/**

 * Relational pipes

 * Copyright © 2020 František Kučera (Frantovo.cz, GlobalCode.info)

 *

 * 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, version 3 of the License.

 *

 * 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, see <http://www.gnu.org/licenses/>.

 */

#pragma once

#include <memory>

#include <atomic>

#include <string>

#include <cstring>

#include <vector>

#include <codecvt>

#include <sys/mman.h>

#include <unistd.h>

#include <pthread.h>

#include <jack/jack.h>

#include <jack/midiport.h>

#include <jack/ringbuffer.h>

#include <relpipe/common/type/typedefs.h>

#include <relpipe/reader/TypeId.h>

#include <relpipe/reader/handlers/RelationalReaderStringHandler.h>

#include <relpipe/reader/handlers/AttributeMetadata.h>

#include "Configuration.h"

#include "JackException.h"

namespace relpipe {

namespace out {

namespace jack {

int dequeueMessages(jack_nframes_t frames, void* arg);

class JackHandler : public relpipe::reader::handlers::RelationalReaderStringHandler {

private:

	Configuration& configuration;

	std::wstring_convert<std::codecvt_utf8<wchar_t>> convertor; // TODO: local system encoding

	std::atomic<bool> continueProcessing{true};

	/**

	 * Is passed through the ring buffer

	 * from the relpipe-reading thread to the jack-writing thread (callback).

	 */

	struct MidiMessage {

		uint8_t buffer[4096] = {0};

		size_t size;

	};

	/**

	 * JACK callbacks (called from the real-time thread)

	 */

	class RealTimeContext {

	public:

		jack_client_t* jackClient = nullptr;

		jack_port_t* jackPort = nullptr;

		jack_ringbuffer_t* ringBuffer = nullptr;

		pthread_mutex_t processingLock = PTHREAD_MUTEX_INITIALIZER;

		pthread_cond_t processingDone = PTHREAD_COND_INITIALIZER;

		const int RING_BUFFER_SIZE = 100;

		int processCallback(jack_nframes_t frames) {

			void* jackPortBuffer = jack_port_get_buffer(jackPort, frames); // jack_port_get_buffer() must be called outside the loop, otherwise it will multiply the MIDI events

			}

			if (pthread_mutex_trylock(&processingLock) == 0) {

				pthread_cond_signal(&processingDone);

				pthread_mutex_unlock(&processingLock);

			}

			return 0;

		}

		int syncCallback(jack_transport_state_t state, jack_position_t* position) {

			return true;

		}

		static int processCallback(jack_nframes_t frames, void* instance) {

			return static_cast<RealTimeContext*> (instance)->processCallback(frames);

		}

		static int syncCallback(jack_transport_state_t state, jack_position_t* position, void* instance) {

			return static_cast<RealTimeContext*> (instance)->syncCallback(state, position);

		}

	} realTimeContext;

	/**

	 * Temporary storage of values read from relational input.

	 */

	class RelationContext {

	public:

		bool skip = false;

		std::vector<relpipe::reader::handlers::AttributeMetadata> attributes;

		bool hasAttribute(const relpipe::common::type::StringX& name) {

			for (auto a : attributes) if (a.getAttributeName() == name) return true;

			return false;

		}

		class RecordContext {

		public:

			enum class Event {

				NOTE,

				CONTROL,

				SYSEX,

				CONNECT,

				DISCONNECT,

				UNKNOWN

			};

			static Event parseEventType(const relpipe::common::type::StringX& name) {

				if (name == L"note") return Event::NOTE;

				else if (name == L"control") return Event::CONTROL;

				else if (name == L"sysex") return Event::SYSEX;

				else if (name == L"connect") return Event::CONNECT;

				else if (name == L"disconnect") return Event::DISCONNECT;

				else return Event::UNKNOWN;

			}

			Event event = Event::UNKNOWN;

			relpipe::common::type::Integer channel;

			relpipe::common::type::Boolean noteOn;

			relpipe::common::type::Integer notePitch;

			relpipe::common::type::Integer noteVelocity;

			relpipe::common::type::Integer controllerId;

			relpipe::common::type::Integer controllerValue;

			relpipe::common::type::StringX raw;

			relpipe::common::type::StringX connectionSourcePort;

			relpipe::common::type::StringX connectionDestinationPort;

			size_t attributeIndex = 0;

