path: root/src/localtemp.cpp

 /*******************************************************************************
 *  File: localtemp.cpp                  					*
 *  Version: 0.4            							*
 *  Date: 20260809                    						*
 *  Author: Gaspar Fernández (helyo@totaki.com) 				*
 *										*
 *  Copyright (C) 2008   Gaspar Fernández					*
 *										*
 *  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/>.	*
 *									        *
 ********************************************************************************
 *   Description:
 *     It is part of a Window Maker dockapp called dwgo. This class reads weather
 *  of a selected location from National Weather Service (http://weather.noaa.gov/) 
 *  and parses some information to display it formatted on screen.  
 *     I know it parses unnecesary information, but I'm planning to update dwgo
 *  with some improvements that use all this information.
 *
 *   Change History:
 *    Date (D.M.Y)    Author              Modification
 *    08.05.2008      Gaspar Fernández    Initial release
 *    31.10.2010      Gaspar Fernández    Bug Corrections
 *    09.08.2026      Koudai Kudo         Ported to JMA
 *    
 ********************************************************************************/  

#include "localtemp.h"
#include "MySock.h"
#include "dwgo.h"		// Theme numbers

using namespace std;

/*************************************************************
 *     Constructur: localtemp                                *
 *************************************************************
 *  Description:                                             *
 *     Initializes variables                                 *
 *                                                           *
 * Input:                                                    *
 *    char *metar - ICAO name locator (4 chars)              *
 *    char location_name - Amedas station code (5 digits)    *
 *                                                           *
 * Change History:                                           *
 *  Date      Author      Modification                       *
 *                                                           *
 *************************************************************/ 
localtemp::localtemp(char *metar, char *location_name)
{
  this->metar=metar;
  this->location_name=location_name;
  this->celsius=0;
  this->fahrenheit=0;
  this->loaded=false;
  this->theme=DEFAULT_THEME;
}

/*************************************************************
 *     Method: set_temp                                      *
 *************************************************************
 *  Description:                                             *
 *     Extract temperature information. In Celsius and       *
 *  Fahrenheit                                               *
 *                                                           *
 * Input:                                                    *
 *    string tmp_str - Temporary string containing           *
 *  temperature in Celsius and Fahrenheit                    *
 *                                                           *
 * Change History:                                           *
 *  Date      Author      Modification                       *
 *                                                           *
 *************************************************************/ 
void localtemp::set_temp(double temp_c)
{
  this->celsius=(int)(temp_c+0.5);
  this->fahrenheit=(int)(temp_c*9.0/5.0+32.0+0.5);
}

/*************************************************************
 *     Method: set_humidity                                  *
 *************************************************************
 *  Description:                                             *
 *     Extract humidity information.                         *
 *                                                           *
 * Input:                                                    *
 *   int hum - Relative humidity, from the "humidity" field  *
 *  of the Amedas JSON                                       *
 *                                                           *
 * Change History:                                           *
 *  Date      Author      Modification                       *
 *                                                           *
 *************************************************************/ 
void localtemp::set_humidity(int hum)
{
  this->humidity=hum;
}

/*************************************************************
 *     Method: get_ob_info                                   *
 *************************************************************
 *  Description:                                             *
 *     Works out which theme to use from the 10 minute       *
 *  precipitation figure and current temperature, since      *
 *  Amedas doesn't report general sky conditions the way     *
 *  METAR does.                                              *
 *                                                           *
 * Input:                                                    *
*   double precip10m - 10 minute precipitation, in mm, as    *
 *  read from the "precipitation10m" field of the Amedas     *
 *  JSON (0 or negative means no precipitation reported)     *
 *                                                           *
 * Change History:                                           *
 *  Date      Author      Modification                       *
 *                                                           *
 *************************************************************/ 
void localtemp::get_ob_info(double precip10m)
{
  mInfo.CB=false;
  mInfo.fog=undef_fog;		// Not reported by Amedas

  if (precip10m>0.0)
  {
    if (this->celsius<=2)
	    mInfo.rain=snow;
    else
	    mInfo.rain=rain;
      mInfo.sky=undef_sky;
  }
  else
  {
    mInfo.rain=undef_rain;
    mInfo.sky=clear;
  }

