/*
 * Copyright (C) 2010 Apple Inc. All rights reserved.
 * Copyright (C) 2011 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#include "config.h"

#if USE(3D_GRAPHICS)

#include "GraphicsContext3D.h"

#include "Extensions3DOpenGL.h"
#include "IntRect.h"
#include "IntSize.h"
#include "NotImplemented.h"

#include <algorithm>
#include <cstring>
#include <wtf/MainThread.h>
#include <wtf/UnusedParam.h>
#include <wtf/text/CString.h>

#if PLATFORM(MAC)
#include <OpenGL/gl.h>
#elif PLATFORM(GTK) || PLATFORM(EFL) || PLATFORM(QT)
#include "OpenGLShims.h"
#endif

namespace WebCore {

void GraphicsContext3D::readPixelsAndConvertToBGRAIfNecessary(int x, int y, int width, int height, unsigned char* pixels)
{
    ::glReadPixels(x, y, width, height, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, pixels);
}

void GraphicsContext3D::validateAttributes()
{
    Extensions3D* extensions = getExtensions();
    validateDepthStencil("GL_EXT_packed_depth_stencil");
    if (m_attrs.antialias) {
        bool isValidVendor = true;
        // Currently in Mac we only turn on antialias if vendor is NVIDIA,
        // or if ATI and on 10.7.2 and above.
        const char* vendor = reinterpret_cast<const char*>(::glGetString(GL_VENDOR));
        if (!vendor || (!std::strstr(vendor, "NVIDIA") && !(std::strstr(vendor, "ATI") && systemAllowsMultisamplingOnATICards())))
            isValidVendor = false;
        if (!isValidVendor || !extensions->supports("GL_ANGLE_framebuffer_multisample") || isGLES2Compliant())
            m_attrs.antialias = false;
        else
            extensions->ensureEnabled("GL_ANGLE_framebuffer_multisample");
    }
}

bool GraphicsContext3D::reshapeFBOs(const IntSize& size)
{
    const int width = size.width();
    const int height = size.height();
    GLuint colorFormat, internalDepthStencilFormat = 0;
    if (m_attrs.alpha) {
        m_internalColorFormat = GL_RGBA8;
        colorFormat = GL_RGBA;
    } else {
        m_internalColorFormat = GL_RGB8;
        colorFormat = GL_RGB;
    }
    if (m_attrs.stencil || m_attrs.depth) {
        // We don't allow the logic where stencil is required and depth is not.
        // See GraphicsContext3D::validateAttributes.

        Extensions3D* extensions = getExtensions();
        // Use a 24 bit depth buffer where we know we have it.
        if (extensions->supports("GL_EXT_packed_depth_stencil"))
            internalDepthStencilFormat = GL_DEPTH24_STENCIL8_EXT;
        else
            internalDepthStencilFormat = GL_DEPTH_COMPONENT;
    }

    bool mustRestoreFBO = false;

    // Resize multisample FBO.
    if (m_attrs.antialias) {
        GLint maxSampleCount;
        ::glGetIntegerv(GL_MAX_SAMPLES_EXT, &maxSampleCount);
        GLint sampleCount = std::min(8, maxSampleCount);
        if (sampleCount > maxSampleCount)
            sampleCount = maxSampleCount;
        if (m_boundFBO != m_multisampleFBO) {
            ::glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, m_multisampleFBO);
            mustRestoreFBO = true;
        }
        ::glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, m_multisampleColorBuffer);
        ::glRenderbufferStorageMultisampleEXT(GL_RENDERBUFFER_EXT, sampleCount, m_internalColorFormat, width, height);
        ::glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_RENDERBUFFER_EXT, m_multisampleColorBuffer);
        if (m_attrs.stencil || m_attrs.depth) {
            ::glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, m_multisampleDepthStencilBuffer);
            ::glRenderbufferStorageMultisampleEXT(GL_RENDERBUFFER_EXT, sampleCount, internalDepthStencilFormat, width, height);
            if (m_attrs.stencil)
                ::glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_STENCIL_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, m_multisampleDepthStencilBuffer);
            if (m_attrs.depth)
                ::glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, m_multisampleDepthStencilBuffer);
        }
        ::glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, 0);
        if (glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT) != GL_FRAMEBUFFER_COMPLETE_EXT) {
            // FIXME: cleanup.
            notImplemented();
        }
    }

