defmodule Datum do
    @moduledoc """
    Datum type for the validator.

    Provides encoding to Plutus data and decoding from Plutus data.
    """

    alias Sutra.Data.Plutus.{Constr, PList}

<%= if @is_enum do %>
    @type t() :: <%= @type_union %>

<%= @variant_modules %>

    @doc "Returns the constructor index for a variant name"
    def constructor_index(name) do
      case name do
<%= for v <- @variants do %>        <%= inspect(v["title"]) %> -> {:ok, <%= v["index"] %>}
<% end %>        _ -> {:error, :unknown_variant}
      end
    end

    @doc "Returns the variant name for a constructor index"
    def variant_name(index) do
      case index do
<%= for v <- @variants do %>        <%= v["index"] %> -> {:ok, <%= inspect(v["title"]) %>}
<% end %>        _ -> {:error, :unknown_index}
      end
    end

    @doc "Decodes Plutus data to the appropriate variant"
    def from_plutus(%Constr{index: index} = data) do
      case index do
<%= for v <- @variants do %>        <%= v["index"] %> -> <%= v["title"] %>.from_plutus(data)
<% end %>        _ -> {:error, :unknown_constructor}
      end
    end
    def from_plutus(_), do: {:error, :invalid_data}
<% else %>
    defstruct <%= inspect(@struct_fields) %>

    @type t() :: %__MODULE__{
<%= @field_types %>
    }

    @doc "Creates a new Datum"
    def new(attrs \\ %{}), do: struct(__MODULE__, attrs)

    @doc "Converts to Plutus data"
    def to_plutus(%__MODULE__{} = data) do
      fields = [
<%= @to_plutus_fields %>
      ]
      %Constr{index: <%= @index %>, fields: fields}
    end

    @doc "Converts from Plutus data"
    def from_plutus(%Constr{index: <%= @index %>, fields: field_values}) do
      case field_values do
        [<%= @field_pattern %>] ->
          {:ok, %__MODULE__{
<%= @from_plutus_fields %>
          }}
        _ ->
          {:error, :field_count_mismatch}
      end
    end
    def from_plutus(_), do: {:error, :invalid_data}
<% end %>
  end