/*
    Copyright (C) 2012-2021 Carl Hetherington <cth@carlh.net>

    This file is part of DCP-o-matic.

    DCP-o-matic is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    DCP-o-matic is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with DCP-o-matic.  If not, see <http://www.gnu.org/licenses/>.

*/


/** @file  src/job_manager.cc
 *  @brief A simple scheduler for jobs.
 */


#include "analyse_audio_job.h"
#include "analyse_subtitles_job.h"
#include "cross.h"
#include "film.h"
#include "job.h"
#include "job_manager.h"
#include "util.h"
#include <boost/thread.hpp>


using std::dynamic_pointer_cast;
using std::function;
using std::list;
using std::make_shared;
using std::shared_ptr;
using std::string;
using std::weak_ptr;
using boost::bind;
using boost::optional;


JobManager* JobManager::_instance = nullptr;


JobManager::JobManager()
{

}


void
JobManager::start()
{
	_scheduler = boost::thread(boost::bind(&JobManager::scheduler, this));
#ifdef DCPOMATIC_LINUX
	pthread_setname_np(_scheduler.native_handle(), "job-scheduler");
#endif
}


JobManager::~JobManager()
{
	boost::this_thread::disable_interruption dis;

	for (auto& i: _connections) {
		i.disconnect();
	}

	{
		boost::mutex::scoped_lock lm(_mutex);
		_terminate = true;
		_schedule_condition.notify_all();
	}

	try {
		_scheduler.join();
	} catch (...) {}
}


shared_ptr<Job>
JobManager::add(shared_ptr<Job> j)
{
	{
		boost::mutex::scoped_lock lm(_mutex);
		_jobs.push_back(j);
		_schedule_condition.notify_all();
	}

	emit(boost::bind(boost::ref(JobAdded), weak_ptr<Job>(j)));

	return j;
}


shared_ptr<Job>
JobManager::add_after(shared_ptr<Job> after, shared_ptr<Job> j)
{
	{
		boost::mutex::scoped_lock lm(_mutex);
		auto i = find(_jobs.begin(), _jobs.end(), after);
		DCPOMATIC_ASSERT(i != _jobs.end());
		_jobs.insert(i, j);
		_schedule_condition.notify_all();
	}

	emit(boost::bind(boost::ref(JobAdded), weak_ptr<Job>(j)));

	return j;
}


list<shared_ptr<Job>>
JobManager::get() const
{
	boost::mutex::scoped_lock lm(_mutex);
	return _jobs;
}


bool
JobManager::work_to_do() const
{
	boost::mutex::scoped_lock lm(_mutex);
	auto i = _jobs.begin();
	while (i != _jobs.end() && (*i)->finished()) {
		++i;
	}

	return i != _jobs.end();
}


bool
JobManager::errors() const
{
	boost::mutex::scoped_lock lm(_mutex);
	for (auto i: _jobs) {
		if (i->finished_in_error()) {
			return true;
		}
	}

	return false;
}


void
JobManager::scheduler()
{
	start_of_thread("JobManager");

	while (true) {

		boost::mutex::scoped_lock lm(_mutex);

		if (_terminate) {
			break;
		}

		bool have_running = false;
		for (auto i: _jobs) {
			if ((have_running || _paused) && i->running()) {
				/* We already have a running job, or are totally paused, so this job should not be running */
				i->pause_by_priority();
			} else if (!have_running && !_paused && (i->is_new() || i->paused_by_priority())) {
				/* We don't have a running job, and we should have one, so start/resume this */
				if (i->is_new()) {
					_connections.push_back(i->FinishedImmediate.connect(bind(&JobManager::job_finished, this)));
					i->start();
				} else {
					i->resume();
				}
				auto last = _last_active_job.lock();
				emit(boost::bind(boost::ref(ActiveJobsChanged), last ? last->json_name() : std::string{}, i->json_name()));
				_last_active_job = i;
				have_running = true;
			} else if (!have_running && i->running()) {
				have_running = true;
			}
		}

		_schedule_condition.wait(lm);
	}
}


void
JobManager::job_finished()
{
	{
		boost::mutex::scoped_lock lm(_mutex);
		auto job = _last_active_job.lock();
		emit(boost::bind(boost::ref(ActiveJobsChanged), job ? job->json_name() : string{}, optional<string>()));
		_last_active_job = {};
	}