    // resize regular FBO
    if (m_boundFBO != m_fbo) {
        mustRestoreFBO = true;
        ::glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, m_fbo);
    }
    ::glBindTexture(GL_TEXTURE_2D, m_texture);
    ::glTexImage2D(GL_TEXTURE_2D, 0, m_internalColorFormat, width, height, 0, colorFormat, GL_UNSIGNED_BYTE, 0);
    ::glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, m_texture, 0);
    ::glBindTexture(GL_TEXTURE_2D, m_compositorTexture);
    ::glTexImage2D(GL_TEXTURE_2D, 0, m_internalColorFormat, width, height, 0, colorFormat, GL_UNSIGNED_BYTE, 0);
    ::glBindTexture(GL_TEXTURE_2D, 0);
    if (!m_attrs.antialias && (m_attrs.stencil || m_attrs.depth)) {
        ::glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, m_depthStencilBuffer);
        ::glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, internalDepthStencilFormat, width, height);
        if (m_attrs.stencil)
            ::glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_STENCIL_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, m_depthStencilBuffer);
        if (m_attrs.depth)
            ::glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT, GL_RENDERBUFFER_EXT, m_depthStencilBuffer);
        ::glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, 0);
    }
    if (glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT) != GL_FRAMEBUFFER_COMPLETE_EXT) {
        // FIXME: cleanup
        notImplemented();
    }

    if (m_attrs.antialias) {
        ::glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, m_multisampleFBO);
        if (m_boundFBO == m_multisampleFBO)
            mustRestoreFBO = false;
    }

    return mustRestoreFBO;
}

void GraphicsContext3D::resolveMultisamplingIfNecessary(const IntRect& rect)
{
    ::glBindFramebufferEXT(GL_READ_FRAMEBUFFER_EXT, m_multisampleFBO);
    ::glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER_EXT, m_fbo);

    IntRect resolveRect = rect;
    if (rect.isEmpty())
        resolveRect = IntRect(0, 0, m_currentWidth, m_currentHeight);

    ::glBlitFramebufferEXT(resolveRect.x(), resolveRect.y(), resolveRect.maxX(), resolveRect.maxY(), resolveRect.x(), resolveRect.y(), resolveRect.maxX(), resolveRect.maxY(), GL_COLOR_BUFFER_BIT, GL_LINEAR);
}

void GraphicsContext3D::renderbufferStorage(GC3Denum target, GC3Denum internalformat, GC3Dsizei width, GC3Dsizei height)
{
    makeContextCurrent();
    switch (internalformat) {
    case DEPTH_STENCIL:
        internalformat = GL_DEPTH24_STENCIL8_EXT;
        break;
    case DEPTH_COMPONENT16:
        internalformat = GL_DEPTH_COMPONENT;
        break;
    case RGBA4:
    case RGB5_A1:
        internalformat = GL_RGBA;
        break;
    case RGB565:
        internalformat = GL_RGB;
        break;
    }
    ::glRenderbufferStorageEXT(target, internalformat, width, height);
}

void GraphicsContext3D::getIntegerv(GC3Denum pname, GC3Dint* value)
{
    // Need to emulate MAX_FRAGMENT/VERTEX_UNIFORM_VECTORS and MAX_VARYING_VECTORS
    // because desktop GL's corresponding queries return the number of components
    // whereas GLES2 return the number of vectors (each vector has 4 components).
    // Therefore, the value returned by desktop GL needs to be divided by 4.
    makeContextCurrent();
    switch (pname) {
    case MAX_FRAGMENT_UNIFORM_VECTORS:
        ::glGetIntegerv(GL_MAX_FRAGMENT_UNIFORM_COMPONENTS, value);
        *value /= 4;
        break;
    case MAX_VERTEX_UNIFORM_VECTORS:
        ::glGetIntegerv(GL_MAX_VERTEX_UNIFORM_COMPONENTS, value);
        *value /= 4;
        break;
    case MAX_VARYING_VECTORS:
        ::glGetIntegerv(GL_MAX_VARYING_FLOATS, value);
        *value /= 4;
        break;
    default:
        ::glGetIntegerv(pname, value);
    }
}

