/*

Copyright (c) 2016-2019, 2021, Arvid Norberg
Copyright (c) 2021, Alden Torres
All rights reserved.

You may use, distribute and modify this code under the terms of the BSD license,
see LICENSE file.
*/

#include "libtorrent/session.hpp"
#include "libtorrent/torrent_handle.hpp"
#include "libtorrent/settings_pack.hpp"
#include "libtorrent/alert_types.hpp"
#include "libtorrent/aux_/deadline_timer.hpp"
#include "settings.hpp"
#include "fake_peer.hpp"
#include "utils.hpp"
#include "create_torrent.hpp"
#include "simulator/simulator.hpp"
#include "simulator/utils.hpp"
#include <iostream>

using namespace sim;
using namespace lt;

using sim::asio::ip::address_v4;

// this is the general template for these tests. create the session with custom
// settings (Settings), set up the test, by adding torrents with certain
// arguments (Setup), run the test and verify the end state (Test)
template <typename Setup, typename Torrent, typename Test, typename Check>
void run_test(Setup const& setup, Torrent const& torrent
	, Test const& test, Check const& check)
{
	// setup the simulation
	sim::default_config network_cfg;
	sim::simulation sim{network_cfg};
	std::unique_ptr<sim::asio::io_context> ios = make_io_context(sim, 0);
	lt::session_proxy zombie;

	// setup settings pack to use for the session (customization point)
	lt::settings_pack pack = settings();

	// create session
	std::shared_ptr<lt::session> ses = std::make_shared<lt::session>(pack, *ios);

	setup(*ses);

	fake_peer p1(sim, "60.0.0.0");
	fake_peer p2(sim, "60.0.0.1");
	fake_peer p3(sim, "60.0.0.2");
	std::array<fake_peer*, 3> test_peers = {{ &p1, &p2, &p3 }};

	// add torrent
	lt::add_torrent_params params = ::create_torrent(0, false);
	params.flags &= ~lt::torrent_flags::auto_managed;
	params.flags &= ~lt::torrent_flags::paused;
	ses->async_add_torrent(std::move(params));

	lt::torrent_handle h;
	print_alerts(*ses, [&](lt::session& ses, lt::alert const* a) {
		auto at = lt::alert_cast<add_torrent_alert>(a);
		if (at == nullptr) return;
		h = at->handle;

		// disable the print_alert object from polling any more alerts
		ses.set_alert_notify([]{});

		torrent(ses, h, test_peers);
	});

	sim::timer t1(sim, lt::seconds(5)
		, [&](boost::system::error_code const&)
	{
		test(*ses, h, test_peers);
	});

	// set up a timer to fire later, to verify everything we expected to happen
	// happened
	sim::timer t2(sim, lt::seconds(10)
		, [&](boost::system::error_code const&)
	{
		check(*ses, h, test_peers);

		// shut down
		zombie = ses->abort();
		ses.reset();
	});

	sim.run();
}

// make sure the torrent disconnects all its peers when it's paused
TORRENT_TEST(torrent_paused_disconnect)
{
	run_test(
		[](lt::session&) {},
		[](lt::session&, lt::torrent_handle h, std::array<fake_peer*, 3>&) {
			add_fake_peers(h, 3);
		},

		[](lt::session&, lt::torrent_handle h, std::array<fake_peer*, 3>& test_peers) {
			check_accepted(test_peers, {{true, true, true}});
			check_connected(test_peers, {{true, true, true}});
			check_disconnected(test_peers, {{false, false, false}});
			h.pause();
		},

		[](lt::session&, lt::torrent_handle h, std::array<fake_peer*, 3>& test_peers) {
			check_disconnected(test_peers, {{true, true, true}});
			TEST_CHECK(h.status().flags & torrent_flags::paused);
		});
}

// make sure the torrent disconnects all its peers when the session is paused
TORRENT_TEST(session_paused_disconnect)
{
	run_test(
		[](lt::session&) {},
		[](lt::session&, lt::torrent_handle h, std::array<fake_peer*, 3>&) {
			add_fake_peers(h, 3);
		},

		[](lt::session& ses, lt::torrent_handle h, std::array<fake_peer*, 3>& test_peers) {
			check_accepted(test_peers, {{true, true, true}});
			check_connected(test_peers, {{true, true, true}});
			check_disconnected(test_peers, {{false, false, false}});
			ses.pause();
		},

		[](lt::session&, lt::torrent_handle h, std::array<fake_peer*, 3>& test_peers) {
			check_disconnected(test_peers, {{true, true, true}});

			// the torrent isn't paused, the session is
			TEST_CHECK(!(h.status().flags & torrent_flags::paused));
		});
}

// make sure a torrent is not connecting to any peers when added to a paused
// session
TORRENT_TEST(paused_session_add_torrent)
{
	run_test(
		[](lt::session& ses) { ses.pause(); },
		[](lt::session&, lt::torrent_handle h, std::array<fake_peer*, 3>&) {
			add_fake_peers(h, 3);
		},

		[](lt::session&, lt::torrent_handle, std::array<fake_peer*, 3>& test_peers) {
			check_accepted(test_peers, {{false, false, false}});
		},

		[](lt::session&, lt::torrent_handle h, std::array<fake_peer*, 3>&) {
			// the torrent isn't paused, the session is
			TEST_CHECK(!(h.status().flags & torrent_flags::paused));
		});
}

