[api] Added php decoder used on the web site

1 files changed, 106 insertions, 0 deletions

diff --git a/api/src/php/mwm_api.php b/api/src/php/mwm_api.php
new file mode 100644
index 0000000000..085d4e2adf
--- /dev/null
+++ b/api/src/php/mwm_api.php
@@ -0,0 +1,106 @@
+<?php
+
+// @TODO add tests
+
+// Returns array(lat, lon, zoom) or empty array in the case of error
+function DecodeGe0LatLonZoom($latLonZoom)
+{
+  $MAPSWITHME_MAX_POINT_BYTES = 10;
+  $MAPSWITHME_MAX_COORD_BITS = $MAPSWITHME_MAX_POINT_BYTES * 3;
+
+  $FAILED = array();
+
+  $base64ReverseArray = GetBase64ReverseArray();
+
+  $zoom = $base64ReverseArray[ord($latLonZoom[0])];
+  if ($zoom > 63)
+    return $FAILED;
+  $zoom = $zoom / 4. + 4.;
+
+  $latLonStr = substr($latLonZoom, 1);
+  $latLonBytes = strlen($latLonStr);
+  $lat = 0;
+  $lon = 0;
+  for($i = 0, $shift = $MAPSWITHME_MAX_COORD_BITS - 3; $i < $latLonBytes; $i++, $shift -= 3)
+  {
+    $a = $base64ReverseArray[ord($latLonStr[$i])];
+    $lat1 =  ((($a >> 5) & 1) << 2 |
+                 (($a >> 3) & 1) << 1 |
+                 (($a >> 1) & 1));
+    $lon1 =  ((($a >> 4) & 1) << 2 |
+                 (($a >> 2) & 1) << 1 |
+                        ($a & 1));
+    $lat |= $lat1 << $shift;
+    $lon |= $lon1 << $shift;
+  }
+
+  $middleOfSquare = 1 << (3 * ($MAPSWITHME_MAX_POINT_BYTES - $latLonBytes) - 1);
+  $lat += $middleOfSquare;
+  $lon += $middleOfSquare;
+
+  $lat = round($lat / ((1 << $MAPSWITHME_MAX_COORD_BITS) - 1) * 180.0 - 90.0, 5);
+  $lon = round($lon / (1 << $MAPSWITHME_MAX_COORD_BITS) * 360.0 - 180.0, 5);
+
+  if ($lat <= -90.0 || $lat >= 90.0)
+    return $FAILED;
+  if ($lon <= -180.0 || $lon >= 180.0)
+    return $FAILED;
+
+  return array($lat, $lon, $zoom);
+}
+
+// Returns decoded name
+function DecodeGe0Name($name)
+{
+  return str_replace('_', ' ', rawurldecode($name));
+}
+
+// Returns empty array in the case of error.
+// In the good case, returns array(lat, lon, zoom) or array(lat, lon, zoom, name)
+function DecodeGe0Url($url)
+{
+  $MAPSWITHME_ZOOM_POSITION = 6;
+  $NAME_POSITON_IN_URL = 17;
+
+  $FAILED = array();
+  if (strlen($url) < 16 || strpos($url, "ge0://") != 0)
+    return $FAILED;
+
+  $base64ReverseArray = GetBase64ReverseArray();
+
+  $latLonZoom = DecodeGe0LatLonZoom(substr($url, 6, 10));
+  if (empty($latLonZoom))
+    return $FAILED;
+
+  if (strlen($url) < $NAME_POSITON_IN_URL)
+    return $latLonZoom;
+
+  $name = DecodeGe0Name(substr($url, $NAME_POSITON_IN_URL));
+  array_push($latLonZoom, $name);
+  return $latLonZoom;
+}
+
+// Internal helper function
+function GetBase64ReverseArray()
+{
+  static $base64Alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
+  $base64ReverseArray = array();
+  // fill array with 255's
+  array_pad($base64ReverseArray, 256, 255);
+
+  for ($i = 0; $i < 64; $i++)
+  {
+    $c = $base64Alphabet[$i];
+    $base64ReverseArray[ord($c)] = $i;
+  }
+  return $base64ReverseArray;
+}
+
+
+//////////////////////////////////////
+// Tests are below
+//print_r(DecodeGe0Url("ge0://B4srhdHVVt/Some_Name"));
+//print_r(DecodeGe0Url("ge0://AwAAAAAAAA/%d0%9c%d0%b8%d0%bd%d1%81%d0%ba_%d1%83%d0%bb._%d0%9b%d0%b5%d0%bd%d0%b8%d0%bd%d0%b0_9"));
+
+?>
+