#pragma once

#include "clusters.hpp"
#include <vector>

template <typename Grid>
struct Solution {
	using Trace = std::vector<typename Grid::Position>;
	Trace current_trace;
	std::vector<Trace> solution_traces;
};

template <typename T>
auto pop(std::vector<T> & v){
	v.erase(v.end()-1);
}

template <typename Grid, typename Rules>
auto solve_impl(Grid const & grid, Rules const & rules, Solution<Grid> & s){
	if(grid.empty()){
		// solved path
		s.solution_traces.push_back(s.current_trace);
		return;
	}

	auto&& clusters = all_clusters(grid, rules);
	if(clusters.empty()){
		// unsolvable path
		return;
	}

	for(auto&& c : clusters){
		// remove the cluster
		s.current_trace.push_back(*c.begin());
		auto new_grid = make_empty(grid, c);

		// recurse
		solve_impl(new_grid, rules, s);

		// go on with next cluster
		pop(s.current_trace);
	}
	return;
}

template <typename Grid, typename Rules>
auto solve(Grid const & grid, Rules const & rules){
	Solution<Grid> s;
	s.current_trace.reserve(10);
	solve_impl(grid, rules, s);
	return s;
}