/*
 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
 * Copyright (c) 2022, the SerenityOS developers.
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <LibGUI/Button.h>
#include <LibGUI/ComboBox.h>
#include <LibGUI/Desktop.h>
#include <LibGUI/Event.h>
#include <LibGUI/ListView.h>
#include <LibGUI/Model.h>
#include <LibGUI/Scrollbar.h>
#include <LibGUI/TextBox.h>
#include <LibGUI/TextEditor.h>
#include <LibGUI/Window.h>

REGISTER_WIDGET(GUI, ComboBox)

namespace GUI {

class ComboBoxEditor final : public TextEditor {
    C_OBJECT(ComboBoxEditor);

public:
    Function<void(int delta)> on_mousewheel;
    Function<void(KeyEvent& event)> on_keypress;

private:
    ComboBoxEditor()
        : TextEditor(TextEditor::SingleLine)
    {
    }

    virtual void mousewheel_event(MouseEvent& event) override
    {
        if (!is_focused())
            set_focus(true);
        if (on_mousewheel)
            on_mousewheel(event.wheel_delta_y());
        event.accept();
    }

    virtual void keydown_event(KeyEvent& event) override
    {
        if (event.key() == Key_Escape) {
            if (is_focused())
                set_focus(false);
            event.accept();
        } else {
            on_keypress(event);
            TextEditor::keydown_event(event);
        }
    }
};

ComboBox::ComboBox()
{
    REGISTER_DEPRECATED_STRING_PROPERTY("placeholder", editor_placeholder, set_editor_placeholder);
    REGISTER_BOOL_PROPERTY("model_only", only_allow_values_from_model, set_only_allow_values_from_model);
    REGISTER_INT_PROPERTY("max_visible_items", max_visible_items, set_max_visible_items);

    set_min_size({ 40, 22 });
    set_preferred_size({ SpecialDimension::OpportunisticGrow, 22 });

    m_editor = add<ComboBoxEditor>();
    m_editor->set_frame_style(Gfx::FrameStyle::NoFrame);
    m_editor->on_return_pressed = [this] {
        if (on_return_pressed)
            on_return_pressed();
    };
    m_editor->on_up_pressed = [this] {
        navigate(AbstractView::CursorMovement::Up);
    };
    m_editor->on_down_pressed = [this] {
        navigate(AbstractView::CursorMovement::Down);
    };
    m_editor->on_pageup_pressed = [this] {
        navigate(AbstractView::CursorMovement::PageUp);
    };
    m_editor->on_pagedown_pressed = [this] {
        navigate(AbstractView::CursorMovement::PageDown);
    };
    m_editor->on_mousewheel = [this](int delta) {
        // Since we can only show one item at a time we don't want to
        // skip any. So just move one item at a time.
        navigate_relative(delta > 0 ? 1 : -1);
    };
    m_editor->on_mousedown = [this] {
        if (only_allow_values_from_model())
            m_open_button->click();
    };
    m_editor->on_keypress = [this](KeyEvent& event) {
        if (!m_only_allow_values_from_model)
            return;
        if (!m_list_window->is_visible() && event.key() <= Key_Z && event.key() >= Key_A && event.modifiers() == Mod_None) {
            open();
            m_list_window->event(event);
        }
    };

    m_open_button = add<Button>();
    m_open_button->set_button_style(Gfx::ButtonStyle::ThickCap);
    m_open_button->set_icon(MUST(Gfx::Bitmap::load_from_uri("resource://icons/16x16/downward-triangle.png"sv)));
    m_open_button->set_focus_policy(GUI::FocusPolicy::NoFocus);
    m_open_button->on_click = [this](auto) {
        if (!m_list_view->item_count())
            return;
        if (m_list_window->is_visible())
            close();
        else
            open();
    };

    m_list_window = add<Window>(window());
    m_list_window->set_window_type(GUI::WindowType::Popup);

    m_list_view = m_list_window->set_main_widget<ListView>();
    m_list_view->set_should_hide_unnecessary_scrollbars(true);
    m_list_view->set_alternating_row_colors(false);
    m_list_view->set_hover_highlighting(true);
    m_list_view->set_frame_style(Gfx::FrameStyle::Plain);
    m_list_view->set_activates_on_selection(true);
    m_list_view->on_selection_change = [this] {
        VERIFY(model());
        auto const& index = m_list_view->selection().first();
        if (m_updating_model)
            selection_updated(index);
    };

    m_list_view->on_activation = [this](auto& index) {
        deferred_invoke([this, index] {
            selection_updated(index);
            if (on_change)
                on_change(m_editor->text(), index);
        });
        close();
    };

    m_list_view->on_escape_pressed = [this] {
        close();
    };
}

ComboBox::~ComboBox() = default;

void ComboBox::set_editor_placeholder(StringView placeholder)
{
    m_editor->set_placeholder(placeholder);
}

