sac_thumbnails

defmodule SacThumbnails do
  @moduledoc """
  Create thumbnails from images and videos.
  """

  alias SacThumbnails.Animations
  alias SacThumbnails.ExtractFrame
  alias SacThumbnails.Gifs
  alias SacThumbnails.Draw

  import Mogrify

  @doc """
  Create a thumbnail image.

  Image format is inferred from output path file extension.
  To override, pass the `:format` option.

  Options:

  * `:width` - Width of the thumbnail. Defaults to input width.
  * `:height` - Height of the thumbnail. Defaults to input height.
  * `:max_width` - Maximum width of the thumbnail.
  * `:max_height` - Maximum height of the thumbnail.
  * `:circle` - Rounded or not.
  * `:format` - Output format for the thumbnail. Defaults to `output_path` extension, or `"png"` if indeterminate.
  * `:time_offset` - Timestamp in seconds at which to take screenshot, for videos and GIFs.
    By default picks a time near the beginning, based on video duration.
  """
  def scale(%{width: width, height: height} = image, path)
      when height != 0 and not is_nil(width) do
    scale_xy =
      case width > height do
        true -> width / height
        false -> height / width
      end

    image |> resize("#{width * scale_xy}x#{height * scale_xy}") |> save(path: path)
    image
  end

  def scale(image, _path), do: image

  def create_thumbnail(input_path, output_path, opts \\ []) do
    input_path = Path.expand(input_path)
    output_path = Path.expand(output_path)
    max_width = number_opt(opts, :max_width, 1_000_000_000_000)
    max_height = number_opt(opts, :max_height, 1_000_000_000_000)
    format = normalize_format(Keyword.get(opts, :format, image_format_from_path(output_path)))
    circle_shape = Keyword.get(opts, :circle, false)
    duration = Animations.duration(input_path)
    frame_time = number_opt(opts, :time_offset, frame_time(duration))
    replace = Keyword.get(opts, :replace, false)
    desired_width = number_opt(opts, :width, nil)
    |> IO.inspect()
    IO.inspect(opts)
    desired_height = number_opt(opts, :height, nil)

    single_frame_path =
      ExtractFrame.single_frame(input_path, frame_time, output_ext: ".#{format}")

    single_frame_path
    |> Mogrify.open()
    |> verbose()
    |> resize_if_different(desired_width, desired_height)
    |> resize_to_limit("#{max_width}x#{max_height}")
    |> optimize_image()
    |> save(path: output_path, in_place: replace)

    if(circle_shape) do
      circle_thumb_generator(output_path)
    end

    :ok = File.rm!(single_frame_path)
  end

  @doc """
  Create an animated GIF preview.

  Options:

  * `:width` - Width of the thumbnail. Defaults to input width.
  * `:height` - Height of the thumbnail. Defaults to input height.
  * `:max_width` - Maximum width of the thumbnail.
  * `:max_height` - Maximum height of the thumbnail.
  * `:frame_count` - Number of frames to output. Default 4.
  * `:fps` - Frames per second of output GIF. Default 1.
  * `:optimize` - Add mogrify options to reduce output size. Default true.
  """
  @spec animated_gif_thumbnail(binary, binary, Keyword.t()) :: :ok
  def animated_gif_thumbnail(input_path, output_path, opts \\ []) do
    input_path = Path.expand(input_path)
    output_path = Path.expand(output_path)

    max_width = number_opt(opts, :max_width, 1_000_000_000_000)
    max_height = number_opt(opts, :max_height, 1_000_000_000_000)
    desired_width = number_opt(opts, :width, nil)
    desired_height = number_opt(opts, :height, nil)
    frame_count = number_opt(opts, :frame_count, 4)
    fps = number_opt(opts, :fps, 1)
    optimize = Keyword.get(opts, :optimize, true)

    multi_frame_path =
      ExtractFrame.multiple_frames(input_path, frame_count, fps, output_ext: ".gif")

    multi_frame_path
    |> Mogrify.open()
    |> verbose()
    |> resize_if_different(desired_width, desired_height)
    |> resize_to_limit("#{max_width}x#{max_height}")
    |> optimize_mogrify_image(optimize)
    |> save(path: output_path)

    :ok = File.rm!(multi_frame_path)
  end

  defp image_format_from_path(path) do
    case Path.extname(path) do
      "" -> "png"
      # remove "."
      extname -> String.slice(extname, 1..-1)
    end
  end

  defp normalize_format(format) do
    if String.starts_with?(format, "."), do: String.slice(format, 1..-1), else: format
  end

  defp frame_time(:no_duration), do: 0
  defp frame_time(short) when short < 4, do: 0
  defp frame_time(medium) when medium < 10, do: 1
  defp frame_time(long), do: 0.1 * long

  defp resize_if_different(image, nil, nil), do: image

  defp resize_if_different(%{width: width, height: height} = image, desired_width, desired_height) do
    if width != desired_width or height != desired_height do
      image |> resize("#{desired_width}x#{desired_height}")
    else
      image
    end
  end

  defp draw_circle(%_{width: origin_x, height: origin_y} = image) do
    perim_y = perim(origin_y, origin_x)
    perim_x = perim(origin_x, origin_y)
    size = max(origin_x, origin_y)

    image
    |> gravity("center")
    |> resize_if_different(size, size)
    |> resize_to_limit("#{10_000_000}x#{10_000_000}")
    # |> Draw.circle(origin_y, origin_y, perim_x, perim_y)
    |> Draw.circle(size, size, perim_x, perim_y)

    # image |> Draw.circle(200, 200, 200, 0)
  end

  defp perim(a, b) when a > b, do: a
  defp perim(_a, _b), do: 0

  def circle_thumb_generator(output_path) do
    tmp = ExtractFrame.single_frame(output_path, 0)

    %Mogrify.Image{path: tmp, ext: "png"}
    |> verbose()
    |> scale(output_path)
    |> canvas(:none)
    |> custom(:fill, Path.expand(output_path))
    |> draw_circle()
    |> create(path: tmp)

    tmp
    |> Mogrify.open()
    |> optimize_image()
    |> save(path: output_path)

    Path.dirname(output_path)
    |> (fn x -> Path.wildcard("#{x}/*.*g~*") end).()
    |> Enum.map(&File.rm(&1))

    :ok = File.rm!(tmp)
  end

  defp optimize_mogrify_image(image, true = _optimize) do
    Gifs.optimize_mogrify_image(image)
  end

  defp optimize_mogrify_image(image, false = _optimize), do: image

  defp optimize_image(image) do
    image
    # |> quality("50")
    |> custom(:interlace, :line)
    |> image_operator(:strip)
    # |> custom(:density, "1000")
    |> custom("fuzz", "10%")
    |> custom("layers", "Optimize")
  end

  defp number_opt(opts, key, default) do
    value = Keyword.get(opts, key)
    if is_number(value), do: value, else: default
  end
end