/**

 * djm-fix

 * Copyright © 2025 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/>.

 */

#include <iostream>

#include <iomanip>

#include "MessageCodec.h"

Message MessageCodec::decode(std::vector<uint8_t> data) {

	using ERR = std::invalid_argument;

	if (data.empty() || data.front() != 0xf0 || data.back() != 0xf7)

		throw ERR("not a MIDI SysEx message");

	// Manufacturer MIDI SysEx ID Numbers:

	//   00H 40H 05H = AlphaTheta Corporation

	//   00H 40H 06H = Pioneer Corporation

	if (data.size() < 4

			|| data[1] != 0x00

			|| data[2] != 0x40

			|| data[3] != 0x05)

		throw ERR("wrong message Manufacturer MIDI SysEx ID");

	if (data.size() < 8) throw ERR("missing model");

	uint8_t model = data[7];

	if (data.size() < 10) throw ERR("missing message type");

	MessageType msgType;

	if /**/ (data[9] == 0x11) msgType = MessageType::D11_GREETING;

	else if (data[9] == 0x12) msgType = MessageType::H12_SEED1;

	else if (data[9] == 0x13) msgType = MessageType::D13_HASH1_SEED2;

	else if (data[9] == 0x14) msgType = MessageType::H14_HASH2;

	else if (data[9] == 0x15) msgType = MessageType::D15_CONFIRMATION;

	else throw ERR("unsupported message type");

	if (data.size() < 11) throw ERR("missing message length");

	if (data[10] != data.size() - 10) throw ERR("wrong message length");

	std::vector<Field> fields;

	for (size_t start = 11; data.size() > start + 1;) {

		FieldType fieldType;

		if /**/ (data[start] == 0x01) fieldType = FieldType::F01;

		else if (data[start] == 0x02) fieldType = FieldType::F02;

		else if (data[start] == 0x03) fieldType = FieldType::F03;

		else if (data[start] == 0x04) fieldType = FieldType::F04;

		else if (data[start] == 0x05) fieldType = FieldType::F05;

		else throw ERR("unsupported field type");

		size_t fieldSize = data[start + 1];

		if (data.size() < start + fieldSize + 1) throw ERR("field overflow");

		//                                    ^ 0xf7 messsage end

		std::vector<uint8_t> fieldData(

				data.begin() + start + 2,

				data.begin() + start + fieldSize);

		fields.push_back({fieldType, fieldData});

		start += fieldSize;

	}

	return Message(msgType, model, fields);

}

std::vector<uint8_t> MessageCodec::encode(Message msg) {

	using ERR = std::invalid_argument;

	std::vector<uint8_t> data;

	data.push_back(0xf0);

	data.push_back(0x00);

	data.push_back(0x40);

	data.push_back(0x05);

	data.push_back(0x00);

	data.push_back(0x00);

	data.push_back(0x00);

	data.push_back(msg.model);

	data.push_back(0x00);

	data.push_back((uint8_t) msg.type);

	uint8_t msgLength = 2; // 2 = type + lenght

	for (const auto& field : msg.fields) msgLength += field.data.size() + 2;

	data.push_back(msgLength);

	for (const auto& field : msg.fields) {

		size_t fieldSize = field.data.size() + 2;

		if (fieldSize > 256) throw ERR("message field too long");

		data.push_back((uint8_t) field.type);

		data.push_back((uint8_t) (fieldSize));

		data.insert(data.end(), field.data.begin(), field.data.end());

	}

	data.push_back(0xf7);

	return data;

}