trolley/receiver.php

<?php
	//Description:	This script will receive jsons from the application.
	//		After validating a json it will store it in db.txt.
	//		When activated this script will also activate dbcleaner.php.
	include 'dbcleaner.php'; //Will activate dbcleaner.php script everyday.

	function read_and_delete_first_line($filename) //This function will delete the first line of db.txt.
        {
                $file = file($filename); //Makes the contents of db.txt into an array.
                array_shift($file); //Removes the first element of the array.
                file_put_contents($filename, $file); //Rewrites db.txt with the contents of the array.
        }
	date_default_timezone_set('America/Puerto_Rico'); //Changes the default time of this PHP script to Puerto Rico.
        $decoded_location  = json_decode(file_get_contents('php://input')); //Receives input from app and decodes the json recived.
	//$f = file("unused/testinput.txt");//For testing purposes.
	//$decoded_location  = json_decode($f[0]); //For testing purposes.
	if(isset($decoded_location->latitude) && isset($decoded_location->longitude)) //Checks if the decoded json contains latitude and longitude keys. If false the json will be discarted.
	{
		if(is_float($decoded_location->latitude) && is_float($decoded_location->longitude))//Checks if the values of latitudes and longitudes are floating numbers. If false the json will be discarted.
		{	
			if(($decoded_location->latitude >= -90 && $decoded_location->latitude <= 90) && ($decoded_location->longitude >= -180 && $decoded_location->longitude <= 180)) //Checks if the latitude and longitude values are in the range of real latitudes and longitudes. A latitude cannot exceed from the range (-90,90); A longitude cannot exceed from the range (-180,180). If false the json will be discarted.
			{
				$decoded_location->inTime = date('h:i:s a',time()); //Adds a new property to the object we get after decoding the json and stores the current time.
				$encoded_location = json_encode($decoded_location); //Reencodes the object back into a json with the new inTime property.
        			$file = 'db.txt';
        			$totalLines = intval(exec("wc -l '$file'")); //Counts how many lines db.txt has.
        			//echo $totalLines. "\n"; //For testing purposes
        			if($totalLines > 24) //If db.txt has more than a specified amount of lines, it will delete the first line of db.txt.
				{
					read_and_delete_first_line($file);
				}
				$db = fopen("db.txt","a") or die("FAILED TO ACCESS DATABASE"); //Opens db.txt in append mode. If it somehow fails to open the database, an error message will be displayed.
				fwrite($db,$encoded_location. "\n"); //Writes the newly encoded json into db.txt.
				fclose($db); //Closes db.txt
        			//$totalLines = intval(exec("wc -l '$file'")); //For testing purposes
				//echo $totalLines; //For testing purposes
			}
		}
	}
?>