package observer.gui;
//[C] 2002 Sun Microsystems, Inc.---
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.List;
import java.util.ArrayList;

import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;

public class RunObserverPattern {
        public static void main(String[] arguments) {
                System.out.println("Example for the Observer pattern");
                System.out.println("This demonstration uses a central observable");
                System.out.println(" object to send change notifications to several");
                System.out.println(" JPanels in a GUI. Each JPanel is an Observer,");
                System.out.println(" receiving notifcations when there has been some");
                System.out.println(" change in the shared Task that is being edited.");
                System.out.println();

                System.out.println("Creating the ObserverGui");
                ObserverGui application = new ObserverGui();
                application.createGui();
        }
}

class Task {
        private String name = "";

        private String notes = "";

        private double timeRequired;

        public Task() {
        }

        public Task(String newName, String newNotes, double newTimeRequired) {
                name = newName;
                notes = newNotes;
                timeRequired = newTimeRequired;
        }

        public String getName() {
                return name;
        }

        public String getNotes() {
                return notes;
        }

        public double getTimeRequired() {
                return timeRequired;
        }

        public void setName(String newName) {
                name = newName;
        }

        public void setTimeRequired(double newTimeRequired) {
                timeRequired = newTimeRequired;
        }

        public void setNotes(String newNotes) {
                notes = newNotes;
        }

        public String toString() {
                return name + " " + notes;
        }
}

class TaskChangeObservable {
        private List<TaskChangeObserver> observers = new ArrayList<TaskChangeObserver>();

        public void addTaskChangeObserver(TaskChangeObserver observer) {
                if (!observers.contains(observer)) {
                        observers.add(observer);
                }
        }

        public void removeTaskChangeObserver(TaskChangeObserver observer) {
                observers.remove(observer);
        }

        public void selectTask(Task task) {
                for (TaskChangeObserver o : observers) {
                        o.taskSelected(task);
                }
        }

        public void addTask(Task task) {
                for (TaskChangeObserver o : observers) {
                        o.taskSelected(task);
                }
        }

        public void updateTask(Task task) {
                for (TaskChangeObserver o : observers) {
                        o.taskChanged(task);
                }
        }
}

interface TaskChangeObserver {
        public void taskAdded(Task task);
        public void taskChanged(Task task);
        public void taskSelected(Task task);
}

@SuppressWarnings("serial")
class TaskEditorPanel
extends JPanel implements ActionListener, TaskChangeObserver
{
        private JPanel controlPanel, editPanel;

        private JButton add, update, exit;

        private JTextField taskName, taskNotes, taskTime;

        private TaskChangeObservable notifier;

        private Task editTask;

        public TaskEditorPanel(TaskChangeObservable newNotifier) {
                notifier = newNotifier;
                createGui();
        }

        public void createGui() {
                setLayout(new BorderLayout());
                editPanel = new JPanel();
                editPanel.setLayout(new GridLayout(3, 2));
                taskName = new JTextField(20);
                taskNotes = new JTextField(20);
                taskTime = new JTextField(20);
                editPanel.add(new JLabel("Task Name"));
                editPanel.add(taskName);
                editPanel.add(new JLabel("Task Notes"));
                editPanel.add(taskNotes);
                editPanel.add(new JLabel("Time Required"));
                editPanel.add(taskTime);

                controlPanel = new JPanel();
                add = new JButton("Add Task");
                update = new JButton("Update Task");
                exit = new JButton("Exit");
                controlPanel.add(add);
                controlPanel.add(update);
                controlPanel.add(exit);
                add.addActionListener(this);
                update.addActionListener(this);
                exit.addActionListener(this);
                add(controlPanel, BorderLayout.SOUTH);
                add(editPanel, BorderLayout.CENTER);
        }

        public void setTaskChangeObservable(TaskChangeObservable newNotifier) {
                notifier = newNotifier;
        }

        public void actionPerformed(ActionEvent event) {
                Object source = event.getSource();
                if (source == add) {
                        double timeRequired = 0.0;
                        try {
                                timeRequired = Double.parseDouble(taskTime.getText());
                        } catch (NumberFormatException exc) {
                        }
                        notifier.addTask(new Task(taskName.getText(), taskNotes.getText(),
                                        timeRequired));
                } else if (source == update) {
                        editTask.setName(taskName.getText());
                        editTask.setNotes(taskNotes.getText());
                        try {
                                editTask
                                .setTimeRequired(Double.parseDouble(taskTime.getText()));
                        } catch (NumberFormatException exc) {
                        }
                        notifier.updateTask(editTask);
                } else if (source == exit) {
                        System.exit(0);
                }

        }

        public void taskAdded(Task task) {
        }

        public void taskChanged(Task task) {
        }

        public void taskSelected(Task task) {
                editTask = task;
                taskName.setText(task.getName());
                taskNotes.setText(task.getNotes());
                taskTime.setText("" + task.getTimeRequired());
        }
}

@SuppressWarnings("serial")
class TaskHistoryPanel extends JPanel implements TaskChangeObserver {
        private JTextArea displayRegion;

        public TaskHistoryPanel() {
                createGui();
        }

        public void createGui() {
                setLayout(new BorderLayout());
                displayRegion = new JTextArea(10, 40);
                displayRegion.setEditable(false);
                add(new JScrollPane(displayRegion));
        }

        public void taskAdded(Task task) {
                displayRegion.append("Created task " + task + "\n");
        }

        public void taskChanged(Task task) {
                displayRegion.append("Updated task " + task + "\n");
        }

        public void taskSelected(Task task) {
                displayRegion.append("Selected task " + task + "\n");
        }
}

@SuppressWarnings("all")
class TaskSelectorPanel
extends JPanel implements ActionListener, TaskChangeObserver
{
        private JComboBox selector = new JComboBox();

        private TaskChangeObservable notifier;

        public TaskSelectorPanel(TaskChangeObservable newNotifier) {
                notifier = newNotifier;
                createGui();
        }

        public void createGui() {
                selector = new JComboBox();
                selector.addActionListener(this);
                add(selector);
        }

        public void actionPerformed(ActionEvent evt) {
                notifier.selectTask((Task) selector.getSelectedItem());
        }

        public void setTaskChangeObservable(TaskChangeObservable newNotifier) {
                notifier = newNotifier;
        }

        public void taskAdded(Task task) {
                selector.addItem(task);
        }

        public void taskChanged(Task task) {
        }

        public void taskSelected(Task task) {
        }
}

class ObserverGui {
        public void createGui() {
                JFrame mainFrame = new JFrame("Observer Pattern Example");
                Container content = mainFrame.getContentPane();
                content.setLayout(new BoxLayout(content, BoxLayout.Y_AXIS));
                TaskChangeObservable observable = new TaskChangeObservable();
                TaskSelectorPanel select = new TaskSelectorPanel(observable);
                TaskHistoryPanel history = new TaskHistoryPanel();
                TaskEditorPanel edit = new TaskEditorPanel(observable);
                observable.addTaskChangeObserver(select);
                observable.addTaskChangeObserver(history);
                observable.addTaskChangeObserver(edit);
                observable.addTask(new Task());
                content.add(select);
                content.add(history);
                content.add(edit);
                mainFrame.addWindowListener(new WindowCloseManager());
                mainFrame.pack();
                mainFrame.setVisible(true);
        }

        private static class WindowCloseManager extends WindowAdapter {
                public void windowClosing(WindowEvent evt) {
                        System.exit(0);
                }
        }
}