crimes.php

crimes.php

<?php
  error_reporting(E_ERROR | E_PARSE);
  header('Content-Type: application/json');

  class API {
    const CACHE_FILE = "./addresses.txt";

    private $hash = array();

    public $crimes = array();

    public function __construct() {
      if (!file_exists(self::CACHE_FILE)) {
        if (!file_put_contents(self::CACHE_FILE, '')) {
          throw new Exception('Could not create cache file!');
        }
      }
      if (!is_writable(self::CACHE_FILE)) {
        throw new Exception( 'Cache file is not writable.');
      }
      $this->hash = $this->storage_hash();
    }

    // Make sure the server this is requesting from is authorized by google.
    // https://console.developers.google.com
    private function lookup($address) {
      $string = str_replace (" ", "+", urlencode($address));
      $response = json_decode($this->req("https://maps.googleapis.com/maps/api/geocode/json?address=".$string), true);
      if ($response['status'] != 'OK') {
        return null;
      }
      $geometry = $response['results'][0]['geometry'];
      $longitude = $geometry['location']['lat'];
      $latitude = $geometry['location']['lng'];
      $array = array(
        'latitude' => $geometry['location']['lng'],
        'longitude' => $geometry['location']['lat'],
        'location_type' => $geometry['location_type'],
      );
      return $array;
    }

    private function storage_hash() {
      if ($contents = file_get_contents(self::CACHE_FILE)) {
        if (!empty($contents) && $hash = unserialize($contents)) {
          // var_dump($hash);
          return $hash;
        }
      }
      return array();
    }

    private function to_cache($address, $coords) {
      $this->hash[$address] = $coords;
      if (!file_put_contents(self::CACHE_FILE, serialize($this->hash))) {
        throw new Exception("Could not wriite to cache.");
      }
    }

    private function req($url) {
      $curl = curl_init();
      curl_setopt_array($curl, array(
        CURLOPT_RETURNTRANSFER => 1,
        CURLOPT_URL => $url,
        CURLOPT_USERAGENT => "Lev Interactive Experiment"
      ));
      $res = curl_exec($curl);
      curl_close($curl);
      return $res;
    }

    public static function response($arr) {
      if (isset($arr['error'])) {
        http_response_code(400);
      }
      return json_encode($arr, JSON_PRETTY_PRINT);
    }

    public function load() {
      $this->crimes = array();
      $xml = simplexml_load_string(
        $this->req("http://data.octo.dc.gov/feeds/crime_incidents/crime_incidents_current.xml"),
        null,
        LIBXML_NOCDATA
      );
      if (!$xml) {
        throw new Exception("Sorry, data.octo.dc.gov must be down.");
      }
      foreach($xml->entry as $entry) {
        $data = $entry->content->children('dcst', true)->ReportedCrime->children('dcst', true);
        $data = json_decode(json_encode($data));
        if (isset($this->hash[$data->blocksiteaddress])) {
          $data->coords = $this->hash[$data->blocksiteaddress];
        } else {
          $data->coords = $this->lookup($data->blocksiteaddress);
          $this->to_cache($data->blocksiteaddress, $data->coords);
        }
        $this->crimes[] = $data;
      }
    }
  }

  try {
    $api = new API();
    $api->load();
    echo API::response($api->crimes);
  } catch(Exception $e) {
    echo API::response($e->getMessage());
  }