// Copyright (c) 2017, 2021 Pieter Wuille

// Copyright (c) 2021 The Bitcoin Core developers

// Distributed under the MIT software license, see the accompanying

// file COPYING or http://www.opensource.org/licenses/mit-license.php.

// Bech32 and Bech32m are string encoding formats used in newer

// address types. The outputs consist of a human-readable part

// (alphanumeric), a separator character (1), and a base32 data

// section, the last 6 characters of which are a checksum. The

// module is namespaced under bech32 for historical reasons.

//

// For more information, see BIP 173 and BIP 350.

#ifndef BITCOIN_BECH32_H

#define BITCOIN_BECH32_H

#include <stdint.h>

#include <string>

#include <vector>

namespace bech32

{

static constexpr size_t CHECKSUM_SIZE = 6;

static constexpr char SEPARATOR = '1';

enum class Encoding {

    INVALID, //!< Failed decoding

    BECH32,  //!< Bech32 encoding as defined in BIP173

    BECH32M, //!< Bech32m encoding as defined in BIP350

};

/** Character limits for Bech32(m) encoded strings. Character limits are how we provide error location guarantees.

 *  These values should never exceed 2^31 - 1 (max value for a 32-bit int), since there are places where we may need to

 *  convert the CharLimit::VALUE to an int. In practice, this should never happen since this CharLimit applies to an address encoding

 *  and we would never encode an address with such a massive value */

enum CharLimit : size_t {

    BECH32 = 90,            //!< BIP173/350 imposed character limit for Bech32(m) encoded addresses. This guarantees finding up to 4 errors.

};

/** Encode a Bech32 or Bech32m string. If hrp contains uppercase characters, this will cause an

 *  assertion error. Encoding must be one of BECH32 or BECH32M. */

std::string Encode(Encoding encoding, const std::string& hrp, const std::vector<uint8_t>& values);

struct DecodeResult

{

    Encoding encoding;         //!< What encoding was detected in the result; Encoding::INVALID if failed.

    std::string hrp;           //!< The human readable part

    std::vector<uint8_t> data; //!< The payload (excluding checksum)

    DecodeResult() : encoding(Encoding::INVALID) {}

    DecodeResult(Encoding enc, std::string&& h, std::vector<uint8_t>&& d) : encoding(enc), hrp(std::move(h)), data(std::move(d)) {}

};

/** Decode a Bech32 or Bech32m string. */

DecodeResult Decode(const std::string& str, CharLimit limit = CharLimit::BECH32);

/** Return the positions of errors in a Bech32 string. */

std::pair<std::string, std::vector<int>> LocateErrors(const std::string& str, CharLimit limit = CharLimit::BECH32);

} // namespace bech32

#endif // BITCOIN_BECH32_H