/*

Copyright (c) 2018, Steven Siloti
Copyright (c) 2013-2021, Arvid Norberg
Copyright (c) 2016-2018, Alden Torres
Copyright (c) 2018, d-komarov
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:

    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in
      the documentation and/or other materials provided with the distribution.
    * Neither the name of the author nor the names of its
      contributors may be used to endorse or promote products derived
      from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.

*/

#include "libtorrent/session.hpp"
#include "libtorrent/session_settings.hpp"
#include "libtorrent/session_params.hpp"
#include "libtorrent/alert_types.hpp"
#include "libtorrent/bencode.hpp"
#include "libtorrent/time.hpp"
#include "libtorrent/aux_/path.hpp"
#include "libtorrent/torrent_info.hpp"
#include "libtorrent/read_resume_data.hpp"
#include "libtorrent/write_resume_data.hpp"
#include <tuple>
#include <functional>
#include <random>

#include "test.hpp"
#include "test_utils.hpp"
#include "setup_transfer.hpp"
#include "settings.hpp"
#include <iostream>

using namespace lt;
using std::ignore;

namespace {

int peer_disconnects = 0;

bool on_alert(alert const* a)
{
	auto const* const pd = alert_cast<peer_disconnected_alert>(a);
	if (pd && pd->error != make_error_code(errors::self_connection))
		++peer_disconnects;
	else if (alert_cast<peer_error_alert>(a))
		++peer_disconnects;

	return false;
}

void cleanup()
{
	error_code ec;
	remove_all("tmp1_priority", ec);
	remove_all("tmp2_priority", ec);
	remove_all("tmp1_priority_moved", ec);
	remove_all("tmp2_priority_moved", ec);
}

void test_transfer(settings_pack const& sett, bool test_deprecated = false)
{
	// this allows shutting down the sessions in parallel
	std::vector<session_proxy> sp;

	cleanup();

	lt::settings_pack pack = sett;

	// we need a short reconnect time since we
	// finish the torrent and then restart it
	// immediately to complete the second half.
	// using a reconnect time > 0 will just add
	// to the time it will take to complete the test
	pack.set_int(settings_pack::min_reconnect_time, 0);

	pack.set_bool(settings_pack::enable_outgoing_utp, false);
	pack.set_bool(settings_pack::enable_incoming_utp, false);

	pack.set_int(settings_pack::out_enc_policy, settings_pack::pe_disabled);
	pack.set_int(settings_pack::in_enc_policy, settings_pack::pe_disabled);
	pack.set_bool(settings_pack::allow_multiple_connections_per_ip, false);
	pack.set_int(settings_pack::unchoke_slots_limit, 8);

	pack.set_bool(settings_pack::enable_upnp, false);
	pack.set_bool(settings_pack::enable_natpmp, false);
	pack.set_bool(settings_pack::enable_lsd, false);
	pack.set_bool(settings_pack::enable_dht, false);

	pack.set_str(settings_pack::listen_interfaces, test_listen_interface());
#if TORRENT_ABI_VERSION == 1
	pack.set_bool(settings_pack::rate_limit_utp, true);
#endif

	lt::session ses1(pack);

	pack.set_str(settings_pack::listen_interfaces, test_listen_interface());
	lt::session ses2(pack);

	torrent_handle tor1;
	torrent_handle tor2;

	error_code ec;
	create_directory("tmp1_priority", ec);
	ofstream file("tmp1_priority/temporary");
	std::shared_ptr<torrent_info> t = ::create_torrent(&file, "temporary", 16 * 1024, 13, false);
	file.close();

	wait_for_listen(ses1, "ses1");
	wait_for_listen(ses2, "ses2");

	peer_disconnects = 0;

	// test using piece sizes smaller than 16kB
	std::tie(tor1, tor2, ignore) = setup_transfer(&ses1, &ses2, nullptr
		, true, false, true, "_priority", 8 * 1024, &t, false, nullptr);

	int const num_pieces = tor2.torrent_file()->num_pieces();
	aux::vector<download_priority_t, piece_index_t> priorities(std::size_t(num_pieces), 1_pri);
	// set half of the pieces to priority 0
	std::fill(priorities.begin(), priorities.begin() + (num_pieces / 2), 0_pri);
	tor2.prioritize_pieces(priorities);
	std::cout << "setting priorities: ";
	for (auto p : priorities) std::cout << int(static_cast<std::uint8_t>(p)) << " ";
	std::cout << '\n';

	for (int i = 0; i < 200; ++i)
	{
		print_alerts(ses1, "ses1", true, true, &on_alert);
		print_alerts(ses2, "ses2", true, true, &on_alert);

		torrent_status st1 = tor1.status();
		torrent_status st2 = tor2.status();

		if (i % 10 == 0)
		{
			print_ses_rate(i / 10.f, &st1, &st2);
		}

		// st2 is finished when we have downloaded half of the pieces
		if (st2.is_finished) break;

		if (st2.state != torrent_status::downloading)
		{
			static char const* state_str[] =
				{"checking (q)", "checking", "dl metadata"
				, "downloading", "finished", "seeding", "allocating", "checking (r)"};
			std::cout << "st2 state: " << state_str[st2.state] << std::endl;
		}

