to "Click here", post_url(@post) %> to learn more!
+    </p>
+    <p>
+      Have a great day!
+    </p>
+  </body>
+  <footer>
+    Annoyed? You can <%= link_to("turn off notifications here", edit_user_registration_url) %>.
+  </footer>
+</html>

app/views/user_mailer/notify_followers_of_post_update.erb

@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <meta content='text/html; charset=utf-8' http-equiv='content-type' />
+  </head>
+  <body>
+    <h1>Hello!</h1>
+    <p>
+      There is a new update on the post you're following <b><%= @comment.post.title %></b>:
+    </p>
+    <p>
+      <i><%= @comment.body %></i>
+    </p>
+    <p>
+      <%= link_to "Click here", post_url(@comment.post) %> to have your say!
+    </p>
+    <p>
+      Have a great day!
+    </p>
+  </body>
+  <footer>
+    Annoyed? You can <%= link_to("turn off notifications here", edit_user_registration_url) %>.
+  </footer>
+</html>

app/views/user_mailer/notify_post_owner.html.erb

@@ -1,17 +1,24 @@
 <!DOCTYPE html>
 <html>
   <head>
-    <meta content='text/html; charset=UTF-8' http-equiv='Content-Type' />
+    <meta content='text/html; charset=utf-8' http-equiv='content-type' />
   </head>
   <body>
     <h1>Hello, <%= @user.full_name %></h1>
     <p>
-      There is a new comment by <%= @comment.user.full_name %> on your post <b><%= @comment.post.title %></b>
+      There is a new comment by <b><%= @comment.user.full_name %></b> on your post <b><%= @comment.post.title %></b>:
+    </p>
+    <p>
+      <i><%= @comment.body %></i>
+    </p>
+    <p>
+      <%= link_to "Click here", post_url(@comment.post) %> to have your say!
+    </p>
+    <p>
+      Have a great day!
     </p>
-    <p> To see this comment, <%= link_to "Click here", post_url(@comment.post) %> </p>
-    <p>Have a great day!</p>
   </body>
   <footer>
-    Annoyed ? You can <%= link_to("turn off notifications here", edit_user_registration_url) %>
+    Annoyed? You can <%= link_to("turn off notifications here", edit_user_registration_url) %>.
   </footer>
 </html>

config/database.yml

@@ -21,10 +21,12 @@ default: &default
   host: db
   username: <%= ENV['POSTGRES_USER'] %>
   password: <%= ENV['POSTGRES_PASSWORD'] %>
-  database: <%= ENV['POSTGRES_USER'] %>
 
 development:
   <<: *default
+
+  database: <%= ENV['POSTGRES_USER'] %>
+
   # The specified database role being used to connect to postgres.
   # To create additional roles in postgres see `$ createuser --help`.
   # When left blank, postgres will use the default role. This is
@@ -57,7 +59,8 @@ development:
 # Do not set this db to the same as development or production.
 test:
   <<: *default
-  database: app_test
+  
+  database: <%= ENV['POSTGRES_USER'] %>_test
   
 # As with config/credentials.yml, you never want to store sensitive information,
 # like your database password, in your source code. If your source code is
@@ -80,3 +83,5 @@ test:
 #
 production:
   <<: *default
+
+  database: <%= ENV['POSTGRES_USER'] %>

config/routes.rb

@@ -15,9 +15,12 @@ Rails.application.routes.draw do
   devise_for :users
 
   resources :posts, only: [:index, :create, :show, :update] do
+    resource :follows, only: [:create, :destroy]
+    resources :follows, only: [:index]
     resource :likes, only: [:create, :destroy]
     resources :likes, only: [:index]
     resources :comments, only: [:index, :create, :update]
+    resources :post_status_changes, only: [:index]
   end
   
   resources :boards, only: [:index, :create, :update, :destroy, :show] do

db/migrate/20220512184400_create_follows.rb

@@ -0,0 +1,12 @@
+class CreateFollows < ActiveRecord::Migration[6.0]
+  def change
+    create_table :follows do |t|
+      t.references :user, null: false, foreign_key: true
+      t.references :post, null: false, foreign_key: true
+
+      t.timestamps
+    end
+
+    add_index :follows, [:user_id, :post_id], unique: true
+  end
+end

db/migrate/20220521161950_create_post_status_changes.rb

@@ -0,0 +1,11 @@
+class CreatePostStatusChanges < ActiveRecord::Migration[6.0]
+  def change
+    create_table :post_status_changes do |t|
+      t.references :user, null: false, foreign_key: true
+      t.references :post, null: false, foreign_key: true
+      t.references :post_status, foreign_key: true
+
+      t.timestamps
+    end
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2021_01_26_215831) do
+ActiveRecord::Schema.define(version: 2022_05_21_161950) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -37,6 +37,16 @@ ActiveRecord::Schema.define(version: 2021_01_26_215831) do
     t.index ["user_id"], name: "index_comments_on_user_id"
   end
 
