/*
 * Create text files with a table comparing local temperature and barometric
 * pressurs to remote observations.
 *
 * Format:
 *
 * Date     Difference    # legible date
 *
 * Greg Lehey, 17 December 2009
 *
 * FIXME.  This needs rethinking.  In particular, startup parameters are a mess.
 * Read on, brave programmer.
 *
 * $Id: local-compare.c,v 1.5 2010/02/07 03:38:26 grog Exp $
 */

#include "wh1080.h"
#include <syslog.h>

#define STAMPSIZE 32                            /* size of time stamp to print out */

char *stations [] = {"94852",                   /* Ballarat airport */
                     "94863",                   /* Sheoaks */
                     "94866"};                  /* Melbourne airport */

const int station_count = sizeof (stations) / sizeof (char *);

/* MySQL stuff */
MYSQL *mysql;
MYSQL_RES *mysql_result_BoM;
MYSQL_RES *mysql_result_local;
MYSQL_ROW mysql_row_BoM;
MYSQL_ROW mysql_row_local;
char mysql_querytext [1024];                    /* build up queries here */

/* Command line options */
int debug;                                      /* -d */
int verbose;                                    /* -v */

/*
 * Temperatures for calculation:  two pairs of BoM time and temperature,
 * and one time and temperature between them for local.
 */
time_t interval_starttime;
float interval_starttemp;
time_t interval_endtime;
float interval_endtemp;
time_t local_time;
float local_temp;
float interval_temp;                            /* interpolated BoM temperature */
/* barometric pressure stuff */
float interval_startpressure;
float interval_endpressure;
float interval_pressure;                        /* interpolated BoM pressure */
float local_pressure;

/* XXX get time zone in here */
const int my2k = 946731600;                     /* difference between UNIX and GNU epochs  */
char *startdate_text;                           /* start date, YYYY-MM-DD */
char *enddate_text;                             /* and end date (default: 24 hours later) */
/* Same times in struct tm format */
struct tm startdate;
struct tm enddate;
time_t endtime_t;

void usage (char *myname)
{
  fprintf (stderr,
           "Usage: %s YYYY-MM-DD YYYY-MM-DD [-d] [-v] [station-id] [user] [passwd] [host] [db]\n",
           myname);
  exit (1);
}

/*
 * Make files with comparative data for temperatures.
 *
 * The remote observations are relatively infrequent, while the local
 * observations are frequent.  We interpolate the "remote" values linearly to
 * estimate the temperature at the time of a local observation, but it doesn't
 * make sense to do that for all local observations.  Instead, we just take the
 * one immediately after the remote observation, then skip to the next remote
 * observation.
 */
void mktempcompare (char *stationid)
{
  char filename [PATH_MAX];
  FILE *myfile;                                 /* output file */
  int finishing = 0;                            /* set to exit loop */

  /* Create a file name for this comparison */
  strcpy (filename, config.comparefile);
  strcat (filename, "-");
  strcat (filename, stationid);
  myfile = fopen (filename, "w");
  if (! myfile)
  {
    syslog (LOG_ERR | LOG_DAEMON,
            "Can't open %s: %s (%d)\n",
            filename,
            strerror (errno),
            errno );
    exit (1);
  }
  chmod (filename, 0666);                       /* let anybody access it */
  sprintf (mysql_querytext,
           "SELECT unix_timestamp(timestamp(date, time)), outside_temp\n"
           "FROM remote_observations\n"
           "WHERE station_id = '%s'\n"
           "  AND date >= '%s'\n"
           "  AND date <= '%s'\n"
           "ORDER BY date, time;\n",
           stationid,
           startdate_text,
           enddate_text );
  if (domyquery (mysql_querytext, &mysql_result_BoM))
    exit (1);                                   /* failed and reported */
  if (mysql_row_BoM = mysql_fetch_row (mysql_result_BoM)) /* got something */
  {
    interval_starttime = atol (mysql_row_BoM [0]);
    interval_starttemp = atof (mysql_row_BoM [1]);
    /* Next row for first interval */
    if (! (mysql_row_BoM = mysql_fetch_row (mysql_result_BoM))) /* got something ?*/
      exit (1);                                 /* no */
    interval_endtime = atol (mysql_row_BoM [0]);
    interval_endtemp = atof (mysql_row_BoM [1]);

