如何在引导程序4的相同PHP页面中重置密码模式和显示配置文件模式

I have 2 different pages: resetpassword.php and profile.php, both are working fine which able to interact with Database. However, now I plan to merge both of it into 1 page which contain of 2 modals (Bootstrap 4). So after merging, profile content can view user profile, but resetpassword does not work as before.

Below are the consolidate code after merging into 1 page (merging.php)

PHP - for view user profile

<?php

// Initialize the session
session_start();

// Check if the user is logged in, if not then redirect them to login page
if(!isset($_SESSION["loggedin"]) || $_SESSION["loggedin"] !== true){
    header("location: index.php");  //login.php
    exit;
}

// To get DB information for user session, this to for profile page
require_once "config/config.php";

//$link below is get from config.php
$stmt = $link->prepare('SELECT name, username, email, divunit FROM users WHERE id = ?');

// In this case we can use the account ID to get the account info.
$stmt->bind_param('i', $_SESSION['id']);
$stmt->execute();
$stmt->bind_result($name, $username, $email, $divunit);
$stmt->fetch();
$stmt->close();

?>

PHP - for Reset Password

// Define variables and initialize with empty values
$new_password = $confirm_password = "";
$new_password_err = $confirm_password_err = "";

// Processing form data when form is submitted
if($_SERVER["REQUEST_METHOD"] == "POST"){

    // Validate new password
    if(empty(trim($_POST["new_password"]))){
        $new_password_err = "Please enter your password.";     
    } elseif(strlen(trim($_POST["new_password"])) < 6){
        $new_password_err = "Password must have atleast 6 characters.";
    } else{
        $new_password = trim($_POST["new_password"]);
    }

    // Validate confirm password
    if(empty(trim($_POST["confirm_password"]))){
        $confirm_password_err = "Please confirm the new password.";
    } else{
        $confirm_password = trim($_POST["confirm_password"]);
        if(empty($new_password_err) && ($new_password != $confirm_password)){
            $confirm_password_err = "Password did not match.";
        }
    }

    // Check input errors before updating the database
    if(empty($new_password_err) && empty($confirm_password_err)){
        // Prepare an update statement
        $sql = "UPDATE users SET password = ? WHERE id = ?";

        if($stmt = mysqli_prepare($link, $sql)){
            // Bind variables to the prepared statement as parameters
            mysqli_stmt_bind_param($stmt, "si", $param_password, $param_id);

            // Set parameters
            $param_password = password_hash($new_password, PASSWORD_DEFAULT);
            $param_id = $_SESSION["id"];

            // Attempt to execute the prepared statement
            if(mysqli_stmt_execute($stmt)){
                // Password updated successfully. Destroy the session, and redirect to login page
                session_destroy();
                header("location: index.php");   //login.php
                exit();
            } else{
                echo "Oops! Something went wrong. Please try again later.";
            }
        }

        // Close statement
        mysqli_stmt_close($stmt);
    }

    // Close connection
    mysqli_close($link);
}

HTML - Bootstrap Modal

<a id="menuResetPassword" href="#" data-toggle="modal" data-target="#reset-password-modal">Reset Password</a>

<div class="modal fade" id="reset-password-modal" tabindex="-1" role="dialog" aria-labelledby="myLargeModalLabel" aria-hidden="true">
            <div class="modal-dialog modal-dialog-centered">
                <div class="modal-content">
                    <div class="modal-header">
                        <h4 class="modal-title" id="myLargeModalLabel">Reset Password</h4>
                        <button type="button" class="close" data-dismiss="modal" aria-hidden="true">×</button>
                    </div>
                    <div class="modal-body">
                        <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="post">                        
                            .....
                        </form>
                    </div>
                </div>
            </div>
        </div>