		TEST_CHECK(st1.state == torrent_status::seeding
			|| st1.state == torrent_status::checking_resume_data
			|| st1.state == torrent_status::checking_files);
		TEST_CHECK(st2.state == torrent_status::downloading
			|| st2.state == torrent_status::checking_resume_data);

		if (peer_disconnects >= 2)
		{
			std::printf("too many disconnects (%d), exiting\n", peer_disconnects);
			break;
		}

		// if nothing is being transferred after 3 seconds, we're failing the test
		if (st1.upload_payload_rate == 0 && i > 30)
		{
			std::cout << "no upload in " << (i / 10) << " seconds, failing\n";
			break;
		}

		std::this_thread::sleep_for(lt::milliseconds(100));
	}

	TEST_CHECK(!tor2.status().is_seeding);
	TEST_CHECK(tor2.status().is_finished);

	if (tor2.status().is_finished)
		std::cout << "torrent is finished (50% complete)" << std::endl;
	else return;

	std::vector<download_priority_t> priorities2 = tor2.get_piece_priorities();
	std::copy(priorities2.begin(), priorities2.end()
		, std::ostream_iterator<download_priority_t>(std::cout, ", "));
	std::cout << std::endl;
	TEST_CHECK(std::equal(priorities.begin(), priorities.end(), priorities2.begin()));

	std::cout << "force recheck" << std::endl;
	tor2.force_recheck();

	priorities2 = tor2.get_piece_priorities();
	std::copy(priorities2.begin(), priorities2.end()
		, std::ostream_iterator<download_priority_t>(std::cout, ", "));
	std::cout << std::endl;
	TEST_CHECK(std::equal(priorities.begin(), priorities.end(), priorities2.begin()));

	peer_disconnects = 0;

	// when we're done checking, we're likely to be put in downloading state
	// for a split second before transitioning to finished. This loop waits
	// for the finished state
	torrent_status st2;
	for (int i = 0; i < 50; ++i)
	{
		print_alerts(ses1, "ses1", true, true, &on_alert);
		print_alerts(ses2, "ses2", true, true, &on_alert);

		st2 = tor2.status();
		if (i % 10 == 0)
		{
			std::cout << int(st2.progress * 100) << "% " << std::endl;
		}
		if (st2.state == torrent_status::finished) break;
		std::this_thread::sleep_for(lt::milliseconds(100));
	}

	TEST_EQUAL(st2.state, torrent_status::finished);

	if (st2.state != torrent_status::finished)
		return;

	std::cout << "recheck complete" << std::endl;

	priorities2 = tor2.get_piece_priorities();
	std::copy(priorities2.begin(), priorities2.end(), std::ostream_iterator<download_priority_t>(std::cout, ", "));
	std::cout << std::endl;
	TEST_CHECK(std::equal(priorities.begin(), priorities.end(), priorities2.begin()));

	tor2.pause();
	wait_for_alert(ses2, torrent_paused_alert::alert_type, "ses2");

	std::printf("save resume data\n");
	tor2.save_resume_data();

	std::vector<char> resume_data;

	time_point start = clock_type::now();
	while (true)
	{
		ses2.wait_for_alert(seconds(10));
		std::vector<alert*> alerts;
		ses2.pop_alerts(&alerts);
		if (alerts.empty()) break;
		for (std::vector<alert*>::iterator i = alerts.begin()
			, end(alerts.end()); i != end; ++i)
		{
			alert* a = *i;
			std::cout << "ses2: " << a->message() << std::endl;
			if (alert_cast<save_resume_data_alert>(a))
			{
				resume_data = write_resume_data_buf(alert_cast<save_resume_data_alert>(a)->params);
				std::printf("saved resume data\n");
				goto done;
			}
			else if (alert_cast<save_resume_data_failed_alert>(a))
			{
				std::printf("save resume failed\n");
				goto done;
			}
			if (total_seconds(clock_type::now() - start) > 10)
				goto done;
		}
	}
done:
	TEST_CHECK(resume_data.size());

