#include <computeManager/computeManager.h>
#include <iostream>
#include <stdexcept>
#include <string>
#include <string_view>
#include <algorithm>

namespace smo {
namespace compute {

// Helper function to parse OpenCL version string
static std::pair<int, int> parseOpenClVersion(const std::string& versionStr)
{
	size_t spacePos = versionStr.find(' ');
	if (spacePos == std::string::npos) { return {-1, -1}; }

	std::string versionNum = versionStr.substr(spacePos + 1);
	size_t dotPos = versionNum.find('.');
	if (dotPos == std::string::npos) { return {-1, -1}; }

	try {
		int major = std::stoi(versionNum.substr(0, dotPos));
		int minor = std::stoi(versionNum.substr(dotPos + 1));
		return {major, minor};
	} catch (const std::exception&) {
		return {-1, -1};
	}
}

// Helper function to validate OpenCL version
static bool validateOpenClVersion(
	std::string_view versionStr, std::string_view versionType,
	int minMajor, int minMinor)
{
	auto [major, minor] = parseOpenClVersion(std::string(versionStr));

	if (major == -1 && minor == -1)
	{
		std::cerr << __func__ << ": failed to parse OpenCL " << versionType
			<< " version: " << versionStr << std::endl;
		return false;
	}

	if (major < minMajor || (major == minMajor && minor < minMinor))
	{
		std::cerr << __func__ << ": OpenCL " << versionType << " version "
			<< major << "." << minor << " found, but " << minMajor << "."
			<< minMinor << " or higher is required" << std::endl;
		return false;
	}

	std::cout << __func__ << ": OpenCL " << versionType << " version: "
		<< versionStr << std::endl;
	return true;
}

ComputeDevice::ComputeDevice(cl_platform_id platformId, cl_device_id deviceId)
: platform(platformId), device(deviceId),
context(nullptr), commandQueue(nullptr)
{
	cl_int err;

	// Create context for this device
	context = clCreateContext(
		nullptr, 1, &device,
		nullptr, nullptr, &err);

	if (err != CL_SUCCESS || !context)
	{
		throw std::runtime_error(
			std::string(__func__) + ": failed to create context for device: " +
			std::to_string(err));
	}

	// Create command queue
	cl_command_queue_properties queueProps = 0;
	commandQueue = clCreateCommandQueue(
		context, device, queueProps, &err);

	if (err != CL_SUCCESS || !commandQueue)
	{
		clReleaseContext(context);
		context = nullptr;
		throw std::runtime_error(
			std::string(__func__) + ": failed to create command queue for "
			"device: " + std::to_string(err));
	}
}

void ComputeManager::initialize()
{
	if (initialized) { return; }

	cl_int err;

	// Get number of platforms
	cl_uint numPlatforms = 0;
	err = clGetPlatformIDs(0, nullptr, &numPlatforms);
	if (err != CL_SUCCESS)
	{
		throw std::runtime_error(
			std::string(__func__) + ": failed to get OpenCL platforms: " +
			std::to_string(err));
	}
	if (numPlatforms == 0)
	{
		throw std::runtime_error(
			std::string(__func__) + ": no OpenCL platforms found");
	}

	// Get all platforms
	std::vector<cl_platform_id> platforms(numPlatforms);
	err = clGetPlatformIDs(numPlatforms, platforms.data(), nullptr);
	if (err != CL_SUCCESS)
	{
		throw std::runtime_error(
			std::string(__func__) + ": failed to enumerate OpenCL platforms: " +
			std::to_string(err));
	}

	// Enumerate devices for each platform
	for (cl_uint p = 0; p < numPlatforms; ++p)
	{
		cl_platform_id platform = platforms[p];

		// Check platform version
		char platformVersion[128];
		err = clGetPlatformInfo(
			platform, CL_PLATFORM_VERSION,
			sizeof(platformVersion), platformVersion, nullptr);

		if (err == CL_SUCCESS)
		{
			if (!validateOpenClVersion(platformVersion, "platform", 1, 2))
			{
				std::cout << __func__ << ": skipping platform " << p
					<< " with incompatible OpenCL version "
					<< std::string(platformVersion) << std::endl;
				continue;
			}
		}

		// Get number of devices
		cl_uint numDevices = 0;
		err = clGetDeviceIDs(
			platform, CL_DEVICE_TYPE_ALL, 0, nullptr, &numDevices);

		if (err != CL_SUCCESS || numDevices == 0)
		{
			std::cout << __func__ << ": skipping platform " << p
				<< " with no devices" << std::endl;
			continue;
		}

