<?php
/*
************************************************************************
**
**  Copyright (c) 2009..2013 by
**    Core|Vision B.V.
**    Hambakenwetering 1
**    5231 DD  's-Hertogenbosch
**    The Netherlands
**
**  All Rights Reserved
**
************************************************************************
*/
/*
************************************************************************
**
**  Project name:   Dual Inventive: MTinfo Support Scripts
**  Filename:       plot-rssi.php
**  Date:           July 9, 2009
**  File version:   $Revision: 1.2 $
**                  $Date: 2013/12/19 14:49:58 $
**
************************************************************************
*/
/*
************************************************************************
**
**  Display received signal strength in a graph.
**
**  Mandatory parameters, via "GET", all of which are retrieved from
**  the database
**    zkl           - database ID of the ZKL to query
**    logfile       - sdcard,rpgmcount,startup of the logfile to plot
**      and/or
**    tmin,tmax     - date/time of the time frame (the current time will
**                    be used if tmax is ommitted)
**  Optional output options:
**    w             - width of the output image
**    h             - height of the output image
**    hide_title    - do not device id-code and date
**    hide_info     - do not show additional info
**
**  Notes:
**  - If both 'logfile' and a 'tmin'/'tmax' are specified, then the data
**    from the logfile will be scaled to the specified time frame.
**  - If _no_ 'logfile' is specified, all logfiles with data in the time
**    frame will be shown.
**  - Logfiles with an invalid date (i.e. 1970-1-1) are _never_ plotted.
**
************************************************************************
*/

//
//  Check inputs for SQL statement injection and such.
//  Items not tested below are not vulnerable for SQL statement injection, e.g.
//    a time is always converted using 'strtotime()' and other items are only
//    used in the PHP but never in the composition of an SQL statement
//  [security audit 2013-10-23]
//
if(
  (isset($_GET['zkl']) && !is_numeric($_GET['zkl'])) ||
  (isset($_GET['logfile']) && !preg_match('/^[0-9]+,[0-9]+,[0-9]+$/', $_GET['logfile']) && !in_array($_GET['logfile'], array('log_tcp','log_versienummer','log_realtime','log_secure_zkl'))) ||
  (isset($_GET['db']) && dirname($_GET['db']) != ".")
) {
  // don't do anything fancy or interruptive as fiddling with the GET parameters
  //  is intended by the author
  die("Parameter error");
}

require_once("../include/graphics.php");
require_once("../include/i18n.php");
require_once("../include/cp3000-tcpclient.php");
require_once("support.inc.php");

set_time_limit(0);

// which table?
$use_log_realtime = isset($_GET['log_realtime']);

// read the database information
if( isset($_GET['db']) ) $db_info = read_database(DBCONFIG_DIR, $_GET['db']);
else $db_info = array();
if( !isset($db_info['host'])   ) $db_info['host']   = "localhost";
if( !isset($db_info['user'])   ) $db_info['user']   = "root";
if( !isset($db_info['passwd']) ) $db_info['passwd'] = "";
if( !isset($db_info['db'])     ) $db_info['db']     = "di_zkl";

// open the database
$db_data_handle = mysql_connect($db_info['host'], $db_info['user'], $db_info['passwd']);
if( $db_data_handle === FALSE ) {
  echo mysql_error();
  exit(1);
}
mysql_select_db($db_info['database'], $db_data_handle);
if( $db_info['main'] ) {
  $db_main_info = read_database(DBCONFIG_DIR, $db_info['main']);
  $db_main_handle = mysql_connect($db_main_info['host'], $db_main_info['user'], $db_main_info['passwd'], true);
  if( $db_main_handle === FALSE ) {
    echo mysql_error();
    exit(1);
  }
  mysql_select_db($db_main_info['database'], $db_main_handle);
}
else {
  $db_main_handle = $db_data_handle;
  $db_main_info = $db_info;
}

// determine width and height
$width  = $_GET['w'];
$height = $_GET['h'];
if( !$width )  $width = 640;
if( !$height ) $height = 480;
  