	if (resume_data.empty())
		return;

	std::printf("%s\n", &resume_data[0]);

	ses2.remove_torrent(tor2);

	std::cout << "removed" << std::endl;

	std::this_thread::sleep_for(lt::milliseconds(100));

	std::cout << "re-adding" << std::endl;
	add_torrent_params p;
	TORRENT_UNUSED(test_deprecated);
#if TORRENT_ABI_VERSION == 1
	if (test_deprecated)
	{
		p.resume_data = resume_data;
	}
	else
#endif
	{
		error_code ec1;
		p = read_resume_data(resume_data, ec1);
		TEST_CHECK(!ec1);
	}
	p.flags &= ~torrent_flags::paused;
	p.flags &= ~torrent_flags::auto_managed;
	p.ti = t;
	p.save_path = "tmp2_priority";

	tor2 = ses2.add_torrent(p, ec);
	tor2.prioritize_pieces(priorities);
	std::cout << "resetting priorities" << std::endl;
	tor2.resume();

	// wait for torrent 2 to settle in back to finished state (it will
	// start as checking)
	torrent_status st1;
	for (int i = 0; i < 5; ++i)
	{
		print_alerts(ses1, "ses1", true, true, &on_alert);
		print_alerts(ses2, "ses2", true, true, &on_alert);

		st1 = tor1.status();
		st2 = tor2.status();

		TEST_CHECK(st1.state == torrent_status::seeding);

		if (st2.is_finished) break;

		std::this_thread::sleep_for(lt::milliseconds(100));
	}

	// torrent 2 should not be seeding yet, it should
	// just be 50% finished
	TEST_CHECK(!st2.is_seeding);
	TEST_CHECK(st2.is_finished);

	std::fill(priorities.begin(), priorities.end(), 1_pri);
	tor2.prioritize_pieces(priorities);
	std::cout << "setting priorities to 1" << std::endl;
	TEST_EQUAL(tor2.status().is_finished, false);

	std::copy(priorities.begin(), priorities.end()
		, std::ostream_iterator<download_priority_t>(std::cout, ", "));
	std::cout << std::endl;

	// drain alerts
	print_alerts(ses1, "ses1", true, true, &on_alert);
	print_alerts(ses2, "ses2", true, true, &on_alert);

	peer_disconnects = 0;

	// this loop makes sure ses2 reconnects to the peer now that it's
	// in download mode again. If this fails, the reconnect logic may
	// not work or be inefficient
	st1 = tor1.status();
	st2 = tor2.status();
	for (int i = 0; i < 130; ++i)
	{
		print_alerts(ses1, "ses1", true, true, &on_alert);
		print_alerts(ses2, "ses2", true, true, &on_alert);

		st1 = tor1.status();
		st2 = tor2.status();

		if (i % 10 == 0)
			print_ses_rate(i / 10.f, &st1, &st2);

		if (st2.is_seeding) break;

		TEST_EQUAL(st1.state, torrent_status::seeding);
		TEST_EQUAL(st2.state, torrent_status::downloading);

		if (peer_disconnects >= 2)
		{
			std::printf("too many disconnects (%d), exiting\n", peer_disconnects);
			break;
		}

		std::this_thread::sleep_for(lt::milliseconds(100));
	}

	st2 = tor2.status();
	if (!st2.is_seeding)
		std::printf("ses2 failed to reconnect to ses1!\n");
	TEST_CHECK(st2.is_seeding);

	sp.push_back(ses1.abort());
	sp.push_back(ses2.abort());
}

} // anonymous namespace

TORRENT_TEST(priority)
{
	using namespace lt;
	settings_pack p = settings();
	test_transfer(p);
	cleanup();
}

#if TORRENT_ABI_VERSION == 1
TORRENT_TEST(priority_deprecated)
{
	using namespace lt;
	settings_pack p = settings();
	test_transfer(p, true);
	cleanup();
}
#endif

