/*
 *  Copyright (C) 2005-2018 Team Kodi
 *  This file is part of Kodi - https://kodi.tv
 *
 *  SPDX-License-Identifier: GPL-2.0-or-later
 *  See LICENSES/README.md for more information.
 */

#include "PTSTracker.h"

#include "DVDCodecs/DVDCodecUtils.h"
#include "cores/VideoPlayer/Interface/TimingConstants.h"
#include "utils/StringUtils.h"
#include "utils/log.h"

#include <algorithm>
#include <cmath>

#define MAXERR DVD_MSEC_TO_TIME(2.5)

CPtsTracker::CPtsTracker()
{
  ResetVFRDetection();
  Flush();
}

void CPtsTracker::ResetVFRDetection(void)
{
  m_minframeduration = DVD_NOPTS_VALUE;
  m_maxframeduration = DVD_NOPTS_VALUE;
  m_VFRCounter = 0;
  m_patternCounter = 0;
  m_lastPattern.clear();
}

void CPtsTracker::Flush()
{
  m_pattern.clear();
  m_ringpos       = 0;
  m_prevpts       = DVD_NOPTS_VALUE;
  m_ringfill      = 0;
  m_haspattern    = false;
  m_patternlength = 0;
  m_frameduration = DVD_NOPTS_VALUE;
  memset(m_diffring, 0, sizeof(m_diffring));
}

void CPtsTracker::Add(double pts)
{
  //can't get a diff with just one pts
  if (m_prevpts == DVD_NOPTS_VALUE)
  {
    m_prevpts = pts;
    return;
  }

  //increase the ringbuffer position
  m_ringpos = (m_ringpos + 1) % DIFFRINGSIZE;
  //add the current diff to the ringbuffer
  m_diffring[m_ringpos] = pts - m_prevpts;
  //save the pts
  m_prevpts = pts;

  if (m_ringfill < DIFFRINGSIZE)
    m_ringfill++;

  //only search for patterns if we have full ringbuffer
  if (m_ringfill < DIFFRINGSIZE)
    return;

  //get the current pattern in the ringbuffer
  std::vector<double> pattern;
  GetPattern(pattern);

  //check if the pattern is the same as the saved pattern
  //and if it is actually a pattern
  if (!CheckPattern(pattern))
  {
    if (m_haspattern)
    {
      m_VFRCounter++;
      m_lastPattern = m_pattern;
      CLog::Log(LOGDEBUG, "CPtsTracker: pattern lost on diff {:f}, number of losses {}", GetDiff(0),
                m_VFRCounter);
      Flush();
    }

    //no pattern detected or current pattern broke/changed
    //save detected pattern so we can check it with the next iteration
    m_pattern = pattern;

    return;
  }
  else
  {
    if (!m_haspattern)
    {
      m_haspattern = true;
      m_patternlength = m_pattern.size();

      if (!m_lastPattern.empty() && !CheckPattern(m_lastPattern))
      {
        m_patternCounter++;
      }

      double frameduration = CalcFrameDuration();
      CLog::Log(LOGDEBUG, "CPtsTracker: detected pattern of length {}: {}, frameduration: {:f}",
                (int)pattern.size(), GetPatternStr(), frameduration);
    }
  }

  m_frameduration = CalcFrameDuration();
}

//gets a diff diffnr into the past
inline double CPtsTracker::GetDiff(int diffnr)
{
  //m_ringpos is the last added diff, so if we want to go in the past we have to move back in the ringbuffer
  int pos = m_ringpos - diffnr;
  if (pos < 0)
    pos += DIFFRINGSIZE;

  return m_diffring[pos];
}

//calculate the current pattern in the ringbuffer
void CPtsTracker::GetPattern(std::vector<double>& pattern)
{
  int difftypesbuff[DIFFRINGSIZE]; //difftypes of the diffs, difftypesbuff[0] is the last added diff,
                                   //difftypesbuff[1] the one added before that etc

  //get the difftypes
  std::vector<double> difftypes;
  for (int i = 0; i < m_ringfill; i++)
  {
    bool hasmatch = false;
    for (unsigned int j = 0; j < difftypes.size(); j++)
    {
      if (MatchDiff(GetDiff(i), difftypes[j]))
      {
        hasmatch = true;
        break;
      }
    }

    //if we don't have a match with a saved difftype, we add it as a new one
    if (!hasmatch)
      difftypes.push_back(GetDiff(i));
  }

