/*	SimpleTextEditor.java
*/

import java.awt.*;
import java.awt.event.*;
import java.awt.datatransfer.*;
import java.io.*;
import javax.swing.*;
import javax.swing.text.*;


/**	SimpleTextEditor is a very basic text editor application which supports
*	File Open, File Save, and the basic text editor functions for cut, copy 
*	and paste and interfaces with the system clipboard.
*/
public class SimpleTextEditor implements ActionListener{

	JFrame frame;
	JTextArea editor;	
	//clipboard 
	Clipboard clipboard;
	// clipboardstring is the Transferrable object used to store
	// String text data for clear, cut, copy, and paste operations
	StringSelection clipboardstring; 
	boolean debug = false; //set to true for debugging messages
	Font editorfont = new Font("Monospaced",Font.PLAIN,12);
	int tabsize = 5; 


	/**	
	*/
	public static void main(String[] args){

		SimpleTextEditor simpletexteditor = new SimpleTextEditor();
		simpletexteditor.init();

	}

	/**	Initializes the button controls, a textarea for an editor to display 
	*	or enter text, and adds the components to a frame window and displays
	*	it. A clipboard object is set up so that this application can interface
	*	with other applications for cut copy and paste operations provided this
	*	is allowed by the SecuityManager if active. If the security manager
	*	does not allow it, it creates a clipboard object which will only support
	*	cut, copy,and paste operations from this application.
	*	
	*/
	public void init(){
		SecurityManager securitymanager = System.getSecurityManager();
		if (securitymanager != null){
			try{
				securitymanager.checkSystemClipboardAccess();
				clipboard = Toolkit.getDefaultToolkit().getSystemClipboard();
				if (debug) System.out.println("Using system clipboard");
			}catch (SecurityException se){
				showExceptionErrorMessage("SystemClipboardAccess is denied. Using application clipboard.");
				clipboard = new Clipboard("SimpleTextEditor");
				System.out.println("SystemClipboardAccess is denied.");
				System.out.println("SecurityException: " + se.getMessage());
				if (debug) System.out.println("Using application clipboard");

			}
		}else{
			clipboard = Toolkit.getDefaultToolkit().getSystemClipboard();
			if (debug) System.out.println("Using system clipboard");
		}
		
		frame = new JFrame("SimpleTextEditor");
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		//button controls
		JPanel controlpanel = new JPanel();
		JButton openbutton = new JButton("Open A File");
		JButton writebutton = new JButton("Save To File");
		JButton clearbutton = new JButton("Clear");
		JButton cutbutton = new JButton("Cut");
		JButton copybutton = new JButton("Copy");
		JButton pastebutton = new JButton("Paste");
		JButton exitbutton = new JButton("Exit");
		exitbutton.addActionListener(this);
		openbutton.addActionListener(this);
		writebutton.addActionListener(this);
		clearbutton.addActionListener(this);
		cutbutton.addActionListener(this);
		copybutton.addActionListener(this);
		pastebutton.addActionListener(this);
		controlpanel.add(writebutton);
		controlpanel.add(openbutton);
		controlpanel.add(clearbutton);
		controlpanel.add(cutbutton);
		controlpanel.add(copybutton);
		controlpanel.add(pastebutton);
		controlpanel.add(exitbutton);
		frame.getContentPane().add(controlpanel,"North");
		//editor
		editor = new JTextArea(new PlainDocument(),"",30,60); //initializes a JTextArea with width 60 and height 30 
		editor.setFont(editorfont);
		editor.setTabSize(tabsize);
		JScrollPane scrollpane = new JScrollPane(editor);
		frame.getContentPane().add(scrollpane,"Center");
		frame.pack();
		frame.show();
	}

	/**	Brings up a simple FileSave dialog for the user to enter a file name,
	*	and creates a file based on that name in the selected directory.
	*/
	public File getAFileForSave(){
		File file = null;
		File currentdirectory = new File(".");
		JFileChooser filechooser = new JFileChooser(currentdirectory);
		int replycode = filechooser.showSaveDialog(frame);
		if (replycode == JFileChooser.APPROVE_OPTION){
			file = filechooser.getSelectedFile();
		}
		return file;

	}

	/**	Brings up as imple file open dialog and returns the file selected by the user.
	*/
	public File getAFileToOpen(){
		File file = null;
		File currentdirectory = new File(".");
		JFileChooser filechooser = new JFileChooser(currentdirectory);
		int replycode = filechooser.showOpenDialog(frame);
		if (replycode == JFileChooser.APPROVE_OPTION){
			file = filechooser.getSelectedFile();
		}
		return file;
	}

