/**

 * 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>

namespace relpipe {

namespace in {

namespace asn1 {

namespace lib {

class ASN1ContentHandler {

public:

	enum class CollectionType : uint64_t {

		Constructed, // TODO: special event?

		Sequence = 16,

		Set = 17

	};

	enum class StringType : uint64_t {

		OctetString,

		UTF8String,

		NumericString,

		PrintableString,

		T61String,

		VideotexString,

		IA5String,

		GraphicString,

		VisibleString,

		GeneralString,

		UniversalString,

		CharacterString,

		BMPString,

	};

	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();

		}

	};

	virtual ~ASN1ContentHandler() = default;

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

	virtual void writeStreamStart() = 0;

	virtual void writeStreamEnd() = 0;

	virtual void writeCollectionStart(CollectionType type) = 0;

	virtual void writeCollectionEnd() = 0;

	virtual void writeBoolean(bool value) = 0;

	virtual void writeNull() = 0;

	virtual void writeInteger(Integer value) = 0;

	virtual void writeString(StringType type, std::string value) = 0;

	virtual void writeOID(ObjectIdentifier value) = 0;

	// Object descriptor

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

	// Enumerated

	// Embedded PVD

	// Relative OID

	// OID-IRI

	// Relative OID-IRI

};

class ASN1ContentHandlerProxy : public ASN1ContentHandler {

private:

	std::vector<std::shared_ptr<ASN1ContentHandler>> handlers;

public:

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

		handlers.push_back(handler);

	}

#define handler for (auto ___h : handlers) ___h

	void writeStreamStart() override {

		handler->writeStreamStart();

	}

	void writeStreamEnd() override {

		handler->writeStreamEnd();

	}

	void writeCollectionStart(CollectionType type) override {

		handler->writeCollectionStart(type);

	}

	void writeCollectionEnd() override {

		handler->writeCollectionEnd();

	}

	void writeBoolean(bool value) override {

		handler->writeBoolean(value);

	}

	void writeNull() override {

		handler->writeNull();

	}

	void writeInteger(Integer value) override {

		handler->writeInteger(value);

	}

	void writeString(StringType type, std::string value) override {

		handler->writeString(type, value);

	}

	void writeOID(ObjectIdentifier value) override {

		handler->writeOID(value);

	}

#undef handler

};

}

}

}

}