Simple login, Signup and Image upload using PHP

web_service.php

<?php

header("Accept: application/json");
header("Content-Type: application/json");

define('LOGIN_SUCCESS_MESSAGE', 'You are successfully login');
define('LOGIN_FAIL_MESSAGE', 'Invalid email or password');
define('SIGNUP_SUCCESS_MESSAGE', 'Signup successfull please login with email and password');
define('SIGNUP_FAIL_MESSAGE', 'Signup fails');
define('MAIL_SEND_SUCCESS', 'Mail send successfully.');
define('MAIL_SEND_FAIL', 'Error while sending the mail');
define('DATA_SUCCESSFULLY_SUBMITTED', 'Data stored successfully.');
define('FAIL_DATA_SUMBIT', 'error while submitting data.');


class Web_service {

    protected $email = "";
    protected $psw = "";
    protected $login_status = false;
    protected $upload_status = false;
    protected $db = "";
    
    protected $host = "";
    protected $database = "";
    protected $user = "";
    protected $password = "";

    function __construct() {
        $this->db = $this->Connect($this->host, $this->database, $this->user, $this->password);
    }

    public function Connect($host, $database, $user, $password) {
        $this->db = mysqli_connect($host, $user, $password, $database);
        if (mysqli_connect_errno()) {
            echo "Failed to connect to MySQL: " . mysqli_connect_error();
        } else {
            return $this->db;
        }
    }

    function doLogin($data) {
        $email = htmlspecialchars(strip_tags($data->email));
        $psw = htmlspecialchars(strip_tags($data->password));
        $return_arr = array();
        $return_arr["results"] = array();
        $return_object = array();
        if (!empty($email) && !empty($psw)) {
            $query = 'SELECT username FROM registration where username="' . $email . '"and password="' . $psw . '"';
            $result = mysqli_query($this->db, $query);
            if (mysqli_num_rows($result) > 0) {
                $row = mysqli_fetch_row($result);
                $this->login_status = true;
                $return_arr = array(
                    "status" => true,
                    "message" => LOGIN_SUCCESS_MESSAGE,
                    "username" => $row[0]
                );
            } else {
                $this->login_status = false;
                $return_arr = array(
                    "status" => false,
                    "message" => LOGIN_FAIL_MESSAGE
                );
            }
            echo json_encode($return_arr);
        }
    }

    function doSignup($data) {
        $email = htmlspecialchars(strip_tags($data->email));
        $psw = htmlspecialchars(strip_tags($data->password));
        $return_arr = array();
        $return_arr["results"] = array();
        $return_object = array();
        if (!empty($email) && !empty($psw)) {
            $query = 'INSERT INTO users SET email= "' . $email . '", password= "' . md5($psw) . '", status=1';
            $result = mysqli_query($this->db, $query);
            if (mysqli_affected_rows($this->db) > 0) {
                $this->login_status = true;
                $return_arr = array(
                    "status" => true,
                    "message" => SIGNUP_SUCCESS_MESSAGE
                );
            } else {
                $this->login_status = false;
                $return_arr = array(
                    "status" => false,
                    "message" => SIGNUP_FAIL_MESSAGE
                );
            }
            echo json_encode($return_arr);
        }
    }

    function forgotPassword($data) {
        $email = htmlspecialchars(strip_tags($data->email));
        $return_arr = array();
        $return_arr["results"] = array();
        $return_object = array();
        if (!empty($email)) {
            $query = 'SELECT * from users WHERE email= "' . $email . '"';
            $result = mysqli_query($this->db, $query);
            if (mysqli_num_rows($result) > 0) {
                $new_password = $this->get_random_string();
                $update_query = 'UPDATE users SET  password= "' . md5($new_password) . '" WHERE email= "' . $email . '"';
                $update_result = mysqli_query($this->db, $update_query);
                if (mysqli_affected_rows($this->db) > 0) {
                    $message = "Username : " . $email . "\n";
                    $message .= "Password : " . $new_password;
                    mail($email, "New Login Credentials", $message);
                    $return_arr = array(
                        "status" => true,
                        "message" => MAIL_SEND_SUCCESS
                    );
                }
            } else {
                $return_arr = array(
                    "status" => false,
                    "message" => MAIL_SEND_FAIL
                );
            }
            echo json_encode($return_arr);
        }
    }