		} recordContext;

	} relationContext;

	static void jackErrorCallback(const char * message) {

		std::wstring_convert < std::codecvt_utf8<wchar_t>> convertor; // TODO: local system encoding

		std::wcerr << L"JACK: " << convertor.from_bytes(message) << std::endl;

	}

	void finalize() {

		// Close JACK connection:

		jack_deactivate(realTimeContext.jackClient);

		jack_client_close(realTimeContext.jackClient);

		jack_ringbuffer_free(realTimeContext.ringBuffer);

		pthread_mutex_unlock(&realTimeContext.processingLock);

	}

	void failInConstructor(const relpipe::common::type::StringX& errorMessage) {

		finalize();

		throw JackException(errorMessage);

	}

	/**

	 * Wait for the signal that is emitted at the end of the real-time processCallback() cycle.

	 */

	void waitForRTCycle() {

		pthread_cond_wait(&realTimeContext.processingDone, &realTimeContext.processingLock);

	}

public:

	JackHandler(Configuration& configuration) : configuration(configuration) {

		pthread_mutex_lock(&realTimeContext.processingLock);

		// Initialize JACK connection:

		std::string clientName = convertor.to_bytes(configuration.client);

		realTimeContext.jackClient = jack_client_open(clientName.c_str(), JackNullOption, nullptr);

		if (realTimeContext.jackClient == nullptr) failInConstructor(L"Could not create JACK client.");

		realTimeContext.ringBuffer = jack_ringbuffer_create(realTimeContext.RING_BUFFER_SIZE * sizeof (MidiMessage));

		jack_set_process_callback(realTimeContext.jackClient, RealTimeContext::processCallback, &realTimeContext);

		jack_set_sync_callback(realTimeContext.jackClient, RealTimeContext::syncCallback, &realTimeContext);

		// TODO: report also other events (connections etc.)

		jack_set_error_function(jackErrorCallback);

		jack_set_info_function(jackErrorCallback);

		realTimeContext.jackPort = jack_port_register(realTimeContext.jackClient, convertor.to_bytes(configuration.port).c_str(), JACK_DEFAULT_MIDI_TYPE, JackPortIsOutput, 0);

		if (realTimeContext.jackPort == nullptr) failInConstructor(L"Could not register the JACK port.");

		if (mlockall(MCL_CURRENT | MCL_FUTURE)) fwprintf(stderr, L"Warning: Can not lock memory.\n");

		int jackError = jack_activate(realTimeContext.jackClient);

		if (jackError) failInConstructor(L"Could not activate the JACK client.");

		// Connect to configured destination ports:

		const char* jackPortName = jack_port_name(realTimeContext.jackPort);

		for (auto destinationPort : configuration.connectTo) {

			int error = jack_connect(realTimeContext.jackClient, jackPortName, convertor.to_bytes(destinationPort).c_str());

			if (error) failInConstructor(L"Connection to the JACK port failed: " + destinationPort);

		}

		// Wait for a port connection, because it does not make much sense to send MIDI events nowhere:

		while (jack_port_connected(realTimeContext.jackPort) < configuration.requiredConnections) usleep(10000);

	}

	void startRelation(const relpipe::common::type::StringX name, std::vector<relpipe::reader::handlers::AttributeMetadata> attributes) override {

		relationContext = RelationContext();

		relationContext.attributes = attributes;

		// TODO: configurable relation name

		if (!relationContext.hasAttribute(L"event")) {

			relationContext.skip = true;

			fwprintf(stderr, L"Relation „%ls“ will be ignored because mandatory attribute „event“ is missing.\n", name.c_str());

		}

	}

	void attribute(const relpipe::common::type::StringX& value) override {

		if (relationContext.skip) return;

		// TODO: switch to RelationalReaderValueHandler

		RelationContext& rel = relationContext;

