#include "voxel_graph_runtime.h"
#include "../../util/funcs.h"
#include "../../util/macros.h"
#include "../../util/noise/fast_noise_lite.h"
#include "../../util/profiling.h"
#include "image_range_grid.h"
#include "range_utility.h"
#include "voxel_generator_graph.h"
#include "voxel_graph_node_db.h"

#include <core/math/math_funcs.h>
#include <modules/opensimplex/open_simplex_noise.h>
#include <scene/resources/curve.h>
#include <unordered_set>

//#ifdef DEBUG_ENABLED
//#define VOXEL_DEBUG_GRAPH_PROG_SENTINEL uint16_t(12345) // 48, 57 (base 10)
//#endif

namespace zylann::voxel {

VoxelGraphRuntime::VoxelGraphRuntime() {
	clear();
}

VoxelGraphRuntime::~VoxelGraphRuntime() {
	clear();
}

void VoxelGraphRuntime::clear() {
	_program.clear();
}

VoxelGraphRuntime::CompilationResult VoxelGraphRuntime::compile(const ProgramGraph &graph, bool debug) {
	VoxelGraphRuntime::CompilationResult result = _compile(graph, debug);
	if (!result.success) {
		clear();
	}
	return result;
}

VoxelGraphRuntime::CompilationResult VoxelGraphRuntime::_compile(const ProgramGraph &graph, bool debug) {
	clear();

	std::vector<uint32_t> order;
	std::vector<uint32_t> terminal_nodes;
	std::unordered_map<uint32_t, uint32_t> node_id_to_dependency_graph;

	// Not using the generic `get_terminal_nodes` function because our terminal nodes do have outputs
	graph.for_each_node_const([&terminal_nodes](const ProgramGraph::Node &node) {
		const VoxelGraphNodeDB::NodeType &type = VoxelGraphNodeDB::get_singleton()->get_type(node.type_id);
		if (type.category == VoxelGraphNodeDB::CATEGORY_OUTPUT) {
			terminal_nodes.push_back(node.id);
		}
	});

	if (!debug) {
		// Exclude debug nodes
		unordered_remove_if(terminal_nodes, [&graph](uint32_t node_id) {
			const ProgramGraph::Node *node = graph.get_node(node_id);
			const VoxelGraphNodeDB::NodeType &type = VoxelGraphNodeDB::get_singleton()->get_type(node->type_id);
			return type.debug_only;
		});
	}

	graph.find_dependencies(terminal_nodes, order);

	uint32_t xzy_start_index = 0;

	// Optimize parts of the graph that only depend on X and Z,
	// so they can be moved in the outer loop when blocks are generated, running less times.
	// Moves them all at the beginning.
	{
		std::vector<uint32_t> immediate_deps;
		std::unordered_set<uint32_t> nodes_depending_on_y;
		std::vector<uint32_t> order_xz;
		std::vector<uint32_t> order_xzy;

		for (size_t i = 0; i < order.size(); ++i) {
			const uint32_t node_id = order[i];
			const ProgramGraph::Node *node = graph.get_node(node_id);

			bool depends_on_y = false;

			if (node->type_id == VoxelGeneratorGraph::NODE_INPUT_Y) {
				nodes_depending_on_y.insert(node_id);
				depends_on_y = true;
			}

			if (!depends_on_y) {
				immediate_deps.clear();
				graph.find_immediate_dependencies(node_id, immediate_deps);

				for (size_t j = 0; j < immediate_deps.size(); ++j) {
					const uint32_t dep_node_id = immediate_deps[j];

					if (nodes_depending_on_y.find(dep_node_id) != nodes_depending_on_y.end()) {
						depends_on_y = true;
						nodes_depending_on_y.insert(node_id);
						break;
					}
				}
			}

			if (depends_on_y) {
				order_xzy.push_back(node_id);
			} else {
				order_xz.push_back(node_id);
			}
		}

		xzy_start_index = order_xz.size();