    /*
     * Now we have an initial interval.  Get the first local record after start
     * of interval.
     */
    sprintf (mysql_querytext,
             "SELECT unix_timestamp(timestamp(date, time)), outside_temp\n"
             "FROM %s\n"
             "WHERE station_id = '%s'\n"
             "  AND date >= '%s'\n"
             "  AND date <= '%s'\n"
             "ORDER BY date, time;\n",
             config.db_table,
             config.station_id,
             startdate_text,
             enddate_text );
    if (domyquery (mysql_querytext, &mysql_result_local))
      exit (1);                                 /* failed and reported */
    while (mysql_row_local = mysql_fetch_row (mysql_result_local)) /* got something */
    {
      local_time = atol (mysql_row_local [0]);
      local_temp = atof (mysql_row_local [1]);
      if (local_time > interval_starttime)      /* we're in business */
      {
        while (local_time > interval_endtime)   /* beyond current BoM readings */
        {
          interval_starttime = interval_endtime;
          interval_starttemp = interval_endtemp;
          /* Next row for first interval */
          if (! (mysql_row_BoM = mysql_fetch_row (mysql_result_BoM))) /* finished? */
          {
            fclose (myfile);
            return;
          }
          interval_endtime = atol (mysql_row_BoM [0]);
          interval_endtemp = atof (mysql_row_BoM [1]);
        }

        /*
         * Now our local reading is between start and end times.  Interpolate
         * to get BoM temperature at this time.
         */
        interval_temp = interval_starttemp
          + (interval_endtemp - interval_starttemp)
          * (local_time - interval_starttime) / (interval_endtime - interval_starttime);
        fprintf (myfile,
                 "%d %d %2.1f %2.1f %2.1f # %s",
                 local_time,
                 local_time - my2k,
                 local_temp,
                 interval_temp,
                 interval_temp - local_temp,
                 ctime (&local_time) );

        if (finishing)
        {
          fclose (myfile);
          return;
        }
        /* Next remote row */
        interval_starttime = interval_endtime;
        interval_starttemp = interval_endtemp;
        if (! (mysql_row_BoM = mysql_fetch_row (mysql_result_BoM))) /* finished? */
          finishing = 1;
        else
        {
          interval_endtime = atol (mysql_row_BoM [0]);
          interval_endtemp = atof (mysql_row_BoM [1]);
        }
      }
    }
  }
}

/*
 * Make files with comparative data for barometric pressures.
 */
void mkpresscompare (char *stationid)
{
  char filename [PATH_MAX];
  FILE *myfile;                                 /* output file */
  int finishing = 0;                            /* set to exit loop */

  /* Create a file name for this comparison */
  strcpy (filename, config.comparefile);
  strcat (filename, "-pressure-");
  strcat (filename, stationid);
  myfile = fopen (filename, "w");
  if (! myfile)
  {
    syslog (LOG_ERR | LOG_DAEMON,
            "Can't open %s: %s (%d)\n",
            filename,
            strerror (errno),
            errno );
    exit (1);
  }
  chmod (filename, 0666);                       /* let anybody access it */
  sprintf (mysql_querytext,
           "SELECT unix_timestamp(timestamp(date, time)), pressure_msl\n"
           "FROM remote_observations\n"
           "WHERE station_id = '%s'\n"
           "  AND date >= '%s'\n"
           "  AND date <= '%s'\n"
           "  AND pressure_msl IS NOT NULL\n"
           "ORDER BY date, time;\n",
           stationid,
           startdate_text,
           enddate_text );
  if (domyquery (mysql_querytext, &mysql_result_BoM))
    exit (1);                                   /* failed and reported */
  if (mysql_row_BoM = mysql_fetch_row (mysql_result_BoM)) /* got something */
  {
    interval_starttime = atol (mysql_row_BoM [0]);
    interval_startpressure = atof (mysql_row_BoM [1]);

    /*
     * Next row for first interval.
     *
     * The BoM doesn't issue this information very frequently, so we'll accept a
     * single reading if we have to.  In this case, we just pretend that the
     * pressure is constant.
     */
    if (! (mysql_row_BoM = mysql_fetch_row (mysql_result_BoM))) /* got something ?*/
    {
      finishing = 1;                            /* no, just do one more result */
      interval_endtime = interval_starttime + 100;
      interval_endpressure = interval_startpressure;
    }
    else
    {
      interval_endtime = atol (mysql_row_BoM [0]);
      interval_endpressure = atof (mysql_row_BoM [1]);
    }

