/*
    KWin - the KDE window manager
    This file is part of the KDE project.

    SPDX-FileCopyrightText: 2007 Lubos Lunak <l.lunak@kde.org>
    SPDX-FileCopyrightText: 2007 Christian Nitschkowski <christian.nitschkowski@kdemail.net>
    SPDX-FileCopyrightText: 2011 Martin Gräßlin <mgraesslin@kde.org>

    SPDX-License-Identifier: GPL-2.0-or-later
*/

#include "magnifier.h"
// KConfigSkeleton
#include "magnifierconfig.h"

#include <QAction>
#include <kstandardaction.h>

#include "core/renderviewport.h"
#include "effect/effecthandler.h"
#include "opengl/glutils.h"
#include "opengl/openglcontext.h"
#include <KGlobalAccel>

using namespace std::chrono_literals;

namespace KWin
{

const int FRAME_WIDTH = 5;

MagnifierEffect::MagnifierEffect()
    : m_zoom(1)
    , m_targetZoom(1)
    , m_lastPresentTime(std::chrono::milliseconds::zero())
    , m_texture(nullptr)
    , m_fbo(nullptr)
{
    MagnifierConfig::instance(effects->config());
    QAction *a;
    a = KStandardAction::zoomIn(this, &MagnifierEffect::zoomIn, this);
    KGlobalAccel::self()->setDefaultShortcut(a, QList<QKeySequence>() << (Qt::META | Qt::Key_Plus) << (Qt::META | Qt::Key_Equal));
    KGlobalAccel::self()->setShortcut(a, QList<QKeySequence>() << (Qt::META | Qt::Key_Plus) << (Qt::META | Qt::Key_Equal));

    a = KStandardAction::zoomOut(this, &MagnifierEffect::zoomOut, this);
    KGlobalAccel::self()->setDefaultShortcut(a, QList<QKeySequence>() << (Qt::META | Qt::Key_Minus));
    KGlobalAccel::self()->setShortcut(a, QList<QKeySequence>() << (Qt::META | Qt::Key_Minus));

    a = KStandardAction::actualSize(this, &MagnifierEffect::toggle, this);
    KGlobalAccel::self()->setDefaultShortcut(a, QList<QKeySequence>() << (Qt::META | Qt::Key_0));
    KGlobalAccel::self()->setShortcut(a, QList<QKeySequence>() << (Qt::META | Qt::Key_0));

    connect(effects, &EffectsHandler::mouseChanged, this, &MagnifierEffect::slotMouseChanged);
    connect(effects, &EffectsHandler::windowAdded, this, &MagnifierEffect::slotWindowAdded);

    const auto windows = effects->stackingOrder();
    for (EffectWindow *window : windows) {
        slotWindowAdded(window);
    }

    reconfigure(ReconfigureAll);
}

MagnifierEffect::~MagnifierEffect()
{
    // Save the zoom value.
    MagnifierConfig::setInitialZoom(m_targetZoom);
    MagnifierConfig::self()->save();
}

bool MagnifierEffect::supported()
{
    return effects->openglContext() && effects->openglContext()->supportsBlits();
}

void MagnifierEffect::reconfigure(ReconfigureFlags)
{
    MagnifierConfig::self()->read();
    int width, height;
    width = MagnifierConfig::width();
    height = MagnifierConfig::height();
    m_magnifierSize = QSize(width, height);
    // Load the saved zoom value.
    m_targetZoom = MagnifierConfig::initialZoom();
    if (m_targetZoom != m_zoom) {
        toggle();
    }
}

void MagnifierEffect::prePaintScreen(ScreenPrePaintData &data, std::chrono::milliseconds presentTime)
{
    const int time = m_lastPresentTime.count() ? (presentTime - m_lastPresentTime).count() : 0;

    if (m_zoom != m_targetZoom) {
        double diff = time / animationTime(500ms);
        if (m_targetZoom > m_zoom) {
            m_zoom = std::min(m_zoom * std::max(1 + diff, 1.2), m_targetZoom);
        } else {
            m_zoom = std::max(m_zoom * std::min(1 - diff, 0.8), m_targetZoom);
            if (m_zoom == 1.0) {
                // zoom ended - delete FBO and texture
                m_fbo.reset();
                m_texture.reset();
            }
        }
    }

