defmodule DaProductApp.TransactionEventChain do
  @moduledoc """
  Ecto schema for the transaction event chain. Each row references an event in
  a source table (qr_validations, transaction_events, followup_requests, etc.)
  and links to the previous event for the same transaction, enabling traversal.
  """

  use Ecto.Schema
  import Ecto.Changeset

  schema "transaction_event_chain" do
    field :transaction_id, :integer
    field :event_type, :string
    field :event_ref_table, :string
    field :event_ref_id, :integer
    field :prev_event_id, :integer
    field :payload, :string

    timestamps()
  end

  @required ~w(transaction_id event_type event_ref_table)a

  def changeset(struct, attrs) do
    struct
    |> cast(attrs, [:transaction_id, :event_type, :event_ref_table, :event_ref_id, :prev_event_id, :payload])
    |> validate_required(@required)
  end
end