defmodule Raxol.UI.Rendering.Pipeline.Stages do
  @moduledoc """
  Defines and executes the rendering pipeline stages for UI components.
  """

  @doc """
  Executes the rendering pipeline stages.

  This function processes the render operation through various stages
  to produce the final rendered output.
  """
  @spec execute_render_stages(tuple(), any(), module(), any(), any()) :: any()
  def execute_render_stages(operation, tree, renderer_module, context, options) do
    # Process through the pipeline stages
    tree
    |> validate_tree()
    |> preprocess(operation)
    |> apply_styles()
    |> layout()
    |> render(renderer_module, context, options)
    |> postprocess()
  end

  # Stage 1: Validate the tree structure
  defp validate_tree(tree) do
    # Basic validation - ensure tree is not nil
    case tree do
      nil -> %{}
      tree -> tree
    end
  end

  # Stage 2: Preprocess based on operation type
  defp preprocess(tree, operation) do
    case operation do
      {:replace, _tree} ->
        # Full replacement - use the tree as-is
        tree

      {:update, region, subtree} ->
        # Partial update - merge subtree into region
        Map.put(tree, :region, region)
        |> Map.put(:subtree, subtree)

      _ ->
        tree
    end
  end

  # Stage 3: Apply styles to the tree
  defp apply_styles(tree) do
    # Apply any pending styles or transformations
    tree
    |> apply_default_styles()
    |> apply_theme_styles()
    |> apply_custom_styles()
  end

  defp apply_default_styles(tree) do
    # Apply default styles if not present
    Map.put_new(tree, :style, %{})
  end

  defp apply_theme_styles(tree) do
    # Apply theme-based styles
    # This would integrate with the theme system
    tree
  end

  defp apply_custom_styles(tree) do
    # Apply any custom styles from the tree
    tree
  end

  # Stage 4: Layout calculation
  defp layout(tree) do
    # Calculate layout positions and dimensions
    tree
    |> calculate_dimensions()
    |> calculate_positions()
    |> apply_constraints()
  end

  defp calculate_dimensions(tree) do
    # Calculate width and height based on content and constraints
    Map.put_new(tree, :dimensions, %{width: 0, height: 0})
  end

  defp calculate_positions(tree) do
    # Calculate x and y positions
    Map.put_new(tree, :position, %{x: 0, y: 0})
  end

  defp apply_constraints(tree) do
    # Apply any layout constraints (min/max width/height, etc.)
    tree
  end

  # Stage 5: Render using the specified renderer
  defp render(tree, renderer_module, context, options) do
    # Delegate to the renderer module if available
    if renderer_module && function_exported?(renderer_module, :render, 3) do
      renderer_module.render(tree, context, options)
    else
      # Fallback rendering
      default_render(tree)
    end
  end

  defp default_render(tree) do
    # Basic rendering fallback
    %{
      rendered: true,
      content: tree,
      output: generate_output(tree)
    }
  end

  defp generate_output(tree) do
    # Generate the actual output (string, buffer, etc.)
    case tree do
      %{content: content} when is_binary(content) -> content
      %{text: text} when is_binary(text) -> text
      _ -> ""
    end
  end

  # Stage 6: Post-processing
  defp postprocess(rendered) do
    rendered
    |> optimize_output()
    |> apply_effects()
    |> finalize()
  end

  defp optimize_output(rendered) do
    # Optimize the rendered output (remove redundant operations, etc.)
    rendered
  end

  defp apply_effects(rendered) do
    # Apply any post-render effects (shadows, animations, etc.)
    rendered
  end

  defp finalize(rendered) do
    # Final cleanup and preparation for display
    rendered
  end

  @doc """
  Executes a simplified render for performance-critical paths.
  """
  @spec fast_render(any(), module()) :: any()
  def fast_render(tree, renderer_module) do
    tree
    |> validate_tree()
    |> render(renderer_module, nil, nil)
  end

  @doc """
  Executes only the layout stage.
  """
  @spec layout_only(any()) :: any()
  def layout_only(tree) do
    tree
    |> validate_tree()
    |> layout()
  end

  @doc """
  Executes only the style application stage.
  """
  @spec style_only(any()) :: any()
  def style_only(tree) do
    tree
    |> validate_tree()
    |> apply_styles()
  end
end