// get information about the device
$query = "SELECT serienr,idcode,tcp_server,mcu_versie,wcpu_versie,IFNULL(gebruiker,eigenaar) AS gebruiker FROM zkl WHERE id=" . $_GET['zkl'];
$result = mysql_run($query, $db_main_handle);
$zkl_info = mysql_fetch_assoc($result);
if( $zkl_info['gebruiker'] ) {
  $query = "SELECT tz,i18n FROM klant WHERE id=" . $zkl_info['gebruiker'];
  $result = mysql_run($query, $db_main_handle);
  $tz_info = mysql_fetch_assoc($result);
}
else {
  $tz_info = array( 'tz' => date("e"), 'i18n' => "nl" );
}
if( $_GET['tz'] ) $tz_info['tz'] = $_GET['tz'];
if( $_GET['lc'] ) $tz_info['i18n'] = $_GET['lc'];
$zkl_info['tz']          = $tz_info['tz'];
$zkl_info['i18n']        = $tz_info['i18n'];
$zkl_info['mcu_versie']  = zkl_get_fw_version($zkl_info['mcu_versie']);
$zkl_info['wcpu_versie'] = zkl_get_fw_version($zkl_info['wcpu_versie']);
putenv("TZ=" . $zkl_info['tz']);
i18n_settext_language($zkl_info['i18n']);
setlocale(LC_ALL, $zkl_info['i18n']);

// get timeframe and log files
$logfiles = array();
if( isset($_GET['tmin']) ) {
  $tmin = strtotime($_GET['tmin']);
  if( isset($_GET['tmax']) && $_GET['tmax'] ) $tmax = strtotime($_GET['tmax']);
  else $tmax = time();
  if( isset($_GET['logfile']) ) {
    if( is_array($_GET['logfile']) ) foreach( $_GET['logfile'] as $logfile ) {
      list($sdcard,$rpgmcount,$startup) = explode(',', $logfile);
      $query  = "SELECT MIN(t) AS tmin,MAX(t) AS tmax ";
      $query .= "FROM log_zkl ";
      $query .= "WHERE ";
      $query .= "  zkl=" . $_GET['zkl'] . " AND ";
      $query .= "  sdcard=" . $sdcard . " AND ";
      $query .= "  rpgmcount=" . $rpgmcount . " AND ";
      $query .= "  startup=" . $startup;
      $result = mysql_run($query, $db_data_handle);
      $row = mysql_fetch_assoc($result);
       if( $row['tmax'] > time() ) {
        error_log($_SERVER['PHP_SELF'] . ": logfile " . $_GET['zkl'] . "-" . $sdcard . "," . $rpgmcount . "," . $startup . " has bogus 'max(t)'; using 'now'");
        $row['tmax'] = time();
      }
      array_push($logfiles, array('sdcard' => $sdcard, 'rpgmcount' => $rpgmcount, 'startup' => $startup, 'tmin' => $row['tmin'], 'tmax' => $row['tmax']));
    }
    else {
      list($sdcard,$rpgmcount,$startup) = explode(',', $_GET['logfile']);
      $query  = "SELECT MIN(t) AS tmin,MAX(t) AS tmax ";
      $query .= "FROM log_zkl ";
      $query .= "WHERE ";
      $query .= "  zkl=" . $_GET['zkl'] . " AND ";
      $query .= "  sdcard=" . $sdcard . " AND ";
      $query .= "  rpgmcount=" . $rpgmcount . " AND ";
      $query .= "  startup=" . $startup;
      $result = mysql_run($query, $db_data_handle);
      $row = mysql_fetch_assoc($result);
      if( $row['tmax'] > time() ) {
        error_log($_SERVER['PHP_SELF'] . ": logfile " . $_GET['zkl'] . "-" . $sdcard . "," . $rpgmcount . "," . $startup . " has bogus 'max(t)'; using 'now'");
        $row['tmax'] = time();
      }
      array_push($logfiles, array('sdcard' => $sdcard, 'rpgmcount' => $rpgmcount, 'startup' => $startup, 'tmin' => $row['tmin'], 'tmax' => $row['tmax']));
    }
  }
  else if( $use_log_realtime ) {
    // fake a log file for the drawing loop below
    array_push($logfiles,
      array(
        'sdcard' => 0,
        'rpgmcount' => 0,
        'startup' => 0,
        'tmin' => $tmin,
        'tmax' => $tmax
      )
    );
  }
  else if( !isset($_GET['file']) ) {
    // retrieve logfiles from the database
    $query  = "SELECT sdcard,rpgmcount,startup,MIN(t) AS tmin,MIN(t_log) AS tlog_min,MAX(t) AS tmax ";
    $query .= "FROM log_zkl ";
    $query .= "WHERE ";
    $query .= "  zkl=" . $_GET['zkl'] . " AND ";
    $query .= "  t BETWEEN '" . $tmin . "' AND '". $tmax . "' ";
    $query .= "GROUP BY sdcard,rpgmcount,startup";
    $result = mysql_run($query, $db_data_handle);
    while( $row = mysql_fetch_assoc($result) ) {
      array_push($logfiles, $row);
    }
  }
}
else if( !isset($_GET['file']) ) {
  if( !isset($_GET['logfile']) ) {
    error_log($_SERVER['PHP_SELF'] . ": no log file or time range defined");
    exit(1);
  }
  list($sdcard,$rpgmcount,$startup) = explode(',', $_GET['logfile']);
  $query  = "SELECT MIN(t) AS tmin,MAX(t) AS tmax ";
  $query .= "FROM log_zkl ";
  $query .= "WHERE ";
  $query .= "  zkl=" . $_GET['zkl'] . " AND ";
  $query .= "  sdcard=" . $sdcard . " AND ";
  $query .= "  rpgmcount=" . $rpgmcount . " AND ";
  $query .= "  startup=" . $startup;
  $result = mysql_run($query, $db_data_handle);
  $row = mysql_fetch_assoc($result);
  if( $row['tmin'] < strtotime("2000-1-1") ) {
    error_log($_SERVER['PHP_SELF'] . ": logfile " . $_GET['zkl'] . "-" . $sdcard . "," . $rpgmcount . "," . $startup . " has bogus 'min(t)'; using only data from 2000");
    $result = mysql_run($query . " AND t >= " . strtotime('2000-1-1'), $db_data_handle);
    $row = mysql_fetch_assoc($result);
  }
  $tmin = $row['tmin'];
  if( isset($_GET['tmax']) ) $tmax = strtotime($_GET['tmax']);
  else {
    if( $row['tmax'] > time() ) {
      error_log($_SERVER['PHP_SELF'] . ": logfile " . $_GET['zkl'] . "-" . $sdcard . "," . $rpgmcount . "," . $startup . " has bogus 'max(t)'; using 'now'");
      $tmax = time();
    }
    else $tmax = $row['tmax'];
  }
  array_push($logfiles, array('sdcard' => $sdcard, 'rpgmcount' => $rpgmcount, 'startup' => $startup, 'tmin' => $tmin, 'tmax' => $tmax));
}
if( $tmin >= $tmax ) {
  error_log($_SERVER['PHP_SELF'] . ":  empty time range: " . strftime("%D %T", $tmin) . "-" . strftime("%D %T", $tmax));
  exit(1);
}
$tz_offset = date("Z", $tmin);
$duration = $tmax - $tmin;

