defmodule Raxol.Core.Renderer.View.Components.Scroll do
  @moduledoc """
  Handles scrollable views for the Raxol view system.
  Provides viewport management, scrollbar rendering, and content scrolling.
  """

  @doc """
  Creates a new scrollable view.

  ## Options
    * `:viewport` - Viewport size {width, height}
    * `:offset` - Initial scroll offset {x, y}
    * `:scrollbars` - Whether to show scrollbars (boolean)
    * `:fg` - Foreground color
    * `:bg` - Background color

  ## Examples

      Scroll.new(content, viewport: {80, 24})
      Scroll.new(content, offset: {0, 10}, scrollbars: true)
  """
  def new(content, opts \\ []) do
    offset = Keyword.get(opts, :offset, {0, 0})

    # Validate offset
    case {is_tuple(offset), tuple_size(offset), is_integer(elem(offset, 0)),
          is_integer(elem(offset, 1))} do
      {true, 2, true, true} -> :ok
      _ -> raise ArgumentError, "Scroll offset must be a tuple of two integers"
    end

    %{
      type: :scroll,
      children: [content],
      viewport: Keyword.get(opts, :viewport),
      offset: offset,
      scrollbars: Keyword.get(opts, :scrollbars, true),
      fg: Keyword.get(opts, :fg),
      bg: Keyword.get(opts, :bg)
    }
  end

  @doc """
  Calculates the layout of a scrollable view.
  """
  def calculate_layout(scroll, available_size) do
    {viewport_width, viewport_height} = scroll.viewport
    {offset_x, offset_y} = scroll.offset

    # Calculate content size
    content_size = calculate_content_size(scroll.children, available_size)

    # Calculate scrollbar visibility and position
    scrollbar_info =
      calculate_scrollbars(content_size, {viewport_width, viewport_height})

    # Apply viewport clipping and offset
    clipped_content =
      apply_viewport(
        scroll.children,
        content_size,
        {offset_x, offset_y},
        {viewport_width, viewport_height}
      )

    # Add scrollbars if enabled
    case scroll.scrollbars do
      true ->
        add_scrollbars(
          clipped_content,
          scrollbar_info,
          {viewport_width, viewport_height}
        )

      false ->
        clipped_content
    end
  end

  defp calculate_content_size(_children, available_size) do
    # Calculate the total size of all children
    # This would handle:
    # - Child dimensions
    # - Layout constraints
    # - Overflow handling
    {width, height} = available_size
    {width, height}
  end

  defp calculate_scrollbars(
         {content_width, content_height},
         {viewport_width, viewport_height}
       ) do
    # Calculate if scrollbars are needed and their positions
    horizontal_needed = content_width > viewport_width
    vertical_needed = content_height > viewport_height

    %{
      horizontal: %{
        needed: horizontal_needed,
        position:
          case horizontal_needed do
            true -> calculate_scrollbar_position(content_width, viewport_width)
            false -> 0
          end
      },
      vertical: %{
        needed: vertical_needed,
        position:
          case vertical_needed do
            true ->
              calculate_scrollbar_position(content_height, viewport_height)

            false ->
              0
          end
      }
    }
  end

  defp calculate_scrollbar_position(_content_size, _viewport_size) do
    # Calculate scrollbar position based on content and viewport size
    # This would handle:
    # - Proportional positioning
    # - Minimum/maximum bounds
    # - Smooth scrolling
    0
  end

  defp apply_viewport(
         children,
         _content_size,
         {_offset_x, _offset_y},
         {_viewport_width, _viewport_height}
       ) do
    # Apply viewport clipping and offset to content
    # This would handle:
    # - Content clipping
    # - Offset application
    # - Partial content rendering
    children
  end

  defp add_scrollbars(
         content,
         _scrollbar_info,
         {_viewport_width, _viewport_height}
       ) do
    # Add scrollbars to the content
    # This would handle:
    # - Scrollbar rendering
    # - Position calculation
    # - Visual styling
    content
  end

  @doc """
  Updates the scroll offset of a view.
  """
  def update_offset(scroll, {new_x, new_y}) do
    # Validate and constrain the new offset
    {content_width, content_height} =
      calculate_content_size(scroll.children, scroll.viewport)

    {viewport_width, viewport_height} = scroll.viewport

    constrained_x = max(0, min(new_x, content_width - viewport_width))
    constrained_y = max(0, min(new_y, content_height - viewport_height))

    %{scroll | offset: {constrained_x, constrained_y}}
  end
end
