defmodule CHAT.Application do
  @moduledoc """
  `CHAT.Application` is an
  `Erlang/OTP` application powered by N2O messaging protocol.
  It is implemented as a ring of protocol nodes.
  """
  use Application
  use N2O

  def start(_, _) do
    initialize()
    Supervisor.start_link([], strategy: :one_for_one, name: CHAT.Supervisor)
  end

  @doc """
  Manual startup and conifiguring during startup the following Erlang/OTP
  applications: `:cowboy`, `:syn`, `:kvs` and `:n2o`.

  Example:

  ```elixir
  iex(1)> Supervisor.which_children(:n2o)
  [
    {{:ws, '/ws/chat/1'}, #PID<0.258.0>, :worker, [:n2o_wsnode]},
    {{:ws, '/ws/chat/2'}, #PID<0.257.0>, :worker, [:n2o_wsnode]},
    {{:ws, '/ws/chat/3'}, #PID<0.256.0>, :worker, [:n2o_wsnode]},
    {{:ws, '/ws/chat/4'}, #PID<0.255.0>, :worker, [:n2o_wsnode]},
    {{:caching, 'timer'}, #PID<0.201.0>, :worker, [:n2o]}
  ]
  ```

  In example you see two rings: `mqtt` and `ws` for MQTT and WebSocket workers respectively.

  File `config/config.exs` should contain `proto` N2O parameter, the module
  which contains N2O protocol that will be runned inside ring worker:

  ```elixir
  config :n2o,
    proto: CHAT.Server,
    ws_server: false
  ```

  In CHAT application this `:n2o_wsnode` worker is `CHAT.Server` module.
  Also we need to disable WebSocket ring creationg at N2O startup and create it manually during CHAT startup
  as PI protocol `:init` function contains SYN registration which is dependency only for CHAT,
  the higher level that N2O, which is zero-dependency library.
  """
  def initialize() do
    :cowboy.start_tls(:http, :n2o_cowboy.env(:chat), %{env: %{dispatch: :n2o_cowboy2.points()}})
    :kvs.join
    :syn.init
    :n2o.start_ws
  end
end