defmodule Infer.Image do
  @moduledoc """
  Image 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 jpeg.

  ## Examples

      iex> binary = File.read!("test/images/sample.jpg")
      iex> Infer.Image.jpeg?(binary)
      true

      iex> binary = File.read!("test/images/sample.jp2")
      iex> Infer.Image.jpeg?(binary)
      false

  """
  @spec jpeg?(binary()) :: boolean()
  def jpeg?(<<0xFF, 0xD8, 0xFF>> <> _), do: true
  def jpeg?(_binary), do: false

  @doc """
  Takes the binary file contents as arguments. Returns `true` if it's a jpeg2000.

  ## Examples

      iex> binary = File.read!("test/images/sample.jp2")
      iex> Infer.Image.jpeg2000?(binary)
      true

      iex> binary = File.read!("test/images/sample.jpg")
      iex> Infer.Image.jpeg2000?(binary)
      false

  """
  @spec jpeg2000?(binary()) :: boolean()
  def jpeg2000?(<<0x0, 0x0, 0x0, 0xC, 0x6A, 0x50, 0x20, 0x20, 0xD, 0xA, 0x87, 0xA, 0x0, _rest::binary>>), do: true
  def jpeg2000?(_binary), do: false

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

  ## Examples

      iex> binary = File.read!("test/images/sample.png")
      iex> Infer.Image.png?(binary)
      true

      iex> binary = File.read!("test/images/sample.jpg")
      iex> Infer.Image.png?(binary)
      false

  """
  @spec png?(binary()) :: boolean()
  def png?(<<0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A, _rest::binary>>), do: true
  def png?(_binary), do: false

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

  ## Examples

      iex> binary = File.read!("test/images/sample.gif")
      iex> Infer.Image.gif?(binary)
      true

      iex> binary = File.read!("test/images/sample.jpg")
      iex> Infer.Image.gif?(binary)
      false

  """
  @spec gif?(binary()) :: boolean()
  def gif?(<<0x47, 0x49, 0x46, _rest::binary>>), do: true
  def gif?(_binary), do: false

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

  ## Examples

      iex> binary = File.read!("test/images/sample.webp")
      iex> Infer.Image.webp?(binary)
      true

      iex> binary = File.read!("test/images/sample.gif")
      iex> Infer.Image.webp?(binary)
      false

  """
  @spec webp?(binary()) :: boolean()
  def webp?(<<_head::binary-size(8), 0x57, 0x45, 0x42, 0x50, _rest::binary>>), do: true
  def webp?(_binary), do: false

  @doc """
  Takes the binary file contents as arguments. Returns `true` if it's a cr2.

  ## Examples

      iex> binary = File.read!("test/images/sample.cr2")
      iex> Infer.Image.cr2?(binary)
      true

      iex> binary = File.read!("test/images/sample.tiff")
      iex> Infer.Image.cr2?(binary)
      false

  """
  @spec cr2?(binary()) :: boolean()
  def cr2?(<<0x49, 0x49, 0x2A, 0x0, _data::binary-size(4), 0x43, 0x52, 0x02, _rest::binary>>), do: true
  def cr2?(<<0x4D, 0x4D, 0x0, 0x2A, _data::binary-size(4), 0x43, 0x52, 0x02, _rest::binary>>), do: true
  def cr2?(_binary), do: false

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

  ## Examples

      iex> binary = File.read!("test/images/sample.tiff")
      iex> Infer.Image.tiff?(binary)
      true

      iex> binary = File.read!("test/images/sample.cr2")
      iex> Infer.Image.tiff?(binary)
      false

  """
  @spec tiff?(binary()) :: boolean()
  def tiff?(<<0x49, 0x49, 0x2A, 0x0, _data::binary-size(4), i_8, i_9, _rest::binary>> = binary) when i_8 != <<0x43>> and i_9 != <<0x52>>,
    do: !cr2?(binary)

  def tiff?(<<0x4D, 0x4D, 0x0, 0x2A, _data::binary-size(4), i_8, i_9, _rest::binary>> = binary) when i_8 != <<0x43>> and i_9 != <<0x52>>,
    do: !cr2?(binary)

  def tiff?(_binary), do: false

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

  ## Examples

      iex> binary = File.read!("test/images/sample.bmp")
      iex> Infer.Image.bmp?(binary)
      true

      iex> binary = File.read!("test/images/sample.png")
      iex> Infer.Image.bmp?(binary)
      false

  """
  @spec bmp?(binary()) :: boolean()
  def bmp?(<<0x42, 0x4D, _rest::binary>>), do: true
  def bmp?(_binary), do: false

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

  ## Examples

      iex> binary = File.read!("test/images/sample.jxr")
      iex> Infer.Image.jxr?(binary)
      true

      iex> binary = File.read!("test/images/sample.png")
      iex> Infer.Image.jxr?(binary)
      false

  """
  @spec jxr?(binary()) :: boolean()
  def jxr?(<<0x49, 0x49, 0xBC, _rest::binary>>), do: true
  def jxr?(_binary), do: false

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

  ## Examples

      iex> binary = File.read!("test/images/sample.psd")
      iex> Infer.Image.psd?(binary)
      true

      iex> binary = File.read!("test/images/sample.png")
      iex> Infer.Image.psd?(binary)
      false

  """
  @spec psd?(binary()) :: boolean()
  def psd?(<<0x38, 0x42, 0x50, 0x53, _rest::binary>>), do: true
  def psd?(_binary), do: false

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

  ## Examples

      iex> binary = File.read!("test/images/sample.ico")
      iex> Infer.Image.ico?(binary)
      true

      iex> binary = File.read!("test/images/sample.png")
      iex> Infer.Image.ico?(binary)
      false

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

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

  ## Examples

      iex> binary = File.read!("test/images/sample.heif")
      iex> Infer.Image.heif?(binary)
      true

      iex> binary = File.read!("test/images/sample.avif")
      iex> Infer.Image.heif?(binary)
      false

  """
  @spec heif?(binary()) :: boolean()
  def heif?(<<ftyp_length::binary-size(4), "ftyp", _::binary>> = binary) when bit_size(ftyp_length) >= 16 do
    case get_ftyp(binary) do
      {"heic", _minor, _compatbile} -> true
      {major, _minor, compatible} when major in ["mif1", "msf1"] -> 'heic' in compatible
      _ -> false
    end
  end

  def heif?(_binary), do: false

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

  ## Examples

      iex> binary = File.read!("test/images/sample.avif")
      iex> Infer.Image.avif?(binary)
      true

      iex> binary = File.read!("test/images/sample.heif")
      iex> Infer.Image.avif?(binary)
      false

  """
  @spec avif?(binary()) :: boolean()
  def avif?(<<ftyp_length::binary-size(4), "ftyp", _::binary>> = binary) when bit_size(ftyp_length) >= 16 do
    case get_ftyp(binary) do
      {major, _minor, _compatbile} when major in ["avif", "avis"] -> true
      {_major, _minor, compatible} -> 'avif' in compatible || 'avis' in compatible
      _ -> false
    end
  end

  def avif?(_binary), do: false

  defp get_ftyp(<<ftyp_length::binary-size(4), "ftyp", major::binary-size(4), minor::binary-size(4), rest::binary>>) do
    compatible =
      rest
      |> :binary.bin_to_list()
      |> Stream.chunk_every(4)
      |> Enum.take(Enum.max([Integer.floor_div(bit_size(ftyp_length), 4) - 4, 0]))

    {major, minor, compatible}
  end
end