#ifndef ADDRESS_H
#define ADDRESS_H

#include <stdint.h>
#include <ostream>

namespace ns3 {

/**
 * \brief a polymophic address class
 *
 * This class is very similar in design and spirit to the BSD sockaddr
 * structure: they are both used to hold multiple types of addresses
 * together with the type of the address.
 *
 * A new address class defined by a user needs to:
 *   - allocate a type id with Address::Register
 *   - provide a method to convert his new address to an Address 
 *     instance. This method is typically a member method named ConvertTo:
 *     Address MyAddress::ConvertTo (void) const;
 *   - provide a method to convert an Address instance back to
 *     an instance of his new address type. This method is typically
 *     a static member method of his address class named ConvertFrom:
 *     static MyAddress MyAddress::ConvertFrom (const Address &address);
 *   - the ConvertFrom method is expected to check that the type of the
 *     input Address instance is compatible with its own type.
 *
 * Typical code to create a new class type looks like:
 * \code
 * // this class represents addresses which are 2 bytes long.
 * class MyAddress
 * {
 * public:
 *   Address ConvertTo (void) const;
 *   static MyAddress ConvertFrom (void);
 * private:
 *   static uint8_t GetType (void);
 * };
 *
 * Address MyAddress::ConvertTo (void) const
 * {
 *   return Address (GetType (), m_buffer, 2);
 * }
 * MyAddress MyAddress::ConvertFrom (const Address &address)
 * {
 *   MyAddress ad;
 *   NS_ASSERT (address.CheckCompatible (GetType (), 2));
 *   address.CopyTo (ad.m_buffer, 2);
 *   return ad;
 * }
 * uint8_t MyAddress::GetType (void)
 * {
 *   static uint8_t type = Address::Register ();
 *   return type;
 * }
 * \endcode
 */
class Address 
{
public:
  enum {
    /**
     * The maximum size of a byte buffer which
     * can be stored in an Address instance.
     */
    MAX_SIZE = 30
  };

  /**
   * Create an invalid address
   */
  Address ();
  /**
   * \param type the type of the Address to create
   * \param buffer a pointer to a buffer of bytes which hold
   *        a serialized representation of the address in network
   *        byte order.
   * \param len the length of the buffer.
   * 
   * Create an address from a type and a buffer. This constructor
   * is typically invoked from the conversion functions of various
   * address types when they have to convert themselves to an 
   * Address instance.
   */
  Address (uint8_t type, const uint8_t *buffer, uint8_t len);
  Address (const Address & address);
  Address &operator = (const Address &address);

  /**
   * \returns true if this address is invalid, false otherwise.
   *
   * An address is invalid if and only if it was created
   * through the default constructor and it was never
   * re-initialized.
   */
  bool IsInvalid (void) const;
  /**
   * \returns the length of the underlying address.
   */
  uint8_t GetLength (void) const;
  /**
   * \param buffer buffer to copy the address bytes to.
   * \returns the number of bytes copied.
   */
  uint32_t CopyTo (uint8_t buffer[MAX_SIZE]) const;
  /**
   * \param buffer buffer to copy the whole address data structure to
   * \param len the size of the buffer
   * \returns the number of bytes copied.
   */
  uint32_t CopyAllTo (uint8_t *buffer, uint8_t len) const;
  /**
   * \param buffer pointer to a buffer of bytes which contain
   *        a serialized representation of the address in network
   *        byte order.
   * \param len length of buffer
   * \returns the number of bytes copied.
   *
   * Copy the input buffer to the internal buffer of this address 
   * instance.
   */
  uint32_t CopyFrom (const uint8_t *buffer, uint8_t len);
  /**
   * \param buffer pointer to a buffer of bytes which contain
   *        a copy of all the members of this Address class.
   * \param len the length of the buffer
   * \returns the number of bytes copied.
   */
  uint32_t CopyAllFrom (const uint8_t *buffer, uint8_t len);
  /**
   * \param type a type id as returned by Address::Register
   * \param len the length associated to this type id.
   *
   * \returns true if the type of the address stored internally
   * is compatible with the requested type, false otherwise.
   */
  bool CheckCompatible (uint8_t type, uint8_t len) const;
  /**
   * \param type a type id as returned by Address::Register
   * \returns true if the type of the address stored internally
   * is compatible with the requested type, false otherwise.
   *
   * This method checks that the types are _exactly_ equal.
   * This method is really used only by the PacketSocketAddress
   * and there is little point in using it otherwise so, 
   * you have been warned: DO NOT USE THIS METHOD.
   */
  bool IsMatchingType (uint8_t type) const;
  /**
   * Allocate a new type id for a new type of address.
   * \returns a new type id.
   */
  static uint8_t Register (void);
private:
  friend bool operator == (const Address &a, const Address &b);
  friend bool operator < (const Address &a, const Address &b);
  friend std::ostream& operator<< (std::ostream& os, const Address & address);

  uint8_t m_type;
  uint8_t m_len;
  uint8_t m_data[MAX_SIZE];
};

bool operator == (const Address &a, const Address &b);
bool operator != (const Address &a, const Address &b);
bool operator < (const Address &a, const Address &b);
std::ostream& operator<< (std::ostream& os, const Address & address);

} // namespace ns3


#endif /* ADDRESS_H */