+  create_table "follows", force: :cascade do |t|
+    t.bigint "user_id", null: false
+    t.bigint "post_id", null: false
+    t.datetime "created_at", precision: 6, null: false
+    t.datetime "updated_at", precision: 6, null: false
+    t.index ["post_id"], name: "index_follows_on_post_id"
+    t.index ["user_id", "post_id"], name: "index_follows_on_user_id_and_post_id", unique: true
+    t.index ["user_id"], name: "index_follows_on_user_id"
+  end
+
   create_table "likes", force: :cascade do |t|
     t.bigint "user_id", null: false
     t.bigint "post_id", null: false
@@ -47,6 +57,17 @@ ActiveRecord::Schema.define(version: 2021_01_26_215831) do
     t.index ["user_id"], name: "index_likes_on_user_id"
   end
 
+  create_table "post_status_changes", force: :cascade do |t|
+    t.bigint "user_id", null: false
+    t.bigint "post_id", null: false
+    t.bigint "post_status_id"
+    t.datetime "created_at", precision: 6, null: false
+    t.datetime "updated_at", precision: 6, null: false
+    t.index ["post_id"], name: "index_post_status_changes_on_post_id"
+    t.index ["post_status_id"], name: "index_post_status_changes_on_post_status_id"
+    t.index ["user_id"], name: "index_post_status_changes_on_user_id"
+  end
+
   create_table "post_statuses", force: :cascade do |t|
     t.string "name", null: false
     t.string "color", null: false
@@ -93,8 +114,13 @@ ActiveRecord::Schema.define(version: 2021_01_26_215831) do
   add_foreign_key "comments", "comments", column: "parent_id"
   add_foreign_key "comments", "posts"
   add_foreign_key "comments", "users"
+  add_foreign_key "follows", "posts"
+  add_foreign_key "follows", "users"
   add_foreign_key "likes", "posts"
   add_foreign_key "likes", "users"
+  add_foreign_key "post_status_changes", "post_statuses"
+  add_foreign_key "post_status_changes", "posts"
+  add_foreign_key "post_status_changes", "users"
   add_foreign_key "posts", "boards"
   add_foreign_key "posts", "post_statuses"
   add_foreign_key "posts", "users"

docker-compose.yml

@@ -6,7 +6,7 @@ services:
       - POSTGRES_USER
       - POSTGRES_PASSWORD
     volumes:
-      - ./tmp/db:/var/lib/postgresql/data
+      - dbdata:/var/lib/postgresql/data
   web:
     build:
       context: .
@@ -26,4 +26,7 @@ services:
     ports:
       - "3000:3000"
     depends_on:
-      - db
+      - db
+    
+volumes:
+  dbdata:

spec/factories/follows.rb

@@ -0,0 +1,6 @@
+FactoryBot.define do
+  factory :follow do
+    user
+    post
+  end
+end

spec/factories/post_status_changes.rb

@@ -0,0 +1,7 @@
+FactoryBot.define do
+  factory :post_status_change do
+    user
+    post
+    post_status
+  end
+end

spec/mailers/user_mailer_spec.rb

@@ -8,15 +8,16 @@ RSpec.describe UserMailer, type: :mailer do
     let(:mail) { UserMailer.notify_post_owner(comment: comment) }
 
     it "renders the headers" do
-      expect(mail.subject).to eq("[#{ENV.fetch('APP_NAME')}] - New comment on #{post.title}")
+      expect(mail.subject).to eq("[#{ENV.fetch('APP_NAME')}] New comment on #{post.title}")
       expect(mail.to).to eq(["notified@example.com"])
       expect(mail.from).to eq(["notifications@example.com"])
     end
 
-    it "renders the body" do
-      expect(mail.body.encoded).to include("Hello, #{user.full_name}")
-      expect(mail.body.encoded).to include("There is a new comment by")
-      expect(mail.body.encoded).to include('Annoyed ? You can <a href="http://localhost:3000/users/edit">turn off notifications here</a>')
+    it "renders the user name, post title, replier name and comment body" do
+      expect(mail.body.encoded).to include(user.full_name)
+      expect(mail.body.encoded).to include(post.title)
+      expect(mail.body.encoded).to include(comment.user.full_name)
+      expect(mail.body.encoded).to include(comment.body)
     end
   end
 end

spec/models/follow_spec.rb

@@ -0,0 +1,26 @@
+require 'rails_helper'
+
+RSpec.describe Follow, type: :model do
+  let(:follow) { FactoryBot.build(:follow) }
+
+  it 'is valid' do
+    expect(follow).to be_valid
+  end
+
+  it 'must have a user_id' do
+    follow.user = nil
+    expect(follow).to be_invalid
+  end
+
+  it 'must have a post_id' do
+    follow.post = nil
+    expect(follow).to be_invalid
+  end
+
+  it 'must be unique on user and post' do
+    follow
+    f = Follow.new(user_id: follow.user_id, post_id: follow.post_id)
+
+    expect(f).to be_invalid
+  end
+end

spec/models/post_status_change_spec.rb

@@ -0,0 +1,24 @@
+require 'rails_helper'
+
+RSpec.describe PostStatusChange, type: :model do
+  let(:post_status_change) { FactoryBot.build(:post_status_change) }
+  
+  it 'should be valid' do
+    expect(post_status_change).to be_valid
+  end
+
+  it 'must have a post' do
+    post_status_change.post = nil
+    expect(post_status_change).to be_invalid
+  end
+
+  it 'must have a user' do
+    post_status_change.user = nil
+    expect(post_status_change).to be_invalid
+  end
+
+  it 'can have a null post status' do
+    post_status_change.post_status = nil
+    expect(post_status_change).to be_valid
+  end
+end