defmodule Raxol.Plugins.PluginConfig do
  @moduledoc """
  Handles persistence of plugin configurations.
  Stores and loads plugin configurations from disk.
  """

  @config_dir ".config/raxol/plugins"
  @config_file "plugin_config.json"

  @type t :: %__MODULE__{
          plugin_configs: %{String.t() => map()},
          enabled_plugins: [String.t()]
        }

  defstruct [
    :plugin_configs,
    :enabled_plugins
  ]

  @doc """
  Creates a new plugin configuration manager.
  """
  def new do
    %__MODULE__{
      plugin_configs: %{},
      enabled_plugins: []
    }
  end

  @doc """
  Loads plugin configurations from disk.
  """
  def load do
    config_path = config_file_path()

    case File.read(config_path) do
      {:ok, content} ->
        decode_config(content)

      {:error, :enoent} ->
        {:ok, new()}

      {:error, reason} ->
        {:error, "Failed to read plugin configuration: #{reason}"}
    end
  end

  defp decode_config(content) do
    case Jason.decode(content) do
      {:ok, decoded} ->
        decoded_with_atom_keys =
          for {key, value} <- decoded, into: %{} do
            {String.to_atom(key), value}
          end

        defaults = Map.from_struct(new())
        merged = Map.merge(defaults, decoded_with_atom_keys)
        config = struct(__MODULE__, merged)
        {:ok, config}

      {:error, reason} ->
        {:error, "Failed to decode plugin configuration: #{reason}"}
    end
  end

  @doc """
  Saves plugin configurations to disk.
  """
  def save(%__MODULE__{} = config) do
    config_path = config_file_path()
    config_dir = Path.dirname(config_path)

    # Ensure config directory exists
    File.mkdir_p!(config_dir)

    # Convert struct to map for encoding
    config_map = %{
      plugin_configs: config.plugin_configs,
      enabled_plugins: config.enabled_plugins
    }

    case Jason.encode(config_map) do
      {:ok, encoded} ->
        case File.write(config_path, encoded) do
          :ok ->
            {:ok, config}

          {:error, reason} ->
            {:error, "Failed to write plugin configuration: #{inspect(reason)}"}
        end

      {:error, %Protocol.UndefinedError{} = reason} ->
        struct_name =
          if is_struct(reason.value),
            do: reason.value.__struct__,
            else: "unknown"

        {:error,
         "Failed to encode plugin configuration: Protocol.UndefinedError for #{inspect(struct_name)}"}

      {:error, reason} ->
        {:error, "Failed to encode plugin configuration: #{inspect(reason)}"}
    end
  end

  @doc """
  Gets the configuration for a specific plugin.
  """
  def get_plugin_config(%__MODULE__{} = config, plugin_name)
      when is_binary(plugin_name) do
    Map.get(config.plugin_configs, plugin_name, %{})
  end

  @doc """
  Updates the configuration for a specific plugin.
  """
  def update_plugin_config(%__MODULE__{} = config, plugin_name, plugin_config)
      when is_binary(plugin_name) and is_map(plugin_config) do
    updated_configs = Map.put(config.plugin_configs, plugin_name, plugin_config)
    %{config | plugin_configs: updated_configs}
  end

  @doc """
  Checks if a plugin is enabled.
  """
  def plugin_enabled?(%__MODULE__{} = config, plugin_name)
      when is_binary(plugin_name) do
    plugin_name in config.enabled_plugins
  end

  @doc """
  Enables a plugin.
  """
  def enable_plugin(%__MODULE__{} = config, plugin_name)
      when is_binary(plugin_name) do
    case plugin_name in config.enabled_plugins do
      true ->
        config

      false ->
        %{config | enabled_plugins: [plugin_name | config.enabled_plugins]}
    end
  end

  @doc """
  Disables a plugin.
  """
  def disable_plugin(%__MODULE__{} = config, plugin_name)
      when is_binary(plugin_name) do
    %{
      config
      | enabled_plugins: List.delete(config.enabled_plugins, plugin_name)
    }
  end

  # Private functions

  defp config_file_path do
    # Cross-platform home directory detection
    # Unix/macOS: HOME
    # Windows: USERPROFILE or HOMEPATH
    # Fallback to system tmp directory if all else fails
    home_dir =
      System.get_env("HOME") ||
        System.get_env("USERPROFILE") ||
        System.get_env("HOMEPATH") ||
        System.tmp_dir()

    Path.join([home_dir, @config_dir, @config_file])
  end
end

# Protocol implementation for JSON encoding
if Code.ensure_loaded?(Jason.Encoder) do
  defimpl Jason.Encoder, for: Raxol.Plugins.PluginConfig do
    def encode(%Raxol.Plugins.PluginConfig{} = config, opts) do
      Jason.Encode.map(Map.from_struct(config), opts)
    end
  end
end
