/*!
 * \file    /utl/com/i2c.h
 * \brief   An Abstract base class interface for the i2c bus
 *
 * Copyright (C) 2018 Christos Choutouridis
 *
 * 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, either version 3
 * of the License, or (at your option) any later version.
 *
 * 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
#ifndef _utl_com_i2c_h__
#define _utl_com_i2c_h__

#include <utl/core/impl.h>
#include <utl/core/crtp.h>
#include <utl/meta/meta.h>

namespace utl {

/*!
 * \ingroup Communication
 * \brief   Abstract base class for i2c bus
 */
//!@{

   /*!
    * \brief
    *    this class force a common interface for I2C communication
    *    protocol implementations using CRTP
    * \param   impl_t   The CRTP type (the derived/implementation class typename).
    */
   template <typename impl_t>
   class i2c_i {
      _CRTP_IMPL(impl_t);

   public:
      using type = i2c_i<impl_t>;     //!< Export type as identity meta-function
      //! I2C transmit/receive sequence
      enum class Sequence {
         BYTE =0, //!< Only read/write byte     [8 clocks]
         ACK,     //!< Only send/receive ack    [1 clock]
         BYTEnACK //!< Read/Write byte and ack  [9 clocks]
      };

   /*!
    * \name Object lifetime
    */
   //!@{
   protected:
      i2c_i () = default;              //!< Allow constructor from derived only
      ~i2c_i () = default;             //!< Allow destructor from derived only
      i2c_i (const type&) = delete;    //!< No copies
      type& operator= (const type&) = delete;
   //!@}

   /*!
    * \name Implementation requirements
    * \note
    *    In order for the implementation to have the following as private members
    *    it also need to declare this class as friend
    */
   //!@{
   private:
      uint32_t _clock () const { return impl()._clock (); } //!< clock frequency of the bus [Hz]
      void _clock (uint32_t c) { impl()._clock (c); }       //!< set clock frequency of the bus [Hz]
      void _start()            { impl()._start (); }        //!< Send start functionality
      void _stop()             { impl()._stop (); }         //!< Send stop functionality
      byte_t _rx_data (bool ack, Sequence seq)  { return impl()._rx_data (ack, seq); }
      bool _tx_data (byte_t byte, Sequence seq) { return impl()._tx_data (byte, seq); }
   //!@}

   /*!
    * \name Get/Set functions
    */
   //!@{
   public:
      uint32_t clock () const { return _clock (); }  //!< \return clock frequency of the bus
      void clock (uint32_t f) { _clock (f); }        //!< \brief set clock frequency of the bus
   //!@}

   /*!
    * \name User functions
    */
   //!@{
   public:
      void start() { _start (); }   //!< Send start functionality
      void stop () { _stop (); }    //!< Send stop functionality

      /*!
       * \brief
       *    Receive a byte from the i2c bus.
       * \param  ack    Optional ack bit.
       *    \arg 1  ACK the reception
       *    \arg 0  Don't ACK the reception.
       * \param   seq   The operation sequence to execute
       *    \arg  Sequence::BYTE       Receive only the byte, do not send ack clock
       *    \arg  Sequence::ACK        Send only the ack bit
       *    \arg  Sequence::BYTEnACK   Receive the byte and send the ack bit
       * \return  The byte received.
       */
      byte_t rx_data (bool ack, Sequence seq =Sequence::BYTEnACK) {
         return _rx_data (ack, seq);
      }

      /*!
       * \brief
       *    Transmit a byte to the i2c bus.
       * \param  byte   The byte to send.
       * \param   seq   The operation sequence to execute
       *    \arg  Sequence::BYTE       Transmit only the byte, do not read ack bit
       *    \arg  Sequence::ACK        Read only the ack bit
       *    \arg  Sequence::BYTEnACK   Transmit the byte and read the ack bit
       * \return Slave's ACK bit
       *    \arg false  Slave didn't ACK
       *    \arg true   Slave did ACK
       */
      bool tx_data (byte_t byte, Sequence seq =Sequence::BYTEnACK) {
         return _tx_data (byte, seq);
      }
   //!@}

   };

   /*!
    * \brief
    *    A virtual base class specialization
    * \param   impl_t   = virtual_tag
    */
   template<>
   class i2c_i <virtual_tag> {
   public:
      using type = i2c_i <virtual_tag>;   //!< Export type as identity meta-function

      //! I2C transmit/receive sequence
      enum class Sequence {
         BYTE=0,  //!< Only read/write byte     [8 clocks]
         ACK,     //!< Only send/receive ack    [1 clock]
         BYTEnACK //!< Read/Write byte and ack  [9 clocks]
      };

   /*!
    * \name Object lifetime
    */
   //!@{
   protected:
      i2c_i () = default;                 //!< Allow constructor from derived only
      i2c_i (const type&) = delete;       //!< No copies
      type& operator= (const type&) = delete;
   public:
      virtual ~i2c_i () = default;        //!< Virtual default destructor
   //!@}

