geoPHP::detectFormat()

Complexity

Conditions	21
Paths	31

Size

Total Lines	74
Code Lines	35

Duplication

Lines	0
Ratio	0 %

Importance

Changes

0

<?php
  static function detectFormat(&$input) {
    $mem = fopen('php://memory', 'r+');
    fwrite($mem, $input, 11); // Write 11 bytes - we can detect the vast majority of formats in the first 11 bytes
    fseek($mem, 0);

    $bytes = unpack("c*", fread($mem, 11));

    // If bytes is empty, then we were passed empty input
    if (empty($bytes)) return FALSE;

    // First char is a tab, space or carriage-return. trim it and try again
    if ($bytes[1] == 9 || $bytes[1] == 10 || $bytes[1] == 32) {
      $ltinput = ltrim($input);
      return geoPHP::detectFormat($ltinput);
    }

    // Detect WKB or EWKB -- first byte is 1 (little endian indicator)
    if ($bytes[1] == 1) {
      // If SRID byte is TRUE (1), it's EWKB
      if ($bytes[5]) return 'ewkb';
      else return 'wkb';
    }

    // Detect HEX encoded WKB or EWKB (PostGIS format) -- first byte is 48, second byte is 49 (hex '01' => first-byte = 1)
    if ($bytes[1] == 48 && $bytes[2] == 49) {
      // The shortest possible WKB string (LINESTRING EMPTY) is 18 hex-chars (9 encoded bytes) long
      // This differentiates it from a geohash, which is always shorter than 18 characters.
      if (strlen($input) >= 18) {
        //@@TODO: Differentiate between EWKB and WKB -- check hex-char 10 or 11 (SRID bool indicator at encoded byte 5)
        return 'ewkb:1';
      }
    }

    // Detect GeoJSON - first char starts with {
    if ($bytes[1] == 123) {
      return 'json';
    }

    // Detect EWKT - first char is S
    if ($bytes[1] == 83) {
      return 'ewkt';
    }

    // Detect WKT - first char starts with P (80), L (76), M (77), or G (71)
    $wkt_chars = array(80, 76, 77, 71);
    if (in_array($bytes[1], $wkt_chars)) {
      return 'wkt';
    }

    // Detect XML -- first char is <
    if ($bytes[1] == 60) {
      // grab the first 256 characters
      $string = substr($input, 0, 256);
      if (strpos($string, '<kml') !== FALSE)        return 'kml';
      if (strpos($string, '<coordinate') !== FALSE) return 'kml';
      if (strpos($string, '<gpx') !== FALSE)        return 'gpx';
      if (strpos($string, '<georss') !== FALSE)     return 'georss';
      if (strpos($string, '<rss') !== FALSE)        return 'georss';
      if (strpos($string, '<feed') !== FALSE)       return 'georss';
    }

    // We need an 8 byte string for geohash and unpacked WKB / WKT
    fseek($mem, 0);
    $string = trim(fread($mem, 8));

    // Detect geohash - geohash ONLY contains lowercase chars and numerics
    preg_match('/[a-z0-9]+/', $string, $matches);
    if ($matches[0] == $string) {
      return 'geohash';
    }

    // What do you get when you cross an elephant with a rhino?
    // http://youtu.be/RCBn5J83Poc
    return FALSE;
  }