/*
  This file is part of c-ethash.

  c-ethash is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  c-ethash is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
*/
/** @file ethash_cl_miner.cpp
* @author Tim Hughes <tim@twistedfury.com>
* @date 2015
*/


#define _CRT_SECURE_NO_WARNINGS

#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <assert.h>
#include <queue>
#include <random>
#include <vector>
#include <libethash/util.h>
#include <libethash/ethash.h>
#include "ethash_cl_miner.h"
#include "ethash_cl_miner_kernel.h"

#define ETHASH_BYTES 32
#define ETHASH_CL_MINIMUM_MEMORY 2000000000

// workaround lame platforms
#if !CL_VERSION_1_2
#define CL_MAP_WRITE_INVALIDATE_REGION CL_MAP_WRITE
#define CL_MEM_HOST_READ_ONLY 0
#endif

#undef min
#undef max

using namespace std;

// TODO: If at any point we can use libdevcore in here then we should switch to using a LogChannel
#define ETHCL_LOG(_contents) cout << "[OPENCL]:" << _contents << endl

static void add_definition(std::string& source, char const* id, unsigned value)
{
	char buf[256];
	sprintf(buf, "#define %s %uu\n", id, value);
	source.insert(source.begin(), buf, buf + strlen(buf));
}

ethash_cl_miner::search_hook::~search_hook() {}

ethash_cl_miner::ethash_cl_miner()
:	m_opencl_1_1()
{
}

ethash_cl_miner::~ethash_cl_miner()
{
	finish();
}

std::string ethash_cl_miner::platform_info(unsigned _platformId, unsigned _deviceId)
{
	std::vector<cl::Platform> platforms;
	cl::Platform::get(&platforms);
	if (platforms.empty())
	{
		ETHCL_LOG("No OpenCL platforms found.");
		return std::string();
	}

	// get GPU device of the selected platform
	std::vector<cl::Device> devices;
	unsigned platform_num = std::min<unsigned>(_platformId, platforms.size() - 1);
	platforms[platform_num].getDevices(CL_DEVICE_TYPE_ALL, &devices);
	if (devices.empty())
	{
		ETHCL_LOG("No OpenCL devices found.");
		return std::string();
	}

	// use selected default device
	unsigned device_num = std::min<unsigned>(_deviceId, devices.size() - 1);
	cl::Device& device = devices[device_num];
	std::string device_version = device.getInfo<CL_DEVICE_VERSION>();

	return "{ \"platform\": \"" + platforms[platform_num].getInfo<CL_PLATFORM_NAME>() + "\", \"device\": \"" + device.getInfo<CL_DEVICE_NAME>() + "\", \"version\": \"" + device_version + "\" }";
}

unsigned ethash_cl_miner::get_num_platforms()
{
	std::vector<cl::Platform> platforms;
	cl::Platform::get(&platforms);
	return platforms.size();
}

unsigned ethash_cl_miner::get_num_devices(unsigned _platformId)
{
	std::vector<cl::Platform> platforms;
	cl::Platform::get(&platforms);
	if (platforms.empty())
	{
		ETHCL_LOG("No OpenCL platforms found.");
		return 0;
	}

	std::vector<cl::Device> devices;
	unsigned platform_num = std::min<unsigned>(_platformId, platforms.size() - 1);
	platforms[platform_num].getDevices(CL_DEVICE_TYPE_ALL, &devices);
	if (devices.empty())
	{
		ETHCL_LOG("No OpenCL devices found.");
		return 0;
	}
	return devices.size();
}

bool ethash_cl_miner::haveSufficientGPUMemory(unsigned _platformId)
{
	std::vector<cl::Platform> platforms;
	cl::Platform::get(&platforms);
	if (platforms.empty())
	{
		ETHCL_LOG("No OpenCL platforms found.");
		return false;
	}

	std::vector<cl::Device> devices;
	unsigned platform_num = std::min<unsigned>(_platformId, platforms.size() - 1);
	platforms[platform_num].getDevices(CL_DEVICE_TYPE_ALL, &devices);
	if (devices.empty())
	{
		ETHCL_LOG("No OpenCL devices found.");
		return false;
	}

	for (cl::Device const& device: devices)
	{
		cl_ulong result;
		device.getInfo(CL_DEVICE_GLOBAL_MEM_SIZE, &result);
		if (result >= ETHASH_CL_MINIMUM_MEMORY)
		{
			ETHCL_LOG(
				"Found suitable OpenCL device [" << device.getInfo<CL_DEVICE_NAME>()
				<< "] with " << result << " bytes of GPU memory"
			);
			return true;
		}
		else
			ETHCL_LOG(
				"OpenCL device " << device.getInfo<CL_DEVICE_NAME>()
				<< " has insufficient GPU memory." << result <<
				" bytes of memory found < " << ETHASH_CL_MINIMUM_MEMORY << " bytes of memory required"
			);
	}
	return false;
}

void ethash_cl_miner::finish()
{
	if (m_queue())
		m_queue.finish();
}

bool ethash_cl_miner::init(uint8_t const* _dag, uint64_t _dagSize, unsigned workgroup_size, unsigned _platformId, unsigned _deviceId)
{
	// get all platforms
	std::vector<cl::Platform> platforms;
	cl::Platform::get(&platforms);
	if (platforms.empty())
	{
		ETHCL_LOG("No OpenCL platforms found.");
		return false;
	}