		RelationContext::RecordContext& rec = rel.recordContext;

		const auto attributeName = rel.attributes[rec.attributeIndex].getAttributeName();

		if (attributeName == L"event") rec.event = rec.parseEventType(value);

		else if (attributeName == L"channel") rec.channel = std::stoi(value);

		else if (attributeName == L"controller_id") rec.controllerId = std::stoi(value);

		else if (attributeName == L"controller_value") rec.controllerValue = std::stoi(value);

		else if (attributeName == L"note_on") rec.noteOn = value == L"true";

		else if (attributeName == L"note_pitch") rec.notePitch = std::stoi(value);

		else if (attributeName == L"note_velocity") rec.noteVelocity = std::stoi(value);

		else if (attributeName == L"raw") rec.raw = value;

		else if (attributeName == L"source_port") rec.connectionSourcePort = value;

		else if (attributeName == L"destination_port") rec.connectionDestinationPort = value;

		rec.attributeIndex++;

		if (rec.attributeIndex == rel.attributes.size()) {

			if (!continueProcessing) return;

			MidiMessage m;

			m.size = 0;

			if (rec.event == RelationContext::RecordContext::Event::NOTE) {

				m.size = 3;

				m.buffer[0] = (rec.noteOn ? 0x90 : 0x80) | rec.channel;

				m.buffer[1] = rec.notePitch;

				m.buffer[2] = rec.noteVelocity;

			} else if (rec.event == RelationContext::RecordContext::Event::CONTROL) {

				m.size = 3;

				m.buffer[0] = 0xB0 | rec.channel;

				m.buffer[1] = rec.controllerId;

				m.buffer[2] = rec.controllerValue;

			} else if (rec.event == RelationContext::RecordContext::Event::CONNECT) {

				int result = jack_connect(realTimeContext.jackClient, convertor.to_bytes(rec.connectionSourcePort).c_str(), convertor.to_bytes(rec.connectionDestinationPort).c_str());

				if (result != 0 && result != EEXIST) std::wcerr << L"Unable to connect: „" << rec.connectionSourcePort << L"“ to: „" << rec.connectionDestinationPort << L"“." << std::endl;

			} else if (rec.event == RelationContext::RecordContext::Event::DISCONNECT) {

				int result = jack_disconnect(realTimeContext.jackClient, convertor.to_bytes(rec.connectionSourcePort).c_str(), convertor.to_bytes(rec.connectionDestinationPort).c_str());

				if (result != 0) std::wcerr << L"Unable to disconnect: „" << rec.connectionSourcePort << L"“ from: „" << rec.connectionDestinationPort << L"“." << std::endl;

			} else { // SysEx and other raw messages

				size_t nibble = 0;

				for (int i = 0; i < rec.raw.size() && m.size < sizeof (m.buffer); i++) {

					wchar_t ch = rec.raw[i];

					if (ch == L' ') continue;

					else if (ch >= L'0' && ch <= L'9') m.buffer[m.size] += (ch - '0') /**/ << (nibble % 2 ? 0 : 4);

					else if (ch >= L'a' && ch <= L'f') m.buffer[m.size] += (ch - 'a' + 10) << (nibble % 2 ? 0 : 4);

					else if (ch >= L'A' && ch <= L'F') m.buffer[m.size] += (ch - 'A' + 10) << (nibble % 2 ? 0 : 4);

					else throw JackException(L"Invalid character in the hexadeximal sequence: „" + std::wstring(1, ch) + L"“.");

					nibble++;

					if (nibble % 2 == 0) m.size++;

				}

			}

			if (m.size > 0) jack_ringbuffer_write(realTimeContext.ringBuffer, (const char *) &m, sizeof (m));

			relationContext.recordContext = RelationContext::RecordContext();

		}

	}

	void endOfPipe() {

		// TODO: optionally mute all; probably enabled by default

		// Wait until the ring buffer is empty (messages dequeued from the buffer) and real-time cycle was finished (messages passed to JACK)

		while (continueProcessing && jack_ringbuffer_read_space(realTimeContext.ringBuffer)) pthread_cond_wait(&realTimeContext.processingDone, &realTimeContext.processingLock);

		// There might be a (rare) race condition.

		// Between jack_ringbuffer_read_space() and pthread_cond_wait() the real-time thread might finish the cycle and we will miss the pthread_cond_signal()

		// and will sleep until the next cycle. In endOfPipe() it is not a big problem.

		// But missing the cycle in attribute() might be worse.

		// However it should not happen due to the buffer size

		// and amount of work done in the real-time thread (message copying) vs. amount of work done between the jack_ringbuffer_write_space() and pthread_cond_wait() calls (nothing).

	}

	void finish(int sig) {

		continueProcessing = false;

	}

	virtual ~JackHandler() {

		finalize();

	}

};

}

}

}