/**
 * This is the solution for Week 3, 3.7 Rolling Project Part 2
 * The Enrolment class stores student and unit enrollment details.
 * It provides methods to accept user input and display enrollment information.
 *
 * @author Jimmy
 * @version 1.1
 */
public class Enrolment {
    // Fields
    private String date;
    private Student student;
    private Unit units;

    // Constructors

    /**
     * Default constructor that initializes date, student, units
     */
    public Enrolment() {
        this.date = "";
        this.student = null;
        this.units = null;
    }

    /**
     * Constructs an Enrolment object with the given date, student, and unit.
     *
     * @param date The enrolment date.
     * @param student The enrolled student.
     * @param units The enrolled unit.
     */
    public Enrolment(String date, Student student, Unit units) {
        this.date = date;
        this.student = student;
        this.units = units;
    }

    // Methods

    /**
     * Displays enrolment details.
     */
    public void display() {
        System.out.println("Date: " + date);
        if (student != null) {
            student.display();
        } else {
            System.out.println("No student enrolled.");
        }

        if (units != null) {
            units.display();
        } else {
            System.out.println("No unit assigned.");
        }
    }

    /**
     * Getter for date.
     *
     * @return The current enrolment date.
     */
    public String getDate() {
        return date;
    }

    /**
     * Getter for student.
     *
     * @return The enrolled student.
     */
    public Student getStudent() {
        return student;
    }

    /**
     * Getter for units.
     *
     * @return The enrolled unit.
     */
    public Unit getUnits() {
        return units;
    }

    /**
     * Accept all the required unit information from the user.
     */
    public void inputUnitDetails() {
        Input input = new Input();

        String uniCode = input.acceptStringInput("Enter unique code: ");
        String unitDesc = input.acceptStringInput("Enter description: ");
        int creditPoints = input.acceptIntegerInput("Enter credit points: ");
        this.units = new Unit(uniCode, unitDesc, creditPoints);
    }

    /**
     * Accept all the required student information from the user.
     */
    public void inputStudentDetails() {
        Input input = new Input();

        String name = input.acceptStringInput("Enter student name: ");
        String address = input.acceptStringInput("Enter address: ");
        String phone = input.acceptStringInput("Enter phone number: ");
        String email = input.acceptStringInput("Enter email: ");
        this.student = new Student(name, address, email, phone);
    }

    /**
     * Main method to run the enrolment program.
     *
     * @param args Command line arguments (not used).
     */
    public static void main(String[] args) {
        Enrolment enrolment = new Enrolment();
        enrolment.inputUnitDetails();
        enrolment.inputStudentDetails();
        enrolment.display();
    }

    /**
     * Setter for date.
     *
     * @param date The enrolment date to set.
     */
    public void setDate(String date) {
        this.date = date;
    }

    /**
     * Setter for student.
     *
     * @param student The student to set.
     */
    public void setStudent(Student student) {
        this.student = student;
    }

    /**
     * Setter for units.
     *
     * @param units The unit to set.
     */
    public void setUnits(Unit units) {
        this.units = units;
    }

    /**
     *
     * @return Enrolment information.
     */
    @Override
    public String toString() {
        return "Enrolment [date = " + date +
                ", student = " + (student != null ? student.toString() : "None") +
                ", units = " + (units != null ? units.toString() : "None") + "]";
    }
}

/**
 * This class provides a simple input utility for accepting
 * string, integer, double, and character input from the user.
 * It is used across multiple components of the Rolling Project.
 *
 * @author Jimmy
 * @version 1.1
 */
import java.util.Scanner;

public class Input {
    // Field
    private Scanner scanner;

    // Constructors

    /**
     * Default constructor.
     */
    public Input() {
        scanner = new Scanner(System.in);
    }

    // Methods

    /**
     * Accepts and returns a single character input from the user.
     *
     * @param msg The prompt message.
     * @return The first character of the input, or '\0' if empty.
     */
    public char acceptCharInput(String msg) {
        String input = acceptStringInput(msg);
        return (input != null && !input.isEmpty()) ? input.charAt(0) : '\0';
    }

    /**
     * Accepts and returns a double input from the user.
     *
     * @param msg The prompt message.
     * @return The parsed double value.
     */
    public double acceptDoubleInput(String msg) {
        String input = acceptStringInput(msg);
        return Double.parseDouble(input);
    }

    /**
     * Accepts and returns an integer input from the user.
     *
     * @param msg The prompt message.
     * @return The parsed integer value.
     */
    public int acceptIntegerInput(String msg) {
        String input = acceptStringInput(msg);
        // do validation
        int number = Integer.parseInt(input);
        return number;
    }

    /**
     * Accepts and returns a string input from the user.
     *
     * @param msg The prompt message.
     * @return The trimmed input string.
     */
    public String acceptStringInput(String msg) {
        System.out.print(msg);
        String input = scanner.nextLine().trim();
        return input;
    }
}