// test to set piece and file priority on a torrent that doesn't have metadata
// yet
TORRENT_TEST(no_metadata_prioritize_files)
{
	lt::session ses(settings());

	add_torrent_params addp;
	addp.flags &= ~torrent_flags::paused;
	addp.flags &= ~torrent_flags::auto_managed;
	addp.info_hashes.v1 = sha1_hash("abababababababababab");
	addp.save_path = ".";
	torrent_handle h = ses.add_torrent(addp);

	std::vector<lt::download_priority_t> prios(3);
	prios[0] = lt::dont_download;

	h.prioritize_files(prios);
	// TODO 2: this should wait for an alert instead of just sleeping
	std::this_thread::sleep_for(lt::milliseconds(100));
	TEST_CHECK(h.get_file_priorities() == prios);

	prios[0] = lt::low_priority;
	h.prioritize_files(prios);
	std::this_thread::sleep_for(lt::milliseconds(100));
	TEST_CHECK(h.get_file_priorities() == prios);

	ses.remove_torrent(h);
}

TORRENT_TEST(no_metadata_file_prio)
{
	lt::session ses(settings());

	add_torrent_params addp;
	addp.flags &= ~torrent_flags::paused;
	addp.flags &= ~torrent_flags::auto_managed;
	addp.info_hashes.v1 = sha1_hash("abababababababababab");
	addp.save_path = ".";
	torrent_handle h = ses.add_torrent(addp);

	h.file_priority(0_file, 0_pri);
	// TODO 2: this should wait for an alert instead of just sleeping
	std::this_thread::sleep_for(lt::milliseconds(100));
	TEST_EQUAL(h.file_priority(0_file), 0_pri);
	h.file_priority(0_file, 1_pri);
	std::this_thread::sleep_for(lt::milliseconds(100));
	TEST_EQUAL(h.file_priority(0_file), 1_pri);

	ses.remove_torrent(h);
}

TORRENT_TEST(no_metadata_piece_prio)
{
	lt::session ses(settings());

	add_torrent_params addp;
	addp.flags &= ~torrent_flags::paused;
	addp.flags &= ~torrent_flags::auto_managed;
	addp.info_hashes.v1 = sha1_hash("abababababababababab");
	addp.save_path = ".";
	torrent_handle h = ses.add_torrent(addp);

	// you can't set piece priorities before the metadata has been downloaded
	h.piece_priority(2_piece, 0_pri);
	TEST_EQUAL(h.piece_priority(2_piece), 4_pri);
	h.piece_priority(2_piece, 1_pri);
	TEST_EQUAL(h.piece_priority(2_piece), 4_pri);

	ses.remove_torrent(h);
}

TORRENT_TEST(file_priority_multiple_calls)
{
	settings_pack pack = settings();
	lt::session ses(pack);

	auto t = ::generate_torrent(true);

	add_torrent_params addp;
	addp.flags &= ~torrent_flags::paused;
	addp.flags &= ~torrent_flags::auto_managed;
	addp.save_path = ".";
	addp.ti = t;
	torrent_handle h = ses.add_torrent(addp);

	for (file_index_t const i : t->files().file_range())
		h.file_priority(i, lt::low_priority);

	std::vector<download_priority_t> const expected(
		std::size_t(t->files().num_files()), lt::low_priority);
	for (int i = 0; i < 10; ++i)
	{
		auto const p = h.get_file_priorities();
		if (p == expected) return;
		std::this_thread::sleep_for(milliseconds(500));
	}
	TEST_CHECK(false);
}

TORRENT_TEST(export_file_while_seed)
{
	settings_pack pack = settings();
	lt::session ses(pack);

	error_code ec;
	create_directory("tmp2_priority", ec);
	ofstream file("tmp2_priority/temporary");
	auto t = ::create_torrent(&file, "temporary", 16 * 1024, 13, false);
	file.close();

	add_torrent_params addp;
	addp.flags &= ~torrent_flags::paused;
	addp.flags &= ~torrent_flags::auto_managed;
	addp.save_path = ".";
	addp.ti = t;
	torrent_handle h = ses.add_torrent(addp);

	// write to the partfile
	h.file_priority(file_index_t{0}, lt::dont_download);

	std::vector<char> piece(16 * 1024);
	for (std::size_t i = 0; i < piece.size(); ++i)
		piece[i] = char((i % 26) + 'A');

	// prevent race conditions of adding pieces while checking
	lt::torrent_status st = h.status();
	for (int i = 0; i < 40; ++i)
	{
		print_alerts(ses, "ses", true, true);
		st = h.status();
		if (st.state != torrent_status::checking_files
			&& st.state != torrent_status::checking_resume_data)
			break;
		std::this_thread::sleep_for(lt::milliseconds(100));
	}
	TEST_CHECK(st.state != torrent_status::checking_files
		&& st.state != torrent_status::checking_files);
	TEST_CHECK(st.num_pieces == 0);

	for (piece_index_t i : t->piece_range())
		h.add_piece(i, piece.data());

