// MainForm.cs - Chapter 16 version.

// Copyright 2004 by Jacquie Barker and Grant Palmer - all rights reserved.

// A GUI class.

using System;
using System.Collections;
using System.Windows.Forms;
using System.Drawing;

public class MainForm : Form {

  private Button dropButton, saveButton;
  private Button addButton, logOffButton;
  private TextBox ssnTextBox, nameTextBox, totalTextBox; 
  private ListBox scheduleListBox, registeredListBox; 
  private Label classScheduleLabel, ssnLabel;
  private Label nameLabel, totalCourseLabel;
  private Label registeredLabel;
  private PasswordForm passwordDialog;

  // Maintain a handle on the Student who is logged in.
  // (Whenever this is set to null, nobody is officially logged on.)
  private Student currentUser;

  public MainForm() {

    currentUser = null;

    // Create left-hand side labels
    int labelVertSpace = 40;
    int labelLeft = 5;

    ssnLabel = new Label();
    ssnLabel.Text = "SSN:";
    ssnLabel.Font = new Font(ssnLabel.Font, FontStyle.Bold);
    ssnLabel.AutoSize = true;
    ssnLabel.Top = 5;
    ssnLabel.Left = labelLeft;

    nameLabel = new Label();
    nameLabel.Text = "Name:";
    nameLabel.Font = new Font(nameLabel.Font, FontStyle.Bold);
    nameLabel.AutoSize = true;
    nameLabel.Top = ssnLabel.Top + labelVertSpace;
    nameLabel.Left = labelLeft;

    totalCourseLabel = new Label();
    totalCourseLabel.Text = "Total Courses:";
    totalCourseLabel.Font = new Font(totalCourseLabel.Font, FontStyle.Bold);
    totalCourseLabel.AutoSize = true;
    totalCourseLabel.Top = nameLabel.Top + labelVertSpace;
    totalCourseLabel.Left = labelLeft;

    registeredLabel = new Label();
    registeredLabel.Text = "Registered For:";
    registeredLabel.Font = new Font(registeredLabel.Font, FontStyle.Bold);
    registeredLabel.AutoSize = true;
    registeredLabel.Top = totalCourseLabel.Top + labelVertSpace;
    registeredLabel.Left = labelLeft;

    // Create TextBox components
    ssnTextBox = new TextBox();
    ssnTextBox.Width = 140;
    ssnTextBox.AutoSize = true;
    ssnTextBox.Top = ssnLabel.Top;
    ssnTextBox.Left = totalCourseLabel.Right + 15;

    // Assign an event handler to the SSN TextBox
    ssnTextBox.KeyUp += new KeyEventHandler(SsnTextBoxKeyUp);

    nameTextBox = new TextBox();
    nameTextBox.Width = 140;
    nameTextBox.AutoSize = true;
    nameTextBox.Top = nameLabel.Top;
    nameTextBox.Left = totalCourseLabel.Right + 15;
    nameTextBox.ReadOnly = true;

    totalTextBox = new TextBox();
    totalTextBox.Width = 20;
    totalTextBox.AutoSize = true;  
    totalTextBox.Top = totalCourseLabel.Top;
    totalTextBox.Left = totalCourseLabel.Right + 15;
    totalTextBox.ReadOnly = true;

    // Create right-hand side labels
    classScheduleLabel = new Label();
    classScheduleLabel.Text = "--- Schedule of Classes ---";
    classScheduleLabel.Font = new Font(classScheduleLabel.Font, FontStyle.Bold);
    classScheduleLabel.AutoSize = true;
    classScheduleLabel.Top = 5;
    classScheduleLabel.Left = ssnTextBox.Right + 55;

    // Create "Schedule of Classes" ListBox Component
    scheduleListBox = new ListBox();
    scheduleListBox.Width = 210;
    scheduleListBox.Height = 225;
    scheduleListBox.Top = classScheduleLabel.Bottom + 5;
    scheduleListBox.Left = ssnTextBox.Right + 30;

    // Display an alphabetically sorted course catalog list
    // in the scheduleListBox component.
    ArrayList sortedSections = SRS.scheduleOfClasses.GetSortedSections();
    for(int i = 0; i < sortedSections.Count; ++i) {
      scheduleListBox.Items.Add(sortedSections[i]);
    }

    // Create "Registered For" ListBox Component
    registeredListBox = new ListBox();
    registeredListBox.Width = 210;
    registeredListBox.Top = registeredLabel.Bottom + 5;
    registeredListBox.Height = scheduleListBox.Bottom - registeredListBox.Top + 3;
    registeredListBox.Left = labelLeft;

    // Add event handlers to the ListBox components
    scheduleListBox.SelectedIndexChanged += 
                new EventHandler(ScheduleSelectionChanged);
    registeredListBox.SelectedIndexChanged += 
                new EventHandler(RegisteredSelectionChanged);

