<?php
$username = "mrBigXY";
$password = "ghiEcTb";
$hostname = "localhost";
$database = "planet";

function getRowById($i){
  $q = "SELECT * FROM questions WHERE question_id = ".$i;
  if( $res = $mysqli->query($q) ){
    if( $res->num_rows == 1 ){
      return $result->fetch_assoc();
    }else{
      echo "Error: not one row";
    }
  }else{
    echo "Error: query failed";
  }
  return false;
}

if(isset($_REQUEST["question_id"]){
  $mysqli = new mysqli($hostname, $username, $password, $database);
  if (mysqli_connect_errno()) {
      printf("Connect failed: %s\n", mysqli_connect_error());
      exit();
  }

  $row = getRowById($_REQUEST["question_id"]);
  if(!isset($_REQUEST["answer"])){
    $arr = array("response_type" => 1, "question_id" => 1, "question_name" => $row["question_name"]);
    echo json_encode($arr);
  }else{
    $ans = $_REQUEST["answer"];
    $arr = array("response_type" => 1, "question_id" => -1, "question_name" => $row["question_name"]);
    if($ans == 0){
      $qid = $row["next_question_id_no"];
      $arr["question_id"] = $qid;
      if( $nrow = getRowById($qid) ){
        $arr["question_name"] = $nrow["question_name"];
      }else{
        $arr["response_type"] = 0;
        $arr["question_name"] = $row["answer_no"];
      }
      echo json_encode($arr);
    }else if($ans == 1){
      $qid = $row["next_question_id_yes"];
      $arr["question_id"] = $qid;

      if( $nrow = getRowById($qid) ){
        $arr["question_name"] = $nrow["question_name"];
      }else{
        $arr["response_type"] = 0;
        $arr["question_name"] = $row["answer_yes"];
      }
      echo json_encode($arr);
    }else{
      echo "Error: wrong answer format";
    }
  }
  $mysqli->close();
}

?>