	TEST_CHECK(!exists("temporary"));

	for (int i = 0; i < 40; ++i)
	{
		print_alerts(ses, "ses", true, true, &on_alert);
		if (h.status().is_seeding) break;
		std::this_thread::sleep_for(lt::milliseconds(100));
	}
	TEST_EQUAL(h.status().is_seeding, true);

	// this should cause the file to be exported
	h.file_priority(file_index_t{0}, lt::low_priority);

	for (int i = 0; i < 20; ++i)
	{
		print_alerts(ses, "ses", true, true, &on_alert);
		if (h.file_priority(file_index_t{0}) == lt::low_priority) break;
		std::this_thread::sleep_for(lt::milliseconds(100));
	}

	TEST_CHECK(exists("temporary"));
}

TORRENT_TEST(test_piece_priority_after_resume)
{
	auto const new_prio = lt::low_priority;

	add_torrent_params p;
	auto ti = generate_torrent();
	{
		auto const prio = top_priority;

		p.save_path = ".";
		p.ti = ti;
		p.file_priorities.resize(1, prio);

		lt::session ses(settings());
		torrent_handle h = ses.add_torrent(p);

		TEST_EQUAL(h.piece_priority(0_piece), prio);

		using prio_vec = std::vector<std::pair<lt::piece_index_t, lt::download_priority_t>>;
		h.prioritize_pieces(prio_vec{{0_piece, new_prio}});
		TEST_EQUAL(h.piece_priority(0_piece), new_prio);

		ses.pause();
		h.save_resume_data();

		alert const* a = wait_for_alert(ses, save_resume_data_alert::alert_type);
		save_resume_data_alert const* rd = alert_cast<save_resume_data_alert>(a);

		p = rd->params;
	}
	{
		p.save_path = ".";
		p.ti = ti;

		lt::session ses(settings());
		torrent_handle h = ses.add_torrent(p);

		TEST_EQUAL(h.piece_priority(0_piece), new_prio);
	}
}

namespace {
template <typename Engine>
lt::file_index_t rand_file(Engine& rng, int num_files)
{
	auto i = std::uniform_int_distribution<int>(0, num_files - 1)(rng);
	return file_index_t(i);
}

template <typename Engine>
lt::download_priority_t rand_prio(Engine& rng)
{
	auto i = std::uniform_int_distribution<int>(0, 7)(rng);
	return lt::download_priority_t(static_cast<std::uint8_t>(i));
}
}

TORRENT_TEST(file_priority_stress_test)
{
	add_torrent_params atp;
	auto ti = generate_torrent();
	int const num_files = ti->num_files();

	lt::aux::vector<lt::download_priority_t, lt::file_index_t>
		local_prios(static_cast<std::size_t>(num_files), lt::default_priority);

	atp.save_path = ".";
	atp.ti = ti;
	atp.file_priorities = local_prios;
	atp.flags &= ~torrent_flags::need_save_resume;

	lt::session ses(settings());
	torrent_handle h = ses.add_torrent(atp);
	TEST_CHECK(h.status().need_save_resume == false);

	std::mt19937 rng(0x82daf973);
	bool first = true;
	for (int i = 0; i < 1000; ++i)
	{
		auto const f = rand_file(rng, num_files);
		auto const p = rand_prio(rng);
		h.file_priority(f, p);
		local_prios[f] = p;

		// updating the file priorities is asynchronous, it shouldn't have taken
		// effect quite yet
		if (first)
			TEST_CHECK(h.status().need_save_resume == false);
		first = false;
	}

	auto tp = h.get_file_priorities();
	for (int i = 0; i < 10 && tp != local_prios; ++i)
	{
		std::this_thread::sleep_for(lt::milliseconds(500));
		tp = h.get_file_priorities();
	}

	std::cout << "torrent file prios:\n";
	for (auto const p : tp)
		std::cout << " " << p;
	std::cout << '\n';

	std::cout << "expected file prios:\n";
	for (auto const p : local_prios)
		std::cout << " " << p;
	std::cout << '\n';

	TEST_CHECK(tp == local_prios);
	TEST_CHECK(h.status().need_save_resume == true);

	auto const pp = h.get_piece_priorities();
	auto const& fs = ti->files();
	lt::piece_index_t i(0);

	std::cout << "piece prios:\n";
	for (auto p : pp)
	{
		auto const files = fs.map_block(i, 0, fs.piece_length());
		auto expected_prio = lt::dont_download;
		for (auto const& f: files)
			expected_prio = std::max(local_prios[f.file_index], expected_prio);

		std::cout << " " << p;
		TEST_EQUAL(p, expected_prio);
		++i;
	}
	std::cout << '\n';
}