////////////////////////////////////////////////////////////
//
// SFML - Simple and Fast Multimedia Library
// Copyright (C) 2007-2015 Marco Antognini (antognini.marco@gmail.com),
//                         Laurent Gomila (laurent@sfml-dev.org)
//
// This software is provided 'as-is', without any express or implied warranty.
// In no event will the authors be held liable for any damages arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it freely,
// subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented;
//    you must not claim that you wrote the original software.
//    If you use this software in a product, an acknowledgment
//    in the product documentation would be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such,
//    and must not be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source distribution.
//
////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////
// Headers
////////////////////////////////////////////////////////////
#include <SFML/Window/OSX/SFContext.hpp>
#include <SFML/Window/OSX/WindowImplCocoa.hpp>
#include <SFML/System/Err.hpp>
#include <dlfcn.h>
#include <stdint.h>

#import <SFML/Window/OSX/AutoreleasePoolWrapper.h>

namespace sf
{
namespace priv
{


////////////////////////////////////////////////////////////
SFContext::SFContext(SFContext* shared) :
m_view(0),
m_window(0)
{
    // Ask for a pool.
    retainPool();

    // Create the context
    createContext(shared,
                  VideoMode::getDesktopMode().bitsPerPixel,
                  ContextSettings(0, 0, 0));
}


////////////////////////////////////////////////////////////
SFContext::SFContext(SFContext* shared, const ContextSettings& settings,
                     const WindowImpl* owner, unsigned int bitsPerPixel) :
m_view(0),
m_window(0)
{
    // Ask for a pool.
    retainPool();

    // Create the context.
    createContext(shared, bitsPerPixel, settings);

    // Apply context.
    const WindowImplCocoa* ownerCocoa = static_cast<const WindowImplCocoa*>(owner);
    ownerCocoa->applyContext(m_context);
}


////////////////////////////////////////////////////////////
SFContext::SFContext(SFContext* shared, const ContextSettings& settings,
                     unsigned int width, unsigned int height) :
m_view(0),
m_window(0)
{
    // Ensure the process is setup in order to create a valid window.
    WindowImplCocoa::setUpProcess();

    // Ask for a pool.
    retainPool();

    // Create the context.
    createContext(shared, VideoMode::getDesktopMode().bitsPerPixel, settings);

    // Create a dummy window/view pair (hidden) and assign it our context.
    m_window = [[NSWindow alloc] initWithContentRect:NSMakeRect(0, 0, width, height)
                                           styleMask:NSBorderlessWindowMask
                                             backing:NSBackingStoreBuffered
                                               defer:NO]; // Don't defer it!
    m_view = [[NSOpenGLView alloc] initWithFrame:NSMakeRect(0, 0, width, height)];
    [m_window setContentView:m_view];
    [m_view setOpenGLContext:m_context];
    [m_context setView:m_view];
}


////////////////////////////////////////////////////////////
SFContext::~SFContext()
{
    [m_context clearDrawable];
    [m_context release];

    [m_view release]; // Might be nil but we don't care.
    [m_window release]; // Idem.

    releasePool();
}


////////////////////////////////////////////////////////////
GlFunctionPointer SFContext::getFunction(const char* name)
{
    static void* image = NULL;

    if (!image)
        image = dlopen("/System/Library/Frameworks/OpenGL.framework/Versions/Current/OpenGL", RTLD_LAZY);

    return (image ? reinterpret_cast<GlFunctionPointer>(reinterpret_cast<intptr_t>(dlsym(image, name))) : 0);
}


////////////////////////////////////////////////////////////
bool SFContext::makeCurrent()
{
    [m_context makeCurrentContext];
    return m_context == [NSOpenGLContext currentContext]; // Should be true.
}


////////////////////////////////////////////////////////////
void SFContext::display()
{
    [m_context flushBuffer];
}


////////////////////////////////////////////////////////////
void SFContext::setVerticalSyncEnabled(bool enabled)
{
    GLint swapInterval = enabled ? 1 : 0;

    [m_context setValues:&swapInterval forParameter:NSOpenGLCPSwapInterval];
}


////////////////////////////////////////////////////////////
void SFContext::createContext(SFContext* shared,
                              unsigned int bitsPerPixel,
                              const ContextSettings& settings)
{
    // Save the settings. (OpenGL version is updated elsewhere.)
    m_settings = settings;

    // Choose the attributes of OGL context.
    std::vector<NSOpenGLPixelFormatAttribute> attrs;
    attrs.reserve(20); // max attributes (estimation).