		//#ifdef DEBUG_ENABLED
		//		const uint32_t order_xz_raw_size = order_xz.size();
		//		const uint32_t *order_xz_raw = order_xz.data();
		//		const uint32_t order_xzy_raw_size = order_xzy.size();
		//		const uint32_t *order_xzy_raw = order_xzy.data();
		//#endif

		size_t i = 0;
		for (size_t j = 0; j < order_xz.size(); ++j) {
			order[i++] = order_xz[j];
		}
		for (size_t j = 0; j < order_xzy.size(); ++j) {
			order[i++] = order_xzy[j];
		}
	}

	//#ifdef DEBUG_ENABLED
	//	const uint32_t order_raw_size = order.size();
	//	const uint32_t *order_raw = order.data();
	//#endif

	struct MemoryHelper {
		std::vector<BufferSpec> &buffer_specs;
		unsigned int next_address = 0;

		uint16_t add_binding() {
			const unsigned int a = next_address;
			++next_address;
			BufferSpec bs;
			bs.address = a;
			bs.is_binding = true;
			bs.is_constant = false;
			bs.users_count = 0;
			buffer_specs.push_back(bs);
			return a;
		}

		uint16_t add_var() {
			const unsigned int a = next_address;
			++next_address;
			BufferSpec bs;
			bs.address = a;
			bs.is_binding = false;
			bs.is_constant = false;
			bs.users_count = 0;
			buffer_specs.push_back(bs);
			return a;
		}

		uint16_t add_constant(float v) {
			const unsigned int a = next_address;
			++next_address;
			BufferSpec bs;
			bs.address = a;
			bs.constant_value = v;
			bs.is_binding = false;
			bs.is_constant = true;
			bs.users_count = 0;
			buffer_specs.push_back(bs);
			return a;
		}
	};

	MemoryHelper mem{ _program.buffer_specs };

	// Main inputs X, Y, Z
	_program.x_input_address = mem.add_binding();
	_program.y_input_address = mem.add_binding();
	_program.z_input_address = mem.add_binding();

	std::vector<uint16_t> &operations = _program.operations;
	const VoxelGraphNodeDB &type_db = *VoxelGraphNodeDB::get_singleton();

	// Run through each node in order, and turn them into program instructions
	for (size_t order_index = 0; order_index < order.size(); ++order_index) {
		const uint32_t node_id = order[order_index];
		const ProgramGraph::Node *node = graph.get_node(node_id);
		const VoxelGraphNodeDB::NodeType &type = type_db.get_type(node->type_id);

		CRASH_COND(node == nullptr);
		CRASH_COND(node->inputs.size() != type.inputs.size());
		CRASH_COND(node->outputs.size() != type.outputs.size());

		if (order_index == xzy_start_index) {
			_program.xzy_start_op_address = operations.size();
		}

		const unsigned int dg_node_index = _program.dependency_graph.nodes.size();
		_program.dependency_graph.nodes.push_back(DependencyGraph::Node());
		DependencyGraph::Node &dg_node = _program.dependency_graph.nodes.back();
		dg_node.is_input = false;
		dg_node.op_address = operations.size();
		dg_node.first_dependency = _program.dependency_graph.dependencies.size();
		dg_node.end_dependency = dg_node.first_dependency;
		dg_node.debug_node_id = node_id;
		node_id_to_dependency_graph.insert(std::make_pair(node_id, dg_node_index));

		// We still hardcode some of the nodes. Maybe we can abstract them too one day.
		switch (node->type_id) {
			case VoxelGeneratorGraph::NODE_CONSTANT: {
				CRASH_COND(type.outputs.size() != 1);
				CRASH_COND(type.params.size() != 1);
				const uint16_t a = mem.add_constant(node->params[0].operator float());
				_program.output_port_addresses[ProgramGraph::PortLocation{ node_id, 0 }] = a;
				// Technically not an input or an output, but is a dependency regardless so treat it like an input
				dg_node.is_input = true;
				continue;
			}

			case VoxelGeneratorGraph::NODE_INPUT_X:
				_program.output_port_addresses[ProgramGraph::PortLocation{ node_id, 0 }] = _program.x_input_address;
				dg_node.is_input = true;
				continue;