// fixed upper and lower range
$rssi_min = -110;
$rssi_max = -30;
$rssi_range = 80;

//
//  Draw the graph
//

header("Content-type: image/png");
header('Pragma: no-cache');
header('Expires: ' . date("r"));

// create the image
$im = imagecreatetruecolor($width,$height);
if( function_exists("imageantialias") )
  imageantialias($im, true);
$black   = imagecolorallocate($im,   0,   0,   0);
$white   = imagecolorallocate($im, 255, 255, 255);
$grey    = imagecolorallocate($im, 192, 192, 192);
$lgrey   = imagecolorallocate($im, 240, 240, 240);
$dgrey   = imagecolorallocate($im, 128, 128, 128);
$green   = imagecolorallocate($im,   0, 192,   0);
$lgreen  = imagecolorallocate($im, 192, 255, 192);
$llgreen = imagecolorallocate($im, 248, 255, 248);
$dgreen  = imagecolorallocate($im,   0, 160,   0);
$red     = imagecolorallocate($im, 255,   0,   0);
$lred    = imagecolorallocate($im, 255, 192, 192);
$dred    = imagecolorallocate($im, 160,   0,   0);
$blue    = imagecolorallocate($im,   0,   0, 224);
$dblue   = imagecolorallocate($im,   0,   0, 160);
$purple  = imagecolorallocate($im, 224,   0, 224);
$dpurple = imagecolorallocate($im, 160,   0, 160);
$font    = 2;  // 6x13
$bfont   = 3;  // 7x13 medium bold
$tfont   = 1;  // 5x8

