/* SPDX-License-Identifier: GPL-2.0-or-later */

/** \file
 * \ingroup edinterface
 *
 * This part of the UI-View API is mostly needed to support persistent state of items within the
 * view. Views are stored in #uiBlock's, and kept alive with it until after the next redraw. So we
 * can compare the old view items with the new view items and keep state persistent for matching
 * ones.
 */

#include <memory>
#include <type_traits>
#include <variant>

#include "DNA_screen_types.h"

#include "BKE_screen.h"

#include "BLI_listbase.h"

#include "ED_screen.h"

#include "interface_intern.h"

#include "UI_interface.hh"

#include "UI_grid_view.hh"
#include "UI_tree_view.hh"

using namespace blender;
using namespace blender::ui;

/**
 * Wrapper to store views in a #ListBase. There's no `uiView` base class, we just store views as a
 * #std::variant.
 */
struct ViewLink : public Link {
  using TreeViewPtr = std::unique_ptr<AbstractTreeView>;
  using GridViewPtr = std::unique_ptr<AbstractGridView>;

  std::string idname;
  /* NOTE: Can't use std::get() on this until minimum macOS deployment target is 10.14. */
  std::variant<TreeViewPtr, GridViewPtr> view;
};

template<class T> constexpr void check_if_valid_view_type()
{
  static_assert(std::is_same_v<T, AbstractTreeView> || std::is_same_v<T, AbstractGridView>,
                "Unsupported view type");
}

template<class T> T *get_view_from_link(ViewLink &link)
{
  auto *t_uptr = std::get_if<std::unique_ptr<T>>(&link.view);
  return t_uptr ? t_uptr->get() : nullptr;
}

template<class T>
static T *ui_block_add_view_impl(uiBlock &block, StringRef idname, std::unique_ptr<T> view)
{
  check_if_valid_view_type<T>();

  ViewLink *view_link = MEM_new<ViewLink>(__func__);
  BLI_addtail(&block.views, view_link);

  view_link->view = std::move(view);
  view_link->idname = idname;

  return get_view_from_link<T>(*view_link);
}

AbstractGridView *UI_block_add_view(uiBlock &block,
                                    StringRef idname,
                                    std::unique_ptr<AbstractGridView> tree_view)
{
  return ui_block_add_view_impl<AbstractGridView>(block, idname, std::move(tree_view));
}

AbstractTreeView *UI_block_add_view(uiBlock &block,
                                    StringRef idname,
                                    std::unique_ptr<AbstractTreeView> tree_view)
{
  return ui_block_add_view_impl<AbstractTreeView>(block, idname, std::move(tree_view));
}

void ui_block_free_views(uiBlock *block)
{
  LISTBASE_FOREACH_MUTABLE (ViewLink *, link, &block->views) {
    MEM_delete(link);
  }
}

void UI_block_views_listen(const uiBlock *block, const wmRegionListenerParams *listener_params)
{
  ARegion *region = listener_params->region;

  LISTBASE_FOREACH (ViewLink *, view_link, &block->views) {
    if (AbstractGridView *grid_view = get_view_from_link<AbstractGridView>(*view_link)) {
      if (UI_grid_view_listen_should_redraw(reinterpret_cast<uiGridViewHandle *>(grid_view),
                                            listener_params->notifier)) {
        ED_region_tag_redraw(region);
      }
    }
    else if (AbstractTreeView *tree_view = get_view_from_link<AbstractTreeView>(*view_link)) {
      if (UI_tree_view_listen_should_redraw(reinterpret_cast<uiTreeViewHandle *>(tree_view),
                                            listener_params->notifier)) {
        ED_region_tag_redraw(region);
      }
    }
  }
}

uiTreeViewItemHandle *UI_block_tree_view_find_item_at(const ARegion *region, const int xy[2])
{
  uiButTreeRow *tree_row_but = (uiButTreeRow *)ui_tree_row_find_mouse_over(region, xy);
  if (!tree_row_but) {
    return nullptr;
  }

