#ifndef PACKETPP_DNS_RESOURCE_DATA
#define PACKETPP_DNS_RESOURCE_DATA

#include "DnsResource.h"
#include "IpAddress.h"
#include <memory>
#include <string>
#include <stdint.h>

/// @file

/**
 * \namespace pcpp
 * \brief The main namespace for the PcapPlusPlus lib
 */
namespace pcpp
{

	//Visual studio has always been stupid about returning something useful for __cplusplus
	//Only recently was this fixed - and even then it requires a specific hack to the command line during build
	//Its easier/more consistent to test _MSC_VER in VS
	//https://docs.microsoft.com/en-us/cpp/build/reference/zc-cplusplus?view=vs-2017

	#if __cplusplus > 199711L || _MSC_VER >= 1800 //Maybe this can be 1600 for VS2010
	#define PCPP_SMART_PTR(T) std::unique_ptr<T>
	#else
	#define PCPP_SMART_PTR(T) std::auto_ptr<T>
	#endif

	// forward declarations
	class IDnsResource;

	/**
	 * @class IDnsResourceData
	 * A wrapper class for storing DNS RR (resource record) data. This is the base class which introduces several abstract
	 * methods for derived classes to implement for setting and retrieving the stored data. Each derived class will store
	 * different type of DNS RR data and implement these methods accordingly (for example: IPv4/IPv6 addresses, MX data,
	 * hostnames, raw byte data etc.)
	 */
	class IDnsResourceData
	{
	protected:

		// unimplemented private copy c'tor
		IDnsResourceData(const IDnsResourceData& other);
		IDnsResourceData() { }

		size_t decodeName(const char* encodedName, char* result, IDnsResource* dnsResource) const;
		void encodeName(const std::string& decodedName, char* result, size_t& resultLen, IDnsResource* dnsResource) const;

	public:
		/**
		 * A virtual d'tor, does nothing
		 */
		virtual ~IDnsResourceData() { }

		/**
		 * A templated method which takes a class that derives from IDnsResourceData as the template argument and
		 * checks whether this instance is of this type
		 * @return True if this instance is of the requested type, false otherwise
		 */
		template <class IDnsResourceDataType>
		bool isTypeOf() const { return dynamic_cast<const IDnsResourceDataType*>(this) != NULL; }

		/**
		 * A templated method which take a class that derives from IDnsResourceData as the template argument and tries to
		 * cast the current instance as that type
		 * @return A pointer to the current instance casted as the requested type or NULL if this instance isn't of this type
		 */
		template <class IDnsResourceDataType>
		IDnsResourceDataType* castAs() { return dynamic_cast<IDnsResourceDataType*>(this); }

		/**
		 * @return A string that represents the current DNS RR data
		 */
		virtual std::string toString() const = 0;

		/**
		 * Convert the DNS RR data into a byte array
		 * @param[out] arr A pointer to a pre-allocated byte array where the result will be written to
		 * @param[out] arrLength A reference to a 2-byte number where the result array length will be written to
		 * @param[in] dnsResource A pointer to a DNS resource object where this DNS RR data will be stored
		 * @return True if the DNS RR data was successfully converted into a byte array and written to the given array or
		 * false if stored DNS RR data is invalid or if it could not be written to the given array
		 */
		virtual bool toByteArr(uint8_t* arr, size_t& arrLength, IDnsResource* dnsResource) const = 0;
	};


	/**
	 * @class DnsResourceDataPtr
	 * A smart pointer class that holds pointers of type IDnsResourceData. This object is used in DnsResource#getData()
	 */
	class DnsResourceDataPtr : public PCPP_SMART_PTR(IDnsResourceData)
	{
	public:

		/**
		 * A c'tor to this class
		 * @param[in] ptr A pointer to IDnsResourceData
		 */
		explicit DnsResourceDataPtr(IDnsResourceData* ptr) : PCPP_SMART_PTR(IDnsResourceData)(ptr) {}

		//Visual studio has always been stupid about returning something useful for __cplusplus
		//Only recently was this fixed - and even then it requires a specific hack to the command line during build
		//Its easier/more consistent to test _MSC_VER in VS
		//https://docs.microsoft.com/en-us/cpp/build/reference/zc-cplusplus?view=vs-2017

#if __cplusplus <= 199711L && _MSC_VER < 1800 //Maybe this can be 1600 for VS2010
		DnsResourceDataPtr(const DnsResourceDataPtr& other) : PCPP_SMART_PTR(IDnsResourceData)((DnsResourceDataPtr&)other) {}
#endif

		/**
		 * A templated method which takes a class that derives from IDnsResourceData as the template argument and
		 * checks whether the pointer stored in this object is of this type
		 * @return True if the stored pointer is of the requested type, false otherwise
		 */
		template <class IDnsResourceDataType>
		bool isTypeOf() const { return get()->isTypeOf<IDnsResourceDataType>(); }

