A DSL for routing parsed LINE webhook events (ExLine.Webhook structs) to handlers.

Routes are declared with macros and matched against the event struct plus an event_assigns map you control. Parse the raw payload with ExLine.Webhook.parse/1 first, then route each event.

Example

defmodule MyApp.LineRouter do
  use ExLine.EventRouter

  # Routes can also match on the assigns set by before_action/2 (e.g. the
  # loaded current_user) — declare the more specific route first.
  text "menu", %{current_user: %{role: :admin}}, MyApp.AdminHandler, :menu
  text "menu", MyApp.MenuHandler, :menu

  message :image, MyApp.MediaHandler, :on_image   # any image message
  postback "buy", MyApp.ShopHandler, :buy
  follow MyApp.OnboardHandler, :welcome
  unfollow MyApp.OnboardHandler, :goodbye
  default MyApp.FallbackHandler, :unknown         # REQUIRED: also catches Event.Unknown

  # Preprocess every event before it is matched: load the current user from
  # the event's source and stash the messaging client for handlers to use.
  @impl true
  def before_action(event, assigns) do
    user =
      case event.source do
        %ExLine.Webhook.Source{user_id: id} when is_binary(id) ->
          MyApp.Accounts.get_by_line_id(id)

        _ ->
          nil
      end

    {event, assigns |> Map.put(:current_user, user) |> Map.put(:client, MyApp.client())}
  end
end

# In your webhook controller (after ExLine.Webhook.Signature has verified it):
params["events"] |> ExLine.Webhook.parse() |> Enum.each(&MyApp.LineRouter.call/1)

Because LINE adds event types without notice (and unknown types become ExLine.Webhook.Event.Unknown), always declare a default/2 route so unmatched events never raise.

Ref: https://developers.line.biz/en/reference/messaging-api/#webhook-event-objects