#!/usr/bin/perl -w

# googleTransitHeatmap.pl

# Creates KML representing a 'heatmap' of
# travel times from all points in the bounding box
# to a particular address. 

# THIS SOFTWARE IS SUPPLIED WITHOUT WARRANTY OF ANY KIND, AND MAY BE
# COPIED, MODIFIED OR DISTRIBUTED IN ANY WAY, AS LONG AS THIS NOTICE
# AND ACKNOWLEDGEMENT OF AUTHORSHIP REMAIN.

# original script by Neil Kandalgaonkar <neilk(a)brevity.org>


use strict;

# destination address (url-encoded)
$destinationAddress = '475+Sansome,+San+Francisco,+CA';

# sf (cuts a bit off north beach...)
# my ($minLat, $minLon) = (37.723651, -122.513866); # sw
# my ($maxLat, $maxLon) = (37.803717, -122.378597); # ne

# east bay
my ($minLat, $minLon) = (37.613833, -122.346497); # sw
my ($maxLat, $maxLon) = (37.93297,  -122.103424); # ne


my $delta = 0.00541075999999975;
my $radius = $delta/2;
# my $delta = ($maxLon - $minLon) / 25;

printHeader();
printPlaceMarkData($minLat, $minLon, $maxLat, $maxLon);
printFooter();


sub printPlaceMarkData {
  my ($minLat, $minLon, $maxLat, $maxLon) = @_;
  for (my $lat = $minLat; $lat <= $maxLat; $lat += $delta) {
    for (my $lon = $minLon; $lon <= $maxLon; $lon += $delta) {
      sleep(1);
      print STDERR ".";
      my $averageTime = getAverageTransitTime($lat, $lon);
      if (not defined $averageTime) {
        print STDERR "E";
        next;
      } 
      print STDERR "$lat $lon $averageTime\n";
      printPlaceMark($lat, $lon, $averageTime);
    }
    print STDERR "\n";
  }
}
  
sub getStyle {
  my ($time) = @_;
  my $style;
  if ($time <= 20) {  
    $style = 'Green';
  } elsif ($time > 20 and $time <= 35) {
    $style = 'Yellow';
  } elsif ($time > 35 and $time <= 50) {
    $style = 'Red';
  } else {
    $style = 'Blue';
  }
  return $style;
}

sub printPlaceMark {
  my ($lat, $lon, $time) = @_;
  my $style = getStyle($time);
  $minLat = $lat - $radius;
  $maxLat = $lat + $radius;
  $minLon = $lon - $radius;
  $maxLon = $lon + $radius;
  my @coords;
  foreach my $pair ([$minLat, $minLon], 
                    [$maxLat, $minLon], 
                    [$maxLat, $maxLon], 
                    [$minLat, $maxLon], 
                    [$minLat, $minLon]) {
    my ($thisLat, $thisLon) = @$pair;
    # ugh, Google Earth KML wants x,y not lat,lon
    push @coords, "$thisLon,$thisLat,10";   

  }
  $style = ucfirst($style);
  print <<"EOXML";
      <Placemark>
        <name>$time mins</name>
        <styleUrl>#trans${style}Poly</styleUrl>
        <Polygon>
          <extrude>1</extrude>
          <altitudeMode>relativeToGround</altitudeMode>
          <outerBoundaryIs>
            <LinearRing>
              <coordinates>
                @coords
              </coordinates>
            </LinearRing>
          </outerBoundaryIs>
        </Polygon>
      </Placemark>
EOXML
}

sub getAverageTransitTime {
  my ($lat, $lon) = @_;
  my $averageTime = undef;
  my $url = getGoogleTransitTimeUrl($lat, $lon);
  my $response = qx(curl -s '$url');
  my @time;
  while ($response =~ m/\((\d+) mins\)/g) {
    push @time, int($1);
  }
  if (@time) {
    my $total;
    for my $t (@time) {
      $total += $t;
    }
    $averageTime = $total/@time;
  }
  return $averageTime;
}


sub getGoogleTransitTimeUrl {
  my ($lat, $lon) = @_;
  return   "http://maps.google.com/maps?f=d&source=s_d"
         . "&daddr=$destinationAddress&saddr=$lat,$lon"
         . "&hl=en&mra=ls&dirflg=r&date=08%2F18%2F08&time=9:00am"
         . "&ttype=arr&noexp=0&noal=0";
}

sub printHeader {
  print <<EOXML;
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.1">
  <Document>
    <Style id="transGreenPoly">
      <LineStyle>
        <width>1.5</width>
      </LineStyle>
      <PolyStyle>
        <color>7d00ff00</color>
      </PolyStyle>
    </Style>
    <Style id="transYellowPoly">
      <LineStyle>
        <width>1.5</width>
      </LineStyle>
      <PolyStyle>
        <color>7d00ffff</color>
      </PolyStyle>
    </Style>
    <Style id="transRedPoly">
      <LineStyle>
        <width>1.5</width>
      </LineStyle>
      <PolyStyle>
        <color>7d0000ff</color>
      </PolyStyle>
    </Style>
    <Style id="transBluePoly">
      <LineStyle>
        <width>1.5</width>
      </LineStyle>
      <PolyStyle>
        <color>7dff0000</color>
      </PolyStyle>
    </Style>
    <Folder>
      <name>Heat Map - Flickr Transit Time</name>
      <open>0</open>
      <description>0-20 minutes = green, 21-35 minutes = yellow, 36-50 minutes = red, 51-inf = blue. </description>
 
EOXML
}


sub printFooter {
  print <<EOXML;
    </Folder>
  </Document>
</kml>
EOXML
}