bb

# SPDX-FileCopyrightText: 2025 James Harton
#
# SPDX-License-Identifier: Apache-2.0

defmodule BB.Parameter.Changed do
  @moduledoc """
  Payload type for parameter change events.

  Published via PubSub when a parameter value changes.
  """

  @behaviour BB.Message

  defstruct [:path, :old_value, :new_value, :source]

  @type t :: %__MODULE__{
          path: [atom()],
          old_value: term(),
          new_value: term(),
          source: :local | :remote | :init | :persisted
        }

  @schema Spark.Options.new!(
            path: [
              type: {:list, :atom},
              required: true,
              doc: "The parameter path that changed"
            ],
            old_value: [
              type: :any,
              required: false,
              doc: "The previous value (nil if newly created)"
            ],
            new_value: [
              type: :any,
              required: true,
              doc: "The new value"
            ],
            source: [
              type: {:in, [:local, :remote, :init, :persisted]},
              required: false,
              default: :local,
              doc: "The source of the change"
            ]
          )

  @impl BB.Message
  def schema, do: @schema

  defimpl BB.Message.Payload do
    def schema(_), do: @for.schema()
  end
end