	// use selected platform

	_platformId = std::min<unsigned>(_platformId, platforms.size() - 1);

	ETHCL_LOG("Using platform: " << platforms[_platformId].getInfo<CL_PLATFORM_NAME>().c_str());

	// get GPU device of the default platform
	std::vector<cl::Device> devices;
	platforms[_platformId].getDevices(CL_DEVICE_TYPE_ALL, &devices);
	if (devices.empty())
	{
		ETHCL_LOG("No OpenCL devices found.");
		return false;
	}

	// use selected device
	cl::Device& device = devices[std::min<unsigned>(_deviceId, devices.size() - 1)];
	std::string device_version = device.getInfo<CL_DEVICE_VERSION>();
	ETHCL_LOG("Using device: " << device.getInfo<CL_DEVICE_NAME>().c_str() << "(" << device_version.c_str() << ")");

	if (strncmp("OpenCL 1.0", device_version.c_str(), 10) == 0)
	{
		ETHCL_LOG("OpenCL 1.0 is not supported.");
		return false;
	}
	if (strncmp("OpenCL 1.1", device_version.c_str(), 10) == 0)
		m_opencl_1_1 = true;

	// create context
	m_context = cl::Context(std::vector<cl::Device>(&device, &device + 1));
	m_queue = cl::CommandQueue(m_context, device);

	// use requested workgroup size, but we require multiple of 8
	m_workgroup_size = ((workgroup_size + 7) / 8) * 8;

	// patch source code
	std::string code(ETHASH_CL_MINER_KERNEL, ETHASH_CL_MINER_KERNEL + ETHASH_CL_MINER_KERNEL_SIZE);
	add_definition(code, "GROUP_SIZE", m_workgroup_size);
	add_definition(code, "DAG_SIZE", (unsigned)(_dagSize / ETHASH_MIX_BYTES));
	add_definition(code, "ACCESSES", ETHASH_ACCESSES);
	add_definition(code, "MAX_OUTPUTS", c_max_search_results);
	//debugf("%s", code.c_str());

	// create miner OpenCL program
	cl::Program::Sources sources;
	sources.push_back({code.c_str(), code.size()});

	cl::Program program(m_context, sources);
	try
	{
		program.build({device});
	}
	catch (cl::Error err)
	{
		ETHCL_LOG(program.getBuildInfo<CL_PROGRAM_BUILD_LOG>(device).c_str());
		return false;
	}
	m_hash_kernel = cl::Kernel(program, "ethash_hash");
	m_search_kernel = cl::Kernel(program, "ethash_search");

	// create buffer for dag
	m_dag = cl::Buffer(m_context, CL_MEM_READ_ONLY, _dagSize);
	
	// create buffer for header
	m_header = cl::Buffer(m_context, CL_MEM_READ_ONLY, 32);

	// compute dag on CPU
	try {
		m_queue.enqueueWriteBuffer(m_dag, CL_TRUE, 0, _dagSize, _dag);
	}
	catch (...)
	{
		// didn't work. shitty driver. try allocating in CPU RAM and manually memcpying it.
		void* dag_ptr = m_queue.enqueueMapBuffer(m_dag, true, m_opencl_1_1 ? CL_MAP_WRITE : CL_MAP_WRITE_INVALIDATE_REGION, 0, _dagSize);
		memcpy(dag_ptr, _dag, _dagSize);
		m_queue.enqueueUnmapMemObject(m_dag, dag_ptr);
	}

	// create mining buffers
	for (unsigned i = 0; i != c_num_buffers; ++i)
	{
		m_hash_buf[i] = cl::Buffer(m_context, CL_MEM_WRITE_ONLY | (!m_opencl_1_1 ? CL_MEM_HOST_READ_ONLY : 0), 32*c_hash_batch_size);
		m_search_buf[i] = cl::Buffer(m_context, CL_MEM_WRITE_ONLY, (c_max_search_results + 1) * sizeof(uint32_t));
	}
	return true;
}

void ethash_cl_miner::hash(uint8_t* ret, uint8_t const* header, uint64_t nonce, unsigned count)
{
	struct pending_batch
	{
		unsigned base;
		unsigned count;
		unsigned buf;
	};
	std::queue<pending_batch> pending;
	
	// update header constant buffer
	m_queue.enqueueWriteBuffer(m_header, true, 0, 32, header);

