#ifndef VOXEL_DATA_MAP_H
#define VOXEL_DATA_MAP_H

#include "../util/fixed_array.h"
#include "voxel_data_block.h"

#include <core/hash_map.h>
#include <scene/main/node.h>

// Infinite voxel storage by means of octants like Gridmap, within a constant LOD.
// Convenience functions to access VoxelBuffers internally will lock them to protect against multithreaded access.
// However, the map itself is not thread-safe.
class VoxelDataMap {
public:
	// Converts voxel coodinates into block coordinates.
	// Don't use division because it introduces an offset in negative coordinates.
	static _FORCE_INLINE_ Vector3i voxel_to_block_b(Vector3i pos, int block_size_pow2) {
		return pos >> block_size_pow2;
	}

	_FORCE_INLINE_ Vector3i voxel_to_block(Vector3i pos) const {
		return voxel_to_block_b(pos, _block_size_pow2);
	}

	_FORCE_INLINE_ Vector3i to_local(Vector3i pos) const {
		return Vector3i(
				pos.x & _block_size_mask,
				pos.y & _block_size_mask,
				pos.z & _block_size_mask);
	}

	// Converts block coodinates into voxel coordinates
	_FORCE_INLINE_ Vector3i block_to_voxel(Vector3i bpos) const {
		return bpos * _block_size;
	}

	VoxelDataMap();
	~VoxelDataMap();

	void create(unsigned int block_size_po2, int lod_index);

	_FORCE_INLINE_ unsigned int get_block_size() const { return _block_size; }
	_FORCE_INLINE_ unsigned int get_block_size_pow2() const { return _block_size_pow2; }
	_FORCE_INLINE_ unsigned int get_block_size_mask() const { return _block_size_mask; }

	void set_lod_index(int lod_index);
	unsigned int get_lod_index() const;

	int get_voxel(Vector3i pos, unsigned int c = 0) const;
	void set_voxel(int value, Vector3i pos, unsigned int c = 0);

	float get_voxel_f(Vector3i pos, unsigned int c = VoxelBuffer::CHANNEL_SDF) const;
	void set_voxel_f(real_t value, Vector3i pos, unsigned int c = VoxelBuffer::CHANNEL_SDF);

	void set_default_voxel(int value, unsigned int channel = 0);
	int get_default_voxel(unsigned int channel = 0);

	// Gets a copy of all voxels in the area starting at min_pos having the same size as dst_buffer.
	void get_buffer_copy(Vector3i min_pos, VoxelBuffer &dst_buffer, unsigned int channels_mask);

	void paste(Vector3i min_pos, VoxelBuffer &src_buffer, unsigned int channels_mask, uint64_t mask_value,
			bool create_new_blocks);

	// Moves the given buffer into a block of the map. The buffer is referenced, no copy is made.
	VoxelDataBlock *set_block_buffer(Vector3i bpos, Ref<VoxelBuffer> buffer);

	struct NoAction {
		inline void operator()(VoxelDataBlock *block) {}
	};

	template <typename Action_T>
	void remove_block(Vector3i bpos, Action_T pre_delete) {
		if (_last_accessed_block && _last_accessed_block->position == bpos) {
			_last_accessed_block = nullptr;
		}
		unsigned int *iptr = _blocks_map.getptr(bpos);
		if (iptr != nullptr) {
			const unsigned int i = *iptr;
#ifdef DEBUG_ENABLED
			CRASH_COND(i >= _blocks.size());
#endif
			VoxelDataBlock *block = _blocks[i];
			ERR_FAIL_COND(block == nullptr);
			pre_delete(block);
			memdelete(block);
			remove_block_internal(bpos, i);
		}
	}

	VoxelDataBlock *get_block(Vector3i bpos);
	const VoxelDataBlock *get_block(Vector3i bpos) const;

	bool has_block(Vector3i pos) const;
	bool is_block_surrounded(Vector3i pos) const;

	void clear();

	int get_block_count() const;

	// TODO Rename for_each_block
	template <typename Op_T>
	inline void for_all_blocks(Op_T op) {
		for (auto it = _blocks.begin(); it != _blocks.end(); ++it) {
			op(*it);
		}
	}

	// TODO Rename for_each_block
	template <typename Op_T>
	inline void for_all_blocks(Op_T op) const {
		for (auto it = _blocks.begin(); it != _blocks.end(); ++it) {
			op(*it);
		}
	}

	bool is_area_fully_loaded(const Rect3i voxels_box) const;

private:
	void set_block(Vector3i bpos, VoxelDataBlock *block);
	VoxelDataBlock *get_or_create_block_at_voxel_pos(Vector3i pos);
	VoxelDataBlock *create_default_block(Vector3i bpos);
	void remove_block_internal(Vector3i bpos, unsigned int index);

	void set_block_size_pow2(unsigned int p);

private:
	// Voxel values that will be returned if access is out of map bounds
	FixedArray<uint64_t, VoxelBuffer::MAX_CHANNELS> _default_voxel;

	// Blocks stored with a spatial hash in all 3D directions.
	// RELATIONSHIP = 2 because it delivers better performance with this kind of key and hash (less collisions).
	HashMap<Vector3i, unsigned int, Vector3iHasher, HashMapComparatorDefault<Vector3i>, 3, 2> _blocks_map;
	std::vector<VoxelDataBlock *> _blocks;

	// Voxel access will most frequently be in contiguous areas, so the same blocks are accessed.
	// To prevent too much hashing, this reference is checked before.
	mutable VoxelDataBlock *_last_accessed_block;

	unsigned int _block_size;
	unsigned int _block_size_pow2;
	unsigned int _block_size_mask;

	unsigned int _lod_index = 0;
};

#endif // VOXEL_MAP_H