   /*!
    * \name Implementation requirements
    */
   //!@{
   private:
      virtual uint32_t _clock () const = 0;  //!< \return clock frequency of the bus [Hz]
      virtual void _clock (uint32_t) = 0;    //!< \brief set clock frequency of the bus [Hz]
      virtual void _start() = 0;             //!< Send start functionality
      virtual void _stop() = 0;              //!< Send stop functionality
      virtual byte_t _rx_data (bool ack, Sequence seq) = 0;    //!< Receive a byte from the i2c bus.
      virtual bool _tx_data (byte_t byte, Sequence seq) = 0;   //!< Transmit a byte to the i2c bus.
   //!@}
   /*!
    * \name Get/Set functions
    */
   //!@{
   public:
      uint32_t clock () const { return _clock(); } //!< \return clock frequency of the bus [Hz]
      void clock (uint32_t c) { _clock(c); }       //!< \brief set clock frequency of the bus [Hz]
   //!@}

   /*!
    * \name User functions
    */
   //!@{
   public:
      void start () { _start(); }
      void stop () { _stop(); }
      /*!
       * \brief
       *    Receive a byte from the i2c bus.
       * \param  ack    Optional ack bit.
       *    \arg 1  ACK the reception
       *    \arg 0  Don't ACK the reception.
       * \param   seq   The operation sequence to execute
       *    \arg  Sequence::BYTE       Receive only the byte, do not send ack clock
       *    \arg  Sequence::ACK        Send only the ack bit
       *    \arg  Sequence::BYTEnACK   Receive the byte and send the ack bit
       * \return   The byte received.
       */
      byte_t rx_data (bool ack, Sequence seq =Sequence::BYTEnACK) {
         return _rx_data (ack, seq);
      }
      /*!
       * \brief
       *    Transmit a byte to the i2c bus.
       * \param  byte   The byte to send.
       * \param   seq   The operation sequence to execute
       *    \arg  Sequence::BYTE       Transmit only the byte, do not read ack bit
       *    \arg  Sequence::ACK        Read only the ack bit
       *    \arg  Sequence::BYTEnACK   Transmit the byte and read the ack bit
       * \return Slave's ACK bit
       *    \arg false  Slave didn't ACK
       *    \arg true   Slave did ACK
       */
      bool tx_data (byte_t byte, Sequence seq =Sequence::BYTEnACK) {
         return _tx_data (byte, seq);
      }
   //!@}

   };

#if defined _utl_have_concepts
   /*!
    * i2c interface concept
    */
   template <typename T>
   concept bool I2c_i = requires (T t, const T ct, typename T::Sequence s) {
      // Object type
      requires not_<std::is_copy_constructible<T>::value>::value;
      requires not_<std::is_copy_assignable<T>::value>::value;
      // Methods
      {ct.clock()} -> uint32_t;
      {t.clock(0)} -> void;
      {t.start()}  -> void;
      {t.stop()}   -> void;
      {t.rx_data (1, s)} -> byte_t;
      {t.tx_data (0, s)} -> bool;
   };
#else
   namespace i2c_i_details {
      using std::declval;

      template <class _Tp> using try_cclk_t  = decltype (declval<const _Tp>().clock());
      template <class _Tp> using try_clk_t   = decltype (declval<_Tp>().clock(declval<uint32_t>()));
      template <class _Tp> using try_start_t = decltype (declval<_Tp>().start());
      template <class _Tp> using try_stop_t  = decltype (declval<_Tp>().stop());
      template <class _Tp> using try_rx_data_t
            = decltype (declval<_Tp>().rx_data (declval<bool>(), declval<typename _Tp::Sequence>()));
      template <class _Tp> using try_tx_data_t
            = decltype (declval<_Tp>().tx_data (declval<byte_t>(), declval<typename _Tp::Sequence>()));

      //! Primary template to catch any non I2C interface types
      template <typename _Tp, typename =void>
      struct is_i2c_ : meta::false_ { };

      //! template to catch a proper I2C interface type
      template <typename _Tp>
      struct is_i2c_ <_Tp,
         meta::void_t <
            typename _Tp::Sequence,
            meta::use_if_same_t <uint32_t,try_cclk_t <_Tp>>,
            meta::use_if_same_t <void,    try_clk_t <_Tp>>,
            meta::use_if_same_t <void,    try_start_t <_Tp>>,
            meta::use_if_same_t <void,    try_stop_t <_Tp>>,
            meta::use_if_same_t <byte_t,  try_rx_data_t <_Tp>>,
            meta::use_if_same_t <bool,    try_tx_data_t <_Tp>>
         >
      > : meta::true_ { };
   }
   /*!
    * Value meta-programming function alias for I2C interface checking
    * \param   _Tp  Type to check
    * \return  True if _Tp is a i2c interface
    */
   template <typename _Tp>
   constexpr bool I2c_i = i2c_i_details::is_i2c_<_Tp>::value;
#endif

//!@}

} // namespace utl

#endif // _utl_com_i2c_h__