#include <utility>
#define __NO_STD_VECTOR // Use cl::vector instead of STL version
#include <CL/cl.hpp>

#include <cstdio>
#include <cstdlib>
#include <fstream>
#include <iostream>
#include <string>
#include <iterator>

const std::string hw("Hello World\n");

inline void checkErr(cl_int err, const char * name){
    if (err != CL_SUCCESS) {
		std::cerr << "ERROR: " << name<< " (" << err << ")" << std::endl;
		exit(EXIT_FAILURE);    
	}
}

int main(void)
{
    cl_int err;
    cl::vector< cl::Platform > platformList;
    cl::Platform::get(&platformList);
    checkErr(platformList.size()!=0 ? CL_SUCCESS : -1, "cl::Platform::get");
    std::cerr << "Platform number is: " << platformList.size() << std::endl;
    
    std::string platformVendor;
    platformList[0].getInfo((cl_platform_info)CL_PLATFORM_VENDOR, &platformVendor);
    std::cerr << "Platform is by: " << platformVendor << "\n";
    cl_context_properties cprops[3] = 
        {CL_CONTEXT_PLATFORM, (cl_context_properties)(platformList[0])(), 0};
 
    cl::Context context(
       CL_DEVICE_TYPE_GPU, 
       cprops,
       NULL,
       NULL,
       &err);
    checkErr(err, "Conext::Context()");
    
    char * outH = new char[hw.length()+1];
    cl::Buffer outCL(
		context,
		CL_MEM_WRITE_ONLY | CL_MEM_USE_HOST_PTR,
		hw.length()+1,
		outH,
		&err);
	checkErr(err, "Buffer::Buffer()");
	
	cl::vector<cl::Device> devices;    
	devices = context.getInfo<CL_CONTEXT_DEVICES>();
	checkErr( devices.size() > 0 ? CL_SUCCESS : -1, "devices.size() > 0");
	
	std::ifstream file("C:/MyApps/OpenCL/example1_kernels.cl");
    checkErr(file.is_open() ? CL_SUCCESS:-1, "example1_kernel.cl");
    std::string prog(std::istreambuf_iterator<char>(file),(std::istreambuf_iterator<char>()));
    cl::Program::Sources source(1,std::make_pair(prog.c_str(), prog.length()+1));
    cl::Program program(context, source);
    err = program.build(devices,"");
    checkErr(file.is_open() ? CL_SUCCESS : -1, "Program::build()");

    cl::Kernel kernel(program, "hello", &err);
    checkErr(err, "Kernel::Kernel()");
    err = kernel.setArg(0, outCL);
    checkErr(err, "Kernel::setArg()");
    
    cl::CommandQueue queue(context, devices[0], 0, &err);
    checkErr(err, "CommandQueue::CommandQueue()");
    cl::Event event;
    err = queue.enqueueNDRangeKernel(kernel,cl::NullRange,cl::NDRange(hw.length()+1),cl::NDRange(1, 1),NULL,&event);
    checkErr(err, "ComamndQueue::enqueueNDRangeKernel()");
	event.wait();
	err = queue.enqueueReadBuffer(outCL,CL_TRUE,0,hw.length()+1,outH);
	checkErr(err, "ComamndQueue::enqueueReadBuffer()");
	std::cout << outH;

	delete [] outH;
	return EXIT_SUCCESS;
}