<?php
// Include database connection
require_once 'includes/db_connect.php';

// Start session if not already started
if (session_status() === PHP_SESSION_NONE) {
    session_start();
}

// Redirect if already logged in
if (isset($_SESSION['user_id'])) {
    header("Location: index.php");
    exit;
}

// Initialize variables
$error = '';
$username = '';

// Create users table if it doesn't exist
$createUsersTableQuery = "CREATE TABLE IF NOT EXISTS users (
    id INT AUTO_INCREMENT PRIMARY KEY,
    username VARCHAR(50) NOT NULL UNIQUE,
    email VARCHAR(100),
    password VARCHAR(255) NOT NULL,
    user_type ENUM('student', 'faculty') NOT NULL,
    status ENUM('active', 'inactive') DEFAULT 'active',
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    last_login TIMESTAMP NULL DEFAULT NULL
)";
$conn->query($createUsersTableQuery);

// Check if admin user exists
$adminCheckQuery = "SELECT * FROM users WHERE username = 'admin' AND user_type = 'faculty'";
$adminResult = $conn->query($adminCheckQuery);

if ($adminResult && $adminResult->num_rows === 0) {
    // Create default admin user
    $adminPassword = password_hash('admin', PASSWORD_DEFAULT);
    $createAdminQuery = "INSERT INTO users (username, email, password, user_type) VALUES ('admin', 'admin@example.com', '$adminPassword', 'faculty')";
    $conn->query($createAdminQuery);
}

// Process login form
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $username = trim($_POST['username']);
    $password = $_POST['password'];
    $userType = $_POST['user_type'];
    
    // Basic validation
    if (empty($username) || empty($password) || empty($userType)) {
        $error = "Please enter both username and password and select user type.";
    } else {
        if ($userType === 'faculty') {
            // Faculty login - check against users table
            $query = "SELECT * FROM users WHERE username = ? AND user_type = 'faculty' AND status = 'active'";
            $stmt = $conn->prepare($query);
            $stmt->bind_param("s", $username);
            $stmt->execute();
            $result = $stmt->get_result();
            
            if ($result->num_rows === 1) {
                $user = $result->fetch_assoc();
                
                // Verify password
                if (password_verify($password, $user['password'])) {
                    // Set session variables
                    $_SESSION['user_id'] = $user['id'];
                    $_SESSION['username'] = $user['username'];
                    $_SESSION['user_type'] = 'faculty';
                    
                    // Update last login time
                    $updateQuery = "UPDATE users SET last_login = NOW() WHERE id = ?";
                    $updateStmt = $conn->prepare($updateQuery);
                    $updateStmt->bind_param("i", $user['id']);
                    $updateStmt->execute();
                    
                    // Redirect to home page
                    header("Location: index.php");
                    exit;
                } else {
                    $error = "Invalid username or password.";
                }
            } else {
                $error = "Invalid username or password.";
            }
        } else {
            // Student login - check against students_info table
            $studentCheckQuery = "SHOW TABLES LIKE 'students_info'";
            $tableExists = $conn->query($studentCheckQuery)->num_rows > 0;
            
            if ($tableExists) {
                // Get student data structure
                $columnsQuery = "SHOW COLUMNS FROM students_info";
                $columnsResult = $conn->query($columnsQuery);
                $studentIdField = null;
                
                // Find student ID field (assuming it's either 'student_id', 'Student_ID', or similar)
                while ($column = $columnsResult->fetch_assoc()) {
                    if (preg_match('/(student|stud|roll)[\s_-]?(id|number|no)/i', $column['Field'])) {
                        $studentIdField = $column['Field'];
                        break;
                    }
                }
                
                if ($studentIdField) {
                    $query = "SELECT * FROM students_info WHERE $studentIdField = ?";
                    $stmt = $conn->prepare($query);
                    $stmt->bind_param("s", $username);
                    $stmt->execute();
                    $result = $stmt->get_result();
                    
                    if ($result->num_rows === 1) {
                        $student = $result->fetch_assoc();
                        
                        // For students, password should be same as student ID for simplicity
                        if ($password === $username) {
                            // Create or update user record for this student
                            $userCheckQuery = "SELECT * FROM users WHERE username = ? AND user_type = 'student'";
                            $userCheckStmt = $conn->prepare($userCheckQuery);
                            $userCheckStmt->bind_param("s", $username);
                            $userCheckStmt->execute();
                            $userResult = $userCheckStmt->get_result();
                            
                            if ($userResult->num_rows === 0) {
                                // Create new user record
                                $hashedPassword = password_hash($password, PASSWORD_DEFAULT);
                                $createUserQuery = "INSERT INTO users (username, password, user_type) VALUES (?, ?, 'student')";
                                $createUserStmt = $conn->prepare($createUserQuery);
                                $createUserStmt->bind_param("ss", $username, $hashedPassword);
                                $createUserStmt->execute();
                                $userId = $conn->insert_id;
                            } else {
                                $user = $userResult->fetch_assoc();
                                $userId = $user['id'];
                            }
                            
