/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/***************************************************************************
 *            inputprocessor.cc
 *
 *  Sat Apr 23 20:39:30 CEST 2016
 *  Copyright 2016 Andr� Nusser
 *  andre.nusser@googlemail.com
 ****************************************************************************/

/*
 *  This file is part of DrumGizmo.
 *
 *  DrumGizmo is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation; either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  DrumGizmo 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 Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public License
 *  along with DrumGizmo; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 */
#include "inputprocessor.h"

#include <list>

#include <hugin.hpp>
#include <fstream>
#include <algorithm>

#include "instrument.h"

#include "staminafilter.h"
#include "latencyfilter.h"
#include "velocityfilter.h"

#include "cpp11fix.h"

//TODO: This is just for development purposes. Remove when done.
#include "tracer.h"

//Anonymous namespace for local functions.
namespace
{

//! Applies choke with rampdown time in ms to event starting at offset.
static void applyChoke(Settings& settings, EventSample& event,
                       double length_ms, timepos_t offset)
{
	std::size_t ramp_length = (length_ms / 1000.) * settings.samplerate.load();
	event.rampdown_count = ramp_length;
	event.rampdown_offset = offset;
	event.ramp_length = ramp_length;
}

//! Applies choke group actions to active events based on the input event
static void applyChokeGroup(Settings& settings, DrumKit& kit,
                            Instrument& instr, event_t& event,
                            std::list<Event*>* activeevents)
{
	std::size_t instrument_id = event.instrument;
	if(instr.getGroup() == "")
	{
		return;
	}

	// Add event to ramp down all existing events with the same groupname.
	for(const auto& ch : kit.channels)
	{
		for(auto active_event : activeevents[ch.num])
		{
			if(active_event->getType() == Event::sample)
			{
				auto& event_sample = *static_cast<EventSample*>(active_event);
				if(event_sample.group == instr.getGroup() &&
				   event_sample.instrument_id != instrument_id &&
				   event_sample.rampdown_count == -1) // Only if not already ramping.
				{
					// Fixed group rampdown time of 68ms, independent of samplerate
					applyChoke(settings, event_sample, 68, event.offset);
				}
			}
		}
	}
}

//! Applies directed choke actions to active events based on the input event
static void applyDirectedChoke(Settings& settings, DrumKit& kit,
                               Instrument& instr, event_t& event,
                               std::list<Event*>* activeevents)
{
	for(const auto& choke : instr.getChokes())
	{
		// Add event to ramp down all existing events with the same groupname.
		for(const auto& ch : kit.channels)
		{
			for(auto active_event : activeevents[ch.num])
			{
				if(active_event->getType() == Event::sample)
				{
					auto& event_sample = *static_cast<EventSample*>(active_event);
					if(choke.instrument_id == event_sample.instrument_id &&
					   event_sample.rampdown_count == -1) // Only if not already ramping.
					{
						// choke.choketime is in ms
						applyChoke(settings, event_sample, choke.choketime, event.offset);
					}
				}
			}
		}

	}
}
} //End of anonymous namespace.

InputProcessor::InputProcessor(Settings& settings,
                               DrumKit& kit,
                               std::list<Event*>* activeevents,
                               Random& random)
	: kit(kit)
	, activeevents(activeevents)
	, is_stopping(false)
	, settings(settings)
	, insert_group_id(0)
{
	tracer::trace("building InputProcessor", '\n');

	// Build filter list
	filters.emplace_back(std::make_unique<StaminaFilter>(settings));
	filters.emplace_back(std::make_unique<LatencyFilter>(settings, random));
	filters.emplace_back(std::make_unique<VelocityFilter>(settings, random));
}

bool InputProcessor::process(std::vector<event_t>& events,
                             std::size_t pos,
                             double resample_ratio)
{
	for(auto& event: events)
	{
		if(event.type == EventType::OnSet)
		{
			if(!processOnset(event, pos, resample_ratio))
			{
				continue;
			}
		}

		if(event.type == EventType::Choke)
		{
			if(!processChoke(event, pos, resample_ratio))
			{
				continue;
			}
		}

		if(!processStop(event))
		{
			return false;
		}
	}

	return true;
}

std::size_t InputProcessor::getLatency() const
{
	std::size_t latency = 0;

	for(const auto& filter : filters)
	{
		latency += filter->getLatency();
	}

	return latency;
}

bool InputProcessor::processOnset(event_t& event, std::size_t pos,
                                  double resample_ratio)
{
	tracer::trace("processOnset was called", '\n');

	if(!kit.isValid())
	{
		return false;
	}

	std::size_t instrument_id = event.instrument;
	Instrument* instr = nullptr;

	if(instrument_id < kit.instruments.size())
	{
		instr = kit.instruments[instrument_id].get();
	}

	if(instr == nullptr || !instr->isValid())
	{
		ERR(inputprocessor, "Missing Instrument %d.\n", (int)instrument_id);
		return false;
	}

	auto const original_level = event.velocity;
	for(auto& filter : filters)
	{
		// This line might change the 'event' variable
		bool keep = filter->filter(event, event.offset + pos);

		if(!keep)
		{
			return false; // Skip event completely
		}
	}
	
	//TODO: A lookup map would be much better...
	const size_t max_voices=getMaxVoicesForInstrument(instrument_id);
	//TODO: Somehow this seems like a very specific case of a group.
	applyVoiceLimit(event, max_voices);

	// Mute other instruments in the same group
	applyChokeGroup(settings, kit, *instr, event, activeevents);