			case VoxelGeneratorGraph::NODE_INPUT_Y:
				_program.output_port_addresses[ProgramGraph::PortLocation{ node_id, 0 }] = _program.y_input_address;
				dg_node.is_input = true;
				continue;

			case VoxelGeneratorGraph::NODE_INPUT_Z:
				_program.output_port_addresses[ProgramGraph::PortLocation{ node_id, 0 }] = _program.z_input_address;
				dg_node.is_input = true;
				continue;

			case VoxelGeneratorGraph::NODE_SDF_PREVIEW:
				continue;
		}

		// Add actual operation

		CRASH_COND(node->type_id > 0xff);

		if (order_index == xzy_start_index) {
			_program.default_execution_map.xzy_start_index = _program.default_execution_map.operation_adresses.size();
		}
		_program.default_execution_map.operation_adresses.push_back(operations.size());

		operations.push_back(node->type_id);

		// Inputs and outputs use a convention so we can have generic code for them.
		// Parameters are more specific, and may be affected by alignment so better just do them by hand

		// Add inputs
		for (size_t j = 0; j < type.inputs.size(); ++j) {
			uint16_t a;

			if (node->inputs[j].connections.size() == 0) {
				// No input, default it
				CRASH_COND(j >= node->default_inputs.size());
				float defval = node->default_inputs[j];
				a = mem.add_constant(defval);

			} else {
				ProgramGraph::PortLocation src_port = node->inputs[j].connections[0];
				const uint16_t *aptr = _program.output_port_addresses.getptr(src_port);
				// Previous node ports must have been registered
				CRASH_COND(aptr == nullptr);
				a = *aptr;

				// Register dependency
				auto it = node_id_to_dependency_graph.find(src_port.node_id);
				CRASH_COND(it == node_id_to_dependency_graph.end());
				CRASH_COND(it->second >= _program.dependency_graph.nodes.size());
				_program.dependency_graph.dependencies.push_back(it->second);
				++dg_node.end_dependency;
			}

			operations.push_back(a);

			BufferSpec &bs = _program.buffer_specs[a];
			++bs.users_count;
		}

		// Add outputs
		for (size_t j = 0; j < type.outputs.size(); ++j) {
			const uint16_t a = mem.add_var();

			// This will be used by next nodes
			const ProgramGraph::PortLocation op{ node_id, static_cast<uint32_t>(j) };
			_program.output_port_addresses[op] = a;

			operations.push_back(a);
		}

		// Add space for params size, default is no params so size is 0
		size_t params_size_index = operations.size();
		operations.push_back(0);

		// Get params, copy resources when used, and hold a reference to them
		std::vector<Variant> params_copy;
		params_copy.resize(node->params.size());
		for (size_t i = 0; i < node->params.size(); ++i) {
			Variant v = node->params[i];

			if (v.get_type() == Variant::OBJECT) {
				Ref<Resource> res = v;

				if (res.is_null()) {
					// duplicate() is only available in Resource,
					// so we have to limit to this instead of Reference or Object
					CompilationResult result;
					result.success = false;
					result.message = "A parameter is an object but does not inherit Resource";
					result.node_id = node_id;
					return result;
				}

				res = res->duplicate();

				_program.ref_resources.push_back(res);
				v = res;
			}

			params_copy[i] = v;
		}

		if (type.compile_func != nullptr) {
			CompileContext ctx(*node, operations, _program.heap_resources, params_copy);
			type.compile_func(ctx);
			if (ctx.has_error()) {
				CompilationResult result;
				result.success = false;
				result.message = ctx.get_error_message();
				result.node_id = node_id;
				return result;
			}
			const size_t params_size = ctx.get_params_size_in_words();
			CRASH_COND(params_size > std::numeric_limits<uint16_t>::max());
			operations[params_size_index] = params_size;
		}

		if (type.category == VoxelGraphNodeDB::CATEGORY_OUTPUT) {
			CRASH_COND(node->outputs.size() != 1);
			{
				const uint16_t *aptr = _program.output_port_addresses.getptr(ProgramGraph::PortLocation{ node_id, 0 });
				// Previous node ports must have been registered
				CRASH_COND(aptr == nullptr);
				OutputInfo &output_info = _program.outputs[_program.outputs_count];
				output_info.buffer_address = *aptr;
				output_info.dependency_graph_node_index = dg_node_index;
				output_info.node_id = node_id;
				++_program.outputs_count;
			}

