#include <stdio.h>
#include "cl.h"

// function prototypes:
void	SelectOpenclDevice();
char *	Vendor( cl_uint );
char *	Type( cl_device_type );

// globals:
cl_platform_id   Platform;
cl_device_id     Device;

// vendor ids:
#define ID_AMD		0x1002
#define ID_INTEL	0x8086
#define ID_NVIDIA	0x10de

int
main( int argc, char *argv[ ] )
{
	SelectOpenclDevice( );
	return 0;
}

void
SelectOpenclDevice()
{
		// select which opencl device to use:
		// priority order:
		//	1. a gpu
		//	2. an nvidia or amd gpu
		//	3. an intel gpu
		//	4. an intel cpu

	int bestPlatform = -1;
	int bestDevice = -1;
	cl_device_type bestDeviceType;
	cl_uint bestDeviceVendor;
	cl_int status;		// returned status from opencl calls
				// test against CL_SUCCESS

	fprintf(stderr, "\nSelecting the OpenCL Platform and Device:\n");

	// find out how many platforms are attached here and get their ids:

	cl_uint numPlatforms;
	status = clGetPlatformIDs(0, NULL, &numPlatforms);
	if( status != CL_SUCCESS )
		fprintf(stderr, "clGetPlatformIDs failed (1)\n");

	cl_platform_id* platforms = new cl_platform_id[numPlatforms];
	status = clGetPlatformIDs(numPlatforms, platforms, NULL);
	if( status != CL_SUCCESS )
		fprintf(stderr, "clGetPlatformIDs failed (2)\n");

	for( int p = 0; p < (int)numPlatforms; p++ )
	{
		// find out how many devices are attached to each platform and get their ids:

		cl_uint numDevices;

		status = clGetDeviceIDs(platforms[p], CL_DEVICE_TYPE_ALL, 0, NULL, &numDevices);
		if( status != CL_SUCCESS )
			fprintf(stderr, "clGetDeviceIDs failed (2)\n");

		cl_device_id* devices = new cl_device_id[numDevices];
		status = clGetDeviceIDs(platforms[p], CL_DEVICE_TYPE_ALL, numDevices, devices, NULL);
		if( status != CL_SUCCESS )
			fprintf(stderr, "clGetDeviceIDs failed (2)\n");

		for( int d = 0; d < (int)numDevices; d++ )
		{
			cl_device_type type;
			cl_uint vendor;
			size_t sizes[3] = { 0, 0, 0 };

			clGetDeviceInfo(devices[d], CL_DEVICE_TYPE, sizeof(type), &type, NULL);

			clGetDeviceInfo(devices[d], CL_DEVICE_VENDOR_ID, sizeof(vendor), &vendor, NULL);

			// select:

			if( bestPlatform < 0 )		// not yet holding anything -- we'll accept anything
			{
				bestPlatform = p;
				bestDevice = d;
				Platform = platforms[bestPlatform];
				Device = devices[bestDevice];
				bestDeviceType = type;
				bestDeviceVendor = vendor;
			}
			else					// holding something already -- can we do better?
			{
				if( bestDeviceType == CL_DEVICE_TYPE_CPU )		// holding a cpu already -- switch to a gpu if possible
				{
					if( type == CL_DEVICE_TYPE_GPU )			// found a gpu
					{										// switch to the gpu we just found
						bestPlatform = p;
						bestDevice = d;
						Platform = platforms[bestPlatform];
						Device = devices[bestDevice];
						bestDeviceType = type;
						bestDeviceVendor = vendor;
					}
				}
				else										// holding a gpu -- is a better gpu available?
				{
					if( bestDeviceVendor == ID_INTEL )			// currently holding an intel gpu
					{										// we are assuming we just found a bigger, badder nvidia or amd gpu
						bestPlatform = p;
						bestDevice = d;
						Platform = platforms[bestPlatform];
						Device = devices[bestDevice];
						bestDeviceType = type;
						bestDeviceVendor = vendor;
					}
				}
			}
		}
		delete [ ] devices;
	}
	delete [ ] platforms;


	if( bestPlatform < 0 )
	{
		fprintf(stderr, "Found no OpenCL devices!\n");
	}
	else
	{
		fprintf(stderr, "I have selected Platform #%d, Device #%d\n", bestPlatform, bestDevice);
		fprintf(stderr, "Vendor = %s, Type = %s\n", Vendor(bestDeviceVendor), Type(bestDeviceType) );
	}
}

char *
Vendor( cl_uint v )
{
	switch( v )
	{
		case ID_AMD:
			return (char *)"AMD";
		case ID_INTEL:
			return (char *)"Intel";
		case ID_NVIDIA:
			return (char *)"NVIDIA";
	}
	return (char *)"Unknown";
}

char *
Type( cl_device_type t )
{
	switch( t )
	{
		case CL_DEVICE_TYPE_CPU:
			return (char *)"CL_DEVICE_TYPE_CPU";
		case CL_DEVICE_TYPE_GPU:
			return (char *)"CL_DEVICE_TYPE_GPU";
		case CL_DEVICE_TYPE_ACCELERATOR:
			return (char *)"CL_DEVICE_TYPE_ACCELERATOR";
	}
	return (char *)"Unknown";
}