    if (m_zoom != m_targetZoom) {
        m_lastPresentTime = presentTime;
    } else {
        m_lastPresentTime = std::chrono::milliseconds::zero();
    }

    effects->prePaintScreen(data, presentTime);
    if (m_zoom != 1.0) {
        data.paint += magnifierArea().adjusted(-FRAME_WIDTH, -FRAME_WIDTH, FRAME_WIDTH, FRAME_WIDTH);
    }
}

void MagnifierEffect::paintScreen(const RenderTarget &renderTarget, const RenderViewport &viewport, int mask, const QRegion &region, Output *screen)
{
    effects->paintScreen(renderTarget, viewport, mask, region, screen); // paint normal screen
    if (m_zoom != 1.0) {
        // get the right area from the current rendered screen
        const QRect area = magnifierArea();
        const QPointF cursor = cursorPos();
        const auto scale = viewport.scale();

        QRectF srcArea(cursor.x() - (double)area.width() / (m_zoom * 2),
                       cursor.y() - (double)area.height() / (m_zoom * 2),
                       (double)area.width() / m_zoom, (double)area.height() / m_zoom);
        if (effects->isOpenGLCompositing()) {
            m_fbo->blitFromRenderTarget(renderTarget, viewport, srcArea.toRect(), QRect(QPoint(), m_fbo->size()));
            // paint magnifier
            auto s = ShaderManager::instance()->pushShader(ShaderTrait::MapTexture);
            QMatrix4x4 mvp = viewport.projectionMatrix();
            mvp.translate(area.x() * scale, area.y() * scale);
            s->setUniform(GLShader::Mat4Uniform::ModelViewProjectionMatrix, mvp);
            m_texture->render(area.size() * scale);
            ShaderManager::instance()->popShader();

            GLVertexBuffer *vbo = GLVertexBuffer::streamingBuffer();
            vbo->reset();

            QRectF areaF = scaledRect(area, scale);
            const QRectF frame = scaledRect(area.adjusted(-FRAME_WIDTH, -FRAME_WIDTH, FRAME_WIDTH, FRAME_WIDTH), scale);
            QList<QVector2D> verts;
            verts.reserve(4 * 6 * 2);
            // top frame
            verts.push_back(QVector2D(frame.right(), frame.top()));
            verts.push_back(QVector2D(frame.left(), frame.top()));
            verts.push_back(QVector2D(frame.left(), areaF.top()));
            verts.push_back(QVector2D(frame.left(), areaF.top()));
            verts.push_back(QVector2D(frame.right(), areaF.top()));
            verts.push_back(QVector2D(frame.right(), frame.top()));
            // left frame
            verts.push_back(QVector2D(areaF.left(), frame.top()));
            verts.push_back(QVector2D(frame.left(), frame.top()));
            verts.push_back(QVector2D(frame.left(), frame.bottom()));
            verts.push_back(QVector2D(frame.left(), frame.bottom()));
            verts.push_back(QVector2D(areaF.left(), frame.bottom()));
            verts.push_back(QVector2D(areaF.left(), frame.top()));
            // right frame
            verts.push_back(QVector2D(frame.right(), frame.top()));
            verts.push_back(QVector2D(areaF.right(), frame.top()));
            verts.push_back(QVector2D(areaF.right(), frame.bottom()));
            verts.push_back(QVector2D(areaF.right(), frame.bottom()));
            verts.push_back(QVector2D(frame.right(), frame.bottom()));
            verts.push_back(QVector2D(frame.right(), frame.top()));
            // bottom frame
            verts.push_back(QVector2D(frame.right(), areaF.bottom()));
            verts.push_back(QVector2D(frame.left(), areaF.bottom()));
            verts.push_back(QVector2D(frame.left(), frame.bottom()));
            verts.push_back(QVector2D(frame.left(), frame.bottom()));
            verts.push_back(QVector2D(frame.right(), frame.bottom()));
            verts.push_back(QVector2D(frame.right(), areaF.bottom()));
            vbo->setVertices(verts);