  return tree_row_but->tree_item;
}

uiTreeViewItemHandle *UI_block_tree_view_find_active_item(const ARegion *region)
{
  uiButTreeRow *tree_row_but = (uiButTreeRow *)ui_tree_row_find_active(region);
  if (!tree_row_but) {
    return nullptr;
  }

  return tree_row_but->tree_item;
}

template<class T> static StringRef ui_block_view_find_idname(const uiBlock &block, const T &view)
{
  check_if_valid_view_type<T>();

  /* First get the idname the of the view we're looking for. */
  LISTBASE_FOREACH (ViewLink *, view_link, &block.views) {
    if (get_view_from_link<T>(*view_link) == &view) {
      return view_link->idname;
    }
  }

  return {};
}

template<class T>
static T *ui_block_view_find_matching_in_old_block(const uiBlock &new_block, const T &new_view)
{
  check_if_valid_view_type<T>();

  uiBlock *old_block = new_block.oldblock;
  if (!old_block) {
    return nullptr;
  }

  StringRef idname = ui_block_view_find_idname(new_block, new_view);
  if (idname.is_empty()) {
    return nullptr;
  }

  LISTBASE_FOREACH (ViewLink *, old_view_link, &old_block->views) {
    if (old_view_link->idname == idname) {
      return get_view_from_link<T>(*old_view_link);
    }
  }

  return nullptr;
}

uiTreeViewHandle *ui_block_tree_view_find_matching_in_old_block(
    const uiBlock *new_block, const uiTreeViewHandle *new_view_handle)
{
  BLI_assert(new_block && new_view_handle);
  const AbstractTreeView &new_view = reinterpret_cast<const AbstractTreeView &>(*new_view_handle);

  AbstractTreeView *old_view = ui_block_view_find_matching_in_old_block(*new_block, new_view);
  return reinterpret_cast<uiTreeViewHandle *>(old_view);
}

uiGridViewHandle *ui_block_grid_view_find_matching_in_old_block(
    const uiBlock *new_block, const uiGridViewHandle *new_view_handle)
{
  BLI_assert(new_block && new_view_handle);
  const AbstractGridView &new_view = reinterpret_cast<const AbstractGridView &>(*new_view_handle);

  AbstractGridView *old_view = ui_block_view_find_matching_in_old_block(*new_block, new_view);
  return reinterpret_cast<uiGridViewHandle *>(old_view);
}

uiButTreeRow *ui_block_view_find_treerow_in_old_block(const uiBlock *new_block,
                                                      const uiTreeViewItemHandle *new_item_handle)
{
  uiBlock *old_block = new_block->oldblock;
  if (!old_block) {
    return nullptr;
  }

  const AbstractTreeViewItem &new_item = *reinterpret_cast<const AbstractTreeViewItem *>(
      new_item_handle);
  const AbstractTreeView *old_tree_view = ui_block_view_find_matching_in_old_block(
      *new_block, new_item.get_tree_view());
  if (!old_tree_view) {
    return nullptr;
  }

  LISTBASE_FOREACH (uiBut *, old_but, &old_block->buttons) {
    if (old_but->type != UI_BTYPE_TREEROW) {
      continue;
    }
    uiButTreeRow *old_treerow_but = (uiButTreeRow *)old_but;
    if (!old_treerow_but->tree_item) {
      continue;
    }
    AbstractTreeViewItem &old_item = *reinterpret_cast<AbstractTreeViewItem *>(
        old_treerow_but->tree_item);
    /* Check if the row is from the expected tree-view. */
    if (&old_item.get_tree_view() != old_tree_view) {
      continue;
    }

    if (UI_tree_view_item_matches(new_item_handle, old_treerow_but->tree_item)) {
      return old_treerow_but;
    }
  }

  return nullptr;
}