/**
 * The Student class represents a student with basic contact information,
 * including name, address, phone number, and email. It provides constructors,
 * accessors, mutators, a display method, and a string representation.
 *
 * @author Jimmy
 * @version 1.1
 */
public class Student {

    // Fields
    private String name;
    private String address;
    private String phoneNo;
    private String email;

    // Constructors

    /**
     * No-argument constructor that initializes all fields to "unknown".
     */
    public Student() {
        this.name = "unknown";
        this.address = "unknown";
        this.phoneNo = "unknown";
        this.email = "unknown";
    }

    /**
     * Parameterized constructor to initialize all fields with user-provided values.
     *
     * @param name    The name of the student.
     * @param address The address of the student.
     * @param phoneNo The phone number of the student.
     * @param email   The email address of the student.
     */
    public Student(String name, String address, String phoneNo, String email) {
        this.name = name;
        this.address = address;
        this.phoneNo = phoneNo;
        this.email = email;
    }

    // Methods

    /**
     * Displays the student information by printing the string representation.
     */
    public void display() {
        System.out.println(this);
    }

    /**
     * Returns the address of the student.
     *
     * @return The address.
     */
    public String getAddress() {
        return address;
    }

    /**
     * Returns the email address of the student.
     *
     * @return The email address.
     */
    public String getEmail() {
        return email;
    }

    /**
     * Returns the name of the student.
     *
     * @return The name.
     */
    public String getName() {
        return name;
    }

    /**
     * Returns the phone number of the student.
     *
     * @return The phone number.
     */
    public String getPhoneNo() {
        return phoneNo;
    }

    /**
     * Sets the address of the student.
     *
     * @param address The new address.
     */
    public void setAddress(String address) {
        this.address = address;
    }

    /**
     * Sets the email address of the student.
     *
     * @param email The new email address.
     */
    public void setEmail(String email) {
        this.email = email;
    }

    /**
     * Sets the name of the student.
     *
     * @param name The new name.
     */
    public void setName(String name) {
        this.name = name;
    }

    /**
     * Sets the phone number of the student.
     *
     * @param phoneNo The new phone number.
     */
    public void setPhoneNo(String phoneNo) {
        this.phoneNo = phoneNo;
    }

    /**
     * Returns a string representation of the student object.
     *
     * @return A string containing student details.
     */
    @Override
    public String toString() {
        return "=========================\n" +
                "      Student Info       \n" +
                "=========================\n" +
                "Name      : " + name + "\n" +
                "Address   : " + address + "\n" +
                "Phone No  : " + phoneNo + "\n" +
                "Email     : " + email + "\n" +
                "=========================";
    }
}

/**
 * The Unit class represents an academic unit offered by the university.
 * Each unit has a code, description, and number of credit points.
 *
 * @author Jimmy
 * @version 1.1
 */
public class Unit {

    // Fields
    private String unitCode;
    private String unitDescription;
    private int creditPoints;

    // Constructors

    /**
     * No-argument constructor that initializes all fields to default values.
     */
    public Unit() {
        this.unitCode = "unknown";
        this.unitDescription = "unknown";
        this.creditPoints = 0;
    }

    /**
     * Parameterized constructor to initialize all fields.
     *
     * @param unitCode        The code of the unit.
     * @param unitDescription The description of the unit.
     * @param creditPoints    The number of credit points for the unit.
     */
    public Unit(String unitCode, String unitDescription, int creditPoints) {
        this.unitCode = unitCode;
        this.unitDescription = unitDescription;
        this.creditPoints = creditPoints;
    }

    // Methods

    /**
     * Displays the unit's information by printing its string representation.
     */
    public void display() {
        System.out.println(this);
    }

    /**
     * Returns the number of credit points for the unit.
     *
     * @return The credit points.
     */
    public int getCreditPoints() {
        return creditPoints;
    }

    /**
     * Returns the code of the unit.
     *
     * @return The unit code.
     */
    public String getUnitCode() {
        return unitCode;
    }

    /**
     * Returns the description of the unit.
     *
     * @return The unit description.
     */
    public String getUnitDescription() {
        return unitDescription;
    }

    /**
     * Sets the number of credit points for the unit.
     *
     * @param creditPoints The new number of credit points.
     */
    public void setCreditPoints(int creditPoints) {
        this.creditPoints = creditPoints;
    }

    /**
     * Sets the code of the unit.
     *
     * @param unitCode The new unit code.
     */
    public void setUnitCode(String unitCode) {
        this.unitCode = unitCode;
    }

    /**
     * Sets the description of the unit.
     *
     * @param unitDescription The new unit description.
     */
    public void setUnitDescription(String unitDescription) {
        this.unitDescription = unitDescription;
    }

    /**
     * Returns a string representation of the unit.
     *
     * @return A string with unit details.
     */
    @Override
    public String toString() {
        return "=========================\n" +
                "        Unit Info        \n" +
                "=========================\n" +
                "Unit Code        : " + unitCode + "\n" +
                "Description      : " + unitDescription + "\n" +
                "Credit Points    : " + creditPoints + "\n" +
                "=========================";
    }
}