# `WhatsApp.WebhookPlug`
[🔗](https://github.com/jeffhuen/whatsapp_sdk/blob/main/lib/whatsapp/webhook_plug.ex#L1)

Plug for handling WhatsApp webhook requests in Phoenix.

Handles both subscription verification (GET) and event delivery (POST).

## Usage in Phoenix Router

    forward "/webhook/whatsapp", WhatsApp.WebhookPlug,
      app_secret: "your_app_secret",
      verify_token: "your_verify_token",
      handler: MyApp.WhatsAppHandler

## Handler Module

    defmodule MyApp.WhatsAppHandler do
      @behaviour WhatsApp.WebhookPlug.Handler

      @impl true
      def handle_event(event) do
        # event is the "value" from each change entry
        :ok
      end
    end

## Raw Body Access

The plug reads the raw request body via `Plug.Conn.read_body/1` for
signature validation. In a Phoenix application, the body is typically
consumed by the JSON parser before reaching this plug. To work around
this, configure a custom body reader that caches the raw body:

    # In your endpoint.ex
    plug Plug.Parsers,
      parsers: [:json],
      pass: ["application/json"],
      body_reader: {MyApp.CacheBodyReader, :read_body, []},
      json_decoder: JSON

Then this plug will automatically check `conn.assigns[:raw_body]` first
before falling back to `Plug.Conn.read_body/1`.

# `call`

```elixir
@spec call(Plug.Conn.t(), map()) :: Plug.Conn.t()
```

Handle incoming webhook requests.

Routes requests based on HTTP method:

  * `GET` - Subscription verification
  * `POST` - Event delivery with signature validation
  * Other methods - Returns 405 Method Not Allowed

# `init`

```elixir
@spec init(keyword()) :: map()
```

Initialize the plug with required options.

## Options

  * `:app_secret` (required) - Your Facebook App Secret for signature validation
  * `:verify_token` (required) - The verify token configured in the Meta dashboard
  * `:handler` (required) - A module implementing `WhatsApp.WebhookPlug.Handler`

Raises `KeyError` if any required option is missing.

---

*Consult [api-reference.md](api-reference.md) for complete listing*