#include "load_block_data_request.h"
#include "../util/godot/funcs.h"
#include "../util/macros.h"
#include "../util/profiling.h"
#include "block_generate_request.h"
#include "voxel_server.h"

namespace zylann::voxel {

namespace {
std::atomic_int g_debug_load_block_tasks_count;
}

LoadBlockDataRequest::LoadBlockDataRequest(uint32_t p_volume_id, Vector3i p_block_pos, uint8_t p_lod,
		uint8_t p_block_size, bool p_request_instances, std::shared_ptr<StreamingDependency> p_stream_dependency,
		PriorityDependency p_priority_dependency) :
		_volume_id(p_volume_id),
		_position(p_block_pos),
		_lod(p_lod),
		_block_size(p_block_size),
		_request_voxels(true),
		_request_instances(p_request_instances),
		_stream_dependency(p_stream_dependency),
		_priority_dependency(p_priority_dependency) {
	//
	++g_debug_load_block_tasks_count;
}

LoadBlockDataRequest::~LoadBlockDataRequest() {
	--g_debug_load_block_tasks_count;
}

int LoadBlockDataRequest::debug_get_running_count() {
	return g_debug_load_block_tasks_count;
}

void LoadBlockDataRequest::run(zylann::ThreadedTaskContext ctx) {
	VOXEL_PROFILE_SCOPE();

	CRASH_COND(_stream_dependency == nullptr);
	Ref<VoxelStream> stream = _stream_dependency->stream;
	CRASH_COND(stream.is_null());

	const Vector3i origin_in_voxels = (_position << _lod) * _block_size;

	ERR_FAIL_COND(_voxels != nullptr);
	_voxels = gd_make_shared<VoxelBufferInternal>();
	_voxels->create(_block_size, _block_size, _block_size);

	// TODO We should consider batching this again, but it needs to be done carefully.
	// Each task is one block, and priority depends on distance to closest viewer.
	// If we batch blocks, we have to do it by distance too.

	// TODO Assign max_lod_hint when available

	const VoxelStream::Result voxel_result = stream->load_voxel_block(*_voxels, origin_in_voxels, _lod);

	if (voxel_result == VoxelStream::RESULT_ERROR) {
		ERR_PRINT("Error loading voxel block");

	} else if (voxel_result == VoxelStream::RESULT_BLOCK_NOT_FOUND) {
		Ref<VoxelGenerator> generator = _stream_dependency->generator;

		if (generator.is_valid()) {
			BlockGenerateRequest *r = memnew(BlockGenerateRequest);
			r->voxels = _voxels;
			r->volume_id = _volume_id;
			r->position = _position;
			r->lod = _lod;
			r->block_size = _block_size;
			r->stream_dependency = _stream_dependency;
			r->priority_dependency = _priority_dependency;

			VoxelServer::get_singleton()->push_async_task(r);
			_fallback_on_generator = true;

		} else {
			// If there is no generator... what do we do? What defines the format of that empty block?
			// If the user leaves the defaults it's fine, but otherwise blocks of inconsistent format can
			// end up in the volume and that can cause errors.
			// TODO Define format on volume?
		}
	}

	if (_request_instances && stream->supports_instance_blocks()) {
		ERR_FAIL_COND(_instances != nullptr);

		VoxelStreamInstanceDataRequest instance_data_request;
		instance_data_request.lod = _lod;
		instance_data_request.position = _position;
		VoxelStream::Result instances_result;
		stream->load_instance_blocks(Span<VoxelStreamInstanceDataRequest>(&instance_data_request, 1),
				Span<VoxelStream::Result>(&instances_result, 1));

		if (instances_result == VoxelStream::RESULT_ERROR) {
			ERR_PRINT("Error loading instance block");

		} else if (voxel_result == VoxelStream::RESULT_BLOCK_FOUND) {
			_instances = std::move(instance_data_request.data);
		}
		// If not found, instances will return null,
		// which means it can be generated by the instancer after the meshing process
	}

	_has_run = true;
}

int LoadBlockDataRequest::get_priority() {
	float closest_viewer_distance_sq;
	const int p = _priority_dependency.evaluate(_lod, &closest_viewer_distance_sq);
	_too_far = closest_viewer_distance_sq > _priority_dependency.drop_distance_squared;
	return p;
}

bool LoadBlockDataRequest::is_cancelled() {
	return !_stream_dependency->valid || _too_far;
}

void LoadBlockDataRequest::apply_result() {
	if (VoxelServer::get_singleton()->is_volume_valid(_volume_id)) {
		// TODO Comparing pointer may not be guaranteed
		// The request response must match the dependency it would have been requested with.
		// If it doesn't match, we are no longer interested in the result.
		if (_stream_dependency->valid && !_fallback_on_generator) {
			VoxelServer::BlockDataOutput o;
			o.voxels = _voxels;
			o.instances = std::move(_instances);
			o.position = _position;
			o.lod = _lod;
			o.dropped = !_has_run;
			o.max_lod_hint = _max_lod_hint;
			o.initial_load = false;
			o.type = VoxelServer::BlockDataOutput::TYPE_LOADED;

			VoxelServer::VolumeCallbacks callbacks = VoxelServer::get_singleton()->get_volume_callbacks(_volume_id);
			CRASH_COND(callbacks.data_output_callback == nullptr);
			callbacks.data_output_callback(callbacks.data, o);
		}

	} else {
		// This can happen if the user removes the volume while requests are still about to return
		PRINT_VERBOSE("Stream data request response came back but volume wasn't found");
	}
}

} // namespace zylann::voxel