  // The most important for the display theme is rain, then fog and then sky conditions
  if (mInfo.rain!=undef_rain)
    {
      switch (mInfo.rain)
	{
	case rain: theme=RAINY_THEME; break;
	case snow: theme=SNOWY_THEME; break;
	default: break;
	}
    }
  else if (mInfo.sky!=undef_sky)
    {
      switch (mInfo.sky)
	{
	case clear  : theme=CLEAR_THEME; break;
	default: break;
	}
    }
  else
    theme=DEFAULT_THEME;	// Nothing significant found.
}

/*************************************************************
 *     Method: extract_json_number                           *
 *************************************************************
 *  Description:                                             *
 *     Very small, purpose built JSON scraper. It looks for   *
 *  "key":[ inside the given text and parses the first number *
 *  after it. Amedas values always look like "temp":[26.3,0]  *
 *  (value, quality flag), so we only need the number before  *
 *  the first comma or closing bracket.                        *
 *                                                           *
 * Input:                                                    *
 *   string json - Text to search in (one HHMM observation    *
 *  block)                                                     *
 *   string key  - Field name, e.g. "temp"                    *
 *                                                           *
 * Output:                                                    *
 *   double &value - Parsed number                            *
 *   bool - true if the key was found and a number was read   *
 *                                                           *
 * Change History:                                           *
 *  Date      Author      Modification                       *
 *                                                           *
 *************************************************************/ 
bool localtemp::extract_json_number(const string &json, const string &key, double &value)
{
  string needle="\""+key+"\":[";
  size_t pos=json.find(needle);
  if (pos==string::npos)
    return false;
  pos+=needle.length();
  size_t endpos=json.find_first_of(",]", pos);
  if (endpos==string::npos)
    return false;
  string numstr=json.substr(pos, endpos-pos);
  if (numstr.empty() || numstr=="null")
    return false;
  value=atof(numstr.data());
  return true;
}
/*************************************************************
 *     Method: fetch_latest_time                             *
 *************************************************************
 *  Description:                                             *
 *     Downloads AMEDAS_LATEST_URL, which returns a single    *
 *  ISO-8601 JST timestamp such as                             *
 *  "2024-08-09T15:40:00+09:00", telling us which day's file  *
 *  to request and which HHMM block inside it is the most     *
 *  recent observation.                                        *
 *     It also converts that JST timestamp into a real UTC    *
 *  epoch (obs_utc), because dwgo.cpp's displaytemp() expects *
 *  info_time to be a plain UTC instant: it later does         *
 *  "info_time + tm_diff" and feeds that into localtime() to   *
 *  show it in the viewer's own local time zone. JMA gives us  *
 *  JST (UTC+9) directly, so we build the calendar fields with *
 *  timegm() (which treats a struct tm as UTC, unlike          *
 *  mktime() which would apply the *host*'s time zone) and     *
 *  then subtract 9 hours to land back on true UTC.             *
 *                                                           *
 * Output:                                                    *
 *   string &yyyymmdd - Date, e.g. "20240809"                 *
 *   string &hhmm      - Time, e.g. "1540"                     *
 *   time_t &obs_utc   - Observation instant as a UTC epoch    *
 *   bool - true if we could fetch and parse the timestamp    *
 *                                                           *
 * Change History:                                           *
 *  Date      Author      Modification                       *
 *                                                           *
 *************************************************************/ 
bool localtemp::fetch_latest_time(string &yyyymmdd, string &hhmmss, string &block3h, time_t &obs_utc)
{
  MySock *skt;
  HTTP_Request *http;
  struct tm jst;
  int hour, block;
  char blockbuf[3];

  skt = new MySock((char*)AMEDAS_LATEST_URL);
  http=skt->GetHTTPData();
  delete skt;
  if (http==NULL || http->status!=200 || http->data.length()<19)
    return false;
  // Expected format: YYYY-MM-DDTHH:MM:SS+09:00
  string d=http->data;
  yyyymmdd=d.substr(0,4)+d.substr(5,2)+d.substr(8,2);
  hhmmss=d.substr(11,2)+d.substr(14,2)+d.substr(17,2);
  hour=atoi(d.substr(11,2).data());
  block=(hour/3)*3;		// Point files are split into 3 hour windows: 00,03,06,...,21
  sprintf(blockbuf, "%02d", block);
  block3h=blockbuf;

  memset(&jst, 0, sizeof(jst));
  jst.tm_year=atoi(d.substr(0,4).data())-1900;
  jst.tm_mon =atoi(d.substr(5,2).data())-1;
  jst.tm_mday=atoi(d.substr(8,2).data());
  jst.tm_hour=hour;
  jst.tm_min =atoi(d.substr(14,2).data());
  jst.tm_sec =atoi(d.substr(17,2).data());
  obs_utc=timegm(&jst)-9*3600;	// JST -> UTC (JMA has no DST, always UTC+9)
  return true;
}

