/**
 * Relational pipes (library)
 * Copyright © 2018 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 Lesser General Public License as published by the Free Software Foundation;
 *    version 3 of the License or (at your option)
 *  - GNU General Public License as published by the Free Software Foundation;
 *    version 2 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 <string>
#include <iostream>
#include <cassert>
#include <limits>

#include <relpipe/protocol/constants.h>

#include "../../include/relpipe/reader/RelpipeReaderException.h"
#include "../../include/relpipe/reader/typedefs.h"
#include "../DataTypeReader.h"

namespace relpipe {
namespace reader {
namespace types {

using namespace relpipe::protocol;
using namespace relpipe::reader;

/**
 * The prototype does not have various integer and other numeric data types,
 * it just works with one type of integer.
 * But this integer has variable length -- smaller values occupy only one byte, bigger ones, more bytes 1,2,4,8 + first byte (contains length signalization).
 * In the real implementation of relational pipes, there will be DataTypes for particular numeric types.
 * 
 * TODO: support also big endian architectures.
 * TODO: throw exception if a value was stored in bigger type than needed (while reading – there should be only one supported way how to encode a single value)
 * 
 * Example of encoded values:
 * -------------------------------------------------------------------------------------------------
 * $ for n in 0 1 10 250 251 252 65535 65536 4294967295 4294967296 18446744073709551615; do printf '%20s = ' $n; dist/Debug/GNU-Linux/rp-prototype write integer $n | hd | head -n 1; done
 *                    0 = 00000000  00                                                |.|
 *                    1 = 00000000  01                                                |.|
 *                   10 = 00000000  0a                                                |.|
 *                  250 = 00000000  fa                                                |.|
 *                  251 = 00000000  fb fb                                             |..|
 *                  252 = 00000000  fb fc                                             |..|
 *                65535 = 00000000  fc ff ff                                          |...|
 *                65536 = 00000000  fd 00 00 01 00                                    |.....|
 *           4294967295 = 00000000  fd ff ff ff ff                                    |.....|
 *           4294967296 = 00000000  fe 00 00 00 00 01 00 00  00                       |.........|
 * 18446744073709551615 = 00000000  fe ff ff ff ff ff ff ff  ff                       |.........|
 * -------------------------------------------------------------------------------------------------
 * 
 * Example of decoded values:
 * -------------------------------------------------------------------------------------------------
 * $ for n in 0 1 10 250 251 252 65535 65536 4294967295 4294967296 18446744073709551615; do dist/Debug/GNU-Linux/rp-prototype write integer $n | dist/Debug/GNU-Linux/rp-prototype read integer; done;
 * 0
 * 1
 * 10
 * 250
 * 251
 * 252
 * 65535
 * 65536
 * 4294967295
 * 4294967296
 * 18446744073709551615
 * -------------------------------------------------------------------------------------------------
 * 
 * Note: similar format as original idea: https://en.wikipedia.org/wiki/X.690#Length_octets
 * 
 */
class IntegerDataTypeReader : public DataTypeReader<integer_t> {
private:
	static const uint8_t INTEGER_TYPE_UINT8 = 251;
	static const uint8_t INTEGER_TYPE_UINT16 = 252;
	static const uint8_t INTEGER_TYPE_UINT32 = 253;
	static const uint8_t INTEGER_TYPE_UINT64 = 254;
	static const uint8_t INTEGER_TYPE_RESERVED = 255;

	template<typename T> integer_t read(std::istream &input) {
		T value = 0;
		input.read(reinterpret_cast<char *> (&value), sizeof (value));
		return value;
	}

public:

	IntegerDataTypeReader() : DataTypeReader<integer_t>(TypeId::INTEGER, DATA_TYPE_CODE_INTEGER) {
	}

	integer_t readValue(std::istream &input) override {
		uint8_t first;
		input.read(reinterpret_cast<char *> (&first), sizeof (first));
		if (input.good()) {

			if (first < INTEGER_TYPE_UINT8) return first;
			else if (first == INTEGER_TYPE_UINT8) return read<uint8_t>(input);
			else if (first == INTEGER_TYPE_UINT16) return read<uint16_t>(input);
			else if (first == INTEGER_TYPE_UINT32) return read<uint32_t>(input);
			else if (first == INTEGER_TYPE_UINT64) return read<uint64_t>(input);
			else throw RelpipeReaderException(L"Error while parsing integer type: unsupported type");
		} else {
			throw RelpipeReaderException(L"Error while reading integer from the stream.");
		}
	}

	string_t toString(const integer_t &value) override {
		return std::to_wstring(value);
	}

};

}
}
}