	/*
	__kernel void ethash_combined_hash(
		__global hash32_t* g_hashes,
		__constant hash32_t const* g_header,
		__global hash128_t const* g_dag,
		ulong start_nonce,
		uint isolate
		)
	*/
	m_hash_kernel.setArg(1, m_header);
	m_hash_kernel.setArg(2, m_dag);
	m_hash_kernel.setArg(3, nonce);
	m_hash_kernel.setArg(4, ~0u); // have to pass this to stop the compile unrolling the loop

	unsigned buf = 0;
	for (unsigned i = 0; i < count || !pending.empty(); )
	{
		// how many this batch
		if (i < count)
		{
			unsigned const this_count = std::min<unsigned>(count - i, c_hash_batch_size);
			unsigned const batch_count = std::max<unsigned>(this_count, m_workgroup_size);

			// supply output hash buffer to kernel
			m_hash_kernel.setArg(0, m_hash_buf[buf]);

			// execute it!
			m_queue.enqueueNDRangeKernel(
				m_hash_kernel,
				cl::NullRange,
				cl::NDRange(batch_count),
				cl::NDRange(m_workgroup_size)
				);
			m_queue.flush();
		
			pending.push({i, this_count, buf});
			i += this_count;
			buf = (buf + 1) % c_num_buffers;
		}

		// read results
		if (i == count || pending.size() == c_num_buffers)
		{
			pending_batch const& batch = pending.front();

			// could use pinned host pointer instead, but this path isn't that important.
			uint8_t* hashes = (uint8_t*)m_queue.enqueueMapBuffer(m_hash_buf[batch.buf], true, CL_MAP_READ, 0, batch.count * ETHASH_BYTES);
			memcpy(ret + batch.base*ETHASH_BYTES, hashes, batch.count*ETHASH_BYTES);
			m_queue.enqueueUnmapMemObject(m_hash_buf[batch.buf], hashes);

			pending.pop();
		}
	}
}


void ethash_cl_miner::search(uint8_t const* header, uint64_t target, search_hook& hook)
{
	struct pending_batch
	{
		uint64_t start_nonce;
		unsigned buf;
	};
	std::queue<pending_batch> pending;

	uint32_t const c_zero = 0;

	// update header constant buffer
	m_queue.enqueueWriteBuffer(m_header, false, 0, 32, header);
	for (unsigned i = 0; i != c_num_buffers; ++i)
		m_queue.enqueueWriteBuffer(m_search_buf[i], false, 0, 4, &c_zero);

#if CL_VERSION_1_2 && 0
	cl::Event pre_return_event;
	if (!m_opencl_1_1)
		m_queue.enqueueBarrierWithWaitList(NULL, &pre_return_event);
	else
#endif
		m_queue.finish();

	/*
	__kernel void ethash_combined_search(
		__global hash32_t* g_hashes,			// 0
		__constant hash32_t const* g_header,	// 1
		__global hash128_t const* g_dag,		// 2
		ulong start_nonce,						// 3
		ulong target,							// 4
		uint isolate							// 5
	)
	*/
	m_search_kernel.setArg(1, m_header);
	m_search_kernel.setArg(2, m_dag);

	// pass these to stop the compiler unrolling the loops
	m_search_kernel.setArg(4, target);
	m_search_kernel.setArg(5, ~0u);


	unsigned buf = 0;
	std::random_device engine;
	uint64_t start_nonce = std::uniform_int_distribution<uint64_t>()(engine);
	for (; ; start_nonce += c_search_batch_size)
	{
		// supply output buffer to kernel
		m_search_kernel.setArg(0, m_search_buf[buf]);
		m_search_kernel.setArg(3, start_nonce);

		// execute it!
		m_queue.enqueueNDRangeKernel(m_search_kernel, cl::NullRange, c_search_batch_size, m_workgroup_size);
		
		pending.push({start_nonce, buf});
		buf = (buf + 1) % c_num_buffers;

		// read results
		if (pending.size() == c_num_buffers)
		{
			pending_batch const& batch = pending.front();

			// could use pinned host pointer instead
			uint32_t* results = (uint32_t*)m_queue.enqueueMapBuffer(m_search_buf[batch.buf], true, CL_MAP_READ, 0, (1+c_max_search_results) * sizeof(uint32_t));
			unsigned num_found = std::min<unsigned>(results[0], c_max_search_results);

			uint64_t nonces[c_max_search_results];
			for (unsigned i = 0; i != num_found; ++i)
			{
				nonces[i] = batch.start_nonce + results[i+1];
			}

			m_queue.enqueueUnmapMemObject(m_search_buf[batch.buf], results);
			
			bool exit = num_found && hook.found(nonces, num_found);
			exit |= hook.searched(batch.start_nonce, c_search_batch_size); // always report searched before exit
			if (exit)
				break;

			// reset search buffer if we're still going
			if (num_found)
				m_queue.enqueueWriteBuffer(m_search_buf[batch.buf], true, 0, 4, &c_zero);

			pending.pop();
		}
	}

	// not safe to return until this is ready
#if CL_VERSION_1_2 && 0
	if (!m_opencl_1_1)
		pre_return_event.wait();
#endif
}