#include "common.h"

auto hwElsGenV(tsp::Solution const& solution, RNG& rng) {
	return Descent{}(Move2Opt{}(solution, rng));
}

auto hwElsInner(tsp::Solution const& solution, std::vector<RNG>& rngs, std::size_t id, std::size_t nCore) {
	std::size_t n = ELS_GEN;
	std::size_t maxThreads = nCore;

	std::size_t const nThreads = std::min<std::size_t>(maxThreads, ELS_GEN);

	std::vector<std::thread> threads{nThreads-1};
	std::size_t const step = n/nThreads;
	std::size_t const remainBase = n - step*nThreads;
	std::size_t remain = remainBase;

	auto run = [&solution,&rngs](tsp::Solution& out, std::size_t id, std::size_t k) {
		tsp::Solution best{};

		if(k)
			best = hwElsGenV(solution, rngs[id]);
		for(std::size_t i = 1; i < k; ++i) {
			tsp::Solution current = hwElsGenV(solution, rngs[id+i]);
			best = selectMin(std::move(best), std::move(current));
		}

		out = std::move(best);
	};

	std::size_t start{};
	std::vector<tsp::Solution> bests(nThreads);

	for(std::size_t i = 0; i < nThreads-1; ++i) {
		std::size_t offset = !!remain;
		remain -= offset;
		threads[i] = std::thread{run, std::ref(bests[i]), id+start, step+offset};
		start += step+offset;
	}

	run(bests[nThreads-1], id+start, step);

	for(auto& thread: threads) thread.join();

	tsp::Solution best;
	// best = *std::min_element(std::begin(solutions), std::end(solutions));
	if(nThreads)  best = std::move(bests[0]);
	for(std::size_t i = 1; i < nThreads; ++i)
		best = selectMin(std::move(best), std::move(bests[i]));

	return best;
}

auto hwEls(tsp::Solution const& solution, std::vector<RNG>& rngs, std::size_t id, std::size_t nCore) {
	tsp::Solution best = Descent{}(solution);

	for(std::size_t i = 0; i < ELS_ITER_MAX; ++i) {
		tsp::Solution current = hwElsInner(best, rngs, id, nCore);
		best = selectMin(std::move(best), std::move(current));
	}

	return best;
}

auto hwGraspGen(tsp::Problem const& problem, std::vector<RNG>& rngs, std::size_t id, std::size_t nCore = 1) {
	return hwEls(rgreedy()(problem, rngs[id]), rngs, id, nCore);
}

/* *** */

auto hwGraspEls(tsp::Problem const& problem, std::vector<RNG>& rngs) {
	tsp::Solution best;

	auto graspIter = [&](tsp::Problem const& problem, tsp::Solution& s, std::size_t id) {
		tsp::Solution cur = hwGraspGen(problem, rngs, id);
		s = selectMin(std::move(s), std::move(cur));
	};

	if(GRASP_N) {
		auto graspInit = [&](tsp::Problem const& problem, tsp::Solution& s) {
			s = hwGraspGen(problem, rngs, 0);
		};
#ifdef SUBTIME
		timeit(RUSAGE_THREAD, "[GRASP] ", graspInit, problem, best);
#else
		graspInit(problem, best);
#endif
	}

	for(std::size_t i = 1; i < GRASP_N; ++i) {
#ifdef SUBTIME
		timeit(RUSAGE_THREAD, "[GRASP] ", graspIter, problem, best, i*ELS_GEN);
#else
		graspIter(problem, best, i*ELS_GEN);
#endif
	}

	return best;
}

template<std::size_t K>
auto hwGraspElsPar(tsp::Problem const& problem, std::vector<RNG>& rngs) {
	std::size_t const n = GRASP_N;
	std::size_t const maxThreads = K;

	std::size_t const nThreads = std::min<std::size_t>(maxThreads, n);
	std::size_t const cores = maxThreads/nThreads;

	std::vector<std::thread> threads(nThreads-1);
	std::size_t const step = n/nThreads;
	std::size_t const remainBase = n - step*nThreads;
	std::size_t remain = remainBase;

	auto iter0 = [&problem,&rngs](tsp::Solution& best, std::size_t id, std::size_t cores) {
		best = hwGraspGen(problem, rngs, id, cores);
	};
	auto iter = [&problem,&rngs](tsp::Solution& best, std::size_t id, std::size_t cores) {
		tsp::Solution current = hwGraspGen(problem, rngs, id, cores);
		best = selectMin(std::move(best), std::move(current));
	};

	auto run = [&](tsp::Solution& out, std::size_t id, std::size_t k, std::size_t cores) {
		tsp::Solution best{};

		if(k) {
#ifdef SUBTIME
			timeit(RUSAGE_THREAD, "[GRASP] ", iter0, best, id*ELS_GEN, cores);
#else
			iter0(best, id*ELS_GEN, cores);
#endif
		}

		for(std::size_t i = 1; i < k; ++i) {
#ifdef SUBTIME
			timeit(RUSAGE_THREAD, "[GRASP] ", iter, best, (id+i)*ELS_GEN, cores);
#else
			iter(best, (id+1)*ELS_GEN, cores);
#endif
		}

		out = std::move(best);
	};

	std::size_t start{};
	std::vector<tsp::Solution> bests(nThreads);

	for(std::size_t i = 0; i < nThreads-1; ++i) {
		std::size_t offset = !!remain;
		remain -= offset;
		threads[i] = std::thread{run, std::ref(bests[i]), start, step+offset, cores};
		start += step+offset;
	}

	run(bests[nThreads-1], start, step, cores);

	for(std::thread& thread: threads) thread.join();

	tsp::Solution best;
	if(nThreads)  best = std::move(bests[0]);
	for(std::size_t i = 1; i < nThreads; ++i)
		best = selectMin(std::move(best), std::move(bests[i]));

	return best;
}

/* *** */

tsp::Solution hw_seq_v(tsp::Problem const& p, RNG& seeder, Arguments const&) {
	std::size_t n = GRASP_N * ELS_GEN;

	std::vector<RNG> rngs;
	rngs.reserve(n);
	for(std::size_t i = 0; i < n; ++i)
		rngs.emplace_back(seeder());

	return hwGraspEls(p, rngs);
}

tsp::Solution hw_par_v(tsp::Problem const& p, RNG& seeder, Arguments const&) {
	std::size_t n = GRASP_N * ELS_GEN;

	std::vector<RNG> rngs;
	rngs.reserve(n);
	for(std::size_t i = 0; i < n; ++i)
		rngs.emplace_back(seeder());

	return hwGraspElsPar<NTHREADS>(p, rngs);
}