    // Create buttons
    int buttonHeight = 50;
    int buttonWidth = 80;
    int buttonTop = 260;

    dropButton = new Button(); 
    dropButton.Text = "Drop";
    dropButton.Height = buttonHeight;
    dropButton.Width = buttonWidth;
    dropButton.Top = buttonTop;
    dropButton.Left = 10;

    saveButton = new Button(); 
    saveButton.Text = "Save My Schedule";
    saveButton.Height = buttonHeight;
    saveButton.Width = buttonWidth;
    saveButton.Top = buttonTop;
    saveButton.Left = dropButton.Right + 5;

    addButton = new Button(); 
    addButton.Text = "Add";
    addButton.Height = buttonHeight;
    addButton.Width = buttonWidth;
    addButton.Top = buttonTop;
    addButton.Left = saveButton.Right + 100;

    logOffButton = new Button(); 
    logOffButton.Text = "Log Off";
    logOffButton.Height = buttonHeight;
    logOffButton.Width = buttonWidth;
    logOffButton.Top = buttonTop;
    logOffButton.Left = addButton.Right + 5;

    // Assign event handlers to the Buttons
    addButton.Click += new EventHandler(AddButtonClicked);
    dropButton.Click += new EventHandler(DropButtonClicked);
    saveButton.Click += new EventHandler(SaveButtonClicked);
    logOffButton.Click += new EventHandler(LogOffButtonClicked);

    // Initialize the buttons to their proper enabled/disabled
    // state.
    ResetButtons();

    // Add the GUI components to the form
    this.Controls.Add(dropButton);
    this.Controls.Add(saveButton);
    this.Controls.Add(addButton);
    this.Controls.Add(logOffButton);
    this.Controls.Add(classScheduleLabel);
    this.Controls.Add(ssnLabel);
    this.Controls.Add(ssnTextBox);
    this.Controls.Add(nameLabel);
    this.Controls.Add(nameTextBox);
    this.Controls.Add(totalCourseLabel);
    this.Controls.Add(totalTextBox);
    this.Controls.Add(registeredLabel);
    this.Controls.Add(scheduleListBox);
    this.Controls.Add(registeredListBox);

    // Set some appearance properties for the Form
    this.Text = "Student Registration System";
    this.Height = 350;
    this.Width = 500;
    this.MinimumSize = this.Size;
    this.StartPosition = FormStartPosition.CenterScreen;
    this.Visible = true;
  }

  // event handling method for the "Drop" Button
  public void DropButtonClicked(object source, EventArgs e) {
    // Determine which section is selected (note that we must
    // cast it, as it is returned as an Object reference).
    Section selected = (Section)registeredListBox.SelectedItem;

    // Drop the course.
    selected.Drop(currentUser);

    // Display a confirmation message.
    string message = "Course " + 
       selected.RepresentedCourse.CourseNo + " dropped.";
    MessageBox.Show(message, "Request Successful",
            MessageBoxButtons.OK, MessageBoxIcon.Information);

    // Update the list of sections that 
    // this student is registered for.
    registeredListBox.Items.Clear();
    IEnumerator ie = currentUser.GetEnrolledSections();
    while ( ie.MoveNext() ) {
      registeredListBox.Items.Add((Section)ie.Current);
    }

    // Update the field representing student's course total.
    totalTextBox.Text = "" + currentUser.GetCourseTotal();

    // Check states of the various buttons.
    ResetButtons();
  }

  // event handling method for the "Save" Button
  public void SaveButtonClicked(object source, EventArgs e) {
    bool success = currentUser.Persist();
    if (success) {
      // Let the user know that his/her
      // schedule was successfully saved.
      MessageBox.Show("Schedule saved", "Schedule Saved",
            MessageBoxButtons.OK, MessageBoxIcon.Information);
    }
    else {
      // Let the user know that there was a problem.
      string message = "Problem saving your " +
                       "schedule; please contact " +
                       "SRS Support Staff for assistance.";
      MessageBox.Show(message, "Problem Saving Schedule",
               MessageBoxButtons.OK, MessageBoxIcon.Warning);
    }
  }

  // event handling method for the "Add" Button
  public void AddButtonClicked(object source, EventArgs e) {
    // Determine which section is selected (note that we must
    // cast it, as it is returned as an Object reference).
    Section selected = (Section)scheduleListBox.SelectedItem;

    // Attempt to enroll the student in the section, noting
    // the status code that is returned.
    int status = selected.Enroll(currentUser);

    // Report the status to the user.
    if (status == Section.SECTION_FULL) {
      MessageBox.Show("Sorry - that section is full.", "Request Denied",
               MessageBoxButtons.OK, MessageBoxIcon.Warning);
    }
    else {
      if (status == Section.PREREQ_NOT_SATISFIED) {