{:channel_handler, "~> 0.6"}

channel "post:*", MyAppWeb.PostChannel

defmodule MyAppWeb.PostChannel do
  use MyAppWeb, :channel
  use ChannelHandler.Router
end

defmodule MyAppWeb.PostChannel do
  use MyAppWeb, :channel
  use ChannelHandler.Router

  join fn _topic, _payload, socket ->
    {:ok, socket}
  end

  plug MyAppWeb.ChannelPlugs.EnsureAuthenticated

  event "comments:create", MyAppWeb.PostCommentsHandler, :create

  delegate "comments:", MyAppWeb.PostCommentsHandler

  handle "post:create", fn payload, _bindings, socket ->
    case MyApp.Posts.create(payload) do
      {:ok, post} ->
        {:reply, {:ok, post}, socket}

      {:error, reason} ->
        {:reply, {:error, reason}, socket}
    end
  end

  scope "secret:" do
    plug &check_permission/4, :do_secret_stuff

    # You can use splat patterns to match anything with *
    event "foo:*", SuperSecretHandler, :foo

    # Not specifying a prefix matches everything
    delegate SuperSecretHandler
  end

  def check_permission(socket, _payload, _bindings, permission) do
    if MyApp.Authorization.can?(socket.assigns.current_user, permission) do
      # using :cont resumes the event handling
      {:cont, socket, payload, bindings}
    else
      # returning :reply or :noreply halts the event handling
      {:reply, {:error, "Unauthorized"}, socket}
    end
  end
end

defmodule MyAppWeb.PostCommentsHandler do
  use ChannelHandler.Handler

  # Add a plug only for the create action
  plug MyAppWeb.ChannelPlugs.CheckPermission, :comment_posts when action in [:create]
  
  def handle_in(event, payload, bindings, socket) do
    # Do something with the delegated event
  end

  def create(payload, bindings, socket) do
    # Create a comment
  end
end