#include "voxel_stream_cache.h"

bool VoxelStreamCache::load_voxel_block(Vector3i position, uint8_t lod_index, VoxelBufferInternal &out_voxels) {
	const Lod &lod = _cache[lod_index];
	lod.rw_lock.read_lock();
	auto it = lod.blocks.find(position);

	if (it == lod.blocks.end()) {
		// Not in cache, will have to query
		lod.rw_lock.read_unlock();
		return false;

	} else {
		// In cache, serve it

		const VoxelBufferInternal &vb = it->second.voxels;

		// Copying is required since the cache has ownership on its data,
		// and the requests wants us to populate the buffer it provides
		vb.duplicate_to(out_voxels, true);

		lod.rw_lock.read_unlock();
		return true;
	}
}

void VoxelStreamCache::save_voxel_block(Vector3i position, uint8_t lod_index, VoxelBufferInternal &voxels) {
	Lod &lod = _cache[lod_index];
	RWLockWrite wlock(lod.rw_lock);
	auto it = lod.blocks.find(position);

	if (it == lod.blocks.end()) {
		// Not cached yet, create an entry
		Block b;
		b.position = position;
		b.lod = lod_index;
		// TODO Optimization: if we know the buffer is not shared, we could use move instead
		voxels.duplicate_to(b.voxels, true);
		b.has_voxels = true;
		lod.blocks.insert(std::make_pair(position, std::move(b)));
		++_count;

	} else {
		// Cached already, overwrite
		voxels.move_to(it->second.voxels);
		it->second.has_voxels = true;
	}
}

bool VoxelStreamCache::load_instance_block(
		Vector3i position, uint8_t lod_index, std::unique_ptr<VoxelInstanceBlockData> &out_instances) {
	const Lod &lod = _cache[lod_index];
	lod.rw_lock.read_lock();
	auto it = lod.blocks.find(position);

	if (it == lod.blocks.end()) {
		// Not in cache, will have to query
		lod.rw_lock.read_unlock();
		return false;

	} else {
		// In cache, serve it

		if (it->second.instances == nullptr) {
			out_instances = nullptr;

		} else {
			// Copying is required since the cache has ownership on its data
			out_instances = std::make_unique<VoxelInstanceBlockData>();
			it->second.instances->copy_to(*out_instances);
		}

		lod.rw_lock.read_unlock();
		return true;
	}
}

void VoxelStreamCache::save_instance_block(
		Vector3i position, uint8_t lod_index, std::unique_ptr<VoxelInstanceBlockData> instances) {
	Lod &lod = _cache[lod_index];
	RWLockWrite wlock(lod.rw_lock);
	auto it = lod.blocks.find(position);

	if (it == lod.blocks.end()) {
		// Not cached yet, create an entry
		Block b;
		b.position = position;
		b.lod = lod_index;
		b.instances = std::move(instances);
		lod.blocks.insert(std::make_pair(position, std::move(b)));
		++_count;

	} else {
		// Cached already, overwrite
		it->second.instances = std::move(instances);
	}
}

unsigned int VoxelStreamCache::get_indicative_block_count() const {
	return _count;
}