/****************************************************************************
**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the plugins of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Digia.  For licensing terms and
** conditions see http://qt.digia.com/licensing.  For further information
** use the contact form at http://qt.digia.com/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Digia gives you certain additional
** rights.  These rights are described in the Digia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qeglplatformcontext_p.h"
#include "qeglconvenience_p.h"
#include <qpa/qplatformwindow.h>
#include <QtGui/QOpenGLFunctions>

QT_BEGIN_NAMESPACE

/*!
    \class QEGLPlatformContext
    \brief An EGL context implementation.
    \since 5.2
    \internal
    \ingroup qpa

    Implement QPlatformOpenGLContext using EGL. To use it in platform
    plugins a subclass must be created since
    eglSurfaceForPlatformSurface() has to be reimplemented. This
    function is used for mapping platform surfaces (windows) to EGL
    surfaces and is necessary since different platform plugins may
    have different ways of handling native windows (for example, a
    plugin may choose not to back every platform window by a real EGL
    surface). Other than that, no further customization is necessary.
 */

static inline void bindApi(const QSurfaceFormat &format)
{
    switch (format.renderableType()) {
    case QSurfaceFormat::OpenVG:
        eglBindAPI(EGL_OPENVG_API);
        break;
#ifdef EGL_VERSION_1_4
    case QSurfaceFormat::DefaultRenderableType:
        if (!QOpenGLFunctions::isES())
            eglBindAPI(EGL_OPENGL_API);
        else
            eglBindAPI(EGL_OPENGL_ES_API);
        break;
    case QSurfaceFormat::OpenGL:
        eglBindAPI(EGL_OPENGL_API);
        break;
#endif
    case QSurfaceFormat::OpenGLES:
    default:
        eglBindAPI(EGL_OPENGL_ES_API);
        break;
    }
}

QEGLPlatformContext::QEGLPlatformContext(const QSurfaceFormat &format, QPlatformOpenGLContext *share, EGLDisplay display,
                                         EGLenum eglApi)
    : m_eglDisplay(display)
    , m_eglConfig(q_configFromGLFormat(display, format))
    , m_swapInterval(-1)
    , m_swapIntervalEnvChecked(false)
    , m_swapIntervalFromEnv(-1)
{
    init(format, share);
    Q_UNUSED(eglApi);
}

QEGLPlatformContext::QEGLPlatformContext(const QSurfaceFormat &format, QPlatformOpenGLContext *share, EGLDisplay display,
                                         EGLConfig config, EGLenum eglApi)
    : m_eglDisplay(display)
    , m_eglConfig(config)
    , m_swapInterval(-1)
    , m_swapIntervalEnvChecked(false)
    , m_swapIntervalFromEnv(-1)
{
    init(format, share);
    Q_UNUSED(eglApi);
}

void QEGLPlatformContext::init(const QSurfaceFormat &format, QPlatformOpenGLContext *share)
{
    m_format = q_glFormatFromConfig(m_eglDisplay, m_eglConfig);
    m_shareContext = share ? static_cast<QEGLPlatformContext *>(share)->m_eglContext : 0;

    QVector<EGLint> contextAttrs;
    contextAttrs.append(EGL_CONTEXT_CLIENT_VERSION);
    contextAttrs.append(format.majorVersion());
    contextAttrs.append(EGL_NONE);

    bindApi(m_format);
    m_eglContext = eglCreateContext(m_eglDisplay, m_eglConfig, m_shareContext, contextAttrs.constData());
    if (m_eglContext == EGL_NO_CONTEXT && m_shareContext != EGL_NO_CONTEXT) {
        m_shareContext = 0;
        m_eglContext = eglCreateContext(m_eglDisplay, m_eglConfig, 0, contextAttrs.constData());
    }
}

bool QEGLPlatformContext::makeCurrent(QPlatformSurface *surface)
{
    Q_ASSERT(surface->surface()->supportsOpenGL());

    bindApi(m_format);

