#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){
	// are we done yet?
	for(auto&& p : grid.all_positions()){
		if(!grid.empty(p)) goto analyse;
	}
	// yes -> record the solution
	s.solution_traces.push_back(s.current_trace);
	return;

	// no -> try all clusters
	analyse:
	for(auto&& c : all_clusters(grid)){
		if(c.size() < rules.min_cluster_size()) continue;

		// 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;
}