<?php
// Include config file
require_once "includes/config.php";
require_once "includes/session.php";

// Define variables and initialize with empty values
$username = $password = "";
$username_err = $password_err = $login_err = "";

// Processing form data when form is submitted
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // Check if username is empty
    if (empty(trim($_POST["username"]))) {
        $username_err = "Please enter username.";
    } else {
        $username = trim($_POST["username"]);
    }
    
    // Check if password is empty
    if (empty(trim($_POST["password"]))) {
        $password_err = "Please enter your password.";
    } else {
        $password = trim($_POST["password"]);
    }
    
    // Validate credentials
    if (empty($username_err) && empty($password_err)) {
        // Prepare a select statement
        $sql = "SELECT id, username, password, role, is_approved FROM users WHERE username = ?";
        
        if ($stmt = mysqli_prepare($conn, $sql)) {
            // Bind variables to the prepared statement as parameters
            mysqli_stmt_bind_param($stmt, "s", $param_username);
            
            // Set parameters
            $param_username = $username;
            
            // Attempt to execute the prepared statement
            if (mysqli_stmt_execute($stmt)) {
                // Store result
                mysqli_stmt_store_result($stmt);
                
                // Check if username exists, if yes then verify password
                if (mysqli_stmt_num_rows($stmt) == 1) {                    
                    // Bind result variables
                    mysqli_stmt_bind_result($stmt, $id, $username, $hashed_password, $role, $is_approved);
                    if (mysqli_stmt_fetch($stmt)) {
                        if (password_verify($password, $hashed_password)) {
                            // Password is correct, check if user is approved
                            if ($is_approved || $role == "admin") {
                                // Store data in session variables
                                session_start();
                                $_SESSION["loggedin"] = true;
                                $_SESSION["id"] = $id;
                                $_SESSION["username"] = $username;
                                $_SESSION["role"] = $role;
                                
                                // Redirect user to the TOTAL tab by default
                                header("location: index.php?tab=total");
                            } else {
                                // User is not approved
                                $login_err = "Your account is pending approval.";
                            }
                        } else {
                            // Password is not valid
                            $login_err = "Invalid username or password.";
                        }
                    }
                } else {
                    // Username doesn't exist
                    $login_err = "Invalid username or password.";
                }
            } else {
                echo "Oops! Something went wrong. Please try again later.";
            }

            // Close statement
            mysqli_stmt_close($stmt);
        }
    }
    
    // Close connection
    mysqli_close($conn);
}
?>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Login - Stednja App</title>
    <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css">
    <link rel="stylesheet" href="css/style.css">
</head>
<body>
    <div class="wrapper">
        <h2>Login</h2>
        <p>Please fill in your credentials to login.</p>

        <?php 
        if(!empty($login_err)){
            echo '<div class="alert alert-danger">' . $login_err . '</div>';
        }        
        ?>

        <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="post">
            <div class="form-group">
                <label>Username</label>
                <input type="text" name="username" class="form-control <?php echo (!empty($username_err)) ? 'is-invalid' : ''; ?>" value="<?php echo $username; ?>">
                <span class="invalid-feedback"><?php echo $username_err; ?></span>
            </div>    
            <div class="form-group">
                <label>Password</label>
                <input type="password" name="password" class="form-control <?php echo (!empty($password_err)) ? 'is-invalid' : ''; ?>">
                <span class="invalid-feedback"><?php echo $password_err; ?></span>
            </div>
            <div class="form-group">
                <input type="submit" class="btn btn-primary" value="Login">
            </div>
            <p>Don't have an account? <a href="register.php">Sign up now</a>.</p>
        </form>
    </div>
</body>
</html>
