defmodule Infer.Font do
  @moduledoc """
  Font type matchers based on the [magic number](https://en.wikipedia.org/wiki/Magic_number_(programming))
  """

  @doc """
  Takes the binary file contents as arguments. Returns `true` if it's a woff font.
  """
  @spec woff?(binary()) :: boolean()
  def woff?(<<0x77, 0x4F, 0x46, 0x46, 0x00, 0x01, 0x00, 0x00, _rest::binary>>), do: true
  def woff?(_binary), do: false

  @doc """
  Takes the binary file contents as arguments. Returns `true` if it's a woff2 font.
  """
  @spec woff2?(binary()) :: boolean()
  def woff2?(<<0x77, 0x4F, 0x46, 0x32, 0x00, 0x01, 0x00, 0x00, _rest::binary>>), do: true
  def woff2?(_binary), do: false

  @doc """
  Takes the binary file contents as arguments. Returns `true` if it's a ttf font.

  ## Examples

      iex> binary = File.read!("test/fonts/sample.ttf")
      iex> Infer.Font.ttf?(binary)
      true

  """
  @spec ttf?(binary()) :: boolean()
  def ttf?(<<0x00, 0x01, 0x00, 0x00, 0x00, _rest::binary>>), do: true
  def ttf?(_binary), do: false

  @doc """
  Takes the binary file contents as arguments. Returns `true` if it's a otf font.
  """
  @spec otf?(binary()) :: boolean()
  def otf?(<<0x4F, 0x54, 0x54, 0x4F, 0x00>>), do: true
  def otf?(_binary), do: false
end