//
//  Colors and font to use
//
$bgcolor        = imagecolorallocatealpha($im, 255, 255, 255, $_GET['transparent'] ? 127 : 0);
$bgcolor_transp = imagecolorallocatealpha($im, 255, 255, 255, 96);
$gridcolor      = $black;    // main grid and markers
$sgridcolor     = $lgrey;    // guides in the grid
$nextdaycolor   = $grey;    // next day line
$linecolor      = $blue;
$zero_color     = $lred;    // 0 degrees line
$info_color     = $red;      // additional info

//
//  Font selection (dependent on image size)
//
// labels and legenda
if( $width <= 320 || $height <= 240 ) {
  $labelfont = 1;
  $infofont  = 1;
}
else if( $width >= 2048 && $height >= 1536 ) {
  $labelfont = 5;
  $infofont  = 3;
}
else if( $width >= 1280 && $height >= 1024 ) {
  $labelfont = 3;
  $infofont  = 2;
}
else {
  $labelfont = 2;
  $infofont  = 1;
}

//
//  Draw the grid
//

// draw background
imagefill($im, 0, 0, $bgcolor);

// offsets with the drawing grid
// largest value label: 1.000
//  x: left to right
//  y: bottom to top
global $x_off, $x_ext, $y_off, $y_ext;
$x_off = 3 * imagefontwidth($labelfont)                  // value labels + 
       + imagefontheight($labelfont)                     // legend + 
       + (imagefontheight($labelfont) >> 1);             // extra spacing
$x_ext = $width - $x_off - (imagefontheight($labelfont) >> 1);      // + extent of the last date label
$y_off = $height - 3 - strlen(strftime("%X")) * imagefontwidth($labelfont);  // date/time
$y_ext = $y_off;
if( !isset($_GET['hide_title']) ) {
  $y_ext -= imagefontheight($labelfont);                // title
  if( $use_log_realtime ) $y_ext -= imagefontheight($labelfont);
}
else {
  $y_ext -= imagefontheight($labelfont) >> 1;              // extent of the top value label
}

