#include <stddef.h>            // for size_t
#include <algorithm>           // for max, min
#include <ext/alloc_traits.h>  // for __alloc_traits<>::value_type
#include <memory>              // for shared_ptr, allocator_traits<>::value_type
#include <utility>             // for move

#include "ftxui/component/captured_mouse.hpp"  // for CapturedMouse
#include "ftxui/component/event.hpp"  // for Event, Event::ArrowDown, Event::ArrowUp, Event::Return, Event::Tab, Event::TabReverse
#include "ftxui/component/menu.hpp"
#include "ftxui/component/mouse.hpp"  // for Mouse, Mouse::Left, Mouse::Released
#include "ftxui/component/screen_interactive.hpp"  // for Component

namespace ftxui {

/// @brief A list of text. The focused element is selected.
/// @param entries The list of entries in the menu.
/// @param selected The index of the currently selected element.
/// @ingroup component
/// @see MenuBase
///
/// ### Example
///
/// ```cpp
/// auto screen = ScreenInteractive::TerminalOutput();
/// std::vector<std::wstring> entries = {
///     L"entry 1",
///     L"entry 2",
///     L"entry 3",
/// };
/// int selected = 0;
/// auto menu = Menu(&entries, &selected);
/// screen.Loop(menu);
/// ```
///
/// ### Output
///
/// ```bash
/// > entry 1
///   entry 2
///   entry 3
/// ```
Component Menu(const std::vector<std::wstring>* entries, int* selected) {
  return Make<MenuBase>(entries, selected);
}

// static
MenuBase* MenuBase::From(Component component) {
  return static_cast<MenuBase*>(component.get());
}

MenuBase::MenuBase(const std::vector<std::wstring>* entries, int* selected)
    : entries_(entries), selected_(selected) {}

Element MenuBase::Render() {
  Elements elements;
  bool is_menu_focused = Focused();
  boxes_.resize(entries_->size());
  for (size_t i = 0; i < entries_->size(); ++i) {
    bool is_focused = (focused == int(i)) && is_menu_focused;
    bool is_selected = (*selected_ == int(i));

    auto style = is_selected
                     ? (is_focused ? selected_focused_style : selected_style)
                     : (is_focused ? focused_style : normal_style);
    auto focus_management = !is_selected      ? nothing
                            : is_menu_focused ? focus
                                              : select;
    auto icon = is_selected ? L"> " : L"  ";
    elements.push_back(text(icon + entries_->at(i)) | style | focus_management |
                       reflect(boxes_[i]));
  }
  return vbox(std::move(elements));
}

bool MenuBase::OnEvent(Event event) {
  if (!CaptureMouse(event))
    return false;
  if (event.is_mouse())
    return OnMouseEvent(event);

  if (!Focused())
    return false;

  int old_selected = *selected_;
  if (event == Event::ArrowUp || event == Event::Character('k'))
    (*selected_)--;
  if (event == Event::ArrowDown || event == Event::Character('j'))
    (*selected_)++;
  if (event == Event::Tab && entries_->size())
    *selected_ = (*selected_ + 1) % entries_->size();
  if (event == Event::TabReverse && entries_->size())
    *selected_ = (*selected_ + entries_->size() - 1) % entries_->size();

  *selected_ = std::max(0, std::min(int(entries_->size()) - 1, *selected_));

  if (*selected_ != old_selected) {
    focused = *selected_;
    on_change();
    return true;
  }

  if (event == Event::Return) {
    on_enter();
    return true;
  }

  return false;
}

bool MenuBase::OnMouseEvent(Event event) {
  if (!CaptureMouse(event))
    return false;
  for (int i = 0; i < boxes_.size(); ++i) {
    if (!boxes_[i].Contain(event.mouse().x, event.mouse().y))
      continue;

    TakeFocus();
    focused = i;
    if (event.mouse().button == Mouse::Left &&
        event.mouse().motion == Mouse::Released) {
      if (*selected_ != i) {
        *selected_ = i;
        on_change();
      }
      return true;
    }
  }
  return false;
}

}  // namespace ftxui

// Copyright 2020 Arthur Sonzogni. All rights reserved.
// Use of this source code is governed by the MIT license that can be found in
// the LICENSE file.