api.php

<?php if (!defined('BASEPATH')) exit('No direct script access allowed');

class Api extends CI_Controller {

  function __construct() {
    //TODO: all validations should go here, numbers texts everything should be validated
    parent::__construct();
    switch ($this->router->fetch_method()) {
      case "add":
        $json = json_decode(trim(file_get_contents('php://input')));
        if ($json->latitude == ""
            || $json->longitude == ""
            || $json->text == "") {
          echo json_encode(array("error"=>"Cannot add new message"));
          exit;
        }
        break;

      case "get":
        break;

      case "get_map_data":
        break;
    }
  }

  public function index() {
    // Silence is golden.
    exit;
  }

  private function server_time() {
    return time();
  }

  public function get_server_time() {
    echo $this->server_time();
  }

  public function add() {
    $current_time = $this->server_time();
    $json = json_decode(trim(file_get_contents('php://input')));
    $data = array(
      'latitude'  => $json->latitude,
      'longitude' => $json->longitude,
      'text'      => $json->text,
      'pubTime'   => $current_time + ($json->pubDelay ? $json->pubDelay : 0),
      'parent_id' => $json->parent_id ? $json->parent_id : 0
    );
    $this->db->insert('skene_messages', $data);
    // Return the ID of the newly inserted message
    echo $this->db->insert_id();
  }

  public function get() {
    // Available parameters:
    // lat: center location latitude
    // long: center location longitude
    // radius: radius of area in meters
    // timestamp (default: 0): get messages posted after this time. Format: Unix timestamp
    // count (default: 50): maximum number of messages to return
    // parent_id: (default 0): only get messages with this parent_id


    $timestamp = ($this->input->get('timestamp')) ? $this->input->get('timestamp') : 0;
    $count = ($this->input->get('count')) ? $this->input->get('count') : 50;
    $parent_id = ($this->input->get('parent_id')) ? $this->input->get('parent_id') : 0;
    $have_specifics = false;

    if($this->input->get('radius') && $this->input->get('lat') && $this->input->get('long')) {
      $radius = $this->input->get('radius') / 1000; //to km
      $lat = $this->input->get('lat');
      $long = $this->input->get('long');

      // Get min/max latitude and longitue to select messages from the database
      $R = 6371;  // earth's mean radius, km
      // First-cut bounding box (in degrees)
      $max_lat = $lat + rad2deg($radius/$R);
      $min_lat = $lat - rad2deg($radius/$R);
      // Compensate for degrees longitude getting smaller with increasing latitude
      $max_long = $long + rad2deg($radius/$R/cos(deg2rad($lat)));
      $min_long = $long - rad2deg($radius/$R/cos(deg2rad($lat)));
      $have_specifics = true;
    }

    $current_time = $this->server_time();

    // Compose SQL query
    if ($parent_id == 0 && $have_specifics) {
      // Get skenes by location
      $query = $this->db->order_by("id", "desc")->get_where('skene_messages',
                                                            array('parent_id = ' => 0,
                                                                  'latitude >='  => $min_lat,
                                                                  'latitude <='  => $max_lat,
                                                                  'longitude >=' => $min_long,
                                                                  'longitude <=' => $max_long,
                                                                  'pubTime >='   => $timestamp,
                                                                  'pubTime <='   => $current_time),
                                                            $count);
    } elseif ($parent_id == 0) {
      // Get latest skenes from the entire world
      $query = $this->db->order_by("id", "desc")->get_where('skene_messages',
                                                            array('parent_id = ' => 0,
                                                                  'pubTime >='   => $timestamp,
                                                                  'pubTime <='   => $current_time),
                                                            $count);
    } else {
      // Get by parent ID
      $query = $this->db->order_by("id", "desc")->get_where('skene_messages',
                                                            array('parent_id = ' => $parent_id,
                                                                  'pubTime >='   => $timestamp,
                                                                  'pubTime <='   => $current_time),
                                                            $count);
    }

    // Run database query
    $result = $query->result();

    // Output in JSON format
    echo json_encode($result);
  }

  public function get_map_data() {
    // Get N latest conversations.
    // TODO: Try to filter not by first message date, but by last reply date - tricky?

    // Available parameters:
    // min_lat: min/max lat/long of message
    // max_lat: --
    // min_long: --
    // max_long: --
    // timestamp (default: 0): get messages posted after this time. Format: Unix timestamp
    // count (default: 50): maximum number of messages to return

    // Get required parameters
    $min_lat = $this->input->get('min_lat');
    $max_lat = $this->input->get('max_lat');
    $min_long = $this->input->get('min_long');
    $max_long = $this->input->get('max_long');

    // Get optional parameters
    $timestamp = ($this->input->get('timestamp')) ? $this->input->get('timestamp') : 0;
    $count = ($this->input->get('count')) ? $this->input->get('count') : 50;

    $current_time = $this->server_time();

    // Compose SQL query
    $query = $this->db->order_by("id", "desc")->select('latitude, longitude, pubTime')->get_where('skene_messages',
                                                                                                  array('parent_id = ' => 0,
                                                                                                        'latitude  >=' => $min_lat,
                                                                                                        'latitude  <=' => $max_lat,
                                                                                                        'longitude >=' => $min_long,
                                                                                                        'longitude <=' => $max_long,
                                                                                                        'pubTime   >=' => $timestamp,
                                                                                                        'pubTime   <=' => $current_time),
                                                                                                  $count);

          // Run database query
    $result = $query->result();

    // Output in JSON format
    echo json_encode($result);
  }
}