defmodule Mix.Interactive.State do
  @moduledoc """
  State inspection utilities for the interactive MCP shell.

  This module provides functions for inspecting, formatting, and displaying
  the internal state of Hermes MCP client and transport processes, useful
  for debugging and introspection purposes.

  ## Features

  * Retrieves and formats client state information
  * Displays transport state (SSE or STDIO)
  * Pretty-prints nested data structures
  * Shows connection status and diagnostics
  * Highlights pending requests with timing information

  ## Usage

  This module is primarily used by the interactive shell's `show_state` command
  to provide a human-readable view of the system's internal state.

  ```elixir
  # From the commands module:
  Mix.Interactive.State.print_state(client_pid)
  ```
  """

  alias Hermes.Client.Request
  alias Hermes.Transport.SSE
  alias Hermes.Transport.STDIO
  alias Mix.Interactive.UI

  @doc """
  Prints the formatted state of the client and its associated transport.

  ## Parameters

    * `client` - The client process to inspect
  """
  @spec print_state(GenServer.server()) :: :ok
  def print_state(client) do
    client_state = :sys.get_state(client)
    transport = get_transport_info(client_state)
    verbose = System.get_env("HERMES_VERBOSE") == "1"

    print_client_state(client, client_state, verbose)
    print_transport_state(transport.pid, transport.layer, verbose)
  end

  defp get_transport_info(client_state) do
    transport_info = client_state.transport

    layer = if is_map(transport_info), do: transport_info[:layer], else: transport_info

    transport_pid =
      if is_map(transport_info) and Map.has_key?(transport_info, :name) and is_pid(transport_info.name) do
        transport_info.name
      else
        Process.whereis(layer)
      end

    %{layer: layer, pid: transport_pid}
  end

  defp print_client_state(client, state, verbose) do
    IO.puts("\n#{UI.colors().success}Client State (#{inspect(client)}):#{UI.colors().reset}")

    print_protocol_info(state)
    print_client_info(state, verbose)
    print_server_capabilities(state, verbose)
    print_server_info(state, verbose)
    print_pending_requests(state.pending_requests, verbose)

    if verbose do
      print_callbacks_info(state)
    end
  end

  defp print_protocol_info(state) do
    IO.puts("  #{UI.colors().info}Protocol Version:#{UI.colors().reset} #{state.protocol_version}")
  end

  defp print_client_info(state, _verbose) do
    IO.puts("  #{UI.colors().info}Client Info:#{UI.colors().reset}")
    print_map(state.client_info, 4)
  end

  defp print_server_capabilities(state, verbose) do
    if state.server_capabilities do
      IO.puts("  #{UI.colors().info}Server Capabilities:#{UI.colors().reset}")

      if verbose do
        # Show full details in verbose mode
        print_map(state.server_capabilities, 4)
      else
        # Show summary in normal mode
        capability_keys = Map.keys(state.server_capabilities)
        IO.puts("    #{inspect(capability_keys)}")
      end
    else
      IO.puts("  #{UI.colors().warning}Server Capabilities: Not yet established#{UI.colors().reset}")
    end
  end

  defp print_server_info(state, _verbose) do
    if state.server_info do
      IO.puts("  #{UI.colors().info}Server Info:#{UI.colors().reset}")
      print_map(state.server_info, 4)
    else
      IO.puts("  #{UI.colors().warning}Server Info: Not yet established#{UI.colors().reset}")
    end
  end

  defp print_pending_requests(pending_requests, verbose) do
    request_count = map_size(pending_requests)

    if request_count == 0 do
      IO.puts("  #{UI.colors().info}Pending Requests:#{UI.colors().reset} None")
    else
      IO.puts("  #{UI.colors().info}Pending Requests (#{request_count}):#{UI.colors().reset}")
      Enum.each(pending_requests, &print_request(&1, verbose))
    end
  end

  defp print_request({id, request}, verbose) do
    elapsed_ms = Request.elapsed_time(request)
    IO.puts("    #{UI.colors().command}#{id}#{UI.colors().reset} - Method: #{request.method}, Elapsed: #{elapsed_ms}ms")

    if verbose do
      print_request_details(request)
    end
  end

  defp print_request_details(request) do
    IO.puts("      Started at: #{inspect(request.start_time)}")
    IO.puts("      From: #{inspect(request.from)}")
  end

  defp print_callbacks_info(state) do
    IO.puts("  #{UI.colors().info}Callbacks:#{UI.colors().reset}")

    # Progress callbacks
    progress_count = map_size(state.progress_callbacks)

    if progress_count > 0 do
      IO.puts("    #{UI.colors().info}Progress Callbacks (#{progress_count}):#{UI.colors().reset}")

      Enum.each(state.progress_callbacks, fn {token, _callback} ->
        IO.puts("      #{UI.colors().command}#{token}#{UI.colors().reset}")
      end)
    else
      IO.puts("    #{UI.colors().info}Progress Callbacks:#{UI.colors().reset} None")
    end