  //mark each diff with what difftype it is
  for (int i = 0; i < m_ringfill; i++)
  {
    for (unsigned int j = 0; j < difftypes.size(); j++)
    {
      if (MatchDiff(GetDiff(i), difftypes[j]))
      {
        difftypesbuff[i] = j;
        break;
      }
    }
  }

  bool checkexisting = !m_pattern.empty();

  //we check for patterns to the length of DIFFRINGSIZE / 2
  for (int i = 1; i <= m_ringfill / 2; i++)
  {
    //check the existing pattern length first
    int length = checkexisting ? m_pattern.size() : i;

    bool hasmatch = true;
    for (int j = 1; j <= m_ringfill / length; j++)
    {
      int nrdiffs = length;
      //we want to check the full buffer to see if the pattern repeats
      //but we can't go beyond the buffer
      if (j * length + length > m_ringfill)
        nrdiffs = m_ringfill - j * length;

      if (nrdiffs < 1)  //if the buffersize can be cleanly divided by i we're done here
        break;

      if (!MatchDifftype(difftypesbuff, difftypesbuff + j * length, nrdiffs))
      {
        hasmatch = false;
        break;
      }
    }

    if (checkexisting)
    {
      checkexisting = false;
      i--;
    }

    if (hasmatch)
    {
      for (int i = 0; i < length; i++)
      {
        double avgdiff = 0.0;
        for (int j = 0; j < m_ringfill / length; j++)
          avgdiff += GetDiff(j * length + i);

        avgdiff /= m_ringfill / length;
        pattern.push_back(avgdiff);
      }
      break;
    }
  }
  std::sort(pattern.begin(), pattern.end());
}

inline bool CPtsTracker::MatchDiff(double diff1, double diff2)
{
  return fabs(diff1 - diff2) < MAXERR;
}

//check if diffs1 is the same as diffs2
inline bool CPtsTracker::MatchDifftype(int diffs1[], int diffs2[], int nrdiffs)
{
  for (int i = 0; i < nrdiffs; i++)
  {
    if (diffs1[i] != diffs2[i])
      return false;
  }
  return true;
}

//check if our current detected pattern is the same as the one we saved
bool CPtsTracker::CheckPattern(std::vector<double>& pattern)
{
  //if no pattern was detected or if the size of the patterns differ we don't have a match
  if (pattern.empty() || pattern.size() != m_pattern.size())
    return false;

  if (pattern.size() == 1)
  {
    if (pattern[0] < MAXERR)
      return false; //all diffs are too close to 0, can't use this
  }

  //check if the current pattern matches the saved pattern, with an offset of 1
  for (unsigned int i = 0; i < m_pattern.size(); i++)
  {
    double diff = pattern[i];

    if (!MatchDiff(diff, m_pattern[i]))
      return false;
  }

  return true;
}

//calculate how long each frame should last from the saved pattern
//also retrieve information of max and min frame rate duration, for VFR files case
double CPtsTracker::CalcFrameDuration()
{
  if (!m_pattern.empty())
  {
    //take the average of all diffs in the pattern
    double frameduration;
    double current, currentmin, currentmax;

    currentmin = m_pattern[0];
    currentmax = currentmin;
    frameduration = currentmin;
    for (unsigned int i = 1; i < m_pattern.size(); i++)
    {
      current = m_pattern[i];
      if (current>currentmax)
        currentmax = current;
      if (current<currentmin)
        currentmin = current;
      frameduration += current;
    }
    frameduration /= m_pattern.size();

    // Update min and max frame duration, only if data is valid
    bool standard = false;
    double tempduration = CDVDCodecUtils::NormalizeFrameduration(currentmin, &standard);
    if (m_minframeduration == DVD_NOPTS_VALUE)
    {
      if (standard)
        m_minframeduration = tempduration;
    }
    else
    {
      if (standard && (tempduration < m_minframeduration))
        m_minframeduration = tempduration;
    }

    tempduration = CDVDCodecUtils::NormalizeFrameduration(currentmax, &standard);
    if (m_maxframeduration == DVD_NOPTS_VALUE)
    {
      if (standard)
        m_maxframeduration = tempduration;
    }
    else
    {
      if (standard && (tempduration > m_maxframeduration))
        m_maxframeduration = tempduration;
    }

    //frameduration is not completely correct, use a common one if it's close
    return CDVDCodecUtils::NormalizeFrameduration(frameduration);
  }

  return DVD_NOPTS_VALUE;
}

//looks pretty in the log
std::string CPtsTracker::GetPatternStr()
{
  std::string patternstr;

  for (unsigned int i = 0; i < m_pattern.size(); i++)
    patternstr += StringUtils::Format("{:.2f} ", m_pattern[i]);

  StringUtils::Trim(patternstr);

  return patternstr;
}