			// Add fake user for output ports so they can pass the local users check in optimizations
			for (unsigned int j = 0; j < type.outputs.size(); ++j) {
				const ProgramGraph::PortLocation loc{ node_id, j };
				const uint16_t *aptr = _program.output_port_addresses.getptr(loc);
				CRASH_COND(aptr == nullptr);
				BufferSpec &bs = _program.buffer_specs[*aptr];
				// Not expecting existing users on that port
				ERR_FAIL_COND_V(bs.users_count != 0, CompilationResult());
				++bs.users_count;
			}
		}

#ifdef VOXEL_DEBUG_GRAPH_PROG_SENTINEL
		// Append a special value after each operation
		append(operations, VOXEL_DEBUG_GRAPH_PROG_SENTINEL);
#endif
	}

	_program.buffer_count = mem.next_address;

	PRINT_VERBOSE(String("Compiled voxel graph. Program size: {0}b, buffers: {1}")
						  .format(varray(SIZE_T_TO_VARIANT(_program.operations.size() * sizeof(uint16_t)),
								  SIZE_T_TO_VARIANT(_program.buffer_count))));

	CompilationResult result;
	result.success = true;
	return result;
}

static Span<const uint16_t> get_outputs_from_op_address(Span<const uint16_t> operations, uint16_t op_address) {
	const uint16_t opid = operations[op_address];
	const VoxelGraphNodeDB::NodeType &node_type = VoxelGraphNodeDB::get_singleton()->get_type(opid);

	const uint32_t inputs_count = node_type.inputs.size();
	const uint32_t outputs_count = node_type.outputs.size();

	// The +1 is for `opid`
	return operations.sub(op_address + 1 + inputs_count, outputs_count);
}

bool VoxelGraphRuntime::is_operation_constant(const State &state, uint16_t op_address) const {
	Span<const uint16_t> outputs = get_outputs_from_op_address(to_span_const(_program.operations), op_address);

	for (unsigned int i = 0; i < outputs.size(); ++i) {
		const uint16_t output_address = outputs[i];
		const Buffer &buffer = state.get_buffer(output_address);
		if (!(buffer.is_constant || state.get_range(output_address).is_single_value() ||
					buffer.local_users_count == 0)) {
			// At least one of the outputs cannot be predicted in the current area
			return false;
		}
	}

	return true;
}

void VoxelGraphRuntime::generate_optimized_execution_map(
		const State &state, ExecutionMap &execution_map, bool debug) const {
	FixedArray<unsigned int, MAX_OUTPUTS> all_outputs;
	for (unsigned int i = 0; i < _program.outputs_count; ++i) {
		all_outputs[i] = i;
	}
	generate_optimized_execution_map(state, execution_map, to_span_const(all_outputs, _program.outputs_count), debug);
}

// Generates a list of adresses for the operations to execute,
// skipping those that are deemed constant by the last range analysis.
// If a non-constant operation only contributes to a constant one, it will also be skipped.
// This has the effect of optimizing locally at runtime without relying on explicit conditionals.
// It can be useful for biomes, where some branches become constant when not used in the final blending.
void VoxelGraphRuntime::generate_optimized_execution_map(
		const State &state, ExecutionMap &execution_map, Span<const unsigned int> required_outputs, bool debug) const {
	VOXEL_PROFILE_SCOPE();

	// Range analysis results must have been computed
	ERR_FAIL_COND(state.ranges.size() == 0);

	const Program &program = _program;
	const DependencyGraph &graph = program.dependency_graph;

	execution_map.clear();

	// if (program.default_execution_map.size() == 0) {
	// 	// Can't reduce more than this
	// 	return;
	// }

