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/** \file     Contexts.h

 *  \brief    Classes providing probability descriptions and contexts (header)

 */

#pragma once

#include "CommonDef.h"

#include <array>

#include <vector>

namespace vvdec

{

static constexpr int     PROB_BITS   = 15;   // Nominal number of bits to represent probabilities

static constexpr int     PROB_BITS_0 = 10;   // Number of bits to represent 1st estimate

static constexpr int     PROB_BITS_1 = 14;   // Number of bits to represent 2nd estimate

static constexpr int     MASK_0      = ~(~0u << PROB_BITS_0) << (PROB_BITS - PROB_BITS_0);

static constexpr int     MASK_1      = ~(~0u << PROB_BITS_1) << (PROB_BITS - PROB_BITS_1);

static constexpr uint8_t DWS         = 8;   // 0x47 Default window sizes

static constexpr uint8_t CNU         = 35;

class ProbModelTables

{

protected:

  static const uint8_t      m_RenormTable_32  [ 32];          // Std         MP   MPI

};

class BinProbModel : public ProbModelTables

{

public:

  BinProbModel()

  {

    uint16_t half = 1 << (PROB_BITS - 1);

    m_state[0]    = half;

    m_state[1]    = half;

    m_rate0 = 0;

    m_rate1 = DWS;

    m_delta0[0] = ((0xFFFFU) >> (16 - m_rate0));

    m_delta0[1] = ((0xFFFFU) >> (16 - PROB_BITS));

    m_delta1[0] = ((0xFFFFU) >> (16 - m_rate1));

    m_delta1[1] = ((0xFFFFU) >> (16 - PROB_BITS));

  }

  ~BinProbModel() {}

public:

  void            init              ( int qp, int initId );

  void update(unsigned bin)

  {

//    m_state[0] -= (m_state[0] >> m_rate0) & MASK_0;

//    m_state[1] -= (m_state[1] >> m_rate1) & MASK_1;

//    m_state[0] += ( ( bin ? 0x7fffu : 0x0u ) >> m_rate0 ) & MASK_0;

//    m_state[1] += ( ( bin ? 0x7fffu : 0x0u ) >> m_rate1 ) & MASK_1;

    int delta0 = m_delta0[bin] - m_state[0];

    int delta1 = m_delta1[bin] - m_state[1];

    delta0 = delta0 >> m_rate0;

    delta1 = delta1 >> m_rate1;

    m_state[0] += delta0 *(1<< 5);

    m_state[1] += delta1 *2;

  }

  // Variant taking the pre-update state already loaded by lpsmps(). decodeBin() calls

  // m_Bitstream->readByteFlag() between lpsmps() and update(); m_Bitstream is a non-restrict

  // pointer the compiler must assume may alias m_state, forcing a reload of m_state[0]/[1] here.

  // Passing the cached values avoids that reload. Arithmetically identical (s0==m_state[0],

  // s1==m_state[1] at this point), hence bit-exact.

  void update( unsigned bin, unsigned s0, unsigned s1 )

  {

    int delta0 = m_delta0[bin] - (int)s0;

    int delta1 = m_delta1[bin] - (int)s1;

    delta0 = delta0 >> m_rate0;

    delta1 = delta1 >> m_rate1;

    m_state[0] = (uint16_t)( s0 + delta0 * ( 1 << 5 ) );

    m_state[1] = (uint16_t)( s1 + delta1 * 2 );

  }

  void setLog2WindowSize(uint8_t log2WindowSize)

  {

    m_rate0 = 2 + ((log2WindowSize >> 2) & 3);

    m_rate1 = 3 + m_rate0 + (log2WindowSize & 3);

    CHECK(m_rate1 > 9, "Second window size is too large!");

    m_rate0 += 5;

    m_rate1 += 1;

    m_delta0[0] = ((0xFFFFU) >> (16 - m_rate0));

    m_delta1[0] = ((0xFFFFU) >> (16 - m_rate1));

  }

public:

  uint8_t state() const { return (m_state[0] + m_state[1]) >> 8; }

  uint8_t mps() const { return state() >> 7; }

  uint8_t lps( unsigned range ) const

  {

    uint16_t q = state();

    if (q & 0x80)

      q = q ^ 0xff;

    return ((q >> 2) * (range >> 5) >> 1) + 4;

  }

  void lpsmps( unsigned range, unsigned& lps, unsigned& bin ) const

  {

    const uint16_t q = (m_state[0] + m_state[1]) >> 8;

    bin = q >> 7;

    lps = ((((q ^ (-static_cast<int>(bin) & 0xff)) >> 2) * (range >> 5)) >> 1) + 4;

    //if( q & 0x80 )

    //{

    //  CHECK( lps != ( ( ( ( q ^ 0xff ) >> 2 ) * ( range >> 5 ) >> 1 ) + 4 ), "" );

    //  lps = ( ( ( q ^ 0xff ) >> 2 ) * ( range >> 5 ) >> 1 ) + 4;

    //}

    //else

    //{

    //  CHECK( lps != ( ( ( q >> 2 ) * ( range >> 5 ) >> 1 ) + 4 ), "" );

    //  lps = ( ( q >> 2 ) * ( range >> 5 ) >> 1 ) + 4;

    //}

  }

  // Variant that also returns the raw state halves so the caller can feed them to

  // update(bin,s0,s1), avoiding the aliasing-forced reload of m_state[] in update().

  void lpsmps( unsigned range, unsigned& lps, unsigned& bin, unsigned& s0, unsigned& s1 ) const

