defmodule MicrowavepropWeb.LiveHelpers do
  @moduledoc """
  Small helpers shared across LiveView modules. Use sparingly — most
  view-specific logic belongs in its own LiveView.
  """

  # ── Parse helpers ────────────────────────────────────────────────────

  alias Phoenix.LiveView.Socket

  @doc """
  Parses a value into a float, returning `default` for nil, empty, or
  unparseable input. Accepts strings, numbers, or any value with a
  `String.Chars` impl.
  """
  @spec parse_float(term(), float()) :: float()
  def parse_float(nil, default), do: default
  def parse_float("", default), do: default

  def parse_float(value, default) do
    case value |> to_string() |> Float.parse() do
      {n, _} -> n
      :error -> default
    end
  end

  @doc """
  Parses a value into an integer, returning `default` for nil, empty,
  or unparseable input.
  """
  @spec parse_int(term(), integer()) :: integer()
  def parse_int(nil, default), do: default
  def parse_int("", default), do: default

  def parse_int(value, default) do
    case value |> to_string() |> Integer.parse() do
      {n, _} -> n
      :error -> default
    end
  end

  # ── User helpers ─────────────────────────────────────────────────────

  @doc """
  Extracts the current user from a LiveView socket or assigns map.
  Returns the `%User{}` struct or `nil` if not authenticated.
  """
  @spec current_user(Socket.t() | map()) :: Ecto.Schema.t() | nil
  def current_user(%Socket{assigns: assigns}) do
    current_user(assigns)
  end

  @spec current_user(map()) :: Ecto.Schema.t() | nil
  def current_user(%{current_scope: %{user: %_{} = user}}), do: user
  def current_user(%{user: %_{} = user}), do: user
  def current_user(_), do: nil

  # ── PubSub helpers ───────────────────────────────────────────────────

  @doc """
  Subscribes the socket to a Phoenix.PubSub topic, but only when the
  socket is connected (WebSocket). Safe to call unconditionally in mount/3.
  """
  @spec subscribe(Socket.t(), String.t()) :: :ok
  def subscribe(%Socket{} = socket, topic) when is_binary(topic) do
    if Phoenix.LiveView.connected?(socket) do
      Phoenix.PubSub.subscribe(Microwaveprop.PubSub, topic)
    end

    :ok
  end

  # ── URL helpers ──────────────────────────────────────────────────────

  @doc """
  Merges URL params with defaults for handle_params/3. Returns a map of
  merged values suitable for assigning to the socket.
  """
  @spec assign_url_params(map(), map()) :: map()
  def assign_url_params(params, defaults) when is_map(params) and is_map(defaults) do
    Map.merge(defaults, Map.take(params, Map.keys(defaults)))
  end
end