	// This function will run a lot of times so better re-use the same vector
	static thread_local std::vector<uint16_t> to_process;
	to_process.clear();

	for (unsigned int i = 0; i < required_outputs.size(); ++i) {
		const unsigned int output_index = required_outputs[i];
		const unsigned int dg_index = program.outputs[output_index].dependency_graph_node_index;
		to_process.push_back(dg_index);
	}

	enum ProcessResult { NOT_PROCESSED, SKIPPABLE, REQUIRED };

	static thread_local std::vector<ProcessResult> results;
	results.clear();
	results.resize(graph.nodes.size(), NOT_PROCESSED);

	while (to_process.size() != 0) {
		const uint32_t node_index = to_process.back();
		const unsigned int to_process_previous_size = to_process.size();

		// Check needed because Godot never compiles with `_DEBUG`...
#ifdef DEBUG_ENABLED
		CRASH_COND(node_index >= graph.nodes.size());
#endif
		const DependencyGraph::Node &node = graph.nodes[node_index];

		// Ignore inputs because they are not present in the operations list
		if (!node.is_input && is_operation_constant(state, node.op_address)) {
			// Skip this operation for now.
			// If no other dependency reaches it, it will be effectively skipped in the result.
			to_process.pop_back();
			results[node_index] = SKIPPABLE;
			continue;
		}

		for (uint32_t i = node.first_dependency; i < node.end_dependency; ++i) {
			const uint32_t dep_node_index = graph.dependencies[i];
			if (results[dep_node_index] != NOT_PROCESSED) {
				// Already processed
				continue;
			}
			to_process.push_back(dep_node_index);
		}

		if (to_process_previous_size == to_process.size()) {
			to_process.pop_back();
			results[node_index] = REQUIRED;
		}
	}

	if (debug) {
		for (unsigned int node_index = 0; node_index < graph.nodes.size(); ++node_index) {
			const ProcessResult res = results[node_index];
			const DependencyGraph::Node &node = graph.nodes[node_index];
			if (res == REQUIRED) {
				execution_map.debug_nodes.push_back(node.debug_node_id);
			}
		}
	}

	Span<const uint16_t> operations(program.operations.data(), 0, program.operations.size());
	bool xzy_start_not_assigned = true;

	// Now we have to fill buffers with the local constants we may have found.
	// We iterate nodes primarily because we have to preserve a certain order relative to outer loop optimization.
	for (unsigned int node_index = 0; node_index < graph.nodes.size(); ++node_index) {
		const ProcessResult res = results[node_index];
		const DependencyGraph::Node &node = graph.nodes[node_index];

		if (node.is_input) {
			continue;
		}

		switch (res) {
			case NOT_PROCESSED:
				continue;

			case SKIPPABLE: {
				const Span<const uint16_t> outputs = get_outputs_from_op_address(operations, node.op_address);

				for (unsigned int output_index = 0; output_index < outputs.size(); ++output_index) {
					const uint16_t output_address = outputs[output_index];
					const Buffer &buffer = state.get_buffer(output_address);

					if (buffer.is_constant) {
						// Already assigned at prepare-time
						continue;
					}

					CRASH_COND(buffer.is_binding);

					// The node is considered skippable, which means its outputs are either locally constant or unused.
					// Unused buffers can be left as-is, but local constants must be filled in.
					if (buffer.local_users_count > 0) {
						const math::Interval range = state.ranges[output_address];
						// If this interval is not a single value then the node should not have been skippable
						CRASH_COND(!range.is_single_value());
						const float v = range.min;
						for (unsigned int j = 0; j < buffer.size; ++j) {
							buffer.data[j] = v;
						}
					}
				}
			} break;

			case REQUIRED:
				if (xzy_start_not_assigned && node.op_address >= program.xzy_start_op_address) {
					// This should be correct as long as the list of nodes in the graph follows the same re-ordered
					// optimization done in `compile()` such that all nodes not depending on Y come first
					execution_map.xzy_start_index = execution_map.operation_adresses.size();
					xzy_start_not_assigned = false;
				}
				execution_map.operation_adresses.push_back(node.op_address);
				break;

			default:
				CRASH_NOW();
				break;
		}
	}
}

void VoxelGraphRuntime::generate_single(State &state, Vector3 position, const ExecutionMap *execution_map) const {
	generate_set(state, Span<float>(&position.x, 1), Span<float>(&position.y, 1), Span<float>(&position.z, 1), false,
			execution_map);
}

void VoxelGraphRuntime::prepare_state(State &state, unsigned int buffer_size) const {
	const unsigned int old_buffer_count = state.buffers.size();
	if (_program.buffer_count > state.buffers.size()) {
		state.buffers.resize(_program.buffer_count);
	}

