#include "wagon.h"



Wagon::Wagon(int id,int numpixels, Adafruit_NeoPixel *strip,uint8_t *height,float pos, float wagonlength,float startvel,float startacc)
{
  _id = id;
  _numpixels=numpixels;
  _pos = pos;
  _wagonlength = wagonlength;
  _strip=strip;
  _height=height;
  _vel=startvel;
  _acc=startacc;

}

bool Wagon::operator==(const Wagon &r) const {
  return (r._id == _id);
}

void Wagon::updatePhysics(float updatedelayms)
{
  
  /*
  float acceleration=0;
  for (int cpos=int(_pos);cpos>int(_pos-_wagonlength);cpos--){
    acceleration=(_height[(int)cpos]-_height[(int)cpos+1])*0.03;
  }
  acceleration/=int(_wagonlength);
  _vel+= acceleration; //Acceleration from height difference
  _vel*=1-0.001; //resistance
  float airresistance=_vel*_vel *0.005;//air resistance
  if (_vel>=0){
    _vel-=airresistance;
  }else{
    _vel+=airresistance;
  }*/
  #define CONST_G 9.81
  #define PIXELDISTANCE 1.6666667 // 1/60.0 * 100 
  #define C_ROLL 0.001 // = Croll * G    https://de.wikipedia.org/wiki/Rollwiderstand   0.001
  #define AIRRES 0.18 //C_w*A*0.5*rho     Air resistance:  C_w * A * 0.5 * rho  (.... *v^2)
  //http://www.kfz-tech.de/Biblio/Formelsammlung/Luftwiderstand.htm   C_w 0.6 
  //rho  Massendichte luft  1,2041
  //A = 1m^2

  float m=50/_wagonlength; //mass of part of a wagon


  _acc=0;
  int cpos=(int)_pos;
  for (int cpos=(int)_pos;cpos>(int)(_pos-_wagonlength);cpos--){ //for each wagon

    float hdiff=getHeight((int) (cpos-0.5)) - getHeight((int)(cpos+0.5));

    //Serial.print("hdiff=");
    //Serial.print(hdiff);
  
    float beta=atan2(PIXELDISTANCE, hdiff);

    //Serial.print(" beta=");
    //Serial.println(beta);
  
    //_acc += CONST_G * cos(beta) - C_ROLLG*sin(beta) - AIRRES/m*_vel*_vel;

    float aa=CONST_G * cos(beta) *updatedelayms/1000; //Gravity  and m/s^2 time correction
    float bb=C_ROLL*CONST_G*updatedelayms/1000*sin(beta); //roll resistance
    if (_vel<0){
      bb*=-1;
    }
    float cc=AIRRES/m*_vel*_vel; //air resistance
    if (_vel<0){
      cc*=-1;
    }

    //Serial.print("aa="); Serial.print(aa);
    //Serial.print(" bb="); Serial.print(bb);
    //Serial.print(" cc="); Serial.println(cc);
    

    _acc += aa - bb - cc;
    

  }

  _acc*=updatedelayms/1000;
  
  _vel += _acc;
  _pos += _vel/PIXELDISTANCE;
  /*Serial.print(" Vel=");
  Serial.print(_vel);
  Serial.print(" Acc=");
  Serial.println(_acc);*/
}

float Wagon::getHeight(int p){
  if (p<0){
    p=0;
  }else if(p>=_numpixels){
    p=_numpixels-1;
  }
  return _height[p];
}

void Wagon::updateGraphics()
{
  for(int i=_pos;i>_pos-_wagonlength;i--){
    uint32_t c=_strip->Color(0,255,0);
    if (i==int(_pos)){
      c=_strip->Color(0,255,100);
    }
    _strip->setPixelColor(i,c);
  }
  //_strip->setPixelColor(10,_strip->Color(255,0,0));
}

int Wagon::pos()
{
  return _pos;
}

int Wagon::id()
{
  return _id;
}

bool Wagon::alive()
{
  if (_pos>_numpixels){
    return false;
  }
  return true;
}