/*
 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
 * Copyright (c) 2020, Shannon Booth <shannon.ml.booth@gmail.com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <AK/Badge.h>
#include <AK/QuickSort.h>
#include <LibCore/DirIterator.h>
#include <LibGfx/Font.h>
#include <LibGfx/Painter.h>
#include <WindowServer/AppletManager.h>
#include <WindowServer/MenuManager.h>
#include <WindowServer/Screen.h>
#include <WindowServer/WindowManager.h>
#include <unistd.h>

//#define DEBUG_MENUS

namespace WindowServer {

static MenuManager* s_the;
static constexpr int s_search_timeout = 3000;

MenuManager& MenuManager::the()
{
    ASSERT(s_the);
    return *s_the;
}

MenuManager::MenuManager()
{
    s_the = this;
    m_needs_window_resize = true;

    // NOTE: This ensures that the system menu has the correct dimensions.
    set_current_menubar(nullptr);

    m_window = Window::construct(*this, WindowType::Menubar);
    m_window->set_rect(menubar_rect());

    m_search_timer = Core::Timer::create_single_shot(0, [this] {
        m_current_search.clear();
    });
}

MenuManager::~MenuManager()
{
}

bool MenuManager::is_open(const Menu& menu) const
{
    for (size_t i = 0; i < m_open_menu_stack.size(); ++i) {
        if (&menu == m_open_menu_stack[i].ptr())
            return true;
    }
    return false;
}

void MenuManager::draw()
{
    auto& wm = WindowManager::the();
    auto palette = wm.palette();
    auto menubar_rect = this->menubar_rect();

    if (m_needs_window_resize) {
        m_window->set_rect(menubar_rect);
        AppletManager::the().calculate_applet_rects(window());
        m_needs_window_resize = false;
    }

    Gfx::Painter painter(*window().backing_store());

    painter.fill_rect(menubar_rect, palette.window());
    painter.draw_line({ 0, menubar_rect.bottom() - 1 }, { menubar_rect.right(), menubar_rect.bottom() - 1 }, palette.threed_shadow1());
    painter.draw_line({ 0, menubar_rect.bottom() }, { menubar_rect.right(), menubar_rect.bottom() }, palette.threed_shadow2());

    for_each_active_menubar_menu([&](Menu& menu) {
        Color text_color = palette.window_text();
        if (is_open(menu)) {
            painter.fill_rect(menu.rect_in_menubar(), palette.menu_selection());
            painter.draw_rect(menu.rect_in_menubar(), palette.menu_selection().darkened());
            text_color = palette.menu_selection_text();
        }
        painter.draw_text(
            menu.text_rect_in_menubar(),
            menu.name(),
            menu.title_font(),
            Gfx::TextAlignment::CenterLeft,
            text_color);
        return IterationDecision::Continue;
    });

    AppletManager::the().draw();
}

void MenuManager::refresh()
{
    if (!m_window)
        return;
    draw();
    window().invalidate();
}

void MenuManager::event(Core::Event& event)
{
    if (static_cast<Event&>(event).is_mouse_event()) {
        handle_mouse_event(static_cast<MouseEvent&>(event));
        return;
    }

    if (static_cast<Event&>(event).is_key_event()) {
        auto& key_event = static_cast<const KeyEvent&>(event);

        if (key_event.type() == Event::KeyUp && key_event.key() == Key_Escape) {
            close_everyone();
            return;
        }

        if (key_event.key() == Key_Backspace) {
            m_current_search.clear();
            return;
        }

        if (m_current_menu && event.type() == Event::KeyDown
            && ((key_event.key() >= Key_A && key_event.key() <= Key_Z)
                || (key_event.key() >= Key_0 && key_event.key() <= Key_9))) {
            m_current_search.append_code_point(key_event.code_point());
            m_search_timer->restart(s_search_timeout);
            for (int i = 0; i < m_current_menu->item_count(); ++i) {
                auto text = m_current_menu->item(i).text();
                if (text.to_lowercase().starts_with(m_current_search.to_string().to_lowercase())) {
                    m_current_menu->set_hovered_item(i);
                    return;
                }
            }
            return;
        }

        if (event.type() == Event::KeyDown) {

            if (key_event.key() == Key_Left) {
                auto it = m_open_menu_stack.find([&](auto& other) { return m_current_menu == other.ptr(); });
                ASSERT(!it.is_end());