// The grid is drawn _under_ the lines and ornaments like the title etc
for( $rssi = $rssi_min; $rssi <= $rssi_max; $rssi += 10 ) {
  $y = ($y_ext * ($rssi - $rssi_min) / $rssi_range);
  imageline($im, $x_off, $y_off - $y, $x_off + $x_ext, $y_off - $y, $rssi == 0 ? $zero_color : $lgrey);
  imageline($im, $x_off - 2, $y_off - $y, $x_off, $y_off - $y, $black);
  imagestringalign($im,
    $labelfont,
    $x_off - 2, $y_off - $y,
    sprintf("%d", $rssi),
    $gridcolor,
    ALV_MIDDLE | ALH_RIGHT
  );
}
// X tick marks
// find a correct stepping for the date labels first
$x_tick_sec = array(5,15,1*60,5*60,15*60,30*60,60*60,4*60*60,6*60*60,8*60*60,12*60*60,24*60*60,7*24*60*60,30*24*60*60,365*24*60*60);
for(
  $step = 0, $x_tick_step = 0;
  $x_tick_step < (imagefontheight($labelfont) << 1) && $step < count($x_tick_sec);
  $step++
) {
  $x_tick_off   = $x_tick_sec[$step];
  $x_tick_step  = ($x_ext * $x_tick_off) / $duration;
  $x_tick_val   = $x_tick_off - (($tmin + $tz_offset) % $x_tick_off);
  if( $x_tick_val == $x_tick_off ) $x_tick_val = 0;
}
if( $x_tick_off >= (24*60*60) ) {
  if( strtotime("first day of next year", time()) !== FALSE ) {
    // big steps; use days/weeks/months/years for DST and leap years
    if( $x_tick_off == (365*24*60*60) ) {
      $t = strtotime("this year January 01 midnight", $tmin);
      $t_step = "first day of next year";
    }
    else if( $x_tick_off == (30*24*60*60) ) {
      $t = strtotime("first day of this month midnight", $tmin);
      $t_step = "first day of next month";
    }
    else if( $x_tick_off ==  (7*24*60*60) ) {
      $t = strtotime("this week Monday midnight", $tmin);
      $t_step = "+1 weeks";
    }
    else {
      $t = strtotime("midnight", $tmin);
      $t_step = "tomorrow";
    }
  }
  else {
    // "nice" arithmatic is not supported
    if( $x_tick_off == (365*24*60*60) ) {
      $t = strtotime("this year January 01 midnight", $tmin);
      $t_step = "+1 year";
    }
    else if( $x_tick_off == (30*24*60*60) ) {
      $t = strtotime("first day of this month midnight", $tmin);
      $t_step = "+1 month";
    }
    else if( $x_tick_off ==  (7*24*60*60) ) {
      $t = strtotime("this week Monday midnight", $tmin);
      $t_step = "+1 weeks";
    }
    else {
      $t = strtotime("midnight", $tmin);
      $t_step = "tomorrow";
    }
  }
}
else {
  if( $x_tick_off >= 60*60 ) {
    $t_step = "+" . ($x_tick_off / (60*60)) . " hours";
  }
  else if( $x_tick_off >= 60 ) {
    $t_step = "+" . ($x_tick_off / 60) . " minutes";
  }
  else {
    $t_step = "+" . $x_tick_off . " seconds";
  }
  $t = $tmin;
  if( $x_tick_val > 0 ) {
    //error_log("correction " . $x_tick_val . " s");
    $t = strtotime("+" . $x_tick_val . " seconds", $t);
  }
}
//error_log(date("Y-m-d H:i:s", $t) . "(" . $t . ")->" . date("Y-m-d H:i:s", $tmax) . "(" . $tmax . "), " . $t_step . "," . $x_tick_off . "," . $x_step);
while( $t <= $tmax ) {
  if( $t >= $tmin ) {
    $x = ((($t - $tmin) / $duration) * $x_ext);
    if( $x_tick_off >= (24*60*60)  ) {
      if( $x_tick_off == (30*24*60*60) ) {
        // month name
        imageline($im, $x_off + $x, $y_off    , $x_off + $x, $y_off - $y_ext - 1, $nextdaycolor);
        imageline($im, $x_off + $x, $y_off + 2, $x_off + $x, $y_off, $gridcolor);
        imagestringupalign($im, $labelfont, $x_off + $x, $y_off - 2, strftime("%B", $t), $nextdaycolor, ALV_BOTTOM | ALH_LEFT);
      }
      else if( $x_tick_off == (7*24*60*60) ) {
        // month name
        imageline($im, $x_off + $x, $y_off    , $x_off + $x, $y_off - $y_ext - 1, $nextdaycolor);
        imageline($im, $x_off + $x, $y_off + 2, $x_off + $x, $y_off, $gridcolor);
        imagestringupalign($im, $labelfont, $x_off + $x, $y_off - 2, strftime("%V", $t), $nextdaycolor, ALV_BOTTOM | ALH_LEFT);
      }
      else {
        imageline($im, $x_off + $x, $y_off    , $x_off + $x, $y_off - $y_ext - 1, $sgridcolor);
        imageline($im, $x_off + $x, $y_off + 2, $x_off + $x, $y_off, $gridcolor);
      }
      imagestringupalign($im, $labelfont, $x_off + $x, $y_off + 2, strftime("%x", $t), $gridcolor, ALV_TOP | ALH_CENTER);
    }
    else {
      if( strftime("%H%M%S", $t) == "000000" ) {
        imageline($im, $x_off + $x, $y_off    , $x_off + $x, $y_off - $y_ext - 1, $nextdaycolor);
        imageline($im, $x_off + $x, $y_off + 2, $x_off + $x, $y_off, $gridcolor);
        imagestringupalign($im, $labelfont, $x_off + $x, $y_off - 2, strftime("%x", $t), $nextdaycolor, ALV_BOTTOM | ALH_LEFT);
      }
      else {
        imageline($im, $x_off + $x, $y_off    , $x_off + $x, $y_off - $y_ext - 1, $sgridcolor);
        imageline($im, $x_off + $x, $y_off + 2, $x_off + $x, $y_off, $gridcolor);
      }
      imagestringupalign($im, $labelfont, $x_off + $x, $y_off + 2, strftime("%X", $t), $gridcolor, ALV_TOP | ALH_CENTER);
    }
  }
  // increment $t (yup, that's what the line below does)
  $t = strtotime($t_step, $t);
	if( $t === FALSE ) {
	  trigger_error("Date/time error when adding \"" . $t_step . "\"", E_USER_ERROR);
	}
}
if( $x_tick_off < (24*60*60) && (($x_tick_val / $duration) * $x_ext) > imagefontheight($labelfont) ) {
  // show start day only on detailed plots (it is already in the titles)
  imagestringupalign($im, $labelfont, $x_off, $y_off - 2, strftime("%x", $tmin), $grey, ALV_BOTTOM | ALH_LEFT);
}