    // These casts are safe. C++ is much more strict than Obj-C.

    attrs.push_back(NSOpenGLPFAClosestPolicy);
    attrs.push_back(NSOpenGLPFADoubleBuffer);

    if (bitsPerPixel > 24)
    {
        attrs.push_back(NSOpenGLPFAAlphaSize);
        attrs.push_back((NSOpenGLPixelFormatAttribute)8);
    }

    attrs.push_back(NSOpenGLPFADepthSize);
    attrs.push_back((NSOpenGLPixelFormatAttribute)m_settings.depthBits);

    attrs.push_back(NSOpenGLPFAStencilSize);
    attrs.push_back((NSOpenGLPixelFormatAttribute)m_settings.stencilBits);

    if (m_settings.antialiasingLevel > 0)
    {
        /*
         * Antialiasing techniques are described in the
         * "OpenGL Programming Guide for Mac OS X" document.
         *
         * According to this document, the specification currently allows
         * only one multisample buffer.
         *
         * The document also states that software renderers should be avoided
         * because antialisaing techniques are very slow with them.
         */

        // Prefer multisampling over supersampling
        attrs.push_back(NSOpenGLPFAMultisample);

        // Only one buffer is currently available
        attrs.push_back(NSOpenGLPFASampleBuffers);
        attrs.push_back((NSOpenGLPixelFormatAttribute)1);

        // Antialiasing level
        attrs.push_back(NSOpenGLPFASamples);
        attrs.push_back((NSOpenGLPixelFormatAttribute)m_settings.antialiasingLevel);

        // No software renderer - only hardware renderer
        attrs.push_back(NSOpenGLPFAAccelerated);
    }

    // Support for OpenGL 3.2 on Mac OS X Lion and later:
    // SFML 2 Graphics module uses some OpenGL features that are deprecated in
    // OpenGL 3.0 and that are no longer available in 3.1 and 3.2+ with a core context.
    // Therefore the Graphics module won't work as expected.

    // 1.x/2.x are mapped to 2.1 since Apple only support that legacy version.
    // >=3.0 are mapped to a 3.2 core profile.
    bool legacy = m_settings.majorVersion < 3;

    if (legacy)
    {
        m_settings.attributeFlags &= ~ContextSettings::Core;
        m_settings.majorVersion = 2;
        m_settings.minorVersion = 1;
        attrs.push_back(NSOpenGLPFAOpenGLProfile);
        attrs.push_back(NSOpenGLProfileVersionLegacy);
    }
    else
    {
        if (!(m_settings.attributeFlags & ContextSettings::Core))
        {
            sf::err() << "Warning. Compatibility profile not supported on this platform." << std::endl;
            m_settings.attributeFlags |= ContextSettings::Core;
        }
        m_settings.majorVersion = 3;
        m_settings.minorVersion = 2;
        attrs.push_back(NSOpenGLPFAOpenGLProfile);
        attrs.push_back(NSOpenGLProfileVersion3_2Core);
    }

    if (m_settings.attributeFlags & ContextSettings::Debug)
    {
        sf::err() << "Warning. OpenGL debugging not supported on this platform." << std::endl;
        m_settings.attributeFlags &= ~ContextSettings::Debug;
    }

    attrs.push_back((NSOpenGLPixelFormatAttribute)0); // end of array

    // Create the pixel format.
    NSOpenGLPixelFormat* pixFmt = [[NSOpenGLPixelFormat alloc] initWithAttributes:&attrs[0]];

    if (pixFmt == nil)
    {
        sf::err() << "Error. Unable to find a suitable pixel format." << std::endl;
        return;
    }

    // Use the shared context if one is given.
    NSOpenGLContext* sharedContext = shared != NULL ? shared->m_context : nil;

    // Create the context.
    m_context = [[NSOpenGLContext alloc] initWithFormat:pixFmt
                                           shareContext:sharedContext];

    if (m_context == nil)
    {
        sf::err() << "Error. Unable to create the context. Retrying without shared context." << std::endl;
        m_context = [[NSOpenGLContext alloc] initWithFormat:pixFmt
                                             shareContext:nil];

        if (m_context == nil)
            sf::err() << "Error. Unable to create the context." << std::endl;
        else
            sf::err() << "Warning. New context created without shared context." << std::endl;
    }

    // Free up.
    [pixFmt release];

}

} // namespace priv

} // namespace sf

