defmodule SyntropyWeb.Api.AgentConnections do
  @moduledoc """
  Shapes an agent's connection map into the ordered list rendered by the
  agents and history JSON views, resolving bare agent ids to runtime-scoped
  ids when the payload carries an explicit runtime id.
  """

  alias Syntropy.ClusterInfo

  @spec ordered(map()) :: [map()]
  def ordered(%{connections: connections} = agent) when is_map(connections) do
    connections
    |> Enum.sort_by(fn {target_id, _value} -> target_id end)
    |> Enum.map(fn {target_id, connection} ->
      %{
        target_agent_id: connection_target_id(agent, target_id),
        weight: connection.weight,
        interactions: connection.interactions
      }
    end)
  end

  def ordered(%{connections: connections} = agent) when is_list(connections) do
    connections
    |> Enum.map(fn connection ->
      Map.put(
        connection,
        :target_agent_id,
        connection_target_id(agent, connection.target_agent_id)
      )
    end)
    |> Enum.sort_by(& &1.target_agent_id)
  end

  defp connection_target_id(%{} = agent, target_id) when is_binary(target_id) do
    cond do
      String.contains?(target_id, "::") ->
        target_id

      explicit_runtime_id?(agent) ->
        ClusterInfo.runtime_id(target_id, node_id_for(agent))

      true ->
        target_id
    end
  end

  defp explicit_runtime_id?(agent) do
    case payload_value(agent, :runtime_id) do
      runtime_id when is_binary(runtime_id) and runtime_id != "" -> true
      _other -> false
    end
  end

  defp node_id_for(%{} = value), do: payload_value(value, :node_id, "local")

  defp payload_value(payload, key, default \\ nil) when is_map(payload) do
    string_key = Atom.to_string(key)

    cond do
      Map.has_key?(payload, key) -> Map.get(payload, key)
      Map.has_key?(payload, string_key) -> Map.get(payload, string_key)
      true -> default
    end
  end
end