plug :match
  plug Plug.Static, at: "/pub", from: :cerber
  plug :dispatch

  get "/" do
    Logger.info "GET /"
    send_resp(conn, 200, "Hello worldn")
  end

defmodule Server do
  use Plug.Builder
  plug Plug.Logger
  plug Plug.Static, at: "/", from: "/path/to/static"
end

defmodule HttpServer.Application do
  require Logger
  use Application

  def start(_type, _args) do
    children = [
      {Plug.Adapters.Cowboy2, scheme: :http, plug: HttpServer.Router, options: [port: 4002]}
    ]

    opts = [strategy: :one_for_one, name: HttpServer.Supervisor]

    Supervisor.start_link(children, opts)
  end
end

defmodule HttpServer.Router do
  use Plug.Router

  plug(Plug.Logger)
  plug(:redirect_index)
  plug(:match)
  plug(:dispatch)

  forward("/static", to: HttpServer.StaticResources)

  get "/sse" do
    # some other stuff...
    conn
  end

  match _ do
    send_resp(conn, 404, "not found")
  end

  def redirect_index(%Plug.Conn{path_info: path} = conn, _opts) do
    case path do
      [] ->
        %{conn | path_info: ["static", "index.html"]}

      ["favicon.ico"] ->
        %{conn | path_info: ["static", "favicon.ico"]}

      _ ->
        conn
    end
  end
end

defmodule HttpServer.StaticResources do
  use Plug.Builder

  plug(
    Plug.Static,
    at: "/",
    from: :http_server
  )

  plug(:not_found)

  def not_found(conn, _) do
    send_resp(conn, 404, "static resource not found")
  end
end