/**

 * 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 <array>

#include "ASN1Reader.h"

namespace relpipe {

namespace in {

namespace asn1 {

namespace lib {

/**

 * Reads ASN.1 data encoded as BER (DER, CER).

 */

class BasicASN1Reader : public ASN1Reader {

private:

	bool started = false;

	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;

		bool definiteLength;

		size_t length;

	};

	Header readHeader() {

		Header h;

		memset(&h, 0, sizeof (h)); // TODO: remove, not needed

		uint8_t tagByte;

		read(&tagByte, 1);

		h.tagClass = (TagClass) (tagByte >> 6);

		h.pc = (PC) ((tagByte >> 5) & 1);

		h.tag = tagByte & (0xFF >> 3);

		if (h.tag > 30) throw relpipe::writer::RelpipeWriterException(L"not yet implemented, ASN.1 tag > 30"); // FIXME: higher tag values → read more bytes

		uint8_t lengthByte;

		read(&lengthByte, 1);

		if (lengthByte >> 7 == 0) {

			h.definiteLength = true;

			h.length = lengthByte;

		} else if (lengthByte == 0b10000000) {

			h.definiteLength = false;

			h.length = 0;

		} else if (lengthByte == 0xFF) {

			throw relpipe::writer::RelpipeWriterException(L"ASN.1 lengthByte == 0xFF (reserved value)"); // TODO: better exception

		} else {

		}

		return h;

	}

	void readNext() {

		Header typeHeader = readHeader();

		if (!started) {

			handlers.writeStreamStart();

			started = true;

		}

		handlers.writeCollectionStart(ASN1ContentHandler::CollectionType::Sequence);

		handlers.writeNull();

		handlers.writeBoolean(true);

		handlers.writeString(ASN1ContentHandler::StringType::UTF8String, "tagClass:");

		handlers.writeInteger((int64_t) typeHeader.tagClass);

		handlers.writeString(ASN1ContentHandler::StringType::UTF8String, "pc:");

		handlers.writeInteger((int64_t) typeHeader.pc);

		handlers.writeString(ASN1ContentHandler::StringType::UTF8String, "tag:");

		handlers.writeInteger((int64_t) typeHeader.tag);

		handlers.writeString(ASN1ContentHandler::StringType::UTF8String, "definiteLength:");

		handlers.writeBoolean(typeHeader.definiteLength);

		handlers.writeString(ASN1ContentHandler::StringType::UTF8String, "length:");

		handlers.writeInteger((int64_t) typeHeader.length);

		handlers.writeString(ASN1ContentHandler::StringType::UTF8String, "relational pipes");

		handlers.writeCollectionEnd();

	}

protected:

	void update() override {

		while (true) readNext();

	}

public:

	void close() override {

	}

};

}

}

}

}