		/**
		 * A templated method which take a class that derives from IDnsResourceData as the template argument and tries to
		 * cast the pointer stored in this object as that type
		 * @return A pointer to the stored pointer casted as the requested type or NULL if it isn't of this type
		 */
		template <class IDnsResourceDataType>
		IDnsResourceDataType* castAs() { return get()->castAs<IDnsResourceDataType>();}
	};


	/**
	 * @class StringDnsResourceData
	 * A class that represents DNS RR string data, mainly used in DNS RRs that store hostnames (like CNAME, DNAME, NS, etc.)
	 */
	class StringDnsResourceData : public IDnsResourceData
	{
	private:
		std::string m_Data;

	public:

		/**
		 * A c'tor for this class
		 * @param[in] data The string data to store in this object. If this string represents a hostname it's possible
		 * to include a pointer to another string in the DNS layer (as explained here: http://www.zytrax.com/books/dns/ch15/#name).
		 * These pointers are often used to reduce the DNS packet size and avoid unnecessary duplications. The way to include pointers
		 * in a hostname string is to use the following format: 'some.domain.#{offset}' where '#{offset}' is the offset from the
		 * start of the DNS layer. For example: if the string 'yahoo.com' already appears in offset 12 in the packet and you want
		 * to set the DNS RR data as 'my.subdomain.yahoo.com' you may use the following string: 'my.subdomain.#12'.
		 * This will result in writing 'my.subdomain' and a pointer to offset 12
		 */
		explicit StringDnsResourceData(const std::string& data) : m_Data(data) {}

		StringDnsResourceData(const uint8_t* dataPtr, size_t dataLen, IDnsResource* dnsResource);

		~StringDnsResourceData() {}

		/**
		 * Equality operator overload for this class that compares the strings stored in each object
		 * @param[in] other The object to compare with
		 * @return True if the string data is the same in both objects, false otherwise
		 */
		bool operator==(const StringDnsResourceData& other) const { return m_Data == other.m_Data; }

		// implement abstract methods

		std::string toString() const { return m_Data; }
		bool toByteArr(uint8_t* arr, size_t& arrLength, IDnsResource* dnsResource) const;
	};


	/**
	 * @class IPv4DnsResourceData
	 * A class that represents DNS RR IPv4 data, mainly used in DNS RRs of type ::DNS_TYPE_A
	 */
	class IPv4DnsResourceData : public IDnsResourceData
	{
	private:
		IPv4Address m_Data;

	public:

		/**
		 * A c'tor for this class
		 * @param[in] dataPtr A byte array of size 4 that contains an IPv4 address (each byte represents 1 octet)
		 * @param[in] dataLen The byte array size, expected to be 4
		 */
		IPv4DnsResourceData(const uint8_t* dataPtr, size_t dataLen);

		/**
		 * A c'tor for this class
		 * @param[in] addr The IPv4 address to store in this object
		 */
		explicit IPv4DnsResourceData(const IPv4Address& addr) : m_Data(addr) {}

		/**
		 * A c'tor for this class
		 * @param[in] addrAsString A string representation of an IPv4 address to store in this object
		 */
		explicit IPv4DnsResourceData(const std::string& addrAsString) : m_Data(addrAsString) {}

		/**
		 * Equality operator overload for this class that compares the IPv4 addresses stored in each object
		 * @param[in] other The object to compare with
		 * @return True if IPv4 addresses are the same in both objects, false otherwise
		 */
		bool operator==(const IPv4DnsResourceData& other) const { return m_Data == other.m_Data; }

		/**
		 * @return The IPv4 address stored in this object
		 */
		IPv4Address getIpAddress() const { return m_Data; }

		// implement abstract methods

		std::string toString() const { return m_Data.toString(); }
		bool toByteArr(uint8_t* arr, size_t& arrLength, IDnsResource* dnsResource) const;
	};


	/**
	 * @class IPv6DnsResourceData
	 * A class that represents DNS RR IPv6 data, mainly used in DNS RRs of type ::DNS_TYPE_AAAA
	 */
	class IPv6DnsResourceData : public IDnsResourceData
	{
	private:
		IPv6Address m_Data;

	public:

		/**
		 * A c'tor for this class
		 * @param[in] dataPtr A byte array of size 16 that contains an IPv6 address (each byte represents 1 octet)
		 * @param[in] dataLen The byte array size, expected to be 16
		 */
		IPv6DnsResourceData(const uint8_t* dataPtr, size_t dataLen);

		/**
		 * A c'tor for this class
		 * @param[in] addr The IPv6 address to store in this object
		 */
		explicit IPv6DnsResourceData(const IPv6Address& addr) : m_Data(addr) {}

		/**
		 * A c'tor for this class
		 * @param[in] addrAsString A string representation of an IPv6 address to store in this object
		 */
		explicit IPv6DnsResourceData(const std::string& addrAsString) : m_Data(addrAsString) {}

		/**
		 * Equality operator overload for this class that compares the IPv6 addresses stored in each object
		 * @param[in] other The object to compare with
		 * @return True if IPv6 addresses are the same in both objects, false otherwise
		 */
		bool operator==(const IPv6DnsResourceData& other) const { return m_Data == other.m_Data; }