    /*
     * Now we have an initial interval.  Get the first local record after start
     * of interval.
     */
    sprintf (mysql_querytext,
             "SELECT unix_timestamp(timestamp(date, time)), pressure_msl\n"
             "FROM %s\n"
             "WHERE station_id = '%s'\n"
             "  AND date >= '%s'\n"
             "  AND date <= '%s'\n"
             "  AND pressure_msl IS NOT NULL\n"
             "ORDER BY date, time;\n",
             config.db_table,
             config.station_id,
             startdate_text,
             enddate_text );
    if (domyquery (mysql_querytext, &mysql_result_local))
      exit (1);                                 /* failed and reported */
    while (mysql_row_local = mysql_fetch_row (mysql_result_local)) /* got something */
    {
      local_time = atol (mysql_row_local [0]);
      local_pressure = atof (mysql_row_local [1]);
      if (local_time > interval_starttime)      /* we're in business */
      {
        /*
         * Unlike with temperatures, we only look at the first pressure reading
         * newer than the BoM reading.  We have no way of knowing if the BoM has
         * similar changes to what we have locally.
         */
        while (local_time > interval_endtime)   /* beyond current BoM readings */
        {
          interval_starttime = interval_endtime;
          interval_startpressure = interval_endpressure;
          /* Next row for first interval */
          if (! (mysql_row_BoM = mysql_fetch_row (mysql_result_BoM))) /* finished? */
          {
            finishing = 1;
            interval_endtime += 1000;           /* to avoid division by 0 */
          }
          else
          {
            interval_endtime = atol (mysql_row_BoM [0]);
            interval_endpressure = atof (mysql_row_BoM [1]);
          }
        }

        /*
         * Now our local reading is between start and end times.  Interpolate
         * to get BoM pressure at this time.
         */
        interval_pressure = interval_startpressure
          + (interval_endpressure - interval_startpressure)
          * (local_time - interval_starttime) / (interval_endtime - interval_starttime);
        fprintf (myfile,
                 "%d %d %2.1f %2.1f %2.1f # %s",
                 local_time,
                 local_time - my2k,
                 local_pressure,
                 interval_pressure,
                 interval_pressure - local_pressure,
                 ctime (&local_time) );
        local_time = interval_endtime + 1;      /* force the next record */

        if (finishing)
        {
          fclose (myfile);
          return;
        }
        /* Next remote row */
        interval_starttime = interval_endtime;
        interval_starttemp = interval_endtemp;
        if (! (mysql_row_BoM = mysql_fetch_row (mysql_result_BoM))) /* finished? */
          finishing = 1;
        else
        {
          interval_endtime = atol (mysql_row_BoM [0]);
          interval_endtemp = atof (mysql_row_BoM [1]);
        }
      }
    }
  }
  fclose (myfile);
}

int main (int argc, char *argv [])
{
  int station;
  /*
   * This is tacky.  We want to use the standard parameter sequence in
   * read_config (), but that doesn't include dates.  So we require the sequence
   * in usage ().  And that means that we need to find a way to specify the end
   * day.  FIXME.
   */

  if (argc < 3)                                 /* we need at least start date */
    usage (argv [0]);
  startdate_text = argv [1];                    /* start and */
  enddate_text = argv [1];                      /* end date */
  read_config (argc - 2, &argv [2]);            /* this implies that we know argv [0] won't be used */

  mysql = mysql_init (mysql);
  if (! mysql)
  {
    syslog (LOG_ERR | LOG_DAEMON, "Can't initialize MySQL: insufficient memory\n");
    exit (1);
  }
  if (! mysql_real_connect (mysql,              /* DB state */
                            config.db_host,     /* database host */
                            config.db_user,
                            config.db_passwd,
                            config.db,
                            0,
                            NULL,
                            0 ))
  {
    syslog (LOG_ERR | LOG_DAEMON,
            "Can't connect to databaase: %s (%d)\n",
            mysql_error (mysql),
            mysql_errno (mysql) );
    exit (1);
  }

  /* Generate the files */
  for (station = 0; station < station_count; station++)
  {
    mktempcompare (stations [station]);
    mkpresscompare (stations [station]);
  }
  exit (0);
}