//
//  Draw the legend
//
$y_legend_off = $y_off;
$y_legend_off -= ($y_ext - (8+4+7+4) * imagefontwidth($labelfont)) >> 1;
imagestringupalign($im, $labelfont, 0, $y_legend_off - 4 * imagefontwidth($labelfont), "rssi", $gridcolor, ALV_TOP | ALH_LEFT);
imageline($im,
  imagefontheight($labelfont) >> 1, $y_legend_off -  5 * imagefontwidth($labelfont),  /* space */
  imagefontheight($labelfont) >> 1, $y_legend_off -  8 * imagefontwidth($labelfont),  /* line length */
  $linecolor
);
$y_legend_off -= (12+4) * imagefontwidth($labelfont);

imagestringupalign($im, $labelfont, 0, $y_legend_off - 4 * imagefontwidth($labelfont), "(dBm)", $gridcolor, ALV_TOP | ALH_LEFT);

//
//  Draw the border to the left and bottom of the canvas
//
imageline($im, $x_off, $y_off, $x_off, $y_off - $y_ext + 1, $gridcolor);
imageline($im, $x_off, $y_off, $x_off + $x_ext, $y_off, $gridcolor);

//
//  Plot the data
//
foreach( $logfiles as $logfile ) {
  // get tmin,tmax for this logfile
  $log_tmin = $logfile['tmin'];
  $log_tmax = $logfile['tmax'];
  if( $log_tmin < $tmin ) $log_tmin = $tmin;
  if( $log_tmax > $tmax ) $log_tmax = $tmax;
  //error_log("logfile(" . $logfile['sdcard'] . "," . $logfile['rpgmcount'] . "," . $logfile['startup'] . ") " . date("Y-m-d H:i:s", $log_tmin) . "->" . date("Y-m-d H:i:s", $log_tmax));

  //
  $sdcard    = $logfile['sdcard'];
  $rpgmcount = $logfile['rpgmcount'];
  $startup   = $logfile['startup'];

  // cache minimum and maximum id; this is a lot faster for some reason
  if( $use_log_realtime ) {
    $query   = "SELECT MIN(id),MAX(ID) FROM log_realtime WHERE zkl=" . $_GET['zkl'] . " AND t BETWEEN " . $log_tmin . " AND " . $log_tmax;
    if( ($result = mysql_run($query, $db_data_handle)) ) {
      $row     = mysql_fetch_array($result);
      $id_min  = $row[0];
      $id_max  = $row[1];
    }
    else exit(im_print_error($im, "No data"));
    $query   = "SELECT MAX(id) FROM log_realtime WHERE zkl=" . $_GET['zkl'] . " AND t <= " . $log_tmin;
    if( ($result = mysql_run($query, $db_data_handle)) ) {
      $row = mysql_fetch_array($result);
      $id_tmin = $row[0];
    }
    else {
      // no suitable minimum
      $query = "SELECT MIN(id) FROM log_realtime WHERE zkl=" . $_GET['zkl'];
      $result  = mysql_run($query, $db_data_handle);
      $row     = mysql_fetch_array($result);
      $id_tmin = $row[0];
    }
  }

