/*
 * Copyright (C) 2018 Paul Davis (paul@linuxaudiosystems.com)
 *
 * This program 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, or (at your option)
 * any later version.
 *
 * This program 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 this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#include "pbd/i18n.h"

#include "ardour/audioengine.h"
#include "ardour/debug.h"
#include "ardour/disk_reader.h"
#include "ardour/session.h"
#include "ardour/transport_master_manager.h"

#if __cplusplus > 199711L
#define local_signbit(x) std::signbit (x)
#else
#define local_signbit(x) ((((__int64*)(&z))*) & 0x8000000000000000)
#endif

using namespace ARDOUR;
using namespace PBD;

const std::string TransportMasterManager::state_node_name = X_("TransportMasters");
TransportMasterManager* TransportMasterManager::_instance = 0;

TransportMasterManager::TransportMasterManager()
	: _master_speed (0)
	, _master_position (0)
	, _current_master (0)
	, _session (0)
	, _master_invalid_this_cycle (false)
	, master_dll_initstate (0)
{
}

TransportMasterManager::~TransportMasterManager ()
{
	clear ();
}

int
TransportMasterManager::init ()
{
	try {
		/* setup default transport masters. Most people will never need any
		   others
		*/
		add (Engine, X_("JACK Transport"));
		add (MTC, X_("MTC"));
		add (LTC, X_("LTC"));
		add (MIDIClock, X_("MIDI Clock"));
	} catch (...) {
		return -1;
	}

	_current_master = _transport_masters.back();

	return 0;
}

void
TransportMasterManager::set_session (Session* s)
{
	/* Called by AudioEngine in process context, synchronously with it's
	 * own "adoption" of the Session. The call will occur before the first
	 * call to ::pre_process_transport_masters().
	 */

	Glib::Threads::RWLock::ReaderLock lm (lock);

	config_connection.disconnect ();

	_session = s;

	for (TransportMasters::iterator tm = _transport_masters.begin(); tm != _transport_masters.end(); ++tm) {
		(*tm)->set_session (s);
	}

	if (_session) {
		_session->config.ParameterChanged.connect_same_thread (config_connection, boost::bind (&TransportMasterManager::parameter_changed, this, _1));
	}

}

void
TransportMasterManager::parameter_changed (std::string const & what)
{
	if (what == "external-sync") {
		if (!_session->config.get_external_sync()) {
			/* disabled */
			DiskReader::set_no_disk_output (false);
		}
	}
}

TransportMasterManager&
TransportMasterManager::instance()
{
	if (!_instance) {
		_instance = new TransportMasterManager();
	}
	return *_instance;
}

// Called from AudioEngine::process_callback() BEFORE Session::process() is called. Each transport master has processed any incoming data for this cycle,
// and this method computes the transport speed that Ardour should use to get into and remain in sync with the master.
//
double
TransportMasterManager::pre_process_transport_masters (pframes_t nframes, samplepos_t now)
{
	Glib::Threads::RWLock::ReaderLock lm (lock, Glib::Threads::TRY_LOCK);

	if (!lm.locked()) {
		return 1.0;
	}

	boost::optional<samplepos_t> session_pos;

	if (_session) {
		session_pos = _session->audible_sample();
	}

	if (Config->get_run_all_transport_masters_always()) {
		for (TransportMasters::iterator tm = _transport_masters.begin(); tm != _transport_masters.end(); ++tm) {
			if ((*tm)->check_collect()) {
				(*tm)->pre_process (nframes, now, session_pos);
			}
		}
	}

	if (!_session) {
		return 1.0;
	}

	/* if we're not running ALL transport masters, but still have a current
	 * one, then we should run that one all the time so that we know
	 * precisely where it is when we starting chasing it ...
	 */

	if (!Config->get_run_all_transport_masters_always() && _current_master) {
		_current_master->pre_process (nframes, now, session_pos);
	}

	if (!_session->config.get_external_sync()) {
		DEBUG_TRACE (DEBUG::Slave, string_compose ("no external sync, use session actual speed of %1\n", _session->actual_speed() ? _session->actual_speed() : 1.0));
		return _session->actual_speed () ? _session->actual_speed() : 1.0;
	}

	/* --- NOT REACHED UNLESS CHASING (i.e. _session->config.get_external_sync() is true ------*/

	if (!_current_master->ok()) {
		/* stop */
		_session->request_transport_speed (0.0, false, _current_master->request_type());
		DEBUG_TRACE (DEBUG::Slave, "no roll2 - master has failed\n");
		_master_invalid_this_cycle = true;
		return 1.0;
	}

	if (!_current_master->locked()) {
		DEBUG_TRACE (DEBUG::Slave, "no roll4 - not locked\n");
		_master_invalid_this_cycle = true;
		return 1.0;
	}

	double engine_speed;

	if (!_current_master->speed_and_position (_master_speed, _master_position, now)) {
		return 1.0;
	}

	if (_master_speed != 0.0) {

		samplepos_t delta = _master_position;

		if (_session->compute_audible_delta (delta)) {

			if (master_dll_initstate == 0) {

				init_transport_master_dll (_master_speed, _master_position);
				// _master_invalid_this_cycle = true;
				DEBUG_TRACE (DEBUG::Slave, "no roll3 - still initializing master DLL\n");
				master_dll_initstate = _master_speed > 0.0 ? 1 : -1;

				return 1.0;
			}

			/* compute delta or "error" between the computed master_position for
			 * this cycle and the current session position.
			 *
			 * Remember: ::speed_and_position() is being called in process context
			 * but returns the predicted speed+position for the start of this process cycle,
			 * not just the most recent timestamp received by the current master object.
			 */

