<?php
    //Define and initialize variables to connect to database server
    $servername = "localhost";
    $username = "id1148117_xirokx";
    $password = "project";
    $dbName = "id1148117_login";

    //Create database connection
    $con = mysqli_connect($servername, $username, $password, $dbName);

    //check connection - If database connection unsuccessful display error = connection failed
    if ($con->connect_error) {
        die("Connection failed: " . $con->connect_error);
    }

    //check username and password form values are not empty and send (POST) them to database server to verify they exist.
    if(isset($_POST["username"]) && isset($_POST["password"])) {
        $username = $_POST["username"];
        $password = $_POST["password"];

        //using a prepared sql statement to minimise the risk of SQL injection attack AND
        //to create a SQL "SELECT" query template that can be executed on my database table
        $statement = mysqli_prepare($con, "SELECT user_id,name,username,age,password FROM user WHERE username = ? AND password = ?");

        //attaches ("bind's") my form variables to my SQL query
        //"ss" defines the data types for both my variables - username and password are both Strings hence "ss"
        mysqli_stmt_bind_param($statement, "ss", $username, $password);

        //runs the SQL query in my database table
        mysqli_stmt_execute($statement);

        //stores the result of my prepared SQL query to a variable
        mysqli_stmt_store_result($statement);

        //defines each variable to attach the returned result of my prepared SQL SELECT query
        mysqli_stmt_bind_result($statement, $user_id, $name, $username, $age, $password);

        //returns "true" if my prepared SQL statement successfully returned data
        $response = array();
        $response["success"] = true;

        //iterates using a while loop through the returned results of my prepared SQL statement SELECT query
        //and stores these results in my corresponding pre-defined variables
        while(mysqli_stmt_fetch($statement)){
            $response["success"] = true;
            $response["name"] = $name;
            $response["name"] = $name;
            $response["username"] = $username;
            $response["age"] = $age;
            $response["password"] = $password;
        }

        //translates Php response into JSON Object so my mobile application can work with the returned String and continue processing.
        echo json_encode($response);

        //Close database connection to service further db requests and avoid application from slowing down
        $conn->close();
    }
    //if user did not provide values on my login form then return this error
    else {
        echo "check ip address, internet connection, else";
    }
?>