/*

EnvironmentCalculations.h

This code records data from the BME280 sensor and provides an API.
This file is part of the Arduino BME280 library.
Copyright (C) 2016  Tyler Glenn

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU 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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

Written: Oct 7 2017.
Last Updated: Dec 11 2017.
This code is licensed under the GNU LGPL and is open for distrbution
and copying in accordance with the license.
This header must be included in any derived code or copies of the code.

 */

#ifndef TG_ENVIRONMENT_CALCULATIONS_H
#define TG_ENVIRONMENT_CALCULATIONS_H

namespace EnvironmentCalculations
{
  /////////////////////////////////////////////////////////////////
  /// Temperature unit enumeration.
   enum TempUnit
   {
      TempUnit_Celsius,
      TempUnit_Fahrenheit
   };

  /////////////////////////////////////////////////////////////////
  /// Altitude unit enumeration.
   enum AltitudeUnit
   {
      AltitudeUnit_Meters,
      AltitudeUnit_Feet
   };


  /////////////////////////////////////////////////////////////////
  /// Calculate the altitude based on the pressure and temperature
  /// in temptUnit.
  /// @param pressure at the station in any units.
  /// @param altUnit meters or feet. default=AltitudeUnit_Meters
  /// @param referencePressure (usually pressure on MSL)
  ///          in the same units as pressure. default=1013.25hPa (ISA)
  /// @param outdoorTemp temperature at the station in tempUnit
  ///          default=15°C (ISA)
  /// @param temptUnit in °C or °F. default=TempUnit_Celsius
  /// @return Calculated Altitude in altUnit.
  float Altitude(
    float pressure,
    AltitudeUnit altUnit = AltitudeUnit_Meters,
    float referencePressure = 1013.25,   // [hPa] ....ISA value
    float outdoorTemp = 15,              // [°C] .... ISA value
    TempUnit tempUnit = TempUnit_Celsius);

  /////////////////////////////////////////////////////////////////
  /// Calculate the heatindex based on the humidity and temperature
  /// in tempUnit.
  /// The formula based on the Heat Index Equation of the US National Weather Service
  /// http://www.wpc.ncep.noaa.gov/html/heatindex_equation.shtml
  /// @param temperature in tempUnit
  /// @param humidity in percentage
  /// @param temptUnit in °C or °F. default=TempUnit_Celsius
  /// @return Calculated heatindex as float in TempUnit
  float HeatIndex(
    float temperature,		
    float humidity,              
    TempUnit tempUnit = TempUnit_Celsius); 

  /////////////////////////////////////////////////////////////////
  /// Calculate the absolute humidity based on the relative humidity and temperature
  /// in tempUnit.
  /// the formula does work for values between -30°C and 35°C with 0.1°C precision
  /// @param temperature in tempUnit
  /// @param humidity in percentage
  /// @param tempUnit in °C. default=TempUnit_Celsius
  /// @return Calculated absolute humidity in grams/m³
  float AbsoluteHumidity
  (
    float temperature, 
    float humidity,
    TempUnit tempUnit
  );

  /////////////////////////////////////////////////////////////////
  /// Convert current pressure to equivalent sea-level pressure.
  /// @param altitude in altUnit.
  /// @param temp in tempUnit.
  /// @param pressure at the station in any units.
  /// @param altUnit meters or feet. default=AltitudeUnit_Meters
  /// @param tempUnit in °C or °F. default=TempUnit_Celsius
  /// @return Equivalent pressure at sea level. The input pressure
  ///          unit will determine the output
  ///          pressure unit.
  float EquivalentSeaLevelPressure(
    float altitude,
    float temp,
    float pres,
    AltitudeUnit altUnit = AltitudeUnit_Meters,
    TempUnit tempUnit = TempUnit_Celsius);

  /////////////////////////////////////////////////////////////////
  /// Calculate the dew point based on the temperature in tempUnit
  /// and humidity.
  /// @param temp in tempUnit.
  /// @param hum in %.
  /// @param temptUnit in °C or °F. default=TempUnit_Celsius
  float DewPoint(
    float temp,
    float hum,
    TempUnit tempUnit = TempUnit_Celsius);

}

#endif // TG_ENVIRONMENT_CALCULATIONS_H