	// Note: this must be after we resize the vector
	Span<Buffer> buffers(state.buffers, 0, state.buffers.size());
	state.buffer_size = buffer_size;

	for (auto it = _program.buffer_specs.cbegin(); it != _program.buffer_specs.cend(); ++it) {
		const BufferSpec &buffer_spec = *it;
		Buffer &buffer = buffers[buffer_spec.address];

		if (buffer_spec.is_binding) {
			if (buffer.is_binding) {
				// Forgot to unbind?
				CRASH_COND(buffer.data != nullptr);
			} else if (buffer.data != nullptr) {
				// Deallocate this buffer if it wasnt a binding and contained something
				memfree(buffer.data);
			}
		}

		buffer.is_binding = buffer_spec.is_binding;
	}

	// Allocate more buffers if needed
	if (old_buffer_count < state.buffers.size()) {
		for (size_t buffer_index = old_buffer_count; buffer_index < buffers.size(); ++buffer_index) {
			Buffer &buffer = buffers[buffer_index];
			// TODO Put all bindings at the beginning. This would avoid the branch.
			if (buffer.is_binding) {
				// These are supposed to be setup already
				continue;
			}
			// We don't expect previous stuff in those buffers since we just created their slots
			CRASH_COND(buffer.data != nullptr);
			// TODO Use pool?
			// New buffers get an up-to-date size, but must also comply with common capacity
			const unsigned int bs = max(state.buffer_capacity, buffer_size);
			buffer.data = reinterpret_cast<float *>(memalloc(bs * sizeof(float)));
			buffer.capacity = bs;
		}
	}

	// Make old buffers larger if needed
	if (state.buffer_capacity < buffer_size) {
		for (size_t buffer_index = 0; buffer_index < old_buffer_count; ++buffer_index) {
			Buffer &buffer = buffers[buffer_index];
			if (buffer.is_binding) {
				continue;
			}
			if (buffer.data == nullptr) {
				buffer.data = reinterpret_cast<float *>(memalloc(buffer_size * sizeof(float)));
			} else {
				buffer.data = reinterpret_cast<float *>(memrealloc(buffer.data, buffer_size * sizeof(float)));
			}
			buffer.capacity = buffer_size;
		}
		state.buffer_capacity = buffer_size;
	}
	for (auto it = state.buffers.begin(); it != state.buffers.end(); ++it) {
		Buffer &buffer = *it;
		buffer.size = buffer_size;
		buffer.is_constant = false;
	}

	state.ranges.resize(_program.buffer_count);

	// Always reset constants because we don't know if we'll run the same program as before...
	for (auto it = _program.buffer_specs.cbegin(); it != _program.buffer_specs.cend(); ++it) {
		const BufferSpec &bs = *it;
		Buffer &buffer = buffers[bs.address];
		if (bs.is_constant) {
			buffer.is_constant = true;
			buffer.constant_value = bs.constant_value;
			CRASH_COND(buffer.size > buffer.capacity);
			for (unsigned int j = 0; j < buffer_size; ++j) {
				buffer.data[j] = bs.constant_value;
			}
			CRASH_COND(bs.address >= state.ranges.size());
			state.ranges[bs.address] = math::Interval::from_single_value(bs.constant_value);
		}
	}

