/*
 * Copyright (c) 2021, Valtteri Koskivuori <vkoskiv@gmail.com>
 * Copyright (c) 2022, the SerenityOS developers.
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include "MagnifierWidget.h"
#include <LibGUI/ConnectionToWindowServer.h>
#include <LibGUI/DisplayLink.h>
#include <LibGUI/Painter.h>
#include <LibGUI/Window.h>
#include <LibGfx/Rect.h>

MagnifierWidget::MagnifierWidget()
{
    GUI::DisplayLink::register_callback([this](auto) { sync(); });
}

void MagnifierWidget::set_scale_factor(int scale_factor)
{
    VERIFY(scale_factor == 2 || scale_factor == 4 || scale_factor == 8);
    m_scale_factor = scale_factor;
    update();
}

void MagnifierWidget::lock_location(bool lock)
{
    if (lock)
        m_locked_location = GUI::ConnectionToWindowServer::the().get_global_cursor_position();
    else
        m_locked_location = {};
}

void MagnifierWidget::show_grid(bool new_value)
{
    if (m_show_grid == new_value)
        return;
    m_show_grid = new_value;
    update();
}

void MagnifierWidget::set_color_filter(OwnPtr<Gfx::ColorBlindnessFilter> color_filter)
{
    m_color_filter = move(color_filter);
    sync();
}

void MagnifierWidget::display_previous_frame()
{
    --m_frame_offset_from_head;
    auto index = m_grabbed_bitmaps.head_index() + m_frame_offset_from_head;
    m_grabbed_bitmap = m_grabbed_bitmaps.at(index);
    update();
}

void MagnifierWidget::display_next_frame()
{
    ++m_frame_offset_from_head;
    auto index = m_grabbed_bitmaps.head_index() + m_frame_offset_from_head;
    m_grabbed_bitmap = m_grabbed_bitmaps.at(index);
    update();
}

void MagnifierWidget::sync()
{
    if (m_pause_capture)
        return;

    auto size = frame_inner_rect().size();
    Gfx::IntSize grab_size { size.width() / m_scale_factor, size.height() / m_scale_factor };

    if (m_locked_location.has_value()) {
        m_grabbed_bitmap = GUI::ConnectionToWindowServer::the().get_screen_bitmap_around_location(grab_size, m_locked_location.value()).bitmap();
    } else {
        m_grabbed_bitmap = GUI::ConnectionToWindowServer::the().get_screen_bitmap_around_cursor(grab_size).bitmap();
    }
    m_grabbed_bitmaps.enqueue(m_grabbed_bitmap);
    update();
}

void MagnifierWidget::paint_event(GUI::PaintEvent& event)
{
    GUI::Frame::paint_event(event);

    if (!m_grabbed_bitmap)
        return;

    GUI::Painter painter(*this);

    if (m_grabbed_bitmap)
        painter.draw_scaled_bitmap(frame_inner_rect(), *m_grabbed_bitmap, m_grabbed_bitmap->rect(), 1.0, Gfx::Painter::ScalingMode::NearestFractional);

    if (m_show_grid) {
        auto line_color = Color(Color::NamedColor::Magenta);
        line_color.set_alpha(100);

        auto grid_rect = frame_inner_rect();
        if (m_grabbed_bitmap)
            grid_rect = frame_inner_rect().intersected({ 0,
                0,
                m_grabbed_bitmap->rect().width() * m_scale_factor,
                m_grabbed_bitmap->rect().height() * m_scale_factor });

        int start_y = grid_rect.top(),
            start_x = grid_rect.left();

        int end_y = grid_rect.bottom(),
            end_x = grid_rect.right();

        for (int current_y = start_y; current_y <= end_y; current_y += m_scale_factor)
            painter.draw_line({ start_x, current_y }, { end_x, current_y }, line_color);

        for (int current_x = start_y; current_x <= end_x; current_x += m_scale_factor)
            painter.draw_line({ current_x, start_y }, { current_x, end_y }, line_color);
    }
}

void MagnifierWidget::second_paint_event(GUI::PaintEvent&)
{
    if (!m_color_filter)
        return;

    GUI::Painter painter(*this);

    auto target = painter.target();
    auto bitmap_clone_or_error = target->clone();
    if (bitmap_clone_or_error.is_error())
        return;

    auto clone = bitmap_clone_or_error.release_value();
    auto rect = target->rect();

    m_color_filter->apply(*target, rect, *clone, rect);
}