#ifndef FAST_WFC_PROPAGATOR_HPP_
#define FAST_WFC_PROPAGATOR_HPP_

#include "direction.h"
#include "array_3d.h"
#include <array>
#include <tuple>
#include <vector>

class Wave;

/**
 * Propagate information about patterns in the wave.
 */
class Propagator {
public:
	using PropagatorState = std::vector<std::array<std::vector<unsigned>, 4>>;

private:
	/**
	 * The size of the patterns.
	 */
	const std::size_t patterns_size;

	/**
	 * propagator[pattern1][direction] contains all the patterns that can
	 * be placed in next to pattern1 in the direction direction.
	 */
	PropagatorState propagator_state;

	/**
	 * The wave width and height.
	 */
	const unsigned wave_width;
	const unsigned wave_height;

	/**
	 * True if the wave and the output is toric.
	 */
	const bool periodic_output;

	/**
	 * All the tuples (y, x, pattern) that should be propagated.
	 * The tuple should be propagated when wave.get(y, x, pattern) is set to
	 * false.
	 */
	std::vector<std::tuple<unsigned, unsigned, unsigned>> propagating;

	/**
	 * compatible.get(y, x, pattern)[direction] contains the number of patterns
	 * present in the wave that can be placed in the cell next to (y,x) in the
	 * opposite direction of direction without being in contradiction with pattern
	 * placed in (y,x). If wave.get(y, x, pattern) is set to false, then
	 * compatible.get(y, x, pattern) has every element negative or null
	 */
	Array3D<std::array<int, 4>> compatible;

	/**
	 * Initialize compatible.
	 */
	void init_compatible() noexcept;

public:
	/**
	 * Constructor building the propagator and initializing compatible.
	 */
	Propagator(unsigned wave_height, unsigned wave_width, bool periodic_output,
			PropagatorState propagator_state) noexcept
			:
			patterns_size(propagator_state.size()),
			propagator_state(propagator_state),
			wave_width(wave_width),
			wave_height(wave_height),
			periodic_output(periodic_output),
			compatible(wave_height, wave_width, patterns_size) {
		init_compatible();
	}

	/**
	 * Add an element to the propagator.
	 * This function is called when wave.get(y, x, pattern) is set to false.
	 */
	void add_to_propagator(unsigned y, unsigned x, unsigned pattern) noexcept {
		// All the direction are set to 0, since the pattern cannot be set in (y,x).
		std::array<int, 4> temp = {};
		compatible.get(y, x, pattern) = temp;
		propagating.emplace_back(y, x, pattern);
	}

	/**
	 * Propagate the information given with add_to_propagator.
	 */
	void propagate(Wave &wave) noexcept;
};

#endif // FAST_WFC_PROPAGATOR_HPP_