#include "scroller.hpp"

#include "log.hpp"
#include <algorithm>						  // for max, min
#include <ftxui/component/component_base.hpp> // for Component, ComponentBase
#include <ftxui/component/event.hpp>		  // for Event, Event::ArrowDown, Event::ArrowUp, Event::End, Event::Home, Event::PageDown, Event::PageUp
#include <memory>							  // for shared_ptr, allocator, __shared_ptr_access
#include <utility>							  // for move

#include "ftxui/component/component.hpp" // for Make
#include "ftxui/component/mouse.hpp"	 // for Mouse, Mouse::WheelDown, Mouse::WheelUp
#include "ftxui/dom/deprecated.hpp"		 // for text
#include "ftxui/dom/elements.hpp"		 // for operator|, Element, size, vbox, EQUAL, HEIGHT, dbox, reflect, focus, inverted, nothing, select, vscroll_indicator, yflex, yframe
#include "ftxui/dom/node.hpp"			 // for Node
#include "ftxui/dom/requirement.hpp"	 // for Requirement
#include "ftxui/screen/box.hpp"			 // for Box

namespace ftxui { // NOLINT

class CScrollerBase : public ComponentBase {
  public:
	CScrollerBase(Component child) { Add(child); }

  private:
	Element OnRender() final { // NOLINT
		auto focused = Focused() ? focus : ftxui::select;
		auto style	 = Focused() ? inverted : nothing;

		Element background = ComponentBase::Render();
		background->ComputeRequirement();
		size_ = background->requirement().min_y;
		return dbox({
				   std::move(background),
				   vbox({
					   text(L"") | size(HEIGHT, EQUAL, selected_),
					   text(L"") | style | focused,
				   }),
			   }) |
			   vscroll_indicator | yframe | yflex | reflect(box_);
	}

	bool OnEvent(Event event) final { // NOLINT
		if (event.is_mouse() && box_.Contain(event.mouse().x, event.mouse().y))
			TakeFocus();

		int selected_old = selected_;
		if (event == Event::ArrowUp || event == Event::Character('k') ||
			(event.is_mouse() && event.mouse().button == Mouse::WheelUp))
			selected_--;
		if ((event == Event::ArrowDown || event == Event::Character('j') ||
			 (event.is_mouse() && event.mouse().button == Mouse::WheelDown)))
			selected_++;
		if (event == Event::PageDown)
			selected_ += box_.y_max - box_.y_min;
		if (event == Event::PageUp)
			selected_ -= box_.y_max - box_.y_min;
		if (event == Event::Home)
			selected_ = 0;
		if (event == Event::End)
			selected_ = size_;

		if (event == Event::Custom && sticky_select)
			selected_ = size_;

		selected_	  = std::max(0, std::min(size_, selected_));
		sticky_select = selected_ >= size_ - 15;
		return selected_old != selected_;
	}

	bool Focusable() const final { return true; } // NOLINT

	bool sticky_select = true;
	int	 selected_	   = 0;
	int	 size_		   = 0;
	Box	 box_;
};

Component Scroller(Component child) { // NOLINT
	return Make<CScrollerBase>(std::move(child));
}
} // namespace ftxui

// Copyright 2021 Arthur Sonzogni. All rights reserved.
// Use of this source code is governed by the MIT license that can be found in
// the LICENSE file.