matplotex

defmodule Matplotex.Colorscheme.Rgb do
  @moduledoc false
alias Matplotex.Colorscheme.Colormap
  defstruct [
    red: 0.0, # 0-255
    green: 0.0, # 0-255
    blue: 0.0, # 0-255
    alpha: 1.0  # 0-1
  ]

  def rgb(red, green, blue, alpha\\1.0)
  def rgb({red, :percent}, {green, :percent}, {blue, :percent}, alpha)  do
    rgb(red * 255, green * 255, blue * 255, alpha)
  end
  def rgb(red, green, blue, alpha)  do
    %__MODULE__{
      red: cast(red, :red),
      green: cast(green, :green),
      blue: cast(blue, :blue),
      alpha: cast(alpha, :alpha)
    }
  end

  def to_string(struct, type\\nil)

  def to_string(struct, :nil) do
    type = case struct.alpha do
      1.0 -> :hex
      _ -> :rgba
    end
    to_string(struct, type)
  end

  def to_string(%__MODULE__{red: r, green: g, blue: b, alpha: alpha}, :rgba) do
    "rgba(#{round(r)}, #{round(g)}, #{round(b)}, #{alpha})"
  end
  def to_string(%__MODULE__{red: r, green: g, blue: b, alpha: 1.0}, :hex) do
    "#" <> to_hex(r) <> to_hex(g) <> to_hex(b)
  end

  def cast(value, field) when field in [:red, :green, :blue] do
    value/1
    |> min(255.0)
    |> max(0.0)
  end
  def cast(value, :alpha) do
    value/1
    |> min(1.0)
    |> max(0.0)
  end

  defp to_hex(value) when is_float(value), do:
    to_hex(round(value))
  defp to_hex(value) when value < 16, do:
    "0" <> Integer.to_string(value, 16)
  defp to_hex(value) when is_integer(value), do:
    Integer.to_string(value, 16)

    def from_hex!(input) do
      {:ok, color} = from_hex(input)
      color
    end

    def from_cmap!(%Colormap{color: color} = cmap) do
     %Colormap{cmap | color: from_hex!(color) }
    end

    def from_hex("#" <> <<r :: binary-size(2), g :: binary-size(2), b :: binary-size(2)>>) do
      {:ok, rgb(parse_hex(r), parse_hex(g), parse_hex(b))}
    end
    def from_hex("#" <> <<r :: binary-size(1), g :: binary-size(1), b :: binary-size(1)>>) do
      {:ok, rgb(parse_hex(r <> r), parse_hex(g <> g), parse_hex(b <> b))}
    end

    defp parse_hex(s), do: String.to_integer(s, 16)


end


defimpl String.Chars, for: CssColors.RGB do
def to_string(struct) do
 Matplotex.Colorscheme.Rgb.to_string(struct)
end
end