defmodule ExMagick do
  alias ExMagick.CommandBuilder, as: Builder

  @doc """
  Generate the command builder struct.

  ## Examples

      iex> ExMagick.init()
      %ExMagick.CommandBuilder{command: "convert", options: []}

  """
  def init do
    %Builder{}
  end

  @doc """
  Set a file path to the command builder.

  ## Examples

      iex> ExMagick.init()
      ...> |> ExMagick.put_image("test.png")
      %ExMagick.CommandBuilder{command: "convert", options: ["test.png"]}

  """
  def put_image(%Builder{} = builder, path) when is_binary(path) do
    Builder.put_file(builder, path)
  end

  @doc """
  Set a file by base64 encoded image to the command builder.

  ## Examples

      iex> ExMagick.init()
      ...> |> ExMagick.put_base64_image("data:image/png;base64,....")
      %ExMagick.CommandBuilder{command: "convert", options: ["inline:data:data:image/png;base64,...."]}

  """
  def put_base64_image(%Builder{} = builder, encoded_image) do
    # TODO sanitize encoded_image
    Builder.put_file(builder, "inline:data:#{encoded_image}")
  end

  @fill_map [
    fill: :xc,
    gradient: :gradient
  ]
  @doc """
  Set a file by RGB color to the command builder.

  ## Examples

      iex> ExMagick.init()
      ...> |> ExMagick.put_color("#00aaff")
      %ExMagick.CommandBuilder{command: "convert", options: ["xc:#00aaff"]}
      iex> ExMagick.init()
      ...> |> ExMagick.put_color("#00aaff-#ffaa00", fill: :gradient)
      %ExMagick.CommandBuilder{command: "convert", options: ["gradient:#00aaff-#ffaa00"]}

  """
  def put_color(%Builder{} = builder, rgb, opts \\ [fill: :fill]) do
    # TODO sanitize rgb to have # prefix
    # TODO sanitize rgb for gradient
    Builder.put_file(builder, "#{@fill_map[opts[:fill]]}:#{rgb}")
  end

  @doc """
  Set an option to the command builder.

  ## Examples

      iex> ExMagick.init()
      ...> |> ExMagick.put_option("size", "150x150")
      %ExMagick.CommandBuilder{command: "convert", options: ["-size", "150x150"]}

  """
  def put_option(%Builder{} = builder, key, value) do
    Builder.put_option(builder, key, value)
  end

  @doc """
  Output the image from command builder.

  ## Examples

      iex> ExMagick.init()
      ...> |> ExMagick.put_option("size", "150x150")
      ...> |> ExMagick.put_color("#00aaff")
      ...> |> ExMagick.output("tmp/output.png")
      {:ok, "tmp/output.png"}
      iex> {result, _} =
      ...>   ExMagick.init()
      ...>   |> ExMagick.put_color("invalid_color_code")
      ...>   |> ExMagick.output("tmp/output.png")
      iex> result
      :error

  """
  def output(%Builder{} = builder, output_path) do
    builder = Builder.put_file(builder, output_path)

    System.cmd(builder.command, builder.options, stderr_to_stdout: true)
    |> case do
      {_, 0} -> {:ok, output_path}
      {message, _} -> {:error, message}
    end
  end

  def output!(%Builder{} = builder, output_path) do
    {:ok, result_output_path} = output(builder, output_path)
    result_output_path
  end
end