			DEBUG_TRACE (DEBUG::Slave, string_compose ("master DLL: delta = %1 (%2 vs %3) res: %4\n", delta, _master_position, _session->transport_sample(), _current_master->resolution()));

			if (delta > _current_master->resolution()) {

				// init_transport_master_dll (_master_speed, _master_position);

				if (!_session->actively_recording()) {
					DEBUG_TRACE (DEBUG::Slave, string_compose ("slave delta %1 greater than slave resolution %2 => no disk output\n", delta, _current_master->resolution()));
					/* run routes as normal, but no disk output */
					DiskReader::set_no_disk_output (true);
				} else {
					DiskReader::set_no_disk_output (false);
				}
			} else {
				DiskReader::set_no_disk_output (false);
			}

			/* inject DLL with new data */

			DEBUG_TRACE (DEBUG::Slave, string_compose ("feed master DLL t0 %1 t1 %2 e %3 %4 e2 %5 sess %6\n", t0, t1, delta, _master_position, e2, _session->transport_sample()));

			const double e = delta;

			t0 = t1;
			t1 += b * e + e2;
			e2 += c * e;

			engine_speed = (t1 - t0) / nframes;

			DEBUG_TRACE (DEBUG::Slave, string_compose ("slave @ %1 speed %2 cur delta %3 matching speed %4\n", _master_position, _master_speed, delta, engine_speed));

			/* provide a .1% deadzone to lock the speed */
			if (fabs (engine_speed - 1.0) <= 0.001) {
				engine_speed = 1.0;
			}

			if (_current_master->sample_clock_synced() && engine_speed != 0.0f) {

				/* if the master is synced to our audio interface via word-clock or similar, then we assume that its speed is binary: 0.0 or 1.0
				   (since our sample clock cannot change with respect to it).
				*/
				if (engine_speed > 0.0) {
					engine_speed = 1.0;
				} else if (engine_speed < 0.0) {
					engine_speed = -1.0;
				}
			}

			/* speed is set, we're locked, and good to go */
			DEBUG_TRACE (DEBUG::Slave, string_compose ("%1: computed speed-to-follow-master as %2\n", _current_master->name(), engine_speed));

		} else {

			/* session has not finished with latency compensation yet, so we cannot compute the
			   difference between the master and the session.
			*/
			engine_speed = 1.0;
		}

	} else {

		engine_speed = 1.0;
	}

	_master_invalid_this_cycle = false;

	DEBUG_TRACE (DEBUG::Slave, string_compose ("computed resampling ratio as %1 with position = %2 and speed = %3\n", engine_speed, _master_position, _master_speed));

	return engine_speed;
}


void
TransportMasterManager::init_transport_master_dll (double speed, samplepos_t pos)
{
	/* the bandwidth of the DLL is a trade-off,
	 * because the max-speed of the transport in ardour is
	 * limited to +-8.0, a larger bandwidth would cause oscillations
	 *
	 * But this is only really a problem if the user performs manual
	 * seeks while transport is running and slaved to some timecode-y master.
	 */

	AudioEngine* ae = AudioEngine::instance();

	double const omega = 2.0 * M_PI * double(ae->samples_per_cycle()) / 2.0 / double(ae->sample_rate());
	b = 1.4142135623730950488 * omega;
	c = omega * omega;

	const int direction = (speed >= 0.0 ? 1 : -1);

	master_dll_initstate = direction;

	e2 = double (direction * ae->samples_per_cycle());
	t0 = double (pos);
	t1 = t0 + e2;

	DEBUG_TRACE (DEBUG::Slave, string_compose ("[re-]init ENGINE DLL %1 %2 %3 from %4 %5\n", t0,  t1, e2, speed, pos));
}

int
TransportMasterManager::add (SyncSource type, std::string const & name)
{
	int ret = 0;
	boost::shared_ptr<TransportMaster> tm;

	{
		Glib::Threads::RWLock::WriterLock lm (lock);
		tm = TransportMaster::factory (type, name);
		ret = add_locked (tm);
	}

	if (ret == 0) {
		Added (tm);
	}

	return ret;
}

int
TransportMasterManager::add_locked (boost::shared_ptr<TransportMaster> tm)
{
	if (!tm) {
		return -1;
	}

	for (TransportMasters::const_iterator t = _transport_masters.begin(); t != _transport_masters.end(); ++t) {
		if ((*t)->name() == tm->name()) {
			error << string_compose (_("There is already a transport master named \"%1\" - not duplicated"), tm->name()) << endmsg;
			return -1;
		}
	}