	// Apply directed chokes to mute other instruments if needed
	applyDirectedChoke(settings, kit, *instr, event, activeevents);

	auto const power_max = instr->getMaxPower();
	auto const power_min = instr->getMinPower();
	float const power_span = power_max - power_min;
	float const instrument_level = power_min + event.velocity*power_span;
	const auto sample = instr->sample(instrument_level, event.offset + pos);

	if(sample == nullptr)
	{
		ERR(inputprocessor, "Missing Sample.\n");
		return false;
	}

	auto const selected_level = (sample->getPower() - power_min)/power_span;
	settings.velocity_modifier_current.store(selected_level/original_level);

	++insert_group_id; //Insert group id 0 is not allowed.
	for(Channel& ch: kit.channels)
	{
		const auto af = sample->getAudioFile(ch);
		if(af == nullptr || !af->isValid())
		{
			//DEBUG(inputprocessor, "Missing AudioFile.\n");
			continue;
		}
		
		//DEBUG(inputprocessor, "Adding event %d.\n", event.offset);
		auto evt = new EventSample(ch.num, 1.0, af, instr->getGroup(),
		                           instrument_id,
		                           insert_group_id);
		evt->offset = (event.offset + pos) * resample_ratio;
		if(settings.normalized_samples.load() && sample->getNormalized())
		{
			evt->scale *= event.velocity;
		}

		tracer::trace("event added to channel ", ch.num, " for instrument id ", instrument_id, '\n');

		activeevents[ch.num].push_back(evt);
	}

	return true;
}

bool InputProcessor::processChoke(event_t& event,
                                  std::size_t pos,
                                  double resample_ratio)
{
	if(!kit.isValid())
	{
		return false;
	}

	std::size_t instrument_id = event.instrument;
	Instrument* instr = nullptr;

	if(instrument_id < kit.instruments.size())
	{
		instr = kit.instruments[instrument_id].get();
	}

	if(instr == nullptr || !instr->isValid())
	{
		ERR(inputprocessor, "Missing Instrument %d.\n", (int)instrument_id);
		return false;
	}

	for(auto& filter : filters)
	{
		// This line might change the 'event' variable
		bool keep = filter->filter(event, event.offset + pos);

		if(!keep)
		{
			return false; // Skip event completely
		}
	}

	// Add event to ramp down all existing events with the same groupname.
	for(const auto& ch : kit.channels)
	{
		for(auto active_event : activeevents[ch.num])
		{
			if(active_event->getType() == Event::sample)
			{
				auto& event_sample = *static_cast<EventSample*>(active_event);
				if(event_sample.instrument_id == instrument_id &&
				   event_sample.rampdown_count == -1) // Only if not already ramping.
				{
					// Fixed group rampdown time of 68ms, independent of samplerate
					applyChoke(settings, event_sample, 68, event.offset);
				}
			}
		}
	}

	return true;
}

bool InputProcessor::processStop(event_t& event)
{
	if(event.type == EventType::Stop)
	{
		is_stopping = true;
	}

	if(is_stopping)
	{
		// Count the number of active events.
		int num_active_events = 0;
		for(auto& ch: kit.channels)
		{
			num_active_events += activeevents[ch.num].size();
		}

		if(num_active_events == 0)
		{
			// No more active events - now we can stop the engine.
			return false;
		}
	}

	return true;
}

//TODO: Document.
void InputProcessor::applyVoiceLimit(const event_t& event, size_t max_voices)
{
	//Find out how many voices for the instrument we are currently playing...
	const auto instrument_id = event.instrument;
	size_t current_count{0};

	tracer::trace("applyVoiceLimit will count for instrument id ", instrument_id, '\n');

	for(const auto& ch : kit.channels)
	{
		current_count+=std::count_if(std::begin(activeevents[ch.num]),
		                             std::end(activeevents[ch.num]),
		                             [instrument_id](Event const * active_event)
									 {
										return active_event->getType() == Event::sample
											&& static_cast<EventSample const *>(active_event)->instrument_id == instrument_id;
									 });
	}

	//Early exit if the max number of voices has yet to be reached...
	tracer::trace("found ", current_count, " for instrument id ", instrument_id, '\n');
	if(current_count <= max_voices) 
	{
		return;
	}

	//Locate the earliest sample group for this instrument that is not ramping.
	tracer::trace("locating earliest sample group\n");
	std::size_t earliest_group{0};

	for(const auto& ch : kit.channels)
	{
		for(const auto active_event : activeevents[ch.num])
		{
			if(active_event->getType() == Event::sample)
			{
				auto& event_sample = *static_cast<EventSample*>(active_event);

				//Same instrument, not ramping, with a lesser group.
				if(event_sample.instrument_id != instrument_id
				   && -1 == event_sample.rampdown_count
				   //TODO: Not proud of this, not proud of it at all.
				   && (event_sample.insert_group_id < earliest_group
				       || 0 == earliest_group))
				{
					earliest_group=event_sample.insert_group_id;
				}
			}
		}
	}

	tracer::trace("earliest sample group was ", earliest_group, '\n');

	//Ramp down everyone belonging to that group...
	for(const auto& ch : kit.channels)
	{
		for(auto active_event : activeevents[ch.num])
		{
			if(active_event->getType() == Event::sample)
			{
				auto& event_sample = *static_cast<EventSample*>(active_event);
				if(event_sample.insert_group_id == earliest_group)
				{
					tracer::trace("found and ramping in channel ", ch.num, '\n');
					applyChoke(settings, event_sample, 68, event.offset);
				}
			}
		}
	}
}

//TODO: Document.
size_t InputProcessor::getMaxVoicesForInstrument(size_t instrument_id) const 
{
	//TODO: This would depend on the configuration set on the GUI.
	return 16;
}