<?php

/* Database info */
$dbhost = 'localhost';
$dbuser = 'root';
$dbpass = '';
$dbname = 'test';

/* Instantiate new mysqli object */
$conn = new mysqli($dbhost, $dbuser, $dbpass, $dbname);

/* Test mysql connection */
if ($conn->connect_errno) {
    echo "Failed to connect to MySQL: (" . $mysqli->connect_errno . ") " . $mysqli->connect_error;
    exit;
}

/* Get search string */
$search = $_POST['query'];

/* Remove multiple whitespaces from the search string */
$search = preg_replace('/\s+/', ' ',$search);

/* Split search string into array for each word */
$words = explode(' ', $search);

/* Stop words array */
$stopWords = array('is','take','that');

/* Remove any duplicate entries in words array */
$words = array_unique($words);

/* Remove any stop words from the words array */
foreach($stopWords as $word){
    if(($key = array_search($word, $words)) !== false) {
        unset($words[$key]);
    }
}

/* Check if there are any words left to search for */
if(empty($words)){
    echo "Failed to perform search: Please avoid using common words like 'is', 'take' or 'that'.";
    exit;
}

/* Start query */
$query = 'SELECT q_id, question, username, q_date FROM questions WHERE (question ';

/* Loop through search words and build the query */
for($i = 0; $i < count($words); $i++){
    if($i == (count($words) - 1)){
        $query .= 'LIKE ?)';
    } else {
        $query .= 'LIKE ? OR question ';
    }
}

/* Build bind parameters array */
$a_param_type = array();

for($i = 0; $i < count($words); $i++){
    $a_param_type[] = 's';
}

$a_params = array();

$param_type = '';
$n = count($a_param_type);
for($i = 0; $i < $n; $i++) {
    $param_type .= $a_param_type[$i];
}

/* with call_user_func_array, array params must be passed by reference */
$a_params[] = & $param_type;

for($i = 0; $i < $n; $i++) {
    /* with call_user_func_array, array params must be passed by reference */
    $a_params[] = '%'.$words[$i].'%';
}

/* Prepare statement */
$stmt = $conn->prepare($query);
if($stmt === false) {
    trigger_error('Wrong SQL: ' . $query . ' Error: ' . $conn->errno . ' ' . $conn->error, E_USER_ERROR);
}

/* use call_user_func_array, as $stmt->bind_param('s', $param); does not accept params array */
call_user_func_array(array($stmt, 'bind_param'), refValues($a_params));

function refValues($arr){
    if (strnatcmp(phpversion(),'5.3') >= 0) //Reference is required for PHP 5.3+
    {
        $refs = array();
        foreach($arr as $key => $value)
            $refs[$key] = &$arr[$key];
        return $refs;
    }
    return $arr;
}

/* Execute statement */
$stmt->execute();

/* Fetch result */
$res = $stmt->get_result();

/* Count rows */
$cnt = $res->num_rows;

if($cnt > 0){
    while($row = $res->fetch_array(MYSQLI_ASSOC)) {
        $question = $row['question'];

        echo ('<a href="totalqs.php?q_id=' . $row['q_id'] .'" >' . $question .'Asked by:'.' '.$row['username'].' '.$row['q_date'] .' </a>'  . '<br>');
    }
} else {
    echo "No results found";
}

?>