/**

 * Relational pipes

 * Copyright © 2021 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 <vector>

#include <sstream>

#include <iomanip>

#include <cmath>

#include "ProxyVector.h"

namespace relpipe {

namespace in {

namespace asn1 {

namespace lib {

namespace UniversalType {

static const uint64_t EndOfContent = 0x00;

static const uint64_t Boolean = 0x01;

static const uint64_t Integer = 0x02;

static const uint64_t BitString = 0x03;

static const uint64_t OctetString = 0x04;

static const uint64_t Null = 0x05;

static const uint64_t ObjectIdentifier = 0x06;

static const uint64_t ObjectDescriptor = 0x07;

static const uint64_t External = 0x08;

static const uint64_t Real = 0x09;

static const uint64_t Enumerated = 0xA;

static const uint64_t Embedded = 0xB;

static const uint64_t UTF8String = 0xC;

static const uint64_t RelativeObjectIdentifier = 0xD;

static const uint64_t Time = 0xE;

static const uint64_t Reserved = 0xF;

static const uint64_t Sequence = 0x10;

static const uint64_t Set = 0x11;

static const uint64_t NumericString = 0x12;

static const uint64_t PrintableString = 0x13;

static const uint64_t T61String = 0x14;

static const uint64_t VideotexString = 0x15;

static const uint64_t IA5String = 0x16;

static const uint64_t UTCTime = 0x17;

static const uint64_t GeneralizedTime = 0x18;

static const uint64_t GraphicString = 0x19;

static const uint64_t VisibleString = 0x1A;

static const uint64_t GeneralString = 0x1B;

static const uint64_t UniversalString = 0x1C;

static const uint64_t CharacterString = 0x1D;

static const uint64_t BMPString = 0x1E;

static const uint64_t Date = 0x1F;

static const uint64_t TimeOfDay = 0x20;

static const uint64_t DateTime = 0x21;

static const uint64_t Duration = 0x22;

static const uint64_t ObjectIdentifierIRI = 0x23;

static const uint64_t RelativeObjectIdentifierIRI = 0x24;

}

class ASN1ContentHandler {

public:

	enum class TagClass : uint8_t {

		Universal = 0,

		Application = 1,

		ContextSpecific = 2,

		Private = 3

	};

	enum class PC : uint8_t {

		Primitive = 0,

		Constructed = 1

	};

	class Header {

	public:

		TagClass tagClass;

		PC pc;

		uint64_t tag;

	};

	// TODO: separate implementation of particular types from the interface, separate SPI from API?

	class Integer {

	private:

		// TODO: use std::string (of octets, not ASCII) instead of std::vector?

		// TODO: use this class as BigInteger across Relational pipes?

		std::vector<uint8_t> data;

	public:

		/**

		 * @param data integer octets as in BER encoding

		 */

		Integer(std::vector<uint8_t> data) : data(data) {

		}

		virtual ~Integer() {

		}

		size_t size() const {

			return data.size();

		}

		const uint8_t& operator[](std::size_t index) const {

			return data[index];

		}

		const std::string toHex() const {

			std::stringstream hex;

			hex << std::hex << std::setfill('0');

			for (uint8_t b : data) hex << std::setw(2) << (int) b;

			return hex.str();

		}

		const std::string toString() const {

			try {

				return std::to_string(toInt64());

			} catch (...) {

				// integer has more than 64 bits → only HEX form value will be available

				// TODO: support longer values than 64 bits

				// TODO: do not ignore zero-length error?

				return "";

			}

		}

		const int64_t toInt64() const {

			int64_t value = 0;

			if (data.size() > sizeof (value)) throw std::invalid_argument("Integer is too long");

			else if (data.size() == 0) throw std::invalid_argument("Integer has zero length");

			value = data[0];

			bool negative = data[0] & 0x80;

			for (size_t i = 1, limit = data.size(); i < limit; i++) value = (value << 8) | data[i];

			if (negative) value -= std::pow(256, data.size());

			return value;

		}

	};

	class ObjectIdentifier {

	private:

		// TODO: use std::string (of octets, not ASCII) instead of std::vector?

		// TODO: use this class across Relational pipes as one of basic types?

		std::vector<uint8_t> data;

	public:

		/**

		 * @param data integer octets as in BER encoding

		 */

		ObjectIdentifier(std::vector<uint8_t> data) : data(data) {

			// TODO: cache size and element values?

		}

		virtual ~ObjectIdentifier() {

		}

		/**

		 * @return number of elements, not octets

		 */

		size_t size() const {

			return 0; // FIXME: correct OID size

		}

		/**

		 * @param index 0 = root element

		 * @return value of the element at given position

		 */

		const uint8_t& operator[](std::size_t index) const {

			return data[index]; // FIXME: correct OID value

		}

		const std::string toString() const {

			if (data.size() == 0) return "";

			std::stringstream result;

			result << (data[0] / 40) << "." << (data[0] % 40); // first two elements are encoded in the first octet

			for (size_t i = 1, limit = data.size(), octet = 0, element = 0; i < limit; i++) {

				octet = data[i];

				element = element << 7 | (octet & 0xFF >> 1);

				// TODO: throw exception if the element value overflows? (should not happen) or format even longer values

				if ((octet & 1 << 7) == 0) {

					result << "." << element;

					element = 0;

				}

			}

			return result.str();

