Add blog likes and comments support (v3 API alignmen)

[evulins]

Description

Add blog likes and comments support aligned with v3 API (auth-required POSTs, content-based comments body, unified response parsing).

Type of Change

• New feature
• Bug fix
• Breaking change
• Documentation update

Checklist

• Unit/integration tests
• Documentation

Tickets

• Ticket ID

[hanka]

Some comments make be not relevant if some solutions are driven by requirements I'm not aware of :)

[hanka]

probably worth adding an index on postId, so querying comments per post is better optimised

CommentSchema.index({ postId: 1 });

[hanka]

curiosity - only logged in users can comment, and they are assigned to comments. Why the need to keep author separately and additionally set it to 'Anonymous' when the param is blank? Why not just use relation to the user?

[hanka]

is this additional query needed? maybe await savedComment.populate('userId', 'first_name last_name email'); would be enough?

[hanka]

you could add also length validation on model level, like maxlength: [1000, 'Comment must be under 1000 characters'],

[hanka]

this could probably be simplified to sth like this

let user;
try {
  user = await getUserByJWT(req.headers.authorization);
  if (!user) throw new Error('Invalid token');
} catch (error) {
  return {
    ... RESPONSE_CODES.UNAUTHORIZED,
    error: { message:  'User must be logged in to comment' },
  };
}

Additionally, consider checking logged in user at the beginning of createComment. There's not much sense in validating params or doing any additional db requests if there's no authorised user.

General improvement thought - probably check for logged in user is done in other controllers too. Maybe this could be extracted as a helper function or even a middleware applied on the router level, that could be reused. So error handling for unauthorised users could be unified.

[hanka]

if you'd like to use middleware for auth, here's blog post with example of how to do that: https://embed17.medium.com/protect-your-express-js-routes-a-simple-authentication-middleware-tutoria-cd720ef19cb3

[hanka]

curiosity - returned likes are populated with user, so client using this controller's response should know whether it has logged in user or not, and if it has, it could check if current user has liked given post based on users returned with likes. Is this additional userHasLiked needed?

[hanka]

this could be optimised using const count = await Like.countDocuments({ postId });

[hanka]

here too, using countDocuments would avoid loading all likes data just to count them.

[hanka]

logged in user check is basically the same as in the comment controller - having it extracted to a helper would simplify controllers

[hanka]

whole toggle could probably be a bit simplified to sth like this:

export const toggleLike = async (postId, req) => {
  // auth check
  // existing post check
  
  const deleted = await Like.findOneAndDelete({ postId, userId });
  
  if (deleted) {
    const count = await Like.countDocuments({ postId });
    return { ... RESPONSE_CODES.SUCCESS, data: { liked: false, count } };
  }
  
  try {
    await Like.create({ postId, userId });
    const count = await Like.countDocuments({ postId });
    return { ...RESPONSE_CODES.SUCCESS, data: { liked: true, count } };
  } catch (error) {
    // current error handling
  }
};