		/**
		 * @return The IPv6 address stored in this object
		 */
		IPv6Address getIpAddress() const { return m_Data; }

		// implement abstract methods

		std::string toString() const { return m_Data.toString(); }
		bool toByteArr(uint8_t* arr, size_t& arrLength, IDnsResource* dnsResource) const;
	};


	/**
	 * @class MxDnsResourceData
	 * A class that represents DNS RR mail exchange (MX) data, used in DNS RRs of type ::DNS_TYPE_MX
	 */
	class MxDnsResourceData : public IDnsResourceData
	{
	public:

		/**
		 * A struct that represents mail exchange (MX) data
		 */
		struct MxData
		{
			/** Preference value */
			uint16_t preference;
			/** Mail exchange hostname */
			std::string mailExchange;
		};

		/**
		 * A c'tor for this class
		 * @param[in] dataPtr A byte array that contains the raw MX data (as written in the DNS packet)
		 * @param[in] dataLen The byte array size
		 * @param[in] dnsResource A pointer to a DNS resource object where this DNS RR data will be stored
		 */
		MxDnsResourceData(uint8_t* dataPtr, size_t dataLen, IDnsResource* dnsResource);

		/**
		 * A c'tor for this class
		 * @param[in] preference The MX preference value to store in this object
		 * @param[in] mailExchange The MX hostname value to store in this object. It's possible to include a pointer to
		 * another string in the DNS layer (as explained here: http://www.zytrax.com/books/dns/ch15/#name). These pointers
		 * are often used to reduce the DNS packet size and avoid unnecessary duplications. The way to include pointers
		 * in the hostname string is to use the following format: 'some.domain.#{offset}' where '#{offset}' is the offset
		 * from the start of the DNS layer. For example: if the string 'yahoo.com' already appears in offset 12 in the
		 * packet and you want to set the DNS RR data as 'my.subdomain.yahoo.com' you may use the following string:
		 * 'my.subdomain.#12'. This will result in writing 'my.subdomain' and a pointer to offset 12
		 */
		MxDnsResourceData(const uint16_t& preference, const std::string& mailExchange);

		~MxDnsResourceData() {}

		/**
		 * Equality operator overload for this class that compares the MX data stored in each object
		 * @param[in] other The object to compare with
		 * @return True if MX data is the same in both objects, meaning both preference and MX hostname are the same,
		 * false otherwise
		 */
		bool operator==(const MxDnsResourceData& other) const;

		/**
		 * @return The MX data stored in this object
		 */
		MxData getMxData() const { return m_Data; }

		/**
		 * Set the MX data stored in this object
		 * @param[in] preference The MX preference value to store in this object
		 * @param[in] mailExchange The MX hostname value to store in this object
		 */
		void setMxData(uint16_t preference, std::string mailExchange);

		// implement abstract methods

		/**
		 * A string representation of the MX data stored in this object. The string format is as follows:
		 * 'pref: {preference_value}; mx: {mail_exchange_hostname_value}'
		 */
		std::string toString() const;

		bool toByteArr(uint8_t* arr, size_t& arrLength, IDnsResource* dnsResource) const;

	private:
		MxData m_Data;
	};


	/**
	 * @class GenericDnsResourceData
	 * A class that represents generic DNS RR data which cannot be represented in any of the other classes. It stores the
	 * DNS RR data as byte array
	 */
	class GenericDnsResourceData : public IDnsResourceData
	{
	private:
		uint8_t* m_Data;
		size_t m_DataLen;

	public:

		/**
		 * A c'tor for this class
		 * @param[in] dataPtr A byte array that contains the raw data (as it written in the DNS packet). The data will be
		 * copied from this byte array to the object
		 * @param[in] dataLen The byte array size
		 */
		GenericDnsResourceData(const uint8_t* dataPtr, size_t dataLen);

		/**
		 * A c'tor for this class
		 * @param[in] dataAsHexString A hex string that represents the DNS RR data
		 */
		explicit GenericDnsResourceData(const std::string& dataAsHexString);

		/**
		 * A copy c'tor for this class
		 * @param[in] other The instance to copy from
		 */
		GenericDnsResourceData(const GenericDnsResourceData& other);

		~GenericDnsResourceData() { if (m_Data != NULL) delete [] m_Data; }

		GenericDnsResourceData& operator=(const GenericDnsResourceData& other);

		/**
		 * Equality operator overload for this class that compares the raw data stored in each object
		 * @param[in] other The object to compare with
		 * @return True if data is the same in both objects, meaning byte streams are equal, false otherwise
		 */
		bool operator==(const GenericDnsResourceData& other) const;

		// implement abstract methods

		std::string toString() const;
		bool toByteArr(uint8_t* arr, size_t& arrLength, IDnsResource* dnsResource) const;
	};

}

#endif // PACKETPP_DNS_RESOURCE_DATA