// delta max = 0.6544 wrt dewPoint()
// 6.9 x faster than dewPoint()
// reference: http://en.wikipedia.org/wiki/Dew_point
double dewPointFast(double celsius, double humidity)
{
  double a = 17.271;
  double b = 237.7;
  double temp = (a * celsius) / (b + celsius) + log(humidity * 0.01);
  double Td = (b * temp) / (a - temp);
  return Td;
}

int desiredCoolingIthoSpeed(float t, float h, float dp, float buitent, float buitenh, float buitendp) {
  // called if (t > 20.0 || (t > 19.0 && buitent > 24.0))

  // only on extreme humidity we run when the outside temp is higher
  if ((h > 65.0 && dp > (buitendp+2.0))
    || (h > 75.0 && dp > (buitendp+1.0)))  {
    Serial.println("it's hot, but it so humid that we still want to dry..");
    return 1;
  }

  if (buitent < (t-3.0)) {
    // buiten 3 graden koeler
    if (t > 22.0 && (buitent < 18.0) && buitendp <= dp) {
      Serial.println("Extreme cooling (4 degrees) and also drying, use 2!");
      return 2;
    }
    Serial.println("Normal cooling");
    return 1;
  }
  Serial.println("Nothing to cool, default return 0");
  return 0;
}



int desiredDryingIthoSpeed(float t, float h, float dp, float buitent, float buitenh, float buitendp) {
  // by default we send medium
  if (dp - buitendp > 5.0) {
    // buiten veeel droger, maar droger trekken dan 45 heeft echt geen zin
    if (h > 57.0) {
      Serial.println("Much drier outside, h>57 inside, return 2");
      return 2;
    } else if (h < 45.0) {
      Serial.println("Much drier outside, but dry enough inside (h<45), return 0");
      return 0;
    } else {
      Serial.println("Much drier outside, return 1");
      return 1;
    }
  } else if (dp - buitendp > 2.0) {
    // buiten iets droger dan binnen
    if (h > 65.0) {
      Serial.println("Drier outside, h>65 return 2");
      return 2;
    } else if (h < 55.0) {
      Serial.println("Drier outside, h<52 return 0");
      return 0;
    } else {
      Serial.println("Drier outside, return 1");
      return 1;
    }
  } else if (dp - buitendp > 1.0) {
    // buiten marginaal droger dan binnen
    if (h > 75.0) {
      Serial.println("Slightly drier outside, h>75 return 2");
      return 2;
    } else if (h < 62.0) {
      Serial.println("Slightly drier outside, h<62 return 0");
      return 0;
    } else {
      Serial.println("Slightly drier outside, return 1");
      return 1;
    }
  } else if (dp - buitendp > 0.1) {
    if (h > 80.0) {
      Serial.println("Hardly drier outside, h>80 return 2");
      return 2;
    } else if (h < 70.0) {
      Serial.println("Hardly drier outside, h<70 return 0");
      return 0;
    } else {
      Serial.println("Hardly drier outside, return 1");
      return 1;
    }
  } else {
    Serial.println("Wetter or equal outside, return 0");
    // buiten gelijk of natter, dan doen we time based ventilatie
    // en dus niks op basis van de vochtigheid
    return 0;
  }
  Serial.println("default, return 1");
  return 1;
}

int desiredIthoSpeed(float t, float h, float dp, float buitent, float buitenh, float buitendp) {
  // it seems that this particular sesnor thinks it is pretty cool
  if (t > 20.5 || (t > 19.0 && buitent > 24.0)) {
    desiredCoolingIthoSpeed(t,h,dp,buitent,buitenh,buitendp);
  } else {
    desiredDryingIthoSpeed(t,h,dp,buitent,buitenh,buitendp);
  }
}