defmodule ImgDecode do
  @moduledoc """
  Documentation for `ImgDecode`.
  """

  @doc """
  Decode image from a given file

  - **filename**. Path to the image.

  ## Example
  ```elixir
  {:ok, img, shape, type} = ImgDecode.from_file("/path/to/image")
  {h, w, c} = shape
  ```
  """
  def from_file(filename), do: from_file(filename, 0, :u8)

  @doc """
  Decode image from a given file

  - **filename**. Path to the image.
  - **desired_channels**. `0` for auto-detection. Otherwise, the number of desired channels.

  ## Example
  ```elixir
  # if you know the image is a 4-channel image and auto-detection failed
  {:ok, img, shape, type} = ImgDecode.from_file("/path/to/image", 4)
  {h, w, c} = shape
  ```
  """
  def from_file(filename, desired_channels) do
    from_file(filename, desired_channels, :u8)
  end

  @doc """
  Decode image from a given file

  - **filename**. Path to the image.
  - **desired_channels**. `0` for auto-detection. Otherwise, the number of desired channels.
  - **type**. Specify format for each channel. `:u8`, `:u16` or `:f32`.

  ## Example
  ```elixir
  # Use 0 for auto-detecting number of channels
  # but specify each channel is in float (32-bit)
  {:ok, img, shape, type} = ImgDecode.from_file("/path/to/image", 0, :f32)
  {h, w, c} = shape
  ```
  """
  def from_file(filename, desired_channels, type) when is_binary(filename) and desired_channels >= 0 and (type == :u8 or type == :u16 or type == :f32) do
    ImgDecode.Nif.from_file(filename, desired_channels, type)
  end

  @doc """
  Decode image from buffer in memory

  - **buffer**. Buffered raw file data in memory.

  ## Example
  ```elixir
  # image buffer from a file or perhaps download from Internet
  {:ok, buffer} = File.read("/path/to/image")
  # decode the image from memory
  {:ok, img, shape, type} = ImgDecode.from_memory(buffer)
  {h, w, c} = shape
  ```
  """
  def from_memory(buffer), do: from_memory(buffer, 0, :u8)

  @doc """
  Decode image from buffer in memory

  - **buffer**. Buffered raw file data in memory.
  - **desired_channels**. `0` for auto-detection. Otherwise, the number of desired channels.

  ## Example
  ```elixir
  # image buffer from a file or perhaps download from Internet
  {:ok, buffer} = File.read("/path/to/image")
  # decode the image from memory
  # and specify it is a 4-channel image
  {:ok, img, shape, type} = ImgDecode.from_memory(buffer, 4)
  {h, w, c} = shape
  ```
  """
  def from_memory(buffer, desired_channels) do
    from_memory(buffer, desired_channels, :u8)
  end

  @doc """
  Decode image from buffer in memory

  - **buffer**. Buffered raw file data in memory.
  - **desired_channels**. `0` for auto-detection. Otherwise, the number of desired channels.
  - **type**. Specify format for each channel. `:u8`, `:u16` or `:f32`.

  ## Example
  ```elixir
  # image buffer from a file or perhaps download from Internet
  {:ok, buffer} = File.read("/path/to/image")
  # decode the image from memory
  # and specify it is a 3-channel image and each channel is in uint8_t
  {:ok, img, shape, type} = ImgDecode.from_memory(buffer, 3, :u8)
  {h, w, c} = shape
  ```
  """
  def from_memory(buffer, desired_channels, type) when is_binary(buffer) and desired_channels >= 0 and (type == :u8 or type == :u16 or type == :f32) do
    ImgDecode.Nif.from_memory(buffer, desired_channels, type)
  end
end