	_transport_masters.push_back (tm);
	return 0;
}

int
TransportMasterManager::remove (std::string const & name)
{
	int ret = -1;
	boost::shared_ptr<TransportMaster> tm;

	{
		Glib::Threads::RWLock::WriterLock lm (lock);

		for (TransportMasters::iterator t = _transport_masters.begin(); t != _transport_masters.end(); ++t) {
			if ((*t)->name() == name) {
				tm = *t;
				_transport_masters.erase (t);
				ret = 0;
				break;
			}
		}
	}

	if (ret == 0 && tm) {
		Removed (tm);
	}

	return -1;
}

int
TransportMasterManager::set_current_locked (boost::shared_ptr<TransportMaster> c)
{
	if (find (_transport_masters.begin(), _transport_masters.end(), c) == _transport_masters.end()) {
		warning << string_compose (X_("programming error: attempt to use unknown transport master named \"%1\"\n"), c->name());
		return -1;
	}

	_current_master = c;
	_master_speed = 0;
	_master_position = 0;

	master_dll_initstate = 0;

	DEBUG_TRACE (DEBUG::Slave, string_compose ("current transport master set to %1\n", c->name()));

	return 0;
}

int
TransportMasterManager::set_current (boost::shared_ptr<TransportMaster> c)
{
	int ret = -1;
	boost::shared_ptr<TransportMaster> old (_current_master);

	{
		Glib::Threads::RWLock::WriterLock lm (lock);
		ret = set_current_locked (c);
	}

	if (ret == 0) {
		CurrentChanged (old, _current_master); // EMIT SIGNAL
	}

	return ret;
}

int
TransportMasterManager::set_current (SyncSource ss)
{
	int ret = -1;
	boost::shared_ptr<TransportMaster> old (_current_master);

	{
		Glib::Threads::RWLock::WriterLock lm (lock);

		for (TransportMasters::iterator t = _transport_masters.begin(); t != _transport_masters.end(); ++t) {
			if ((*t)->type() == ss) {
				ret = set_current_locked (*t);
				break;
			}
		}
	}

	if (ret == 0) {
		CurrentChanged (old, _current_master); // EMIT SIGNAL
	}

	return ret;
}


int
TransportMasterManager::set_current (std::string const & str)
{
	int ret = -1;
	boost::shared_ptr<TransportMaster> old (_current_master);

	{
		Glib::Threads::RWLock::WriterLock lm (lock);

		for (TransportMasters::iterator t = _transport_masters.begin(); t != _transport_masters.end(); ++t) {
			if ((*t)->name() == str) {
				ret = set_current_locked (*t);
				break;
			}
		}
	}

	if (ret == 0) {
		CurrentChanged (old, _current_master); // EMIT SIGNAL
	}

	return ret;
}


void
TransportMasterManager::clear ()
{
	{
		Glib::Threads::RWLock::WriterLock lm (lock);
		_transport_masters.clear ();
	}

	Removed (boost::shared_ptr<TransportMaster>());
}

int
TransportMasterManager::set_state (XMLNode const & node, int version)
{
	assert (node.name() == state_node_name);

	XMLNodeList const & children = node.children();


	if (!children.empty()) {
		_transport_masters.clear ();
	}

	{
		Glib::Threads::RWLock::WriterLock lm (lock);


		for (XMLNodeList::const_iterator c = children.begin(); c != children.end(); ++c) {

			boost::shared_ptr<TransportMaster> tm = TransportMaster::factory (**c);

			if (add_locked (tm)) {
				continue;
			}

			/* we know it is the last thing added to the list of masters */

			_transport_masters.back()->set_state (**c, version);
		}
	}

	std::string current_master;
	if (node.get_property (X_("current"), current_master)) {
		set_current (current_master);
	} else {
		set_current (MTC);
	}

	return 0;
}

XMLNode&
TransportMasterManager::get_state ()
{
	XMLNode* node = new XMLNode (state_node_name);

	node->set_property (X_("current"), _current_master->name());

	Glib::Threads::RWLock::ReaderLock lm (lock);

	for (TransportMasters::iterator t = _transport_masters.begin(); t != _transport_masters.end(); ++t) {
		node->add_child_nocopy ((*t)->get_state());
	}

	return *node;
}

boost::shared_ptr<TransportMaster>
TransportMasterManager::master_by_type (SyncSource src) const
{
	Glib::Threads::RWLock::ReaderLock lm (lock);

	for (TransportMasters::const_iterator tm = _transport_masters.begin(); tm != _transport_masters.end(); ++tm) {
		if ((*tm)->type() == src) {
			return *tm;
		}
	}

	return boost::shared_ptr<TransportMaster> ();
}