    EGLSurface eglSurface = eglSurfaceForPlatformSurface(surface);

    // shortcut: on some GPUs, eglMakeCurrent is not a cheap operation
    if (eglGetCurrentContext() == m_eglContext &&
        eglGetCurrentDisplay() == m_eglDisplay &&
        eglGetCurrentSurface(EGL_READ) == eglSurface &&
        eglGetCurrentSurface(EGL_DRAW) == eglSurface) {
        return true;
    }

    bool ok = eglMakeCurrent(m_eglDisplay, eglSurface, eglSurface, m_eglContext);
    if (!ok)
        qWarning("QEGLPlatformContext::makeCurrent: eglError: %x, this: %p \n", eglGetError(), this);
#ifdef QEGL_EXTRA_DEBUG
    static bool showDebug = true;
    if (showDebug) {
        showDebug = false;
        const char *str = (const char*)glGetString(GL_VENDOR);
        qWarning("Vendor %s\n", str);
        str = (const char*)glGetString(GL_RENDERER);
        qWarning("Renderer %s\n", str);
        str = (const char*)glGetString(GL_VERSION);
        qWarning("Version %s\n", str);

        str = (const char*)glGetString(GL_SHADING_LANGUAGE_VERSION);
        qWarning("Extensions %s\n",str);

        str = (const char*)glGetString(GL_EXTENSIONS);
        qWarning("Extensions %s\n", str);

    }
#endif

    if (ok) {
        if (!m_swapIntervalEnvChecked) {
            m_swapIntervalEnvChecked = true;
            if (qEnvironmentVariableIsSet("QT_QPA_EGLFS_SWAPINTERVAL")) {
                QByteArray swapIntervalString = qgetenv("QT_QPA_EGLFS_SWAPINTERVAL");
                bool ok;
                const int swapInterval = swapIntervalString.toInt(&ok);
                if (ok)
                    m_swapIntervalFromEnv = swapInterval;
            }
        }
        const int requestedSwapInterval = m_swapIntervalFromEnv >= 0
            ? m_swapIntervalFromEnv
            : surface->format().swapInterval();
        if (requestedSwapInterval >= 0 && m_swapInterval != requestedSwapInterval) {
            m_swapInterval = requestedSwapInterval;
            eglSwapInterval(eglDisplay(), m_swapInterval);
        }
    }

    return ok;
}

QEGLPlatformContext::~QEGLPlatformContext()
{
    if (m_eglContext != EGL_NO_CONTEXT) {
        eglDestroyContext(m_eglDisplay, m_eglContext);
        m_eglContext = EGL_NO_CONTEXT;
    }
}

void QEGLPlatformContext::doneCurrent()
{
    bindApi(m_format);
    bool ok = eglMakeCurrent(m_eglDisplay, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
    if (!ok)
        qWarning("QEGLPlatformContext::doneCurrent(): eglError: %d, this: %p \n", eglGetError(), this);
}

void QEGLPlatformContext::swapBuffers(QPlatformSurface *surface)
{
    bindApi(m_format);
    EGLSurface eglSurface = eglSurfaceForPlatformSurface(surface);
    bool ok = eglSwapBuffers(m_eglDisplay, eglSurface);
    if (!ok)
        qWarning("QEGLPlatformContext::swapBuffers(): eglError: %d, this: %p \n", eglGetError(), this);
}

void (*QEGLPlatformContext::getProcAddress(const QByteArray &procName)) ()
{
    bindApi(m_format);
    return eglGetProcAddress(procName.constData());
}

QSurfaceFormat QEGLPlatformContext::format() const
{
    return m_format;
}

EGLContext QEGLPlatformContext::eglContext() const
{
    return m_eglContext;
}

EGLDisplay QEGLPlatformContext::eglDisplay() const
{
    return m_eglDisplay;
}

EGLConfig QEGLPlatformContext::eglConfig() const
{
    return m_eglConfig;
}

QT_END_NAMESPACE