		// Get all devices
		std::vector<cl_device_id> platformDevices(numDevices);
		err = clGetDeviceIDs(
			platform, CL_DEVICE_TYPE_ALL, numDevices,
			platformDevices.data(), nullptr);

		if (err != CL_SUCCESS)
		{
			throw std::runtime_error(
				std::string(__func__) + ": failed to enumerate devices for "
				"platform " + std::to_string(p) + ": " + std::to_string(err));
		}

		// Create ComputeDevice for each device
		for (cl_uint d = 0; d < numDevices; ++d)
		{
			cl_device_id device = platformDevices[d];

			// Check device version
			char deviceVersion[128];
			err = clGetDeviceInfo(
				device, CL_DEVICE_VERSION,
				sizeof(deviceVersion), deviceVersion, nullptr);

			if (err == CL_SUCCESS)
			{
				if (!validateOpenClVersion(deviceVersion, "device", 1, 2))
				{
					std::cout << __func__ << ": skipping device " << d
						<< " with incompatible OpenCL version "
						<< std::string(deviceVersion) << std::endl;
					continue;
				}
			}

			// Create ComputeDevice (constructor creates context and queue)
			try
			{
				auto deviceObj = std::make_shared<ComputeDevice>(
					platform, device);
				devices.push_back(deviceObj);
			}
			catch (const std::runtime_error& e)
			{
				// Re-throw with more context about which device/platform
				throw std::runtime_error(
					std::string(__func__) + ": failed to create ComputeDevice "
					"for device " + std::to_string(d) + " on platform " +
					std::to_string(p) + ": " + e.what());
			}
		}
	}

	if (devices.empty())
	{
		throw std::runtime_error(
			std::string(__func__) + ": no compatible OpenCL devices found");
	}

	initialized = true;
	std::cout << __func__ << ": Initialized with " << devices.size()
		<< " compute device(s)" << std::endl;
}

void ComputeManager::finalize()
{
	if (!initialized) { return; }

	// Release all devices (their shared_ptrs will clean up contexts/queues)
	devices.clear();
	initialized = false;
	std::cout << __func__ << ": Finalized" << std::endl;
}

ClBuffer::ClBuffer(void* hostPtr, size_t size, cl_mem_flags flags,
	const std::vector<std::shared_ptr<ComputeDevice>>& devices)
	: hostPtr(hostPtr), size(size), flags(flags)
{
	associations.reserve(devices.size());

	// Create a buffer for each device's context
	for (const auto& device : devices)
	{
		if (!device->context) { continue; }

		cl_int err;
		cl_mem_flags bufferFlags = CL_MEM_USE_HOST_PTR | flags;
		cl_mem buffer = clCreateBuffer(
			device->context,
			bufferFlags,
			size, hostPtr,
			&err);

		if (err != CL_SUCCESS || !buffer)
		{
			// Release any buffers already created before throwing
			for (auto& assoc : associations)
			{
				if (assoc.buffer) {
					clReleaseMemObject(assoc.buffer);
				}
			}
			throw std::runtime_error(
				std::string(__func__) + ": failed to create buffer for "
				"device: " + std::to_string(err));
		}

		associations.emplace_back(buffer, device);
	}
}

std::shared_ptr<ClBuffer>
ComputeManager::createUseHostPtrBuffer(
	void* hostPtr, size_t size, cl_mem_flags flags)
{
	if (!initialized)
	{
		std::cerr << __func__ << ": ComputeManager not initialized"
			<< std::endl;
		throw std::runtime_error(
			std::string(__func__) + ": ComputeManager not initialized");
	}

	return std::make_shared<ClBuffer>(hostPtr, size, flags, devices);
}

void ComputeManager::releaseUseHostPtrBuffer(std::shared_ptr<ClBuffer> buffer)
{
	// No-op: ClBuffer's destructor handles cleanup automatically
	// This function exists for API compatibility
	(void)buffer;
}

std::shared_ptr<ComputeDevice> ComputeManager::getDevice()
{
	if (!initialized || devices.empty()) {
		return nullptr;
	}

	// Return first available device
	// In the future, this will filter based on ComputeDeviceConstraints
	return devices[0];
}

void ComputeManager::releaseDevice(std::shared_ptr<ComputeDevice> device)
{
	// Placeholder for future refcounting implementation
	// Devices are only removed in finalize()
	(void)device;
}

} // namespace compute
} // namespace smo