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

Copyright (C) 2010 Martin Gräßlin <kde@martin-graesslin.com>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*********************************************************************/

// This file is included in scene_opengl.cpp
//#include "scene_opengl.h"
#include <QX11Info>

EGLDisplay dpy;
EGLConfig config;
EGLSurface surface;
EGLContext ctx;

SceneOpenGL::SceneOpenGL(Workspace* ws)
    : Scene(ws)
    , init_ok(false)
    , selfCheckDone(true)
{
    if (!initRenderingContext())
        return;

    initEGL();
    if (!hasGLExtension("EGL_KHR_image_pixmap")) {
        kError(1212) << "Required extension EGL_KHR_image_pixmap not found, disabling compositing";
        return;
    }
    initGL();
    if (!hasGLExtension("GL_OES_EGL_image")) {
        kError(1212) << "Required extension GL_OES_EGL_image not found, disabling compositing";
        return;
    }
    debug = qstrcmp(qgetenv("KWIN_GL_DEBUG"), "1") == 0;
    if (!ShaderManager::instance()->isValid()) {
        kError(1212) << "Shaders not valid, ES compositing not possible";
        return;
    }
    ShaderManager::instance()->pushShader(ShaderManager::SimpleShader);

    if (checkGLError("Init")) {
        kError(1212) << "OpenGL compositing setup failed";
        return; // error
    }
    init_ok = true;
}

SceneOpenGL::~SceneOpenGL()
{
    foreach (Window * w, windows)
    delete w;
    // do cleanup after initBuffer()
    eglMakeCurrent(dpy, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
    eglDestroyContext(dpy, ctx);
    eglDestroySurface(dpy, surface);
    eglTerminate(dpy);
    eglReleaseThread();
    SceneOpenGL::EffectFrame::cleanup();
    checkGLError("Cleanup");
}

bool SceneOpenGL::initTfp()
{
    return false;
}

bool SceneOpenGL::initRenderingContext()
{
    dpy = eglGetDisplay(display());
    if (dpy == EGL_NO_DISPLAY)
        return false;
    EGLint major, minor;
    if (eglInitialize(dpy, &major, &minor) == EGL_FALSE)
        return false;
    eglBindAPI(EGL_OPENGL_ES_API);
    initBufferConfigs();
    if (!wspace->createOverlay()) {
        kError(1212) << "Could not get overlay window";
        return false;
    }
    surface = eglCreateWindowSurface(dpy, config, wspace->overlayWindow(), 0);

    const EGLint context_attribs[] = {
        EGL_CONTEXT_CLIENT_VERSION, 2,
        EGL_NONE
    };

    ctx = eglCreateContext(dpy, config, EGL_NO_CONTEXT, context_attribs);
    if (ctx == EGL_NO_CONTEXT)
        return false;
    if (eglMakeCurrent(dpy, surface, surface, ctx) == EGL_FALSE)
        return false;
    kDebug(1212) << "EGL version: " << major << "." << minor;
    EGLint error = eglGetError();
    if (error != EGL_SUCCESS) {
        kWarning(1212) << "Error occurred while creating context " << error;
        return false;
    }
    return true;
}

bool SceneOpenGL::initBuffer()
{
    return false;
}

bool SceneOpenGL::initBufferConfigs()
{
    const EGLint config_attribs[] = {
        EGL_SURFACE_TYPE,         EGL_WINDOW_BIT,
        EGL_RED_SIZE,             1,
        EGL_GREEN_SIZE,           1,
        EGL_BLUE_SIZE,            1,
        EGL_ALPHA_SIZE,           0,
        EGL_RENDERABLE_TYPE,      EGL_OPENGL_ES2_BIT,
        EGL_CONFIG_CAVEAT,        EGL_NONE,
        EGL_NONE,
    };

    EGLint count;
    EGLConfig configs[1024];
    eglChooseConfig(dpy, config_attribs, configs, 1024, &count);

    EGLint visualId = XVisualIDFromVisual((Visual*)QX11Info::appVisual());

    config = configs[0];
    for (int i = 0; i < count; i++) {
        EGLint val;
        eglGetConfigAttrib(dpy, configs[i], EGL_NATIVE_VISUAL_ID, &val);
        if (visualId == val) {
            config = configs[i];
            break;
        }
    }
    return true;
}

bool SceneOpenGL::initDrawableConfigs()
{
    return false;
}

void SceneOpenGL::selfCheckSetup()
{
    // not used in EGL
}

bool SceneOpenGL::selfCheckFinish()
{
    // not used in EGL
    return true;
}

// the entry function for painting
void SceneOpenGL::paint(QRegion damage, ToplevelList toplevels)
{
    QTime t = QTime::currentTime();
    foreach (Toplevel * c, toplevels) {
        assert(windows.contains(c));
        stacking_order.append(windows[ c ]);
    }
    grabXServer();
    int mask = 0;
    paintScreen(&mask, &damage);   // call generic implementation
    ungrabXServer(); // ungrab before flushBuffer(), it may wait for vsync
    if (wspace->overlayWindow())  // show the window only after the first pass, since
        wspace->showOverlay();   // that pass may take long
    lastRenderTime = t.elapsed();
    flushBuffer(mask, damage);
    // do cleanup
    stacking_order.clear();
    checkGLError("PostPaint");
}

void SceneOpenGL::waitSync()
{
    // not used in EGL
}

void SceneOpenGL::flushBuffer(int mask, QRegion damage)
{
    Q_UNUSED(damage)
    glFlush();
    if (mask & PAINT_SCREEN_REGION) {
        // TODO: implement me properly
        eglSwapBuffers(dpy, surface);
    } else {
        eglSwapBuffers(dpy, surface);
    }
    eglWaitGL();
    // TODO: remove for wayland
    XFlush(display());
}

//****************************************
// SceneOpenGL::Texture
//****************************************

void SceneOpenGL::Texture::init()
{
    findTarget();
}

void SceneOpenGL::Texture::release()
{
    mTexture = None;
}

void SceneOpenGL::Texture::findTarget()
{
    mTarget = GL_TEXTURE_2D;
}

bool SceneOpenGL::Texture::load(const Pixmap& pix, const QSize& size,
                                int depth, QRegion region)
{
    Q_UNUSED(size)
    Q_UNUSED(depth)
    Q_UNUSED(region)
    if (mTexture == None) {
        createTexture();
        bind();
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        const EGLint attribs[] = {
            EGL_IMAGE_PRESERVED_KHR, EGL_TRUE,
            EGL_NONE
        };
        EGLImageKHR image = eglCreateImageKHR(dpy, EGL_NO_CONTEXT, EGL_NATIVE_PIXMAP_KHR,
                                              (EGLClientBuffer)pix, attribs);
        glEGLImageTargetTexture2DOES(GL_TEXTURE_2D, (GLeglImageOES)image);
        eglDestroyImageKHR(dpy, image);
        unbind();
        checkGLError("load texture");
    }
    return true;
}

void SceneOpenGL::Texture::bind()
{
    GLTexture::bind();
}

void SceneOpenGL::Texture::unbind()
{
    GLTexture::unbind();
}