  {

    s0 = m_state[0];

    s1 = m_state[1];

    const uint16_t q = ( s0 + s1 ) >> 8;

    bin = q >> 7;

    lps = ((((q ^ (-static_cast<int>(bin) & 0xff)) >> 2) * (range >> 5)) >> 1) + 4;

  }

  static uint8_t  getRenormBitsLPS  ( unsigned LPS )                    { return    m_RenormTable_32  [LPS>>3]; }

  static uint8_t  getRenormBitsRange( unsigned range )                  { return    1; }

private:

  uint16_t m_state[2];

  uint16_t m_rate0;

  uint16_t m_rate1;

  uint16_t m_delta0[2];

  uint16_t m_delta1[2];

};

class CtxSet

{

public:

  CtxSet( uint16_t offset, uint16_t size ) : Offset( offset ), Size( size ) {}

  CtxSet( std::initializer_list<CtxSet> ctxSets );

  uint16_t operator()() const

  {

    return Offset;

  }

  uint16_t operator()( uint16_t inc ) const

  {

    CHECKD( inc >= Size, "Specified context increment (" << inc << ") exceed range of context set [0;" << Size - 1 << "]." );

    return Offset + inc;

  }

private:

  uint16_t Offset;

  uint16_t Size;

};

class ContextSetCfg

{

public:

  // context sets: specify offset and size

  static const CtxSet   SplitFlag;

  static const CtxSet   SplitQtFlag;

  static const CtxSet   SplitHvFlag;

  static const CtxSet   Split12Flag;

  static const CtxSet   ModeConsFlag;

  static const CtxSet   SkipFlag;

  static const CtxSet   MergeFlag;

  static const CtxSet   RegularMergeFlag;

  static const CtxSet   MergeIdx;

  static const CtxSet   PredMode;

  static const CtxSet   MultiRefLineIdx;

  static const CtxSet   IntraLumaPlanarFlag;

  static const CtxSet   CclmModeFlag;

  static const CtxSet   CclmModeIdx;

  static const CtxSet   IPredMode       [2];    // [ ChannelType ]

  static const CtxSet   MipFlag;

  static const CtxSet   DeltaQP;

  static const CtxSet   InterDir;

  static const CtxSet   RefPic;

  static const CtxSet   MmvdFlag;

  static const CtxSet   MmvdMergeIdx;

  static const CtxSet   MmvdStepMvpIdx;

  static const CtxSet   SubblockMergeFlag;

  static const CtxSet   AffineFlag;

  static const CtxSet   AffineType;

  static const CtxSet   AffMergeIdx;

  static const CtxSet   Mvd;

  static const CtxSet   BDPCMMode;

  static const CtxSet   QtRootCbf;

  static const CtxSet   ACTFlag;

  static const CtxSet   QtCbf           [3];    // [ channel ]

  static const CtxSet   SigCoeffGroup   [2];    // [ ChannelType ]

  static const CtxSet   LastX           [2];    // [ ChannelType ]

  static const CtxSet   LastY           [2];    // [ ChannelType ]

  static const CtxSet   SigFlag         [6];    // [ ChannelType + State ]

  static const CtxSet   ParFlag         [2];    // [ ChannelType ]

  static const CtxSet   GtxFlag         [4];    // [ ChannelType + x ]

  static const CtxSet   TsSigCoeffGroup;

  static const CtxSet   TsSigFlag;

  static const CtxSet   TsParFlag;

  static const CtxSet   TsGtxFlag;

  static const CtxSet   TsLrg1Flag;

  static const CtxSet   TsResidualSign;

  static const CtxSet   MVPIdx;

  static const CtxSet   SaoMergeFlag;

  static const CtxSet   SaoTypeIdx;

  static const CtxSet   MTSIndex;

  static const CtxSet   LFNSTIdx;

  static const CtxSet   RdpcmFlag;

  static const CtxSet   RdpcmDir;

  static const CtxSet   SbtFlag;

  static const CtxSet   SbtQuadFlag;

  static const CtxSet   SbtHorFlag;

  static const CtxSet   SbtPosFlag;

  static const CtxSet   ChromaQpAdjFlag;

  static const CtxSet   ChromaQpAdjIdc;

  static const CtxSet   ImvFlag;

  static const CtxSet   CcAlfFilterControlFlag;

  static const CtxSet   BcwIdx;

  static const CtxSet   ctbAlfFlag;

  static const CtxSet   ctbAlfAlternative;

  static const CtxSet   AlfUseTemporalFilt;

  static const CtxSet   CiipFlag;

  static const CtxSet   SmvdFlag;

  static const CtxSet   IBCFlag;

  static const CtxSet   ISPMode;

  static const CtxSet   JointCbCrFlag;

  static const unsigned NumberOfContexts;

  // combined sets for less complex copying

  // NOTE: The contained CtxSet's should directly follow each other in the initalization list;

  //       otherwise, you will copy more elements than you want !!!

  static const CtxSet   Sao;

  static const CtxSet   Alf;

public:

  static const std::vector<uint8_t>&  getInitTable( unsigned initId );

private:

  static std::array<std::vector<uint8_t>, NUMBER_OF_SLICE_TYPES + 1> sm_InitTables;

  static CtxSet addCtxSet( std::initializer_list<std::initializer_list<uint8_t> > initSet2d );

};

class Ctx : public ContextSetCfg

{

public:

  Ctx() = default;

  void init( int qp, int initId );

  const BinProbModel& operator[]( unsigned ctxId ) const { return m_CtxBuffer[ctxId]; }

        BinProbModel& operator[]( unsigned ctxId )       { return m_CtxBuffer[ctxId]; }

private:

  static_vector<BinProbModel, 372> m_CtxBuffer{ ContextSetCfg::NumberOfContexts };

};

}