    # Log callback
    if state.log_callback do
      IO.puts("    #{UI.colors().info}Log Callback:#{UI.colors().reset} Configured")
    else
      IO.puts("    #{UI.colors().info}Log Callback:#{UI.colors().reset} None")
    end
  end

  defp print_transport_state(nil, transport_layer, _verbose) do
    IO.puts(
      "\n#{UI.colors().error}Transport State (#{inspect(transport_layer)}):#{UI.colors().reset} Not available (process not found)"
    )
  end

  defp print_transport_state(transport_pid, transport_layer, verbose) when is_pid(transport_pid) do
    if Process.alive?(transport_pid) do
      transport_state = :sys.get_state(transport_pid)

      case transport_layer do
        SSE -> print_sse_transport_state(transport_pid, transport_state, verbose)
        STDIO -> print_stdio_transport_state(transport_pid, transport_state, verbose)
        _ -> print_unknown_transport_state(transport_pid, transport_state, verbose)
      end
    else
      IO.puts(
        "\n#{UI.colors().error}Transport State (#{inspect(transport_layer)}):#{UI.colors().reset} Not available (process not running)"
      )
    end
  end

  defp print_transport_state(_transport_pid, transport_layer, _verbose) do
    IO.puts(
      "\n#{UI.colors().error}Transport State (#{inspect(transport_layer)}):#{UI.colors().reset} Not available (invalid process identifier)"
    )
  end

  defp print_sse_transport_state(pid, state, verbose) do
    IO.puts("\n#{UI.colors().success}SSE Transport State (#{inspect(pid)}):#{UI.colors().reset}")
    IO.puts("  #{UI.colors().info}Server URL:#{UI.colors().reset} #{state[:server_url]}")
    IO.puts("  #{UI.colors().info}SSE URL:#{UI.colors().reset} #{state[:sse_url]}")

    print_sse_connection_status(state)
    print_sse_stream_task(state)

    if verbose do
      # Print additional transport details in verbose mode
      if map_size(state[:headers] || %{}) > 0 do
        IO.puts("  #{UI.colors().info}Headers:#{UI.colors().reset}")
        print_map(state[:headers], 4)
      end

      if state[:transport_opts] do
        IO.puts("  #{UI.colors().info}Transport Options:#{UI.colors().reset} #{inspect(state[:transport_opts])}")
      end

      if state[:http_options] do
        IO.puts("  #{UI.colors().info}HTTP Options:#{UI.colors().reset} #{inspect(state[:http_options])}")
      end
    end
  end

  defp print_sse_connection_status(state) do
    if state[:message_url] do
      IO.puts("  #{UI.colors().info}Message URL:#{UI.colors().reset} #{state[:message_url]}")
      IO.puts("  #{UI.colors().success}Status:#{UI.colors().reset} Connected")
    else
      IO.puts("  #{UI.colors().warning}Status:#{UI.colors().reset} Connecting/Not connected")
    end
  end

  defp print_sse_stream_task(state) do
    if state[:stream_task] do
      task = state[:stream_task]
      status = if Process.alive?(task.pid), do: "alive", else: "dead"
      IO.puts("  #{UI.colors().info}Stream Task:#{UI.colors().reset} #{inspect(task.pid)} (#{status})")
    end
  end

  defp print_stdio_transport_state(pid, state, verbose) do
    IO.puts("\n#{UI.colors().success}STDIO Transport State (#{inspect(pid)}):#{UI.colors().reset}")
    IO.puts("  #{UI.colors().info}Command:#{UI.colors().reset} #{state.command}")

    print_stdio_args(state)
    print_stdio_connection_status(state)

    if verbose do
      # Print additional transport details in verbose mode
      if state.cwd do
        IO.puts("  #{UI.colors().info}Working Directory:#{UI.colors().reset} #{state.cwd}")
      end

      if state.env do
        IO.puts("  #{UI.colors().info}Environment:#{UI.colors().reset}")
        print_map(state.env, 4)
      end
    end
  end

  defp print_stdio_args(state) do
    if state.args do
      IO.puts("  #{UI.colors().info}Args:#{UI.colors().reset} #{inspect(state.args)}")
    end
  end

  defp print_stdio_connection_status(state) do
    if state.port do
      status = if Port.info(state.port), do: "open", else: "closed"
      IO.puts("  #{UI.colors().info}Port:#{UI.colors().reset} #{inspect(state.port)} (#{status})")
      IO.puts("  #{UI.colors().success}Status:#{UI.colors().reset} Connected")
    else
      IO.puts("  #{UI.colors().warning}Status:#{UI.colors().reset} Not connected")
    end
  end

  defp print_unknown_transport_state(pid, state, verbose) do
    IO.puts("\n#{UI.colors().success}Unknown Transport State (#{inspect(pid)}):#{UI.colors().reset}")

    if verbose do
      # In verbose mode, show the full state with pretty printing
      IO.puts("  #{inspect(state, pretty: true, limit: 50)}")
    else
      # In normal mode, show a summary
      IO.puts("  #{inspect(state, pretty: true, limit: 5)}")
    end
  end

  defp print_map(map, indent_level) when is_map(map) do
    Enum.each(map, fn {key, value} ->
      print_map_entry(key, value, indent_level)
    end)
  end

  defp print_map_entry(key, value, indent_level) do
    indent = String.duplicate(" ", indent_level)

    cond do
      is_map(value) and map_size(value) > 0 ->
        IO.puts("#{indent}#{UI.colors().command}#{key}:#{UI.colors().reset}")
        print_map(value, indent_level + 2)

      is_list(value) and value != [] ->
        IO.puts("#{indent}#{UI.colors().command}#{key}:#{UI.colors().reset}")
        print_list(value, indent_level + 2)

      true ->
        IO.puts("#{indent}#{UI.colors().command}#{key}:#{UI.colors().reset} #{inspect(value)}")
    end
  end

  defp print_list(list, indent_level) do
    indent = String.duplicate(" ", indent_level)

    Enum.each(list, fn item ->
      cond do
        is_map(item) and map_size(item) > 0 ->
          IO.puts("#{indent}-")
          print_map(item, indent_level + 2)

        is_list(item) and item != [] ->
          IO.puts("#{indent}- [...]")
          print_list(item, indent_level + 2)

        true ->
          IO.puts("#{indent}- #{inspect(item)}")
      end
    end)
  end
end