    function getPlants() {
        $return_arr = array();
        $return_arr["results"] = array();
        $query = 'SELECT plantid, notes, status, hrsread  from plant';
        $result = mysqli_query($this->db, $query);
        if (mysqli_num_rows($result) > 0) {
            $plants = array();
            while ($row = mysqli_fetch_assoc($result)) {
                $plant = array();
                $plant['notes'] = $row['notes'];
                $plant['status'] = $row['status'];
                $plant['hrsread'] = $row['hrsread'];
                $plants[$row['plantid']][] = $plant;
            }
            $return_arr = array(
                "status" => true,
                "message" => "success",
                "data" => $plants
            );
        } else {
            $return_arr = array(
                "status" => false,
                "message" => "fail",
                "data" => array()
            );
        }
        echo json_encode($return_arr);
    }

    function submitData($data, $files) {

        $target_dir = "uploads";
        $file_name_array = array();
        $return_arr = array();
        $return_arr["results"] = array();
        $plant = htmlspecialchars(strip_tags($data->plant));
        $description = htmlspecialchars(strip_tags($data->description));
        $user_id = htmlspecialchars(strip_tags($data->user_id));
        $plant_id = htmlspecialchars(strip_tags($data->plant_id));
        $status = htmlspecialchars(strip_tags($data->status));
        $hrsread = htmlspecialchars(strip_tags($data->hrsread));
        if (!file_exists($target_dir)) {
            mkdir($target_dir, 07777, true);
        }
        for ($i = 0; $i < count($files['tmp_name']); $i++) {

            $file_name = $plant_id . "_" . date('YmdHi') . "_" . rand() . ".jpg";
            if (move_uploaded_file($files['tmp_name'][$i], $target_dir . "/" . $file_name)) {

                $query = 'INSERT INTO `images`(`imageref`, `date`, `plantid`, `user`, `notes`) VALUES ("' . $file_name . '","' . date('Y-m-d H:i:s') . '","' . $plant_id . '","' . $user_id . '","' . $description . '")';
                $file_name_array[$i] = $query;
                $result = mysqli_query($this->db, $query);
                if (mysqli_affected_rows($this->db) > 0) {
                    $this->upload_status = $i;
                }
            } else {
                
            }
        }
        $update_plant_query = 'UPDATE `plant` SET hrsread= "'.$hrsread.'",`status`="' . $status . '",`notes`="' . $description . '",`updatedby`="' . $user_id . '",`updateddate`="' . date('Y-m-d H:i:s') . '" WHERE `plantid` = "' . $plant_id . '"';
        $update_result = mysqli_query($this->db, $update_plant_query);
        if (mysqli_affected_rows($this->db) > 0) {
            $return_arr = array(
                "status" => true,
                "message" => DATA_SUCCESSFULLY_SUBMITTED,
                "upload_status" => $this->upload_status == (count($files['tmp_name']) - 1) ? true : false,
                "update_status" => true
            );
        } else {
            $return_arr = array(
                "status" => true,
                "message" => DATA_SUCCESSFULLY_SUBMITTED,
                "upload_status" => $this->upload_status == (count($files['tmp_name']) - 1) ? true : false,
                "update_status" => false
            );
        }

        echo json_encode($return_arr);
    }

    function get_random_string($length = 8) {
        $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
        $string = '';

        for ($i = 0; $i < $length; $i++) {
            $string .= $characters[mt_rand(0, strlen($characters) - 1)];
        }

        return $string;
    }

}

$ws = new Web_service();
$data = json_decode($_POST['formData']);
$method = $data[0]->method;
switch ($method) {
    case 'login':
        $ws->doLogin($data[0]);
        break;
    case 'signup':
        $ws->doSignup($data[0]);
        break;
    case 'forgotpass':
        $ws->forgotPassword($data[0]);
        break;
    case 'getPlants':
        $ws->getPlants();
        break;
    case 'submitData':
        $files = $_FILES['image'];
        $ws->submitData($data[0], $files);
        break;
    case 'syncData':
        $ws->syncData($data);
        break;
    default:
        break;
}