#pragma once

#include "data.hpp"
#include "clusters.hpp"

#include <vector>

template <typename Grid>
struct State {
	using Trace = typename Solutions<Grid>::Trace;
	Trace trace; // current trace being considered
};

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, State<Grid> & state, Solutions<Grid> & solutions){
	if(grid.empty()){
		// solved path
		solutions.traces.push_back(state.trace);
		return;
	}

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

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

		// recurse
		solve_impl(new_grid, rules, state, solutions);

		// go on with next cluster
		pop(state.trace);
	}
	return;
}

template <typename Grid, typename Rules>
auto solve(Grid const & grid, Rules const & rules){
	Solutions<Grid> solutions;
	State<Grid> state;
	state.trace.reserve(10);
	solve_impl(grid, rules, state, solutions);
	return solutions;
}