/* Module for uploading observations to Weather Underground
  (C) britishideas.com
  GPL V2 - see license.txt */

#include <stdio.h>
#include <string.h>
#include <math.h>
#include "wunderground.h"

// file that contains weather underground station ID (first line) and
// password (second line)
#define CREDENTIALS "wunderground_creds.txt"

// API url
#define WUURL "http://rtupdate.wunderground.com/weatherstation/updateweatherstation.php"

// maximum lengths of station id and password
#define STATIONIDLENGTH 50
#define PASSWORDLENGTH  50
// maximum command length
#define CMDLENGTH 1024

// module variables
static char gStationId[STATIONIDLENGTH];
static char gPassword[PASSWORDLENGTH];

// initializes the module
void WUnderground_Init
  (
  void
  )
{
  // read in credentials
  FILE *fp = fopen(CREDENTIALS, "r");
  fgets(gStationId, STATIONIDLENGTH, fp);
  strtok(gStationId, "\n");
  fgets(gPassword,  PASSWORDLENGTH,  fp);
  strtok(gPassword, "\n");
  fclose(fp);
}

// submits an observation
void WUnderground_Observation
  (
  double TemperatureC,                   // temperature in C
  double Humidity,                       // as a percentage
  double WindAveMph,
  double WindGustMph,
  char *WindDirection,                   // string "N", "NNE", "NE", "ENE", "E", etc.
  double TotalRainMm,                    // total since battery change
  double PressureHpa                     // pressure at sea level
  )
{
  char Cmd[CMDLENGTH];
  char UTCTimestamp[20];

  // get temperature in F
  double TemperatureF = (TemperatureC * 9.0 / 5.0) + 32.0;

  // calculate dew point in F
  // see: http://www.gorhamschaffler.com/humidity_formulas.htm
  double Es = 6.11 * pow(10.0, 7.5 * TemperatureC / (237.7 + TemperatureC));
  double E = Humidity * Es / 100.0;
  double Tdc = (-430.22 + 237.7 * log(E)) / (-log(E) + 19.08);
  double DewPointF = (Tdc * 9.0 / 5.0) + 32.0;

  // get wind direction
  double WindDegrees = 0;
       if (!strcmp(WindDirection, "N"))   WindDegrees = 0;
  else if (!strcmp(WindDirection, "NNE")) WindDegrees = 22.5;
  else if (!strcmp(WindDirection, "NE"))  WindDegrees = 45;
  else if (!strcmp(WindDirection, "ENE")) WindDegrees = 67.5;
  else if (!strcmp(WindDirection, "E"))   WindDegrees = 90;
  else if (!strcmp(WindDirection, "ESE")) WindDegrees = 112.5;
  else if (!strcmp(WindDirection, "SE"))  WindDegrees = 135;
  else if (!strcmp(WindDirection, "SSE")) WindDegrees = 157.5;
  else if (!strcmp(WindDirection, "S"))   WindDegrees = 180;
  else if (!strcmp(WindDirection, "SSW")) WindDegrees = 202.5;
  else if (!strcmp(WindDirection, "SW"))  WindDegrees = 225;
  else if (!strcmp(WindDirection, "WSW")) WindDegrees = 247.5;
  else if (!strcmp(WindDirection, "W"))   WindDegrees = 270;
  else if (!strcmp(WindDirection, "WNW")) WindDegrees = 292.5;
  else if (!strcmp(WindDirection, "NW"))  WindDegrees = 315;
  else if (!strcmp(WindDirection, "NNW")) WindDegrees = 337.5;

  strcpy(UTCTimestamp, "timestampgoeshere");

  sprintf(Cmd, "wget -b -a /tmp/wunderground.log -O /tmp/wunderground-result.html \"%s?action=updateraw&ID=%s&PASSWORD=%s&realtime=1&rtfreq=48&dateutc=%s&tempf=%f&humidity=%f&windspeedmph=%f&windgustmph=%f&baromin=%f,&dewptf=%f&winddir=%.1f\"",
    WUURL,
    gStationId,
    gPassword,
    UTCTimestamp,
    TemperatureF,
    Humidity,
    WindAveMph,
    WindGustMph,
    PressureHpa * 0.0295299830714,
    DewPointF,
    WindDegrees
    );

  printf("%s\n", Cmd);
}