<?php
/**
 * 尋找最近的作番地點
 * @url /app-browser_gpslocation-find.php
 * @method POST
 * @return JSON
 * 
 * request
 * {
 *  "lat" 緯度
 *  "lng" 經度
 * }
 *
 * respons json
 * {
 *  "st" : "ok",
 *  "err" : ""
 * }
 **/

$data = [];
$rarr = array('st' => 'ok', 'err' => '');

try {
error_log("api start 1\n",3,"gps.log");
error_log("POST=".print_r($_POST,1)."\n",3,"gps.log");
    if (empty($_POST) || empty($_POST["lat"]) || empty($_POST["lng"])) throw new \Exception("parameter empty");

    foreach ($_POST as $k => $v) {
        $$k = htmlspecialchars(stripslashes(trim($v)));
    }
error_log("api start 2\n",3,"gps.log");
    require_once "db/database.php";
    /* Method.1
    define("EARTH_RADIUS", 6371); //地球半徑，平均半徑為6371km
    /**
     * 計算某個經緯度的周圍某段距離的正方形的四個點
     * @param lng float 經度
     * @param lat float 緯度
     * @param distance float 該點所在圓的半徑，該圓與此正方形內切，默認值為1公里
     * @return array 正方形的四個點的經緯度坐標
     */
    /*
    function returnSquarePoint($lng, $lat, $distance = 5) {
        $dlng = 2*asin(sin($distance/(2*EARTH_RADIUS))/cos(deg2rad($lat)));
        $dlng = rad2deg($dlng);
        $dlat = $distance/EARTH_RADIUS;
        $dlat = rad2deg($dlat);
        return array("left-top" => array("lat" => $lat+$dlat, "lng" => $lng-$dlng),
                     "right-top" => array("lat" => $lat+$dlat, "lng" => $lng+$dlng),
                     "left-bottom" => array("lat" => $lat-$dlat, "lng" => $lng-$dlng),
                     "right-bottom" => array("lat" => $lat-$dlat, "lng" => $lng+$dlng));
    }
    $squares = returnSquarePoint($lng, $lat);
    $sql  = "select address from facility ";
    $sql .= "where latitude > '".$squares["right-bottom"]["lat"]."' and latitude < '".$squares["left-top"]["lat"]."'";
    $sql .= "and longitude > '".$squares["left-top"]["lng"]."' and longitude < '".$squares["right-bottom"]["lng"]."' ";
    $sql .= "group by address";
    */
    /* Method.2 */
    //$latitude = substr($lat, 0, strpos($lat, ".")).substr($lat, strpos($lat, "."), 4);
    $latitude = substr($lat, 0, 6);
    //$longitude = substr($lng, 0, strpos($lng, ".")).substr($lng, strpos($lng, "."), 4);
    $longitude = substr($lng, 0, 7);
    $sql = "select address from facility where latitude like '".$latitude."%' and longitude like '".$longitude."%'";
error_log($sql."\n",3,"gps.log");
    $res = mysqli_query($link, $sql);
    while ($row = mysqli_fetch_row($res)) {
        $data[] = $row[0];
    }
    mysqli_free_result($res);
error_log("data=".print_r($data,1)."\n",3,"gps.log");
    $rarr['content'] = $data;
}catch(\Exception $e) {
    $rarr['st'] = 'err';
    $rarr['err'] = $e->getMessage();
}

echo json_encode($rarr, JSON_UNESCAPED_UNICODE);
?>