import models.*;
import services.*;
import java.util.Scanner;

public class Main {
    private static SchoolSystem school = new SchoolSystem();
    private static Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) {
        school.addCourseToSystem("Potions");
        school.addCourseToSystem("Defense Against Dark Arts");
        school.addCourseToSystem("Transfiguration");

        runMainMenu();
    }

    private static void runMainMenu() {
        while (true) {
            System.out.println("\n    HOGWARTS SCHOOL SYSTEM ");
            System.out.println("1.  Register (Sign Up)");
            System.out.println("2.  Login");
            System.out.println("3.  Exit");
            System.out.print("\nChoose: ");

            int choice = getIntInput();

            switch (choice) {
                case 1:
                    registerMenu();
                    break;
                case 2:
                    loginMenu();
                    break;
                case 3:
                    System.out.println(" Goodbye!");
                    return;
                default:
                    System.out.println(" Invalid choice!");
            }
        }
    }

    private static void registerMenu() {
        System.out.println("\n══════════ REGISTER ══════════");
        System.out.println("1.  Register as Student");
        System.out.println("2.  Register as Teacher");
        System.out.println("3.  Back");
        System.out.print("Choose: ");

        int choice = getIntInput();

        System.out.print("Enter username: ");
        String username = scanner.nextLine();

        String usernameError = User.validateUsername(username);
        if (usernameError != null) {
            System.out.println(" " + usernameError);
            return;
        }

        System.out.print("Enter password: ");
        String password = scanner.nextLine();

        String passwordError = User.validatePassword(password);
        if (passwordError != null) {
            System.out.println(" " + passwordError);
            return;
        }

        boolean success;
        switch (choice) {
            case 1:
                success = school.registerStudent(username, password);
                if (success) {
                    System.out.println(" Student registered successfully!");
                } else {
                    System.out.println(" Username already exists!");
                }
                break;
            case 2:
                success = school.registerTeacher(username, password);
                if (success) {
                    System.out.println(" Teacher registered successfully!");
                } else {
                    System.out.println(" Username already exists!");
                }
                break;
            case 3:
                return;
            default:
                System.out.println(" Invalid choice!");
        }
    }

    private static void loginMenu() {
        System.out.println("\n══════════ LOGIN ══════════");
        System.out.println("1.  Login as Student");
        System.out.println("2.  Login as Teacher");
        System.out.println("3.  Back");
        System.out.print("Choose: ");

        int choice = getIntInput();

        System.out.print("Username: ");
        String username = scanner.nextLine();
        System.out.print("Password: ");
        String password = scanner.nextLine();

        switch (choice) {
            case 1:
                Student student = school.loginStudent(username, password);
                if (student != null) {
                    studentMenu(student);
                } else {
                    System.out.println(" Invalid username or password!");
                }
                break;
            case 2:
                Teacher teacher = school.loginTeacher(username, password);
                if (teacher != null) {
                    teacherMenu(teacher);
                } else {
                    System.out.println(" Invalid username or password!");
                }
                break;
            case 3:
                return;
            default:
                System.out.println(" Invalid choice!");
        }
    }

    // ==================== STUDENT MENU ====================
    private static void studentMenu(Student student) {
        while (true) {
            System.out.println("\n══════════ STUDENT DASHBOARD ══════════");
            System.out.println("Welcome, " + student.getUsername() + "!");
            System.out.println("1.  View All Available Courses");
            System.out.println("2.  Enroll in a Course");
            System.out.println("3.  View My Courses");
            System.out.println("4.  Logout");
            System.out.print("\nChoose: ");

            int choice = getIntInput();

            switch (choice) {
                case 1:
                    System.out.print(school.getAllCoursesDisplay());
                    break;
                case 2:
                    enrollInCourse(student);
                    break;
                case 3:
                    System.out.print(student.getMyCoursesDisplay());
                    break;
                case 4:
                    System.out.println(" Goodbye, " + student.getUsername() + "!");
                    return;
                default:
                    System.out.println(" Invalid choice!");
            }
        }
    }

    private static void enrollInCourse(Student student) {
        System.out.print(school.getAllCoursesDisplay());
        System.out.print("\nEnter Course ID to enroll: ");
        int courseId = getIntInput();

