cmdc_tui

defmodule CmdcTui.EventRouter do
  @moduledoc """
  CMDC EventBus 事件路由器。

  将 `{:cmdc_event, session_id, event}` 中的 event 映射到 State 更新。
  """

  alias CmdcTui.State

  @doc "将 CMDC 事件路由到 State 更新。"
  @spec route(term(), State.t()) :: State.t()

  # -----
  # 生命周期
  # -----

  def route(:agent_start, state) do
    %{state | agent_status: :running, current_streaming: "", current_thinking: ""}
  end

  def route({:agent_end, _messages, token_usage}, state) do
    state
    |> State.update_tokens(token_usage)
    |> Map.put(:agent_status, :idle)
  end

  def route({:agent_abort, _reason}, state), do: %{state | agent_status: :idle}
  def route(:agent_abort, state), do: %{state | agent_status: :idle}

  # -----
  # 流式文本
  # -----

  def route(:message_start, state) do
    %{state | agent_status: :streaming, current_streaming: ""}
  end

  def route({:message_delta, %{delta: text}}, state) do
    state = %{state | current_streaming: state.current_streaming <> text}
    %{state | message_scroll: State.scroll_to_bottom(state)}
  end

  def route({:response_complete, message}, state) do
    content = extract_content(message)

    state
    |> finalize_streaming()
    |> maybe_append_assistant(content)
  end

  # -----
  # 思考链
  # -----

  def route(:thinking_start, state) do
    %{state | show_thinking: true, current_thinking: ""}
  end

  def route({:thinking_delta, %{delta: text}}, state) do
    %{state | current_thinking: state.current_thinking <> text}
  end

  # -----
  # 工具
  # -----

  def route({:tool_execution_start, name, call_id, args}, state) do
    State.upsert_tool(state, call_id, %{
      name: name,
      args: args,
      status: :running,
      started_at: now()
    })
  end

  def route({:tool_execution_end, name, call_id, result}, state) do
    status = if match?({:ok, _}, result), do: :done, else: :error

    State.upsert_tool(state, call_id, %{
      name: name,
      status: status,
      result: result,
      finished_at: now()
    })
  end

  def route({:tool_blocked, name, call_id, reason}, state) do
    State.upsert_tool(state, call_id, %{
      name: name,
      status: :blocked,
      result: {:error, reason},
      started_at: now(),
      finished_at: now()
    })
  end

  # -----
  # Todo
  # -----

  def route({:todo_change, _sid, todos}, state) do
    %{state | todos: todos}
  end

  # -----
  # HITL 审批
  # -----

  def route({:approval_required, approval}, state) do
    %{state | pending_approval: approval}
  end

  def route({:approval_resolved, _approval}, state) do
    # 审批已由 KeyHandler 处理，此处只做兜底清除
    %{state | pending_approval: nil}
  end

  # -----
  # Ask User
  # -----

  def route({:ask_user, session_id, question, options, ref}, state) do
    ask_map = CmdcTui.Dialogs.AskUserDialog.new_ask_map(session_id, question, options, ref)
    %{state | pending_ask: ask_map}
  end

  # -----
  # 兜底
  # -----

  def route(_event, state), do: state

  # ==========================================================================
  # 私有辅助
  # ==========================================================================

  defp finalize_streaming(state) do
    %{state | current_streaming: "", show_thinking: false, current_thinking: ""}
  end

  defp maybe_append_assistant(state, "") do
    state
  end

  defp maybe_append_assistant(state, content) do
    State.append_message(state, %{
      role: :assistant,
      content: content,
      tool_name: nil,
      timestamp: now()
    })
  end

  defp extract_content(%{content: content}) when is_binary(content), do: content
  defp extract_content(_), do: ""

  defp now, do: System.system_time(:millisecond)
end