void GraphicsContext3D::getShaderPrecisionFormat(GC3Denum shaderType, GC3Denum precisionType, GC3Dint* range, GC3Dint* precision)
{
    UNUSED_PARAM(shaderType);
    ASSERT(range);
    ASSERT(precision);

    makeContextCurrent();

    switch (precisionType) {
    case GraphicsContext3D::LOW_INT:
    case GraphicsContext3D::MEDIUM_INT:
    case GraphicsContext3D::HIGH_INT:
        // These values are for a 32-bit twos-complement integer format.
        range[0] = 31;
        range[1] = 30;
        precision[0] = 0;
        break;
    case GraphicsContext3D::LOW_FLOAT:
    case GraphicsContext3D::MEDIUM_FLOAT:
    case GraphicsContext3D::HIGH_FLOAT:
        // These values are for an IEEE single-precision floating-point format.
        range[0] = 127;
        range[1] = 127;
        precision[0] = 23;
        break;
    default:
        ASSERT_NOT_REACHED();
        break;
    }
}

bool GraphicsContext3D::texImage2D(GC3Denum target, GC3Dint level, GC3Denum internalformat, GC3Dsizei width, GC3Dsizei height, GC3Dint border, GC3Denum format, GC3Denum type, const void* pixels)
{
    if (width && height && !pixels) {
        synthesizeGLError(INVALID_VALUE);
        return false;
    }

    GC3Denum openGLInternalFormat = internalformat;
    if (type == GL_FLOAT) {
        if (format == GL_RGBA)
            openGLInternalFormat = GL_RGBA32F_ARB;
        else if (format == GL_RGB)
            openGLInternalFormat = GL_RGB32F_ARB;
    }

    texImage2DDirect(target, level, openGLInternalFormat, width, height, border, format, type, pixels);
    return true;
}

void GraphicsContext3D::depthRange(GC3Dclampf zNear, GC3Dclampf zFar)
{
    makeContextCurrent();
    ::glDepthRange(zNear, zFar);
}

void GraphicsContext3D::clearDepth(GC3Dclampf depth)
{
    makeContextCurrent();
    ::glClearDepth(depth);
}

bool GraphicsContext3D::systemAllowsMultisamplingOnATICards() const
{
#if PLATFORM(MAC)
#if PLATFORM(IOS) || __MAC_OS_X_VERSION_MIN_REQUIRED >= 1080
    return true;
#else
    ASSERT(isMainThread());
    static SInt32 version;
    if (!version) {
        if (Gestalt(gestaltSystemVersion, &version) != noErr)
            return false;
    }
    // See https://bugs.webkit.org/show_bug.cgi?id=77922 for more details
    return version >= 0x1072;
#endif // SNOW_LEOPARD and LION
#else
    return false;
#endif // PLATFORM(MAC)
}

Extensions3D* GraphicsContext3D::getExtensions()
{
    if (!m_extensions)
        m_extensions = adoptPtr(new Extensions3DOpenGL(this));
    return m_extensions.get();
}

void GraphicsContext3D::readPixels(GC3Dint x, GC3Dint y, GC3Dsizei width, GC3Dsizei height, GC3Denum format, GC3Denum type, void* data)
{
    // FIXME: remove the two glFlush calls when the driver bug is fixed, i.e.,
    // all previous rendering calls should be done before reading pixels.
    makeContextCurrent();
    ::glFlush();
    if (m_attrs.antialias && m_boundFBO == m_multisampleFBO) {
        resolveMultisamplingIfNecessary(IntRect(x, y, width, height));
        ::glBindFramebufferEXT(GraphicsContext3D::FRAMEBUFFER, m_fbo);
        ::glFlush();
    }
    ::glReadPixels(x, y, width, height, format, type, data);
    if (m_attrs.antialias && m_boundFBO == m_multisampleFBO)
        ::glBindFramebufferEXT(GraphicsContext3D::FRAMEBUFFER, m_multisampleFBO);
}

}

#endif // USE(3D_GRAPHICS)