        Course course = school.findCourseById(courseId);
        if (course == null) {
            System.out.println(" Course not found! Please enter a valid ID.");
            return;
        }

        if (student.enrollInCourse(course)) {
            System.out.println(" Successfully enrolled in " + course.getName());
        } else {
            System.out.println(" You are already enrolled in this course!");
        }
    }

    // ==================== TEACHER MENU ====================
    private static void teacherMenu(Teacher teacher) {
        while (true) {
            System.out.println("\n══════════ TEACHER DASHBOARD ══════════");
            System.out.println("Welcome, Professor " + teacher.getUsername() + "!");
            System.out.println("1.  View All Available Courses");
            System.out.println("2.  Add New Course to System");
            System.out.println("3.  View My Courses");
            System.out.println("4.  Add Course to My List (by ID)");
            System.out.println("5.  Remove Course from My List (by ID)");
            System.out.println("6.  View Students in My Course (by ID)");
            System.out.println("7.  Logout");
            System.out.print("\nChoose: ");

            int choice = getIntInput();

            switch (choice) {
                case 1:
                    System.out.print(school.getAllCoursesDisplay());
                    break;
                case 2:
                    addNewCourseToSystem(teacher);
                    break;
                case 3:
                    System.out.print(teacher.getMyCoursesDisplay());
                    break;
                case 4:
                    addCourseToTeacher(teacher);
                    break;
                case 5:
                    removeCourseFromTeacher(teacher);
                    break;
                case 6:
                    showStudentsInTeacherCourse(teacher);
                    break;
                case 7:
                    System.out.println(" Goodbye, Professor " + teacher.getUsername() + "!");
                    return;
                default:
                    System.out.println(" Invalid choice!");
            }
        }
    }

    private static void addNewCourseToSystem(Teacher teacher) {
        System.out.print("Enter new course name: ");
        String courseName = scanner.nextLine();

        if (school.addCourseToSystem(courseName)) {
            System.out.println(" Course '" + courseName + "' created successfully!");
            Course newCourse = school.findCourseByName(courseName);
            if (newCourse != null) {
                teacher.addCourse(newCourse);
            }
        } else {
            System.out.println(" Course already exists!");
        }
    }

    private static void addCourseToTeacher(Teacher teacher) {
        System.out.print(school.getAllCoursesDisplay());
        System.out.print("\nEnter Course ID to add to your list: ");
        int courseId = getIntInput();

        Course course = school.findCourseById(courseId);
        if (course == null) {
            System.out.println(" Course not found!");
            return;
        }

        if (teacher.addCourse(course)) {
            System.out.println(" Course '" + course.getName() + "' added to your list!");
        } else {
            System.out.println(" You already teach this course!");
        }
    }

    private static void removeCourseFromTeacher(Teacher teacher) {
        System.out.print(teacher.getMyCoursesDisplay());
        if (teacher.getMyCourses().isEmpty()) return;

        System.out.print("\nEnter Course ID to remove from your list: ");
        int courseId = getIntInput();

        Course course = school.findCourseById(courseId);
        if (course == null) {
            System.out.println(" Course not found!");
            return;
        }

        if (teacher.removeCourse(course)) {
            System.out.println(" Course '" + course.getName() + "' removed from your list!");
        } else {
            System.out.println(" You don't teach this course!");
        }
    }

    private static void showStudentsInTeacherCourse(Teacher teacher) {
        System.out.print(teacher.getMyCoursesDisplay());
        if (teacher.getMyCourses().isEmpty()) return;

        System.out.print("\nEnter Course ID to see students: ");
        int courseId = getIntInput();

        Course course = school.findCourseById(courseId);
        if (course == null) {
            System.out.println(" Course not found!");
            return;
        }

        String result = teacher.getStudentsDisplayForCourse(course);
        System.out.println(result);
    }

    private static int getIntInput() {
        try {
            int value = scanner.nextInt();
            scanner.nextLine();
            return value;
        } catch (Exception e) {
            scanner.nextLine();
            return -1;
        }
    }
}