            ShaderBinder binder(ShaderTrait::UniformColor);
            binder.shader()->setUniform(GLShader::Mat4Uniform::ModelViewProjectionMatrix, viewport.projectionMatrix());
            binder.shader()->setUniform(GLShader::ColorUniform::Color, QColor(0, 0, 0));
            vbo->render(GL_TRIANGLES);
        }
    }
}

void MagnifierEffect::postPaintScreen()
{
    if (m_zoom != m_targetZoom) {
        QRect framedarea = magnifierArea().adjusted(-FRAME_WIDTH, -FRAME_WIDTH, FRAME_WIDTH, FRAME_WIDTH);
        effects->addRepaint(framedarea);
    }
    effects->postPaintScreen();
}

QRect MagnifierEffect::magnifierArea(QPointF pos) const
{
    return QRect(pos.x() - m_magnifierSize.width() / 2, pos.y() - m_magnifierSize.height() / 2,
                 m_magnifierSize.width(), m_magnifierSize.height());
}

void MagnifierEffect::zoomIn()
{
    m_targetZoom *= 1.2;
    if (effects->isOpenGLCompositing() && !m_texture) {
        effects->makeOpenGLContextCurrent();
        m_texture = GLTexture::allocate(GL_RGBA16F, m_magnifierSize);
        if (!m_texture) {
            return;
        }
        m_texture->setContentTransform(OutputTransform());
        m_fbo = std::make_unique<GLFramebuffer>(m_texture.get());
    }
    effects->addRepaint(magnifierArea().adjusted(-FRAME_WIDTH, -FRAME_WIDTH, FRAME_WIDTH, FRAME_WIDTH));
}

void MagnifierEffect::zoomOut()
{
    m_targetZoom /= 1.2;
    if (m_targetZoom <= 1) {
        m_targetZoom = 1;
        if (m_zoom == m_targetZoom) {
            effects->makeOpenGLContextCurrent();
            m_fbo.reset();
            m_texture.reset();
        }
    }
    effects->addRepaint(magnifierArea().adjusted(-FRAME_WIDTH, -FRAME_WIDTH, FRAME_WIDTH, FRAME_WIDTH));
}

void MagnifierEffect::toggle()
{
    if (m_zoom == 1.0) {
        if (m_targetZoom == 1.0) {
            m_targetZoom = 2;
        }
        if (effects->isOpenGLCompositing() && !m_texture) {
            effects->makeOpenGLContextCurrent();
            m_texture = GLTexture::allocate(GL_RGBA16F, m_magnifierSize);
            if (!m_texture) {
                return;
            }
            m_texture->setContentTransform(OutputTransform());
            m_fbo = std::make_unique<GLFramebuffer>(m_texture.get());
        }
    } else {
        m_targetZoom = 1;
    }
    effects->addRepaint(magnifierArea().adjusted(-FRAME_WIDTH, -FRAME_WIDTH, FRAME_WIDTH, FRAME_WIDTH));
}

void MagnifierEffect::slotMouseChanged(const QPointF &pos, const QPointF &old,
                                       Qt::MouseButtons, Qt::MouseButtons, Qt::KeyboardModifiers, Qt::KeyboardModifiers)
{
    if (pos != old && m_zoom != 1) {
        // need full repaint as we might lose some change events on fast mouse movements
        // see Bug 187658
        effects->addRepaintFull();
    }
}

void MagnifierEffect::slotWindowAdded(EffectWindow *w)
{
    connect(w, &EffectWindow::windowDamaged, this, &MagnifierEffect::slotWindowDamaged);
}

void MagnifierEffect::slotWindowDamaged()
{
    if (isActive()) {
        effects->addRepaint(magnifierArea());
    }
}

bool MagnifierEffect::isActive() const
{
    return m_zoom != 1.0 || m_zoom != m_targetZoom;
}

QSize MagnifierEffect::magnifierSize() const
{
    return m_magnifierSize;
}

qreal MagnifierEffect::targetZoom() const
{
    return m_targetZoom;
}

} // namespace

#include "moc_magnifier.cpp"