PHP web service that accepts JSON and return JSON

<?php
header('Content-type: application/json; charset=utf-8');

use Psr\Log\LogLevel;

require 'vendor/autoload.php';

/**
 *
 * Author - Olcay Ertaş
 *
 */
class ArendiWebServices {

    private $db;
    private $host = "localhost";
    private $userName = "yourUserName";
    private $password = "yourPassword";
    private $database = "yourDatabaseName";
    private $logger;

    // Constructor - open DB connection
    function __construct() {
        $this->db = new mysqli($this->host, $this->userName, $this->password, $this->database);
        $this->db->autocommit(FALSE);
        $stmt1 = $this->db->prepare("SET NAMES 'utf8'");
        $stmt1->execute();
        $stmt2 = $this->db->prepare('SET CHARACTER SET "utf8"');
        $stmt2->execute();
        $this->logger = new Katzgrau\KLogger\Logger("log.txt", LogLevel::DEBUG);
    }

    // Destructor - close DB connection
    function __destruct() {
        $this->db->close();
    }

    /**
     * Proje listesini veren method.
     */
    function getProjects() {
        $this->logger->debug("GetProjects: Entrance\n");
        $stmt = $this->db->prepare('SELECT * FROM yourProjectsTable');
        $id = $no = $title = $subject = $description = $attachment = $status = NULL;
        $stmt->bind_result($id, $no, $title, $subject, $description, $attachment, $status);

        if ($stmt->execute()) {
            $this->logger->debug("GetProjects: If\n");
            $result = array();

            while ($stmt->fetch()) {
                $row = array("id" => $id, "no" => $no, "title" => $title,
                    "subject" => $subject, "description" => $description,
                    "attachment" => $attachment, "status" => $status);
                $result[] = $row;
            }

            echo json_encode($result);
        }

        $stmt->close();
        $this->logger->debug("GetProjects: Exit\n");
    }

    /**
     * Method for login, returns user information if user name and password are correct.
     * @param type $email User email address
     * @param type $password User account password.
     */
    function getUser($email, $password) {
        $this->logger->debug("GetUser: Entrance\n");
        $stmt = $this->db->prepare("SELECT * FROM yourUsersTable WHERE email=? && password=?");
        $stmt->bind_param("ss", $email, $password);
        $id = $companyid = $name = $surname = $email2 = $password2 = NULL;
        $stmt->bind_result($id, $companyid, $name, $surname, $email2, $password2);

        if ($stmt->execute()) {
            if ($stmt->fetch()) {
                $stmt->close();
                $log = $id . " - "
                        . $companyid . " - "
                        . $name . " - "
                        . $surname . " - "
                        . $email2 . " - "
                        . $password2 . "\n";
                $this->logger->debug("GetUser: " . $log);
                $stmt2 = $this->db->prepare("SELECT * FROM yourCompanyTable WHERE id=" . $companyid);
                $cid = $cname = $caddress = $cphone = $cwebpage = NULL;
                $stmt2->bind_result($cid, $cname, $caddress, $cphone, $cwebpage);
                $stmt2->execute();
                $stmt2->fetch();
                $result = "{\"success\":\"1\",";
                $result = $result . "\"id\":\"" . $id . "\",";
                $result = $result . "\"companyid\":\"" . $cid . "\",";
                $result = $result . "\"companyname\":\"" . $cname . "\",";
                $result = $result . "\"name\":\"" . $name . "\",";
                $result = $result . "\"surname\":\"" . $surname . "\",";
                $result = $result . "\"email\":\"" . $email2 . "\",";
                $result = $result . "\"password\":\"" . $password2 . "\"}";
                $stmt2->close();
                echo $result;
                $log = $cid . " - "
                        . $cname . " - "
                        . $caddress . " - "
                        . $cphone . " - "
                        . $cwebpage . "\n";
                $this->logger->debug("GetUser: " . $log);
            } else {
                echo "{\"success\":\"0\",\"errorMessage\":\"User name or password is wrong.\",\"email\":\"" . $email . "\",\"password\":\"" . $password . "\"}";
            }
        } else {
            echo "{\"success\":\"0\",\"errorMessage\":\"User name or password is wrong.\"}";
        }
    }

    /**
     * Saves new idea.
     * @param 1 - companyid - User's company id.
     * @param 2 - employeeid - User id
     * @param 3 - title - Idea title
     * @param 4 - description - Idea description.
     * @param 5 - privacy - Idea visibility: 0 everbody can see,
     *            1  Only people in same company can see.
     * @param 6 - attachment - Atachment url
     */
    function saveIdea($ideaData) {
        $this->logger->debug("SaveIdea: Entrance");
        $data = $ideaData;
        $company = $data['company'];
        $employeeName = $data['employeeName'];
        $employeeSurname = $data['employeeSurname'];
        $title = $data['title'];
        $description = $data['description'];
        $privacy = intval($data['privacy']);
        $vote = 0;
        $attachment = $data['attachment'];
        $stmt = $this->db->prepare("INSERT INTO yourIdeaTable VALUES ('', ?, ?, ?, ?, ?, ?, ?, ?)");

        if ($stmt) {
            $stmt->bind_param("sssssiis", $company, $employeeName, $employeeSurname, $title, $description, $privacy, $vote, $attachment);
        } else {
            echo "{\"success\":\"0\",\"error_message\":\"Error while generating query!\"}";
            return;
        }

        if ($stmt === FALSE) {
            $code = $stmt->errorCode();
            $errInfo = $stmt->errorInfo();
            error_log("PREPARE of INSERT query, FAILED\nCode: $code ErrorMessage: $errInfo\n", 3, "php.log");
        } else {
            if ($stmt->execute()) {
                $this->logger->debug("GetUser: Idea saved!");
                echo "{\"success\":\"1\",\"success_message\":\"Idea saved.\"}";
            } else {
                $code = $stmt->errorCode();
                $errInfo = $stmt->errorInfo();
                $this->logger->error("GetUser: Failed to save idea!");
                $this->logger->error("GetUser: Code: $code ErrorMessage: $errInfo\n");
                echo "{\"success\":\"0\",\"error_message\":\"Failed to save idea!\"}";
            }
        }
    }

}

$arendiService = new ArendiWebServices();
$post = file_get_contents('php://input');
$post = json_decode($post, true);

$logger = new Katzgrau\KLogger\Logger("log", LogLevel::DEBUG);
$logger->debug("Arendi Web Services");
$logger->debug("Post data loaded");
$logger->debug("Service instance created");

if (isset($post['request'])) {

    if ($post['request'] == 'login') {
        $logger->debug("Requested service - login");
        $logger->debug($post['userName'] . " - " . $post['password']);
        $arendiService->getUser($post['userName'], $post['password']);
    } else if ($post['request'] == 'getprojects') {
        $logger->debug("Requested service - getprojects");
        $arendiService->getProjects();
    } else if ($post['request'] == 'getMenu') {
        $logger->debug("Requested service - getMenu");
        $arendiService->getMenu();
    } else if ($post['request'] == 'saveIdea') {
        $logger->debug("Requested service - saveIdea");
        //error_log("Incoming data: ".$post."\n", 3, "php.log");
        $arendiService->saveIdea($post);
    } else {
        $logger->debug("Requested service - undefined\n");
        echo '{"success":0,"error_message":"Undefined service!"}';
    }
} else {
    $logger->error("Invalid service request!");
    $logger->error("Request must have a 'request' field!");
    $response = '{"success":0,"error_message":"Invalid service request! Request must have a \'request\' field!"}';
    $jsonResponse = json_encode($response);
    echo $jsonResponse;
}