// Copyright 2016 The SwiftShader Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Display.cpp: Implements the Display class, representing the abstract
// display on which graphics are drawn.

#include "Display.h"

#include "main.h"
#include "mathutil.h"
#include "Device.hpp"
#include "common/debug.h"

#include <algorithm>
#include <vector>
#include <map>

namespace gl
{
typedef std::map<NativeDisplayType, Display*> DisplayMap;
DisplayMap displays;

Display *Display::getDisplay(NativeDisplayType displayId)
{
	if(displays.find(displayId) != displays.end())
	{
		return displays[displayId];
	}

	// FIXME: Check if displayId is a valid display device context
	Display *display = new Display(displayId);

	displays[displayId] = display;
	return display;
}

Display::Display(NativeDisplayType displayId) : displayId(displayId)
{
	mMinSwapInterval = 1;
	mMaxSwapInterval = 0;
}

Display::~Display()
{
	terminate();

	displays.erase(displayId);
}

static void cpuid(int registers[4], int info)
{
	#if defined(_WIN32)
		__cpuid(registers, info);
	#else
		__asm volatile("cpuid": "=a" (registers[0]), "=b" (registers[1]), "=c" (registers[2]), "=d" (registers[3]): "a" (info));
	#endif
}

static bool detectSSE()
{
	#if defined(__APPLE__)
		int SSE = false;
		size_t length = sizeof(SSE);
		sysctlbyname("hw.optional.sse", &SSE, &length, 0, 0);
		return SSE;
	#else
		int registers[4];
		cpuid(registers, 1);
		return (registers[3] & 0x02000000) != 0;
	#endif
}

bool Display::initialize()
{
	if(isInitialized())
	{
		return true;
	}

	if(!detectSSE())
	{
		 return false;
	}

	mMinSwapInterval = 0;
	mMaxSwapInterval = 4;

	if(!isInitialized())
	{
		terminate();

		return false;
	}

	return true;
}

void Display::terminate()
{
	while(!mSurfaceSet.empty())
	{
		destroySurface(*mSurfaceSet.begin());
	}

	while(!mContextSet.empty())
	{
		destroyContext(*mContextSet.begin());
	}
}

gl::Context *Display::createContext(const gl::Context *shareContext)
{
	gl::Context *context = new gl::Context(shareContext);
	mContextSet.insert(context);

	return context;
}

void Display::destroySurface(Surface *surface)
{
	delete surface;
	mSurfaceSet.erase(surface);
}

void Display::destroyContext(gl::Context *context)
{
	delete context;

	if(context == gl::getContext())
	{
		gl::makeCurrent(nullptr, nullptr, nullptr);
	}

	mContextSet.erase(context);
}

bool Display::isInitialized() const
{
	return mMinSwapInterval <= mMaxSwapInterval;
}

bool Display::isValidContext(gl::Context *context)
{
	return mContextSet.find(context) != mContextSet.end();
}

bool Display::isValidSurface(Surface *surface)
{
	return mSurfaceSet.find(surface) != mSurfaceSet.end();
}

bool Display::isValidWindow(NativeWindowType window)
{
	#if defined(_WIN32)
		return IsWindow(window) == TRUE;
	#else
		XWindowAttributes windowAttributes;
		Status status = XGetWindowAttributes(displayId, window, &windowAttributes);

		return status == True;
	#endif
}

GLint Display::getMinSwapInterval()
{
	return mMinSwapInterval;
}

GLint Display::getMaxSwapInterval()
{
	return mMaxSwapInterval;
}

Surface *Display::getPrimarySurface()
{
	if(mSurfaceSet.size() == 0)
	{
		Surface *surface = new Surface(this, WindowFromDC(displayId));

		if(!surface->initialize())
		{
			delete surface;
			return 0;
		}

		mSurfaceSet.insert(surface);

		gl::setCurrentDrawSurface(surface);
	}

	return *mSurfaceSet.begin();
}

NativeDisplayType Display::getNativeDisplay() const
{
	return displayId;
}

DisplayMode Display::getDisplayMode() const
{
	DisplayMode displayMode = {0};

	#if defined(_WIN32)
		HDC deviceContext = GetDC(0);

		displayMode.width = ::GetDeviceCaps(deviceContext, HORZRES);
		displayMode.height = ::GetDeviceCaps(deviceContext, VERTRES);
		unsigned int bpp = ::GetDeviceCaps(deviceContext, BITSPIXEL);

		switch(bpp)
		{
		case 32: displayMode.format = sw::FORMAT_X8R8G8B8; break;
		case 24: displayMode.format = sw::FORMAT_R8G8B8;   break;
		case 16: displayMode.format = sw::FORMAT_R5G6B5;   break;
		default:
			ASSERT(false);   // Unexpected display mode color depth
		}

		ReleaseDC(0, deviceContext);
	#else
		Screen *screen = XDefaultScreenOfDisplay(displayId);
		displayMode.width = XWidthOfScreen(screen);
		displayMode.height = XHeightOfScreen(screen);
		unsigned int bpp = XPlanesOfScreen(screen);

		switch(bpp)
		{
		case 32: displayMode.format = sw::FORMAT_X8R8G8B8; break;
		case 24: displayMode.format = sw::FORMAT_R8G8B8;   break;
		case 16: displayMode.format = sw::FORMAT_R5G6B5;   break;
		default:
			ASSERT(false);   // Unexpected display mode color depth
		}
	#endif

	return displayMode;
}

}