ByteString const& ComboBox::editor_placeholder() const
{
    return m_editor->placeholder();
}

void ComboBox::navigate(AbstractView::CursorMovement cursor_movement)
{
    auto previous_selected = m_list_view->cursor_index();
    m_list_view->move_cursor(cursor_movement, AbstractView::SelectionUpdate::Set);
    auto current_selected = m_list_view->cursor_index();
    selection_updated(current_selected);
    if (previous_selected.row() != current_selected.row() && on_change)
        on_change(m_editor->text(), current_selected);
}

void ComboBox::navigate_relative(int delta)
{
    auto previous_selected = m_list_view->cursor_index();
    m_list_view->move_cursor_relative(delta, AbstractView::SelectionUpdate::Set);
    auto current_selected = m_list_view->cursor_index();
    selection_updated(current_selected);
    if (previous_selected.row() != current_selected.row() && on_change)
        on_change(m_editor->text(), current_selected);
}

void ComboBox::selection_updated(ModelIndex const& index)
{
    if (index.is_valid()) {
        m_selected_index = index;
        auto new_value = index.data().to_byte_string();
        m_editor->set_text(new_value);
    } else {
        m_selected_index.clear();
    }
    if (!m_only_allow_values_from_model)
        m_editor->select_all();
}

void ComboBox::resize_event(ResizeEvent& event)
{
    Widget::resize_event(event);
    int button_height = event.size().height() - frame_thickness() * 2;
    int button_width = 15;
    m_open_button->set_relative_rect(width() - button_width - frame_thickness(), frame_thickness(), button_width, button_height);
    auto editor_rect = frame_inner_rect();
    editor_rect.set_width(editor_rect.width() - button_width);
    m_editor->set_relative_rect(editor_rect);
}

void ComboBox::set_model(NonnullRefPtr<Model> model)
{
    TemporaryChange change(m_updating_model, true);
    m_selected_index.clear();
    m_list_view->set_model(move(model));
}

void ComboBox::clear_selection()
{
    m_selected_index.clear();
    m_editor->clear_selection();
    m_editor->clear();
}

void ComboBox::set_selected_index(size_t index, AllowCallback allow_callback)
{
    if (!m_list_view->model())
        return;
    size_t previous_index = selected_index();
    TemporaryChange change(m_updating_model, true);
    auto model_index = m_list_view->model()->index(index, 0);
    m_list_view->set_cursor(model_index, AbstractView::SelectionUpdate::Set);
    selection_updated(model_index);
    if (previous_index != selected_index() && on_change && allow_callback == AllowCallback::Yes)
        on_change(m_editor->text(), m_list_view->cursor_index());
}

size_t ComboBox::selected_index() const
{
    return m_selected_index.has_value() ? m_selected_index.value().row() : 0;
}

void ComboBox::select_all()
{
    m_editor->select_all();
}

void ComboBox::open()
{
    m_editor->set_focus(true);

    // Force content size update while invisible
    m_list_view->resize({});

    auto frame = m_list_view->frame_thickness() * 2;
    auto max_height = min(m_list_view->item_height() * m_max_visible_items, m_list_view->content_height());
    auto min_width = m_list_view->content_width() + frame;
    Gfx::IntSize size { max(width(), min_width), max_height + frame };
    Gfx::IntRect rect { screen_relative_rect().bottom_left().moved_up(1), size };

    auto desktop = Desktop::the().rect();
    auto min_height = 5 * m_list_view->item_height() + frame;
    auto go_upwards_instead = rect.bottom() - 1 >= desktop.height() && rect.intersected(desktop).height() < min_height;
    if (go_upwards_instead) {
        auto origin = screen_relative_rect().top_left();
        rect = { Gfx::IntPoint { origin.x(), origin.y() - size.height() }, size };
    }

    auto intersection = rect.intersected(desktop);
    rect.set_top(intersection.top());
    rect.set_bottom(intersection.bottom());

    auto remainder = (rect.height() - frame) % m_list_view->item_height();
    go_upwards_instead ? rect.take_from_top(remainder) : rect.take_from_bottom(remainder);

    auto scrollbar_width = m_list_view->vertical_scrollbar().width();
    if (max_height > rect.height() && width() < min_width + scrollbar_width)
        rect.set_width(rect.width() + scrollbar_width);

    m_list_window->set_rect(rect);
    m_list_view->set_min_size(rect.size());

    if (m_selected_index.has_value()) {
        m_list_view->set_cursor(m_selected_index.value(), AbstractView::SelectionUpdate::Set, false);
        auto index_top = m_list_view->vertical_scrollbar().step() * m_selected_index.value().row();
        m_list_view->vertical_scrollbar().set_value(index_top);
    }

    m_list_window->show();
}

void ComboBox::close()
{
    m_list_window->hide();
}

ByteString ComboBox::text() const
{
    return m_editor->text();
}

void ComboBox::set_text(ByteString const& text, AllowCallback allow_callback)
{
    m_editor->set_text(text);
    if (!on_change || allow_callback == AllowCallback::No)
        return;
    auto matches = model()->matches(text.view(), GUI::Model::MatchesFlag::FirstMatchOnly);
    if (!matches.is_empty())
        on_change(text, matches.first());
}

void ComboBox::set_only_allow_values_from_model(bool b)
{
    if (m_only_allow_values_from_model == b)
        return;
    m_only_allow_values_from_model = b;
    m_editor->set_mode(m_only_allow_values_from_model ? TextEditor::DisplayOnly : TextEditor::Editable);
}

Model* ComboBox::model()
{
    return m_list_view->model();
}

Model const* ComboBox::model() const
{
    return m_list_view->model();
}

int ComboBox::model_column() const
{
    return m_list_view->model_column();
}

void ComboBox::set_model_column(int column)
{
    m_list_view->set_model_column(column);
}

}
