#ifndef FAST_WFC_OVERLAPPING_WFC_HPP_
#define FAST_WFC_OVERLAPPING_WFC_HPP_

#include <algorithm>
#include <unordered_map>
#include "core/vector.h"

#include "array_2d.h"
#include "wfc.h"

//Merge this into OverlappingWFC
struct OverlappingWFCOptions {
	bool periodic_input; // True if the input is toric.
	bool periodic_output; // True if the output is toric.
	uint32_t out_height; // The height of the output in pixels.
	uint32_t out_width; // The width of the output in pixels.
	uint32_t symmetry; // The number of symmetries (the order is defined in wfc).
	bool ground; // True if the ground needs to be set (see init_ground).
	uint32_t pattern_size; // The width and height in pixel of the patterns.

	//Get the wave height given these options.
	uint32_t get_wave_height() const {
		return periodic_output ? out_height : out_height - pattern_size + 1;
	}

	//Get the wave width given these options.
	uint32_t get_wave_width() const {
		return periodic_output ? out_width : out_width - pattern_size + 1;
	}
};

//T -> hardcode it to uint32_t, and add support for variant conversion -> set_data(Array) -> maps it to ids 
//Make this inherit from WFC, also WFC should inherit from reference
template <typename T>
class OverlappingWFC {
private:
	Array2D<T> input;

	OverlappingWFCOptions options;

	Vector<Array2D<T>> patterns;

	WFC wfc;

	OverlappingWFC(
			const Array2D<T> &input, const OverlappingWFCOptions &options,
			const int &seed,
			const std::pair<Vector<Array2D<T>>, Vector<double>> &patterns,
			const Vector<PropagatorStateEntry> &propagator) :
			input(input), options(options), patterns(patterns.first), wfc(options.periodic_output, seed, patterns.second, propagator, options.get_wave_height(), options.get_wave_width()) {
		// If necessary, the ground is set.
		if (options.ground) {
			init_ground(wfc, input, patterns.first, options);
		}
	}

	OverlappingWFC(const Array2D<T> &input, const OverlappingWFCOptions &options,
			const int &seed,
			const std::pair<Vector<Array2D<T>>, Vector<double>>
					&patterns) :
			OverlappingWFC(input, options, seed, patterns,
					generate_compatible(patterns.first)) {}

	void init_ground(WFC &wfc, const Array2D<T> &input, const Vector<Array2D<T>> &patterns, const OverlappingWFCOptions &options) {
		uint32_t ground_pattern_id = get_ground_pattern_id(input, patterns, options);

		for (uint32_t j = 0; j < options.get_wave_width(); j++) {
			set_pattern(ground_pattern_id, options.get_wave_height() - 1, j);
		}

		for (uint32_t i = 0; i < options.get_wave_height() - 1; i++) {
			for (uint32_t j = 0; j < options.get_wave_width(); j++) {
				wfc.remove_wave_pattern(i, j, ground_pattern_id);
			}
		}

		wfc.propagate();
	}

	static uint32_t get_ground_pattern_id(const Array2D<T> &input, const Vector<Array2D<T>> &patterns, const OverlappingWFCOptions &options) {
		// Get the pattern.
		Array2D<T> ground_pattern = input.get_sub_array(input.height - 1, input.width / 2, options.pattern_size, options.pattern_size);

		// Retrieve the id of the pattern.
		for (int i = 0; i < patterns.size(); i++) {
			if (ground_pattern == patterns[i]) {
				return i;
			}
		}

		ERR_FAIL_V(0);
	}

	//Return the list of patterns, as well as their probabilities of apparition.
	static std::pair<Vector<Array2D<T>>, Vector<double>> get_patterns(const Array2D<T> &input, const OverlappingWFCOptions &options) {
		std::unordered_map<Array2D<T>, uint32_t> patterns_id;
		Vector<Array2D<T>> patterns;

		// The number of time a pattern is seen in the input image.
		Vector<double> patterns_weight;

		Vector<Array2D<T>> symmetries(8, Array2D<T>(options.pattern_size, options.pattern_size));
		uint32_t max_i = options.periodic_input ? input.height : input.height - options.pattern_size + 1;
		uint32_t max_j = options.periodic_input ? input.width : input.width - options.pattern_size + 1;

		for (uint32_t i = 0; i < max_i; i++) {
			for (uint32_t j = 0; j < max_j; j++) {
				// Compute the symmetries of every pattern in the image.
				symmetries[0].data = input.get_sub_array(i, j, options.pattern_size, options.pattern_size).data;
				symmetries[1].data = symmetries[0].reflected().data;
				symmetries[2].data = symmetries[0].rotated().data;
				symmetries[3].data = symmetries[2].reflected().data;
				symmetries[4].data = symmetries[2].rotated().data;
				symmetries[5].data = symmetries[4].reflected().data;
				symmetries[6].data = symmetries[4].rotated().data;
				symmetries[7].data = symmetries[6].reflected().data;

				// The number of symmetries in the option class define which symetries
				// will be used.
				for (uint32_t k = 0; k < options.symmetry; k++) {
					auto res = patterns_id.insert(std::make_pair(symmetries[k], patterns.size()));