	// Puts sentinel values in buffers to detect non-initialized ones
	// #ifdef DEBUG_ENABLED
	// 	for (unsigned int i = 0; i < state.buffers.size(); ++i) {
	// 		Buffer &buffer = state.buffers[i];
	// 		if (!buffer.is_constant && !buffer.is_binding) {
	// 			CRASH_COND(buffer.data == nullptr);
	// 			for (unsigned int j = 0; j < buffer.size; ++j) {
	// 				buffer.data[j] = -969696.f;
	// 			}
	// 		}
	// 	}
	// #endif

	/*if (use_range_analysis) {
		// TODO To be really worth it, we may need a runtime graph traversal pass,
		// where we build an execution map of nodes that are worthy 🔨

		const float ra_min = _memory[i];
		const float ra_max = _memory[i + _memory.size() / 2];

		buffer.is_constant = (ra_min == ra_max);
		if (buffer.is_constant) {
			buffer.constant_value = ra_min;
		}
	}*/
}

static inline Span<const uint8_t> read_params(Span<const uint16_t> operations, unsigned int &pc) {
	const uint16_t params_size_in_words = operations[pc];
	++pc;
	Span<const uint8_t> params;
	if (params_size_in_words > 0) {
		const size_t params_offset_in_words = operations[pc];
		// Seek to aligned position where params start
		pc += params_offset_in_words;
		params = operations.sub(pc, params_size_in_words).reinterpret_cast_to<const uint8_t>();
		pc += params_size_in_words;
	}
	return params;
}

void VoxelGraphRuntime::generate_set(State &state, Span<float> in_x, Span<float> in_y, Span<float> in_z, bool skip_xz,
		const ExecutionMap *execution_map) const {
	// I don't like putting private helper functions in headers.
	struct L {
		static inline void bind_buffer(Span<Buffer> buffers, int a, Span<float> d) {
			Buffer &buffer = buffers[a];
			CRASH_COND(!buffer.is_binding);
			buffer.data = d.data();
			buffer.size = d.size();
		}

		static inline void unbind_buffer(Span<Buffer> buffers, int a) {
			Buffer &buffer = buffers[a];
			CRASH_COND(!buffer.is_binding);
			buffer.data = nullptr;
		}
	};

	VOXEL_PROFILE_SCOPE();

#ifdef DEBUG_ENABLED
	// Each array must have the same size
	CRASH_COND(!(in_x.size() == in_y.size() && in_y.size() == in_z.size()));
#endif

	const unsigned int buffer_size = in_x.size();

#ifdef TOOLS_ENABLED
	ERR_FAIL_COND(state.buffers.size() < _program.buffer_count);
	ERR_FAIL_COND(state.buffers.size() == 0);
	ERR_FAIL_COND(state.buffer_size < buffer_size);
	ERR_FAIL_COND(state.buffers[0].size < buffer_size);
#ifdef DEBUG_ENABLED
	for (size_t i = 0; i < state.buffers.size(); ++i) {
		const Buffer &b = state.buffers[i];
		CRASH_COND(b.size < buffer_size);
		CRASH_COND(b.size > state.buffer_capacity);
		CRASH_COND(b.size != state.buffer_size);
		if (!b.is_binding) {
			CRASH_COND(b.size > b.capacity);
		}
	}
#endif
#endif

	Span<Buffer> buffers(state.buffers, 0, state.buffers.size());

	// Bind inputs
	if (_program.x_input_address != -1) {
		L::bind_buffer(buffers, _program.x_input_address, in_x);
	}
	if (_program.y_input_address != -1) {
		L::bind_buffer(buffers, _program.y_input_address, in_y);
	}
	if (_program.z_input_address != -1) {
		L::bind_buffer(buffers, _program.z_input_address, in_z);
	}

	const Span<const uint16_t> operations(_program.operations.data(), 0, _program.operations.size());