                // Going "back" a menu should be the previous menu in the stack
                if (it.index() > 0)
                    set_current_menu(m_open_menu_stack.at(it.index() - 1));
                close_everyone_not_in_lineage(*m_current_menu);
                return;
            }

            if (key_event.key() == Key_Right) {
                auto hovered_item = m_current_menu->hovered_item();
                if (hovered_item && hovered_item->is_submenu())
                    m_current_menu->descend_into_submenu_at_hovered_item();
                return;
            }

            if (key_event.key() == Key_Return) {
                auto hovered_item = m_current_menu->hovered_item();

                if (!hovered_item->is_enabled())
                    return;
                if (hovered_item->is_submenu())
                    m_current_menu->descend_into_submenu_at_hovered_item();
                else
                    m_current_menu->open_hovered_item();
                return;
            }
            m_current_menu->dispatch_event(event);
        }
    }

    return Core::Object::event(event);
}

void MenuManager::handle_mouse_event(MouseEvent& mouse_event)
{
    auto* active_window = WindowManager::the().active_window();
    bool handled_menubar_event = false;
    for_each_active_menubar_menu([&](Menu& menu) {
        if (menu.rect_in_menubar().contains(mouse_event.position())) {
            handled_menubar_event = &menu == m_system_menu || !active_window || !active_window->is_modal();
            if (handled_menubar_event)
                handle_menu_mouse_event(menu, mouse_event);
            return IterationDecision::Break;
        }
        return IterationDecision::Continue;
    });
    if (handled_menubar_event)
        return;

    if (has_open_menu()) {
        auto* topmost_menu = m_open_menu_stack.last().ptr();
        ASSERT(topmost_menu);
        auto* window = topmost_menu->menu_window();
        if (!window) {
            dbg() << "MenuManager::handle_mouse_event: No menu window";
            return;
        }
        ASSERT(window->is_visible());

        bool event_is_inside_current_menu = window->rect().contains(mouse_event.position());
        if (event_is_inside_current_menu) {
            WindowManager::the().set_hovered_window(window);
            auto translated_event = mouse_event.translated(-window->position());
            WindowManager::the().deliver_mouse_event(*window, translated_event);
            return;
        }

        if (topmost_menu->hovered_item())
            topmost_menu->clear_hovered_item();
        if (mouse_event.type() == Event::MouseDown || mouse_event.type() == Event::MouseUp) {
            auto* window_menu_of = topmost_menu->window_menu_of();
            if (window_menu_of) {
                bool event_is_inside_taskbar_button = window_menu_of->taskbar_rect().contains(mouse_event.position());
                if (event_is_inside_taskbar_button && !topmost_menu->is_window_menu_open()) {
                    topmost_menu->set_window_menu_open(true);
                    return;
                }
            }

            if (mouse_event.type() == Event::MouseDown) {
                close_bar();
                topmost_menu->set_window_menu_open(false);
            }
        }

        if (mouse_event.type() == Event::MouseMove) {
            for (auto& menu : m_open_menu_stack) {
                if (!menu)
                    continue;
                if (!menu->menu_window()->rect().contains(mouse_event.position()))
                    continue;
                WindowManager::the().set_hovered_window(menu->menu_window());
                auto translated_event = mouse_event.translated(-menu->menu_window()->position());
                WindowManager::the().deliver_mouse_event(*menu->menu_window(), translated_event);
                break;
            }
        }
        return;
    }

    AppletManager::the().dispatch_event(static_cast<Event&>(mouse_event));
}

void MenuManager::handle_menu_mouse_event(Menu& menu, const MouseEvent& event)
{
    bool is_hover_with_any_menu_open = event.type() == MouseEvent::MouseMove
        && has_open_menu()
        && (m_open_menu_stack.first()->menubar() || m_open_menu_stack.first() == m_system_menu.ptr());
    bool is_mousedown_with_left_button = event.type() == MouseEvent::MouseDown && event.button() == MouseButton::Left;
    bool should_open_menu = &menu != m_current_menu && (is_hover_with_any_menu_open || is_mousedown_with_left_button);

    if (is_mousedown_with_left_button)
        m_bar_open = !m_bar_open;

    if (should_open_menu && m_bar_open) {
        close_everyone();
        open_menu(menu);
        return;
    }

    if (!m_bar_open)
        close_everyone();
}

void MenuManager::set_needs_window_resize()
{
    m_needs_window_resize = true;
}

void MenuManager::close_all_menus_from_client(Badge<ClientConnection>, ClientConnection& client)
{
    if (!has_open_menu())
        return;
    if (m_open_menu_stack.first()->client() != &client)
        return;
    close_everyone();
}

void MenuManager::close_everyone()
{
    for (auto& menu : m_open_menu_stack) {
        ASSERT(menu);
        if (menu->menu_window())
            menu->menu_window()->set_visible(false);
        menu->clear_hovered_item();
    }
    m_open_menu_stack.clear();
    m_current_search.clear();
    clear_current_menu();
    refresh();
}

void MenuManager::close_everyone_not_in_lineage(Menu& menu)
{
    Vector<Menu*> menus_to_close;
    for (auto& open_menu : m_open_menu_stack) {
        if (!open_menu)
            continue;
        if (&menu == open_menu.ptr() || open_menu->is_menu_ancestor_of(menu))
            continue;
        menus_to_close.append(open_menu);
    }
    close_menus(menus_to_close);
}