					// If the pattern already exist, we just have to increase its number
					// of appearance.
					if (!res.second) {
						patterns_weight[res.first->second] += 1;
					} else {
						patterns.push_back(symmetries[k]);
						patterns_weight.push_back(1);
					}
				}
			}
		}

		return { patterns, patterns_weight };
	}

	//Return true if the pattern1 is compatible with pattern2 when pattern2 is at a distance (dy,dx) from pattern1.
	static bool agrees(const Array2D<T> &pattern1, const Array2D<T> &pattern2, int dy, int dx) {
		uint32_t xmin = dx < 0 ? 0 : dx;
		uint32_t xmax = dx < 0 ? dx + pattern2.width : pattern1.width;
		uint32_t ymin = dy < 0 ? 0 : dy;
		uint32_t ymax = dy < 0 ? dy + pattern2.height : pattern1.width;

		// Iterate on every pixel contained in the intersection of the two pattern.
		for (uint32_t y = ymin; y < ymax; y++) {
			for (uint32_t x = xmin; x < xmax; x++) {
				// Check if the color is the same in the two patterns in that pixel.
				if (pattern1.get(y, x) != pattern2.get(y - dy, x - dx)) {
					return false;
				}
			}
		}

		return true;
	}

	// Precompute the function agrees(pattern1, pattern2, dy, dx).
	// If agrees(pattern1, pattern2, dy, dx), then compatible[pattern1][direction]
	// contains pattern2, where direction is the direction defined by (dy, dx)
	// (see direction.hpp).
	static Vector<PropagatorStateEntry> generate_compatible(const Vector<Array2D<T>> &patterns) {
		Vector<PropagatorStateEntry> compatible;
		compatible.resize(patterns.size());

		// Iterate on every dy, dx, pattern1 and pattern2
		for (int pattern1 = 0; pattern1 < patterns.size(); pattern1++) {
			for (uint32_t direction = 0; direction < 4; direction++) {
				for (int pattern2 = 0; pattern2 < patterns.size(); pattern2++) {
					if (agrees(patterns[pattern1], patterns[pattern2], directions_y[direction], directions_x[direction])) {
						compatible[pattern1][direction].push_back(pattern2);
					}
				}
			}
		}

		return compatible;
	}

	// Transform a 2D array containing the patterns id to a 2D array containing the pixels.
	Array2D<T> to_image(const Array2D<uint32_t> &output_patterns) const {
		Array2D<T> output = Array2D<T>(options.out_height, options.out_width);

		if (options.periodic_output) {
			for (uint32_t y = 0; y < options.get_wave_height(); y++) {
				for (uint32_t x = 0; x < options.get_wave_width(); x++) {
					output.get(y, x) = patterns[output_patterns.get(y, x)].get(0, 0);
				}
			}
		} else {
			for (uint32_t y = 0; y < options.get_wave_height(); y++) {
				for (uint32_t x = 0; x < options.get_wave_width(); x++) {
					output.get(y, x) = patterns[output_patterns.get(y, x)].get(0, 0);
				}
			}

			for (uint32_t y = 0; y < options.get_wave_height(); y++) {
				const Array2D<T> &pattern = patterns[output_patterns.get(y, options.get_wave_width() - 1)];
				for (uint32_t dx = 1; dx < options.pattern_size; dx++) {
					output.get(y, options.get_wave_width() - 1 + dx) = pattern.get(0, dx);
				}
			}

			for (uint32_t x = 0; x < options.get_wave_width(); x++) {
				const Array2D<T> &pattern = patterns[output_patterns.get(options.get_wave_height() - 1, x)];
				for (uint32_t dy = 1; dy < options.pattern_size; dy++) {
					output.get(options.get_wave_height() - 1 + dy, x) =
							pattern.get(dy, 0);
				}
			}

			const Array2D<T> &pattern = patterns[output_patterns.get(options.get_wave_height() - 1, options.get_wave_width() - 1)];

			for (uint32_t dy = 1; dy < options.pattern_size; dy++) {
				for (uint32_t dx = 1; dx < options.pattern_size; dx++) {
					output.get(options.get_wave_height() - 1 + dy, options.get_wave_width() - 1 + dx) = pattern.get(dy, dx);
				}
			}
		}

		return output;
	}

	uint32_t get_pattern_id(const Array2D<T> &pattern) {
		uint32_t *pattern_id = std::find(patterns.begin(), patterns.end(), pattern);

		if (pattern_id != patterns.end()) {
			return *pattern_id;
		}

		return -1;
	}

	// Set the pattern at a specific position, given its pattern id
	// pattern_id needs to be a valid pattern id, and i and j needs to be in the wave range
	void set_pattern(uint32_t pattern_id, uint32_t i, uint32_t j) {
		for (int p = 0; p < patterns.size(); p++) {
			if (pattern_id != p) {
				wfc.remove_wave_pattern(i, j, p);
			}
		}
	}

public:
	OverlappingWFC(const Array2D<T> &input, const OverlappingWFCOptions &options, int seed) :
			OverlappingWFC(input, options, seed, get_patterns(input, options)) {}

	// Set the pattern at a specific position.
	// Returns false if the given pattern does not exist, or if the
	// coordinates are not in the wave
	bool set_pattern(const Array2D<T> &pattern, uint32_t i, uint32_t j) {
		auto pattern_id = get_pattern_id(pattern);

		if (pattern_id == std::nullopt || i >= options.get_wave_height() || j >= options.get_wave_width()) {
			return false;
		}

		set_pattern(pattern_id, i, j);
		return true;
	}

	// Run the WFC algorithm, and return the result if the algorithm succeeded.
	Array2D<T> run() {
		Array2D<uint32_t> result = wfc.run();

		if (result.width == 0 && result.height == 0) {
			return Array2D<T>(0, 0);
		}

		return to_image(result);
	}
};

#endif // FAST_WFC_WFC_HPP_