	Span<const uint16_t> op_adresses = execution_map != nullptr
			? to_span_const(execution_map->operation_adresses)
			: to_span_const(_program.default_execution_map.operation_adresses);
	if (skip_xz && op_adresses.size() > 0) {
		const unsigned int offset = execution_map != nullptr ? execution_map->xzy_start_index
															 : _program.default_execution_map.xzy_start_index;
		op_adresses = op_adresses.sub(offset);
	}

	for (unsigned int execution_map_index = 0; execution_map_index < op_adresses.size(); ++execution_map_index) {
		unsigned int pc = op_adresses[execution_map_index];

		const uint16_t opid = operations[pc++];
		const VoxelGraphNodeDB::NodeType &node_type = VoxelGraphNodeDB::get_singleton()->get_type(opid);

		const uint32_t inputs_count = node_type.inputs.size();
		const uint32_t outputs_count = node_type.outputs.size();

		const Span<const uint16_t> inputs = operations.sub(pc, inputs_count);
		pc += inputs_count;
		const Span<const uint16_t> outputs = operations.sub(pc, outputs_count);
		pc += outputs_count;

		Span<const uint8_t> params = read_params(operations, pc);

		ERR_FAIL_COND(node_type.process_buffer_func == nullptr);
		ProcessBufferContext ctx(inputs, outputs, params, buffers, execution_map != nullptr);
		node_type.process_buffer_func(ctx);
	}

	// Unbind buffers
	if (_program.x_input_address != -1) {
		L::unbind_buffer(buffers, _program.x_input_address);
	}
	if (_program.y_input_address != -1) {
		L::unbind_buffer(buffers, _program.y_input_address);
	}
	if (_program.z_input_address != -1) {
		L::unbind_buffer(buffers, _program.z_input_address);
	}
}

// TODO Accept float bounds
void VoxelGraphRuntime::analyze_range(State &state, Vector3i min_pos, Vector3i max_pos) const {
	VOXEL_PROFILE_SCOPE();

#ifdef TOOLS_ENABLED
	ERR_FAIL_COND(state.ranges.size() != _program.buffer_count);
#endif

	Span<math::Interval> ranges(state.ranges, 0, state.ranges.size());
	Span<Buffer> buffers(state.buffers, 0, state.buffers.size());

	// Reset users count, as they might be decreased during the analysis
	for (auto it = _program.buffer_specs.cbegin(); it != _program.buffer_specs.cend(); ++it) {
		const BufferSpec &bs = *it;
		Buffer &b = buffers[bs.address];
		b.local_users_count = bs.users_count;
	}

	ranges[_program.x_input_address] = math::Interval(min_pos.x, max_pos.x);
	ranges[_program.y_input_address] = math::Interval(min_pos.y, max_pos.y);
	ranges[_program.z_input_address] = math::Interval(min_pos.z, max_pos.z);

	const Span<const uint16_t> operations(_program.operations.data(), 0, _program.operations.size());

	// Here operations must all be analyzed, because we do this as a broad-phase.
	// Only narrow-phase may skip some operations eventually.
	uint32_t pc = 0;
	while (pc < operations.size()) {
		const uint16_t opid = operations[pc++];
		const VoxelGraphNodeDB::NodeType &node_type = VoxelGraphNodeDB::get_singleton()->get_type(opid);

		const uint32_t inputs_count = node_type.inputs.size();
		const uint32_t outputs_count = node_type.outputs.size();

		const Span<const uint16_t> inputs = operations.sub(pc, inputs_count);
		pc += inputs_count;
		const Span<const uint16_t> outputs = operations.sub(pc, outputs_count);
		pc += outputs_count;

		Span<const uint8_t> params = read_params(operations, pc);

		ERR_FAIL_COND(node_type.range_analysis_func == nullptr);
		RangeAnalysisContext ctx(inputs, outputs, params, ranges, buffers);
		node_type.range_analysis_func(ctx);

#ifdef VOXEL_DEBUG_GRAPH_PROG_SENTINEL
		// If this fails, the program is ill-formed
		CRASH_COND(read<uint16_t>(_program, pc) != VOXEL_DEBUG_GRAPH_PROG_SENTINEL);
#endif
	}
}

bool VoxelGraphRuntime::try_get_output_port_address(ProgramGraph::PortLocation port, uint16_t &out_address) const {
	const uint16_t *aptr = _program.output_port_addresses.getptr(port);
	if (aptr == nullptr) {
		// This port did not take part of the compiled result
		return false;
	}
	out_address = *aptr;
	return true;
}

} // namespace zylann::voxel