void MenuManager::close_menus(const Vector<Menu*>& menus)
{
    for (auto& menu : menus) {
        if (menu == m_current_menu)
            clear_current_menu();
        if (menu->menu_window())
            menu->menu_window()->set_visible(false);
        menu->clear_hovered_item();
        m_open_menu_stack.remove_first_matching([&](auto& entry) {
            return entry == menu;
        });
    }
    refresh();
}

static void collect_menu_subtree(Menu& menu, Vector<Menu*>& menus)
{
    menus.append(&menu);
    for (int i = 0; i < menu.item_count(); ++i) {
        auto& item = menu.item(i);
        if (!item.is_submenu())
            continue;
        collect_menu_subtree(*item.submenu(), menus);
    }
}

void MenuManager::close_menu_and_descendants(Menu& menu)
{
    Vector<Menu*> menus_to_close;
    collect_menu_subtree(menu, menus_to_close);
    close_menus(menus_to_close);
}

void MenuManager::toggle_menu(Menu& menu)
{
    if (is_open(menu)) {
        close_menu_and_descendants(menu);
        return;
    }
    open_menu(menu);
}

void MenuManager::open_menu(Menu& menu, bool as_current_menu)
{
    if (is_open(menu)) {
        if (as_current_menu || current_menu() != &menu) {
            // This menu is already open. If requested, or if the current
            // window doesn't match this one, then set it to this
            set_current_menu(&menu);
        }
        return;
    }

    if (!menu.is_empty()) {
        menu.redraw_if_theme_changed();
        if (!menu.menu_window()) {
            auto& menu_window = menu.ensure_menu_window();
            menu_window.move_to({ menu.rect_in_menubar().x(), menu.rect_in_menubar().bottom() + 2 });
        }
        menu.menu_window()->set_visible(true);
    }

    if (m_open_menu_stack.find([&menu](auto& other) { return &menu == other.ptr(); }).is_end())
        m_open_menu_stack.append(menu.make_weak_ptr());

    if (as_current_menu || !current_menu()) {
        // Only make this menu the current menu if requested, or if no
        // other menu is current
        set_current_menu(&menu);
    }

    refresh();
}

void MenuManager::clear_current_menu()
{
    Menu* previous_current_menu = m_current_menu;
    m_current_menu = nullptr;
    if (previous_current_menu) {
        // When closing the last menu, restore the previous active input window
        auto& wm = WindowManager::the();
        wm.restore_active_input_window(m_previous_input_window);
    }
}

void MenuManager::set_current_menu(Menu* menu)
{
    if (!menu) {
        clear_current_menu();
        return;
    }

    ASSERT(is_open(*menu));
    if (menu == m_current_menu) {
        return;
    }

    m_current_search.clear();

    Menu* previous_current_menu = m_current_menu;
    m_current_menu = menu->make_weak_ptr();

    auto& wm = WindowManager::the();
    if (!previous_current_menu) {
        // When opening the first menu, store the current active input window
        if (auto* active_input = wm.active_input_window())
            m_previous_input_window = active_input->make_weak_ptr();
        else
            m_previous_input_window = nullptr;
    }

    wm.set_active_input_window(m_current_menu->menu_window());
}

void MenuManager::close_bar()
{
    close_everyone();
    m_bar_open = false;
}

Gfx::IntRect MenuManager::menubar_rect() const
{
    return { 0, 0, Screen::the().rect().width(), 19 };
}

void MenuManager::set_current_menubar(MenuBar* menubar)
{
    if (menubar)
        m_current_menubar = menubar->make_weak_ptr();
    else
        m_current_menubar = nullptr;
#ifdef DEBUG_MENUS
    dbg() << "[WM] Current menubar is now " << menubar;
#endif
    Gfx::IntPoint next_menu_location { MenuManager::menubar_menu_margin() / 2, 0 };
    for_each_active_menubar_menu([&](Menu& menu) {
        int text_width = menu.title_font().width(menu.name());
        menu.set_rect_in_menubar({ next_menu_location.x() - MenuManager::menubar_menu_margin() / 2, 0, text_width + MenuManager::menubar_menu_margin(), menubar_rect().height() - 1 });
        menu.set_text_rect_in_menubar({ next_menu_location, { text_width, menubar_rect().height() } });
        next_menu_location.move_by(menu.rect_in_menubar().width(), 0);
        return IterationDecision::Continue;
    });
    refresh();
}

void MenuManager::close_menubar(MenuBar& menubar)
{
    if (current_menubar() == &menubar)
        set_current_menubar(nullptr);
}

void MenuManager::set_system_menu(Menu& menu)
{
    m_system_menu = menu.make_weak_ptr();
    set_current_menubar(m_current_menubar);
}

void MenuManager::did_change_theme()
{
    ++m_theme_index;
    refresh();
}

}