defmodule PhoenixKit.Modules.Billing.WebhookEvent do
  @moduledoc """
  Schema for webhook event logging and idempotency.

  Every webhook received from payment providers is logged here to:
  - Ensure idempotency (same event_id is never processed twice)
  - Track processing status and errors
  - Enable debugging and auditing
  - Support retry logic for failed events

  ## Idempotency

  Before processing a webhook, we check if an event with the same
  `provider` + `event_id` combination exists. If it does, we skip
  processing and return success to prevent retries from provider.

  ## Retry Logic

  Failed events can be retried:
  1. Provider sends retry (we check idempotency, process if not done)
  2. Manual retry via admin interface
  3. Background worker for events stuck in processing
  """

  use Ecto.Schema
  import Ecto.Changeset

  @primary_key {:uuid, UUIDv7, autogenerate: true}

  schema "phoenix_kit_webhook_events" do
    field :id, :integer, read_after_writes: true
    field :provider, :string
    field :event_id, :string
    field :event_type, :string
    field :payload, :map, default: %{}
    field :processed, :boolean, default: false
    field :processed_at, :utc_datetime
    field :error_message, :string
    field :retry_count, :integer, default: 0

    timestamps(type: :utc_datetime)
  end

  @doc """
  Creates a changeset for a webhook event.
  """
  def changeset(event, attrs) do
    event
    |> cast(attrs, [
      :provider,
      :event_id,
      :event_type,
      :payload,
      :processed,
      :processed_at,
      :error_message,
      :retry_count
    ])
    |> validate_required([:provider, :event_id, :event_type])
    |> unique_constraint([:provider, :event_id],
      name: :phoenix_kit_webhook_events_provider_event_id_index
    )
  end

  @doc """
  Changeset for marking an event as processed.
  """
  def processed_changeset(event) do
    event
    |> change(%{
      processed: true,
      processed_at: DateTime.utc_now(),
      error_message: nil
    })
  end

  @doc """
  Changeset for marking an event as failed.
  """
  def failed_changeset(event, error_message) do
    event
    |> change(%{
      processed: false,
      error_message: error_message,
      retry_count: event.retry_count + 1
    })
  end

  # ============================================
  # Status Helpers
  # ============================================

  @doc """
  Returns true if the event was successfully processed.
  """
  def processed?(%__MODULE__{processed: true}), do: true
  def processed?(_), do: false

  @doc """
  Returns true if the event has failed and can be retried.
  """
  def retriable?(%__MODULE__{processed: false, retry_count: count}) when count < 5 do
    true
  end

  def retriable?(_), do: false

  @doc """
  Returns true if the event has exceeded max retries.
  """
  def max_retries_exceeded?(%__MODULE__{retry_count: count}) when count >= 5 do
    true
  end

  def max_retries_exceeded?(_), do: false
end