                            // Set session variables
                            $_SESSION['user_id'] = $userId;
                            $_SESSION['username'] = $username;
                            $_SESSION['user_type'] = 'student';
                            $_SESSION['student_id'] = $student[$studentIdField];
                            
                            // Update last login time
                            $updateQuery = "UPDATE users SET last_login = NOW() WHERE id = ?";
                            $updateStmt = $conn->prepare($updateQuery);
                            $updateStmt->bind_param("i", $userId);
                            $updateStmt->execute();
                            
                            // Redirect to home page
                            header("Location: index.php");
                            exit;
                        } else {
                            $error = "Invalid password. Students should use their student ID as password.";
                        }
                    } else {
                        $error = "Student ID not found in our records.";
                    }
                } else {
                    $error = "Student ID field not found in database structure.";
                }
            } else {
                $error = "Student information table not found.";
            }
        }
    }
}

// Check for success message
$success = '';
if (isset($_SESSION['success_message'])) {
    $success = $_SESSION['success_message'];
    unset($_SESSION['success_message']);
}

// Include header
include 'includes/header.php';
?>

<div class="row mb-4 text-center">
    <div class="col-md-12">
        <h2><i class="fas fa-sign-in-alt me-2"></i> Login to Domain Management System</h2>
        <p class="lead">Access the project database with your credentials</p>
    </div>
</div>

<div class="row">
    <div class="col-md-6 offset-md-3">
        <div class="card shadow-sm">
            <div class="card-header bg-primary text-white">
                <h4 class="mb-0"><i class="fas fa-sign-in-alt me-2"></i> Login</h4>
            </div>
            <div class="card-body">
                <?php if (!empty($error)): ?>
                    <div class="alert alert-danger">
                        <i class="fas fa-exclamation-circle me-2"></i> <?php echo $error; ?>
                    </div>
                <?php endif; ?>
                
                <?php if (!empty($success)): ?>
                    <div class="alert alert-success">
                        <i class="fas fa-check-circle me-2"></i> <?php echo $success; ?>
                    </div>
                <?php endif; ?>
                
                <form method="post" action="login.php">
                    <div class="mb-3">
                        <label for="user_type" class="form-label">Login As</label>
                        <div class="input-group">
                            <span class="input-group-text"><i class="fas fa-users"></i></span>
                            <select name="user_type" id="user_type" class="form-select" required>
                                <option value="">Select User Type</option>
                                <option value="student">Student</option>
                                <option value="faculty">Faculty</option>
                            </select>
                        </div>
                    </div>
                    
                    <div class="mb-3">
                        <label for="username" class="form-label" id="username_label">Username</label>
                        <div class="input-group">
                            <span class="input-group-text"><i class="fas fa-user"></i></span>
                            <input type="text" class="form-control" id="username" name="username" value="<?php echo htmlspecialchars($username); ?>" required>
                        </div>
                        <small class="form-text text-muted student-info d-none">Enter your Student ID</small>
                        <small class="form-text text-muted faculty-info d-none">Faculty username (admin)</small>
                    </div>
                    
                    <div class="mb-4">
                        <label for="password" class="form-label">Password</label>
                        <div class="input-group">
                            <span class="input-group-text"><i class="fas fa-lock"></i></span>
                            <input type="password" class="form-control" id="password" name="password" required>
                            <button class="btn btn-outline-secondary toggle-password" type="button" data-target="#password">
                                <i class="fas fa-eye"></i>
                            </button>
                        </div>
                        <small class="form-text text-muted student-info d-none">Use your Student ID as password</small>
                        <small class="form-text text-muted faculty-info d-none">Default faculty password is 'admin'</small>
                    </div>
                    
                    <div class="d-grid gap-2">
                        <button type="submit" class="btn btn-primary">
                            <i class="fas fa-sign-in-alt me-2"></i> Login
                        </button>
                    </div>
                </form>
            </div>
        </div>
    </div>
</div>

<script>
document.addEventListener('DOMContentLoaded', function() {
    // Show/hide helper text based on user type selection
    const userTypeSelect = document.getElementById('user_type');
    const studentInfoElements = document.querySelectorAll('.student-info');
    const facultyInfoElements = document.querySelectorAll('.faculty-info');
    const usernameLabel = document.getElementById('username_label');
    
    userTypeSelect.addEventListener('change', function() {
        // Hide all helper texts first
        studentInfoElements.forEach(el => el.classList.add('d-none'));
        facultyInfoElements.forEach(el => el.classList.add('d-none'));
        
        // Show appropriate helper text based on selection
        if (this.value === 'student') {
            studentInfoElements.forEach(el => el.classList.remove('d-none'));
            usernameLabel.textContent = 'Student ID';
        } else if (this.value === 'faculty') {
            facultyInfoElements.forEach(el => el.classList.remove('d-none'));
            usernameLabel.textContent = 'Username';
        } else {
            usernameLabel.textContent = 'Username';
        }
    });
});
</script>

<?php
// Include footer
include 'includes/footer.php';

// Close connection
$conn->close();
?>