defmodule PleaseStop do
  import Plug.Conn
  require Logger
  alias PleaseStop.Store

  @moduledoc """
  ## Usage

  To use `PleaseStop` in Phoenix you can use it just like any other plug.

  ```
  scope "/avatars" do
    plug PleaseStop, limit: 5000, ttl: :timer.minutes(1), namespace: :avatars

    scope "/something" do
      plug PleaseStop, limit: 5, ttl: :timer.minutes(10), namespace: :something
    end
  end
  ```

  ### Options

  The options provided to `PleaseStop` are detailed below

  * `limit`: The maximum number of requests you'll accept within the provided `ttl`.
  * `ttl`: The amount of time before the request count is set back to `0`. If the `limit` is reached within this `ttl`, a `429` will be returned and the `conn` will be halted.
  * `namespace`: The namespace where your rate limiting information is kept.
  """

  def init(options) do
    Store.initialise(options)
  end

  def call(conn, %PleaseStop.Store{namespace: namespace}) do
    case Store.over_limit?(namespace) do
       false ->
        Store.increment(namespace) # increment number for that namespace
       true ->
        Logger.warn "#{namespace} has exceeded their limit"
        conn
        |> send_resp(429, "")
        |> halt
    end

    conn
  end
end