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diff --git a/engine/lib/location.php b/engine/lib/location.php
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+<?php
+/**
+ * Elgg geo-location tagging library.
+ *
+ * @package Elgg.Core
+ * @subpackage Location
+ */
+
+/**
+ * Encode a location into a latitude and longitude, caching the result.
+ *
+ * Works by triggering the 'geocode' 'location' plugin
+ * hook, and requires a geocoding plugin to be installed.
+ *
+ * @param string $location The location, e.g. "London", or "24 Foobar Street, Gotham City"
+ * @return string|false
+ */
+function elgg_geocode_location($location) {
+ global $CONFIG;
+
+ if (is_array($location)) {
+ return false;
+ }
+
+ $location = sanitise_string($location);
+
+ // Look for cached version
+ $query = "SELECT * from {$CONFIG->dbprefix}geocode_cache WHERE location='$location'";
+ $cached_location = get_data_row($query);
+
+ if ($cached_location) {
+ return array('lat' => $cached_location->lat, 'long' => $cached_location->long);
+ }
+
+ // Trigger geocode event if not cached
+ $return = false;
+ $return = elgg_trigger_plugin_hook('geocode', 'location', array('location' => $location), $return);
+
+ // If returned, cache and return value
+ if (($return) && (is_array($return))) {
+ $lat = (float)$return['lat'];
+ $long = (float)$return['long'];
+
+ // Put into cache at the end of the page since we don't really care that much
+ $query = "INSERT DELAYED INTO {$CONFIG->dbprefix}geocode_cache "
+ . " (location, lat, `long`) VALUES ('$location', '{$lat}', '{$long}')"
+ . " ON DUPLICATE KEY UPDATE lat='{$lat}', `long`='{$long}'";
+ execute_delayed_write_query($query);
+ }
+
+ return $return;
+}
+
+/**
+ * Return entities within a given geographic area.
+ *
+ * Also accepts all options available to elgg_get_entities().
+ *
+ * @see elgg_get_entities
+ *
+ * @param array $options Array in format:
+ *
+ * latitude => FLOAT Latitude of the location
+ *
+ * longitude => FLOAT Longitude of the location
+ *
+ * distance => FLOAT/ARR (
+ * latitude => float,
+ * longitude => float,
+ * )
+ * The distance in degrees that determines the search box. A
+ * single float will result in a square in degrees.
+ * @warning The Earth is round.
+ *
+ * @see ElggEntity::setLatLong()
+ *
+ * @return mixed If count, int. If not count, array. false on errors.
+ * @since 1.8.0
+ */
+function elgg_get_entities_from_location(array $options = array()) {
+
+ global $CONFIG;
+
+ if (!isset($options['latitude']) || !isset($options['longitude']) ||
+ !isset($options['distance'])) {
+ return false;
+ }
+
+ if (!is_array($options['distance'])) {
+ $lat_distance = (float)$options['distance'];
+ $long_distance = (float)$options['distance'];
+ } else {
+ $lat_distance = (float)$options['distance']['latitude'];
+ $long_distance = (float)$options['distance']['longitude'];
+ }
+
+ $lat = (float)$options['latitude'];
+ $long = (float)$options['longitude'];
+ $lat_min = $lat - $lat_distance;
+ $lat_max = $lat + $lat_distance;
+ $long_min = $long - $long_distance;
+ $long_max = $long + $long_distance;
+
+ $where = array();
+ $wheres[] = "lat_name.string='geo:lat'";
+ $wheres[] = "lat_value.string >= $lat_min";
+ $wheres[] = "lat_value.string <= $lat_max";
+ $wheres[] = "lon_name.string='geo:long'";
+ $wheres[] = "lon_value.string >= $long_min";
+ $wheres[] = "lon_value.string <= $long_max";
+
+ $joins = array();
+ $joins[] = "JOIN {$CONFIG->dbprefix}metadata lat on e.guid=lat.entity_guid";
+ $joins[] = "JOIN {$CONFIG->dbprefix}metastrings lat_name on lat.name_id=lat_name.id";
+ $joins[] = "JOIN {$CONFIG->dbprefix}metastrings lat_value on lat.value_id=lat_value.id";
+ $joins[] = "JOIN {$CONFIG->dbprefix}metadata lon on e.guid=lon.entity_guid";
+ $joins[] = "JOIN {$CONFIG->dbprefix}metastrings lon_name on lon.name_id=lon_name.id";
+ $joins[] = "JOIN {$CONFIG->dbprefix}metastrings lon_value on lon.value_id=lon_value.id";
+
+ // merge wheres to pass to get_entities()
+ if (isset($options['wheres']) && !is_array($options['wheres'])) {
+ $options['wheres'] = array($options['wheres']);
+ } elseif (!isset($options['wheres'])) {
+ $options['wheres'] = array();
+ }
+ $options['wheres'] = array_merge($options['wheres'], $wheres);
+
+ // merge joins to pass to get_entities()
+ if (isset($options['joins']) && !is_array($options['joins'])) {
+ $options['joins'] = array($options['joins']);
+ } elseif (!isset($options['joins'])) {
+ $options['joins'] = array();
+ }
+ $options['joins'] = array_merge($options['joins'], $joins);
+
+ return elgg_get_entities_from_relationship($options);
+}
+
+/**
+ * Returns a viewable list of entities from location
+ *
+ * @param array $options
+ *
+ * @see elgg_list_entities()
+ * @see elgg_get_entities_from_location()
+ *
+ * @return string The viewable list of entities
+ * @since 1.8.0
+ */
+function elgg_list_entities_from_location(array $options = array()) {
+ return elgg_list_entities($options, 'elgg_get_entities_from_location');
+}
+
+// Some distances in degrees (approximate)
+// @todo huh? see warning on elgg_get_entities_from_location()
+define("MILE", 0.01515);
+define("KILOMETER", 0.00932);