	_schedule_condition.notify_all();
}


JobManager *
JobManager::instance()
{
	if (!_instance) {
		_instance = new JobManager();
		_instance->start();
	}

	return _instance;
}


void
JobManager::drop()
{
	delete _instance;
	_instance = nullptr;
}


void
JobManager::analyse_audio(
	shared_ptr<const Film> film,
	shared_ptr<const Playlist> playlist,
	bool from_zero,
	boost::signals2::connection& connection,
	function<void (Job::Result)> ready
	)
{
	{
		boost::mutex::scoped_lock lm(_mutex);

		for (auto i: _jobs) {
			auto a = dynamic_pointer_cast<AnalyseAudioJob>(i);
			if (a && a->path() == film->audio_analysis_path(playlist) && !i->finished_cancelled()) {
				i->when_finished(connection, ready);
				return;
			}
		}
	}

	shared_ptr<AnalyseAudioJob> job;

	{
		boost::mutex::scoped_lock lm(_mutex);

		job = make_shared<AnalyseAudioJob>(film, playlist, from_zero);
		connection = job->Finished.connect(ready);
		_jobs.push_back(job);
		_schedule_condition.notify_all();
	}

	emit(boost::bind(boost::ref(JobAdded), weak_ptr<Job>(job)));
}


void
JobManager::analyse_subtitles(
	shared_ptr<const Film> film,
	shared_ptr<Content> content,
	boost::signals2::connection& connection,
	function<void (Job::Result)> ready
	)
{
	{
		boost::mutex::scoped_lock lm(_mutex);

		for (auto i: _jobs) {
			auto a = dynamic_pointer_cast<AnalyseSubtitlesJob>(i);
			if (a && a->path() == film->subtitle_analysis_path(content) && !i->finished_cancelled()) {
				i->when_finished(connection, ready);
				return;
			}
		}
	}

	shared_ptr<AnalyseSubtitlesJob> job;

	{
		boost::mutex::scoped_lock lm(_mutex);

		job = make_shared<AnalyseSubtitlesJob>(film, content);
		connection = job->Finished.connect(ready);
		_jobs.push_back(job);
		_schedule_condition.notify_all();
	}

	emit(boost::bind(boost::ref(JobAdded), weak_ptr<Job>(job)));
}


void
JobManager::increase_priority (shared_ptr<Job> job)
{
	{
		boost::mutex::scoped_lock lm(_mutex);
		auto iter = std::find(_jobs.begin(), _jobs.end(), job);
		if (iter == _jobs.begin() || iter == _jobs.end()) {
			return;
		}
		swap(*iter, *std::prev(iter));
	}

	_schedule_condition.notify_all();
	emit(boost::bind(boost::ref(JobsReordered)));
}


void
JobManager::decrease_priority(shared_ptr<Job> job)
{
	{
		boost::mutex::scoped_lock lm(_mutex);
		auto iter = std::find(_jobs.begin(), _jobs.end(), job);
		if (iter == _jobs.end() || std::next(iter) == _jobs.end()) {
			return;
		}
		swap(*iter, *std::next(iter));
	}

	_schedule_condition.notify_all();
	emit(boost::bind(boost::ref(JobsReordered)));
}


/** Pause all job processing */
void
JobManager::pause()
{
	boost::mutex::scoped_lock lm(_mutex);
	_paused = true;
	_schedule_condition.notify_all();
}


/** Resume processing jobs after a previous pause() */
void
JobManager::resume()
{
	boost::mutex::scoped_lock lm(_mutex);
	_paused = false;
	_schedule_condition.notify_all();
}


void
JobManager::cancel_all_jobs()
{
	boost::mutex::scoped_lock lm(_mutex);
	auto jobs = _jobs;
	lm.unlock();

	/* Calling Job::cancel() will result in JobManager::job_finished() being called, so we need
	 * to do this without a lock on _mutex.  I think the worst case is that we fail to stop a
	 * job that got started since we lm.unlock()ed.
	 */
	for (auto job: jobs) {
		job->cancel();
	}
}