<?php
// Initialize the session
session_start();
require_once 'php/database.php';
// Check if the user is already logged in, if yes then redirect him to welcome page
if(isset($_SESSION["loggedin"]) && $_SESSION["loggedin"] === true){
    header("location: dashboard.php");
    exit;
} 
 
// Define variables and initialize with empty values
$username = $password = "";
$username_err = $password_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 username, password FROM users WHERE username = ?";
        
        if($stmt = mysqli_prepare($mysqli, $sql)){
            // Bind variables to the prepared statement as parameters
            mysqli_stmt_bind_param($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, $username, $hashed_password);
                    if(mysqli_stmt_fetch($stmt)){
                        if(password_verify($password, $hashed_password)){
                            // Password is correct, so start a new session
                            session_start();
                            
                            // Store data in session variables
                            $_SESSION["loggedin"] = true;
                            $_SESSION["username"] = $username;                            
                            
                            // Redirect user to welcome page
                            header("location: dashboard.php");
                        } else{
                            // Display an error message if password is not valid
                            $password_err = "The password you entered was not valid.";
                        }
                    }
                } else{
                    // Display an error message if username doesn't exist
                    $username_err = "No account found with that username.";
                }
            } else{
                echo "Oops! Something went wrong. Please try again later.";
            }
        }
        
        // Close statement
        mysqli_stmt_close($stmt);
    }
    
    // Close connection
    mysqli_close($mysqli);
}
?>
 
<!DOCTYPE html>
<html lang="en">
<head>
    <link rel="icon" type="image/png" href="/images/favicon.ico">
    <meta charset="UTF-8">
    <title>Login to Robo-Tank Aquarium Controller</title>
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.css">
    <link rel="stylesheet" type="text/css" href="/css/style.css">
    <style type="text/css">
        body{ font: 14px sans-serif; }
        .wrapper{ width: 350px; padding: 20px; }
    </style>
</head>
<body class="loginPage">
    <div id="login">
        <!-- <h2>Login to Robo-Tank Aquarium Controller</h2> -->
        <div class="logoBox"><img class="logo" src="images/logo.jpg" alt="Robo-Tank Logo"></div>
        <p>&nbsp;</p>
        <div class="">
            <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="post">
                <div class="form-group <?php echo (!empty($username_err)) ? 'has-error' : ''; ?>">
                    <label>Username</label>
                    <input type="text" id="loginField" name="username" class="form-control" value="<?php echo $username; ?>" autocomplete="off">
                    <span class="help-block"><?php echo $username_err; ?></span>
                </div>    
                <div class="form-group <?php echo (!empty($password_err)) ? 'has-error' : ''; ?>">
                    <label>Password</label>
                    <input type="password" id="loginField" name="password" class="form-control">
                    <span class="help-block"><?php echo $password_err; ?></span>
                </div>
                <div class="logoBox">
                    <input type="submit" class="loginButton _wide" value="Login">
                </div>
                <!-- <p>Don't have an account? <a href="register.php">Sign up now</a>.</p> -->
                <p>Default username and password = Robo-Tank</p>
            </form>
        </div>
    </div>
</body>
</html>