	/**	Writes the string to the input file.
	*/
	public void writeStringToFile(File file, String s){

		try{
			FileWriter filewriter = new FileWriter(file);
			StringReader stringreader = new StringReader(s);
			BufferedReader bufferedreader = new BufferedReader(stringreader);
			String lineread = "";
			while ((lineread = bufferedreader.readLine()) != null){
				filewriter.write(lineread + "\r\n");
			}
			filewriter.close();
		}catch (FileNotFoundException fnfe){
			System.err.println("FileNotFoundException: " + fnfe.getMessage());
			showExceptionErrorMessage("FileNotFoundException: " + fnfe.getMessage());
		}catch (IOException ioe){
			System.err.println("IOException: " + ioe.getMessage());
			showExceptionErrorMessage("IOException: " + ioe.getMessage());
		}
		

	}

	/**	Appends the contents of the input file to the text editor.
	*/
	public void writeFileToEditor(File file){

		try{
			FileReader filereader = new FileReader(file);
			BufferedReader bufferedreader = new BufferedReader(filereader);
			String lineread = "";
			while ((lineread = bufferedreader.readLine()) != null){
				editor.append(lineread + "\n");
			}
			filereader.close();
		}catch (FileNotFoundException fnfe){
			System.err.println("FileNotFoundException: " + fnfe.getMessage());
			showExceptionErrorMessage("FileNotFoundException: " + fnfe.getMessage());
		}catch (IOException ioe){
			System.err.println("IOException: " + ioe.getMessage());
			showExceptionErrorMessage("IOException: " + ioe.getMessage());
		}

	}

	/**	Provides actions to user input.
	*/
	public void actionPerformed(ActionEvent actionevent){
		String actioncommand = actionevent.getActionCommand();
		if (actioncommand.compareTo("Exit") == 0) {
			System.exit(0);
		}else if (actioncommand.compareTo("Clear") == 0) {
			clear();
		}else if (actioncommand.compareTo("Cut") == 0) {
			cut();
		}else if (actioncommand.compareTo("Copy") == 0) {
			copy();
		}else if (actioncommand.compareTo("Paste") == 0) {
			paste();
		}else if (actioncommand.compareTo("Open A File") == 0) {
			File f = getAFileToOpen();
			writeFileToEditor(f);
		}else if (actioncommand.compareTo("Save To File") == 0) {
			String s = editor.getText();
			File f = getAFileForSave();
			writeStringToFile(f,s);
			showMessage("Contents of the Text Editor saved to file " + f.getName());
		}
	}

	/**	Conveniently displays a message to the user and waits for 
	*	confirmation.
	*/
	public void showMessage(String s){
		JOptionPane.showMessageDialog(frame,s);
	}

	/**	Conveniently displays an exception error message to the user 
	*	and waits for confirmation.
	*/
	public void showExceptionErrorMessage(String s){
		JOptionPane.showMessageDialog(frame,s,s,JOptionPane.ERROR_MESSAGE);
	}


	/**	clear() puts all editor text into the clipboardstring Transferrable 
	*	object and into the clipboard in case the user wants to paste it 
	*	back later in, then clears the editor. Text is also placed in the 
	*	system clipboard so it can be pasted into another application.
	*/
	private void clear(){

		String selectedtext = editor.getText();
		if (selectedtext != null){
			clipboardstring = new StringSelection(selectedtext);
			clipboard.setContents(clipboardstring,clipboardstring);
		}
		editor.setText("");
	}

	/** 	cut deletes selected text and stores the text into the clipboardstring 
	*	Transferrable object and into the clipboard.
	*/
	private void cut(){
		String selectedtext = editor.getSelectedText();
		if (selectedtext != null){
			clipboardstring = new StringSelection(selectedtext);
			clipboard.setContents(clipboardstring,clipboardstring);

			int startmark = editor.getSelectionStart();		
			int endmark = editor.getSelectionEnd();
			editor.replaceRange("",startmark,endmark);
		}		
	}

	/**	copy() stores the selected text from the editor into the 
	*	clipboardstring Transferrable object and into the clipboard.
	*/
	private void copy(){
		String selectedtext = editor.getSelectedText();
		if (selectedtext != null){
			clipboardstring = new StringSelection(selectedtext);
			clipboard.setContents(clipboardstring,clipboardstring);

		}
	}
	
	/**	paste() inserts the string stored from clear, copy or cut at
	*	the current caret position.
	*/
	private void paste(){
		Transferable clipboarddata = clipboard.getContents(clipboardstring);
		try{
			String text =  (String) clipboarddata .getTransferData(DataFlavor.stringFlavor);
			editor.insert(text,editor.getCaretPosition());
		}catch(Exception e){
			System.err.println("Exception: " + e.getMessage());	
			showExceptionErrorMessage("Exception: " + e.getMessage());		
		}
	}
}