defmodule MapHelpers do
  @doc """
  Checks if `map1`'s entries are all contained in `map2`.

  ## Options

  - `:recursive` - Recursively checks if a value is map (Default: `false`)

  ## Examples

  ```
  iex> submap?(%{}, %{})
  true
  iex> submap?(%{a: 1, b: 2}, %{a: 1, b: 2, c: 3})
  true
  iex> submap?(%{a: 1, b: 2, c: 3}, %{a: 1, b: 2})
  false
  iex> submap?(%{a: 1, b: %{}}, %{a: 1, b: %{c: 1}})
  false
  iex> submap?(%{a: 1, b: %{}}, %{a: 1, b: %{c: 1}}, recursive: true)
  true
  ```
  """
  @spec submap?(map, map, [option]) :: boolean when option: {:recursive, boolean}
  def submap?(map1, map2, opts \\ []) when is_map(map1) and is_map(map2) do
    recursive = Keyword.get(opts, :recursive, false)

    map1
    |> Enum.all?(fn
      {k, v} when is_map(v) and recursive ->
        m = map2[k]
        is_map(m) && submap?(v, m)

      {k, v} ->
        map2[k] === v
    end)
  end

  @doc """
  Equivalent to `submap?(map1, map2, recursive: true)`.
  """
  @spec deep_submap?(map, map) :: boolean
  def deep_submap?(map1, map2), do: submap?(map1, map2, recursive: true)
end