		}

	};

	class DateTime {

	public:

		enum class Precision {

			Year,

			Month,

			Day,

			Hour,

			Minute,

			Second,

			Milisecond,

			Nanosecond

		};

		// TODO: timezone (in minutes or 1/4 hours)

		Precision precision = Precision::Second;

		int32_t year = 1970;

		int8_t month = 1;

		int8_t day = 1;

		int8_t hour = 0;

		int8_t minute = 0;

		int8_t second = 0;

		int32_t nanosecond = 0;

		int8_t timezoneHour = 0;

		int8_t timezoneMinute = 0;

		virtual ~DateTime() {

		}

		const std::string toString() const {

			std::stringstream result;

			result << std::setfill('0');

			result << std::setw(4) << (int) year;

			result << "-" << std::setw(2) << (int) month;

			result << "-" << std::setw(2) << (int) day;

			result << "T" << std::setw(2) << (int) hour;

			result << ":" << std::setw(2) << (int) minute;

			result << ":" << std::setw(2) << (int) second;

			if (precision == Precision::Nanosecond) result << "," << (int) nanosecond;

			result << (timezoneHour < 0 ? "-" : "+");

			result << std::setw(2) << (int) std::abs(timezoneHour);

			result << ":" << std::setw(2) << (int) timezoneMinute;

			return result.str();

		}

	};

	virtual ~ASN1ContentHandler() = default;

	// TODO: more metadata, support OID decoding and ASN.1 modules (schema), probably through a plug-in

	// TODO: support also extension extractor plug-ins? (could decode some opaque structures like octet strings and replace them with nested elements) e.g. subjectAltName in https://datatracker.ietf.org/doc/html/rfc5280#section-4.2.1.6

	virtual void writeStreamStart() = 0;

	virtual void writeStreamEnd() = 0;

	virtual void writeCollectionStart(const Header& header) = 0;

	virtual void writeCollectionEnd() = 0;

	virtual void writeBoolean(const Header& header, bool value) = 0;

	virtual void writeNull(const Header& header) = 0;

	virtual void writeInteger(const Header& header, Integer value) = 0;

	/**

	 * @param type original type in ASN.1

	 * @param value original text converted to UTF-8

	 */

	virtual void writeTextString(const Header& header, std::string value) = 0;

	/**

	 * @param value arbitrary sequence of octets (bytes), usually not a human-readable text

	 */

	virtual void writeOctetString(const Header& header, std::string value) = 0;

	/**

	 * @param value arbitrary sequence of bits (booleans), usually not a human-readable text

	 */

	virtual void writeBitString(const Header& header, std::vector<bool> value) = 0;

	virtual void writeOID(const Header& header, ObjectIdentifier value) = 0;

	virtual void writeDateTime(const Header& header, DateTime value) = 0;

	// Object descriptor

	// virtual void writeReal(float value) = 0;

	// Enumerated

	// Embedded PVD

	// Relative OID

	// OID-IRI

	// Relative OID-IRI

	/**

	 * Specific value that was not parsed.

	 * May be processed in a generic way (as binary data or ASCII or UTF-8 string, when possible)

	 * or according to given application, context or private specification.

	 * 

	 * @param value original raw data

	 */

	virtual void writeSpecific(const Header& header, std::string value) = 0;

};

class ASN1ContentHandlerProxy : public ASN1ContentHandler {

private:

	ProxyVector<ASN1ContentHandler> handlers;

public:

	void addHandler(std::shared_ptr<ASN1ContentHandler> handler) {

		handlers.push_back(handler);

	}

	void writeStreamStart() override {

		handlers.forward(&ASN1ContentHandler::writeStreamStart);

	}

	void writeStreamEnd() override {

		handlers.forward(&ASN1ContentHandler::writeStreamEnd);

	}

	void writeCollectionStart(const Header& header) override {

		handlers.forward(&ASN1ContentHandler::writeCollectionStart, header);

	}

	void writeCollectionEnd() override {

		handlers.forward(&ASN1ContentHandler::writeCollectionEnd);

	}

	void writeBoolean(const Header& header, bool value) override {

		handlers.forward(&ASN1ContentHandler::writeBoolean, header, value);

	}

	void writeNull(const Header& header) override {

		handlers.forward(&ASN1ContentHandler::writeNull, header);

	}

	void writeInteger(const Header& header, Integer value) override {

		handlers.forward(&ASN1ContentHandler::writeInteger, header, value);

	}

	void writeTextString(const Header& header, std::string value) override {

		handlers.forward(&ASN1ContentHandler::writeTextString, header, value);

	}

	void writeOctetString(const Header& header, std::string value) override {

		handlers.forward(&ASN1ContentHandler::writeOctetString, header, value);

	}

	void writeBitString(const Header& header, std::vector<bool> value) override {

		handlers.forward(&ASN1ContentHandler::writeBitString, header, value);

	}

	void writeOID(const Header& header, ObjectIdentifier value) override {

		handlers.forward(&ASN1ContentHandler::writeOID, header, value);

	}

	void writeDateTime(const Header& header, DateTime value) override {

		handlers.forward(&ASN1ContentHandler::writeDateTime, header, value);

	}

	void writeSpecific(const Header& header, std::string value) override {

		handlers.forward(&ASN1ContentHandler::writeSpecific, header, value);

	}

};

}

}

}

}