  // get the data
  if( $use_log_realtime ) {
    $query  = "SELECT id,t,gsm_rssi,gsm_berr ";
    $query .= "FROM log_realtime ";
    $query .= "WHERE ";
    $query .= "  zkl=" . $_GET['zkl'] . " AND ";
    $query .= "  (";
    if( $id_tmin ) $query .= "    id=" . $id_tmin . " OR ";
    $query .= "    (";
    $query .= "      id BETWEEN " . $id_min . " AND " . $id_max . " AND ";
    $query .= "      (changes & 0x3000) != 0";
    $query .= "    )";
    $query .= "  ) ";
    $query .= "ORDER BY id";
    $result = mysql_run($query, $db_data_handle);
  }
  else {
    $query  = "SELECT log_zkl.id,t,log_peripheral.code DIV 8 AS gsm_rssi,log_peripheral.code MOD 8 AS gsm_berr ";
    $query .= "FROM log_zkl,log_peripheral ";
    $query .= "WHERE ";
    $query .= "  log_zkl.id=log_peripheral.id AND ";
    $query .= "  log_zkl.zkl=" . $_GET['zkl'] . " AND ";
    $query .= "  log_zkl.sdcard=" . $sdcard . " AND ";
    $query .= "  log_zkl.rpgmcount=" . $rpgmcount . " AND ";
    $query .= "  log_zkl.startup=" . $startup . " AND ";
    $query .= "  log_zkl.major=8 AND log_zkl.minor=24 ";
    $query .= "ORDER BY log_zkl.id";
    $result = mysql_run($query, $db_data_handle);
  }
  //error_log(($use_log_realtime ? "log_realtime" : "log_zkl") . ": " . mysql_num_rows($result) . " rows");
  $rssi = array();
  unset($t_begin);
  while( $row = mysql_fetch_assoc($result) ) {
    $rssi_db = $row['gsm_rssi'];
    
    if( !isset($t_begin) ) {
      $t_begin = $row['t'];
      $rssi = $rssi_db;
    }
    else {
      $t_start = $t_begin;
      $t_this = $t_end = $row['t'];
      if(
        $t_end >= $log_tmin &&
        $t_start <= $log_tmax
      ) {
        if( $t_start < $log_tmin ) {
          $t_start = $log_tmin;
        }
        if( $t_end < $log_tmin ) break;
        else if( $t_end > $log_tmax ) {
          $t_end = $log_tmax;
        }
        
        $prev_level = $rssi;
        imageline($im,
          $x_off + ((($t_start - $tmin) / $duration) * $x_ext), $y_off - ($y_ext * ($prev_level - $rssi_min) / $rssi_range),
          $x_off + ((($t_end   - $tmin) / $duration) * $x_ext), $y_off - ($y_ext * ($prev_level - $rssi_min) / $rssi_range),
          $linecolor
        );
        imageline($im,
          $x_off + ((($t_end   - $tmin) / $duration) * $x_ext), $y_off - ($y_ext * ($prev_level - $rssi_min) / $rssi_range),
          $x_off + ((($t_end   - $tmin) / $duration) * $x_ext), $y_off - ($y_ext * ($rssi_db - $rssi_min) / $rssi_range),
          $linecolor
        );
      }
      $t_begin = $t_this;
      $rssi = $rssi_db;
    }
  }
  // draw last segment
  if( isset($t_begin) ) {
    $t_start = $t_begin;
    $t_end = $log_tmax;
    if(
      $t_end >= $log_tmin &&
      $t_start <= $log_tmax
    ) {
      if( $t_start < $log_tmin ) {
        $t_start = $log_tmin;
      }
      if( $t_end > $log_tmin ) {
        if( $t_end > $log_tmax ) {
          $t_end = $log_tmax;
        }
        
        imageline($im,
          $x_off + ((($t_start - $tmin) / $duration) * $x_ext), $y_off - ($y_ext * ($rssi - $rssi_min) / $rssi_range),
          $x_off + ((($t_end   - $tmin) / $duration) * $x_ext), $y_off - ($y_ext * ($rssi - $rssi_min) / $rssi_range),
          $linecolor
        );
      }
    }
  }
}

//
//  Draw the title, on top of everything else
//
if( !isset($_GET['hide_title']) ) {
  imagestringborderalign($im, $labelfont, $width >> 1, 0, sprintf(_("%s - Signaal - %s tot %s"), $zkl_info['idcode'], strftime("%c", $tmin), strftime("%c", $tmax)), $gridcolor, $bgcolor_transp, ALV_TOP | ALH_CENTER);
  if( $use_log_realtime )
    imagestringborderalign($im, $labelfont, $width >> 1, imagefontheight($labelfont), _("(real-time data log)"), $gridcolor, $bgcolor_transp, ALV_TOP | ALH_CENTER);
}

//
//  Output the final image
//
imagepng($im);
imagedestroy($im);

?>