/*
  uuid.h

  Copyright (c) 2021 Kevin Matz (kevin.matz@gmail.com)

  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:

  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.
*/
#pragma once

#include <cstdint>
#include <cstring>
#include <string>

#define UUID_LENGTH 16

// RFC4122 A Universally Unique IDentifier (UUID) URN Namespace
namespace UUID {

/**
 * @brief The Type enum
 */
enum Type {
  NCS,      //!< Reserved, NCS backward compatibility.
  RFC4122,  //!< The variant specified in this document.
  MS,       //!< Reserved, Microsoft Corporation backward compatibility
  RESVERED, //!< Reserved for future definition.
  NIL
};


/**
 * @brief The RFC4122Version enum
 */
enum RFC4122Version {
  VOID = 0b0000,
  TIME = 0b0001, //!< The time-based version specified in this document.
  DCE  = 0b0010, //!< DCE Security version, with embedded POSIX UIDs.
  MD5  = 0b0011, //!< The name-based version that uses MD5 hashing.
  RAND = 0b0100, //!< The randomly or pseudo-randomly generated version.
  SHA1 = 0b0101  //!< The name-based version that uses SHA-1 hashing.
};


/**
 * @brief The Namespace enum
 */
enum Namespace {
  DNS, //!< the name string is a fully-qualified domain name.
  URL, //!< the name string is a URL.
  OID, //!< the name string is an ISO OID.
  X500 //!< the name string is an X.500 DN in DER or a text output format.
};


/**
 * @brief The NCSFields struct
 */
struct NCSFields {
  uint64_t time : 48;   //!< timestamp
  uint16_t res;         //!< res
  uint8_t  family;      //!< family
  uint64_t node : 56;   //!< node number
}__attribute__((packed));


/**
 * @brief The RFC4122Fields struct
 */
struct RFC4122Fields {
  uint32_t time_low;              //!< timestamp low
  uint16_t time_mid;              //!< timestamp mid
  uint16_t time_hi_version;       //!< timestamp high & version
  uint8_t  clock_seq_hi_variant;  //!< clock sequence high & variant
  uint8_t  clock_seq_low;         //!< clock sequence low
  uint16_t node_low;              //!< node low
  uint32_t node_high;             //!< node high
}__attribute__((packed));


/**
 * @brief UUID_TICKS_BETWEEK_EPOCH
 * The number of 100 ns ticks between the Gregorian epoch `1582-10-15 00:00:00`
 * and the Unix epoch `1970-01-01 00:00:00`.
 */
static const uint64_t UUID_TICKS_BETWEEK_EPOCH = 122192928000000000;

//static const char* NAMESPACE_DNS = "6ba7b810-9dad-11d1-80b4-00c04fd430c8";
//static const char* NAMESPACE_URL = "6ba7b811-9dad-11d1-80b4-00c04fd430c8";
//static const char* NAMESPACE_OID = "6ba7b812-9dad-11d1-80b4-00c04fd430c8";
//static const char* NAMESPACE_X500 = "6ba7b814-9dad-11d1-80b4-00c04fd430c8";

/**
 * @brief The uuid class
 */
class uuid {
public:
  uuid();
  uuid(const uuid&);
  uuid(const uint8_t * raw);
  uuid(const char * c_str);
  uuid(std::string str);

  // accessors
  const uint8_t* bytes() const;
  Type     type() const;
  uint16_t version() const;
  uint64_t time() const;
  uint16_t sequence() const;
  uint64_t node() const;

  // output
  std::string hex() const;   // '12345678123456781234567812345678'
  std::string string() const;// '12345678-1234-5678-1234-567812345678'
  std::string urn() const;   // 'urn:uuid:12345678-1234-5678-1234-567812345678'

  // creators
  void setBytes(const uint8_t * raw);
  virtual uint16_t uuid1(uint64_t node, uint16_t clock_seq);
  virtual void     uuid4();

  // operator overloads
  uuid& operator= (const uuid& other);
  friend bool operator== (const uuid&, const uuid&);

  // typecast overload
  operator const uint8_t *   () const;
  operator const std::string () const;

private:
  uint8_t  raw_[UUID_LENGTH] = {0};
  Type     type_;
  uint16_t version_;
  uint64_t timestamp_;
  uint16_t clock_seq_;
  uint64_t node_;

  void fromArray_(const uint8_t *);
  void fromCstring_(const char *);
  void fromString_(std::string);

  void setType_();
  void setBytes_();
  void setNCSBytes_();
  void setRFC4122Bytes_();

  void setFields_();
  void setNCSFields_();
  void setRFC4122Fields_();

  uint64_t now_();
};

} // namespace UUID


namespace std
{
  /**
   * @brief The hash struct specialization for UUID::uuid
   */
  template<>
  struct hash<UUID::uuid>
  {
    /**
     * @brief operator ()
     * @param id
     * @return
     */
    size_t operator()(UUID::uuid const& id) const noexcept
    {
      return std::hash<std::string>{}(id.hex());
    }
  };
} // namespace std