/*************************************************************
 *     Method: getInfo                                       *
 *************************************************************
 *  Description:                                             *
 *     Fetch information and parse the file                  *
 *                                                           *
 * Output:                                                   *
 *    True if we downloaded it right, false if not.          *
 *                                                           *
 * Change History:                                           *
 *  Date      Author            Modification                 *
 * 20101031  Gaspar Fernández   Bug in skt                   *
 *************************************************************/ 
bool localtemp::getInfo()
{
  char *point_fetch;		               // Amedas point data URL
  MySock *skt;
  HTTP_Request *http;
  string yyyymmdd, hhmmss, block3h;
  time_t obs_utc;
  double temp_c, hum, precip10m;
  this->error=0;        // No error
  this->loaded=false;


  if (!fetch_latest_time(yyyymmdd, hhmmss, block3h, obs_utc))
    return false;

  point_fetch= (char*) malloc(strlen(AMEDAS_POINT_URL)+this->metar.length()+yyyymmdd.length()+block3h.length()+4);
  sprintf(point_fetch, AMEDAS_POINT_URL, this->metar.data(), yyyymmdd.data(), block3h.data());

  skt = new MySock(point_fetch);
  verbsth(VERB_ASTTO, "Open connection: ");
 
  http=skt->GetHTTPData();

  delete skt;			// We don't need this anymore
  free(point_fetch);

  if (http!=NULL)
    {
      if (http->status==200)
	{
	  time(&get_time);	// We got the file at this moment

	  verbsth(VERB_ASTTO, "Get Data: ");

	  this->long_location=this->location_name;
	 
	  string fullkey=yyyymmdd+hhmmss;
	  size_t blockpos=http->data.find("\""+fullkey+"\":");
      
    string selected_key;
    for (size_t pos = 0; pos + 16 < http->data.size(); ++pos) {
        if (http->data[pos] != '"')
            continue;

        string candidate = http->data.substr(pos + 1, 14);

        bool digits = true;
        for (size_t i = 0; i < candidate.size(); ++i) {
            if (candidate[i] < '0' || candidate[i] > '9') {
                digits = false;
                break;
            }
        }

        if (!digits || http->data[pos + 15] != '"')
            continue;

        size_t colon = http->data.find(':', pos + 16);
        if (colon == string::npos)
            continue;

        size_t object_start =
            http->data.find_first_not_of(" \t\r\n", colon + 1);

        if (object_start == string::npos ||
            http->data[object_start] != '{')
            continue;

        if (candidate <= fullkey &&
            (selected_key.empty() || candidate > selected_key)) {
            selected_key = candidate;
            blockpos = pos;
        }
    }
    
	  if (blockpos==string::npos)
	    {
	      blockpos=http->data.rfind("\":{");
	      if (blockpos!=string::npos)
		blockpos=http->data.rfind("\"", blockpos-1);
	    }
	  if (blockpos!=string::npos)
	    {
	      this->ob=http->data.substr(blockpos);
	      if (extract_json_number(this->ob, "temp", temp_c))
		this->set_temp(temp_c);
	      if (extract_json_number(this->ob, "humidity", hum))
		this->set_humidity((int)hum);
	      if (!extract_json_number(this->ob, "precipitation10m", precip10m))
		precip10m=0.0;
	      this->info_time=obs_utc;	// Actual observation instant, in UTC
	      get_ob_info(precip10m);	// Work out theme from precipitation/temperature
	      this->loaded=true;
	      verbsth(VERB_ASTTO, "Close connection: ");
	    }
	  else
	    {
	      this->error=1;
	      verbsth(VERB_WARNING, "Couldn't find observation data in Amedas response.");
	    }
	}
      else
 	{
	  this->error=1;		// Not found
      // Print request
 	  cout<<http->data<<endl;
 	}
    }
  else
    return false;		// If there is a socket error...

  return true;			// Everything is OK (or almost)

}