// make sure the torrent isn't connecting to peers when it's paused
TORRENT_TEST(paused_torrent_add_peers)
{
	run_test(
		[](lt::session&) {},
		[](lt::session&, lt::torrent_handle h, std::array<fake_peer*, 3>&) {
			h.pause();

			add_fake_peers(h, 3);
		},

		[](lt::session&, lt::torrent_handle, std::array<fake_peer*, 3>& test_peers) {
			check_accepted(test_peers, {{false, false, false}});
		},

		[](lt::session&, lt::torrent_handle h, std::array<fake_peer*, 3>&) {
			TEST_CHECK(h.status().flags & torrent_flags::paused);
		});
}

// make sure we post the torrent_paused alert when pausing a torrent
TORRENT_TEST(torrent_paused_alert)
{
	run_test(
		[](lt::session&) {},
		[](lt::session&, lt::torrent_handle, std::array<fake_peer*, 3>&) {},

		[](lt::session&, lt::torrent_handle h, std::array<fake_peer*, 3>&) {
			TEST_CHECK(!(h.status().flags & torrent_flags::paused));
			h.pause();
		},

		[](lt::session& ses, lt::torrent_handle h, std::array<fake_peer*, 3>&) {
			TEST_CHECK(h.status().flags & torrent_flags::paused);

			std::vector<lt::alert*> alerts;
			ses.pop_alerts(&alerts);

			lt::time_point start_time = alerts[0]->timestamp();

			int num_resume = 0;
			int num_paused = 0;
			for (alert* a : alerts)
			{
				std::printf("%-3d %s\n", int(duration_cast<lt::seconds>(a->timestamp()
						- start_time).count()), a->message().c_str());
				if (lt::alert_cast<torrent_resumed_alert>(a)) ++num_resume;
				if (lt::alert_cast<torrent_paused_alert>(a)) ++num_paused;
			}

			TEST_EQUAL(num_resume, 0);
			TEST_EQUAL(num_paused, 1);
		});
}

// make sure we post the torrent_paused alert when pausing the session
TORRENT_TEST(session_paused_alert)
{
	run_test(
		[](lt::session&) {},
		[](lt::session&, lt::torrent_handle, std::array<fake_peer*, 3>&) {},

		[](lt::session& ses, lt::torrent_handle h, std::array<fake_peer*, 3>&) {
			TEST_CHECK(!(h.status().flags & torrent_flags::paused));
			ses.pause();
		},

		[](lt::session& ses, lt::torrent_handle h, std::array<fake_peer*, 3>&) {
			TEST_CHECK(!(h.status().flags & torrent_flags::paused));

			std::vector<lt::alert*> alerts;
			ses.pop_alerts(&alerts);

			lt::time_point start_time = alerts[0]->timestamp();

			int num_resume = 0;
			int num_paused = 0;
			for (alert* a : alerts)
			{
				std::printf("%-3d %s\n", int(duration_cast<lt::seconds>(a->timestamp()
						- start_time).count()), a->message().c_str());
				if (lt::alert_cast<torrent_resumed_alert>(a)) ++num_resume;
				if (lt::alert_cast<torrent_paused_alert>(a)) ++num_paused;
			}

			TEST_EQUAL(num_resume, 0);
			TEST_EQUAL(num_paused, 1);
		});
}

// make sure we post both the paused and resumed alert when pausing and resuming
// the session.
TORRENT_TEST(session_pause_resume)
{
	run_test(
		[](lt::session&) {},
		[](lt::session& ses, lt::torrent_handle h, std::array<fake_peer*, 3>&) {
			TEST_CHECK(!(h.status().flags & torrent_flags::paused));
			ses.pause();
		},

		[](lt::session& ses, lt::torrent_handle h, std::array<fake_peer*, 3>&) {
			TEST_CHECK(!(h.status().flags & torrent_flags::paused));
			ses.resume();
		},

		[](lt::session& ses, lt::torrent_handle h, std::array<fake_peer*, 3>&) {
			TEST_CHECK(!(h.status().flags & torrent_flags::paused));

			std::vector<lt::alert*> alerts;
			ses.pop_alerts(&alerts);

			lt::time_point start_time = alerts[0]->timestamp();

			int num_resume = 0;
			int num_paused = 0;
			for (alert* a : alerts)
			{
				std::printf("%-3d %s\n", int(duration_cast<lt::seconds>(a->timestamp()
						- start_time).count()), a->message().c_str());
				if (lt::alert_cast<torrent_resumed_alert>(a)) ++num_resume;
				if (lt::alert_cast<torrent_paused_alert>(a)) ++num_paused;
			}

			TEST_EQUAL(num_resume, 1);
			TEST_EQUAL(num_paused, 1);
		});
}

// make sure peers added to a (non-paused) torrent in a paused session are
// connected once the session is resumed
TORRENT_TEST(session_pause_resume_connect)
{
	run_test(
		[](lt::session&) {},
		[](lt::session& ses, lt::torrent_handle h, std::array<fake_peer*, 3>&) {
			TEST_CHECK(!(h.status().flags & torrent_flags::paused));
			ses.pause();
			add_fake_peers(h, 3);
		},

		[](lt::session& ses, lt::torrent_handle h, std::array<fake_peer*, 3>& test_peers) {
			TEST_CHECK(!(h.status().flags & torrent_flags::paused));
			check_accepted(test_peers, {{false, false, false}});
			ses.resume();
		},

		[](lt::session&, lt::torrent_handle h, std::array<fake_peer*, 3>& test_peers) {
			TEST_CHECK(!(h.status().flags & torrent_flags::paused));

			check_accepted(test_peers, {{true, true, true}});
		});
}