/*******************************************************************************
 * Copyright (c) 2000, 2006 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/

package org.eclipse.jdt.internal.ui.refactoring;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.ModifyEvent;
import org.eclipse.swt.events.ModifyListener;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Text;

import org.eclipse.jface.util.Assert;

import org.eclipse.jdt.internal.ui.dialogs.TextFieldNavigationHandler;

import org.eclipse.ltk.core.refactoring.RefactoringStatus;
import org.eclipse.ltk.ui.refactoring.UserInputWizardPage;

/**
 * A TextInputWizardPage is a simple UserInputWizardPage with facilities
 * to create a text input field and validate its contents.
 * The text is assumed to be a java identifier, hence CamelCase word jumping is installed.
 */
public abstract class TextInputWizardPage extends UserInputWizardPage{

	private String fInitialValue;
	private Text fTextField;	
	
	public static final String PAGE_NAME= "TextInputPage";//$NON-NLS-1$

	/**
	 * Creates a new text input page.
	 * @param isLastUserPage <code>true</code> if this page is the wizard's last
	 *  user input page. Otherwise <code>false</code>.
	 */
	public TextInputWizardPage(String description, boolean isLastUserPage) {
		this(description, isLastUserPage, ""); //$NON-NLS-1$
	}
	
	/**
	 * Creates a new text input page.
	 * @param isLastUserPage <code>true</code> if this page is the wizard's last
	 *  user input page. Otherwise <code>false</code>
	 * @param initialValue the initial value
	 */
	public TextInputWizardPage(String description, boolean isLastUserPage, String initialValue) {
		super(PAGE_NAME);
		Assert.isNotNull(initialValue);
		setDescription(description);
		fInitialValue= initialValue;
	}
	
	/**
	 * Returns whether the initial input is valid. Typically it is not, because the 
	 * user is required to provide some information e.g. a new type name etc.
	 * 
	 * @return <code>true</code> iff the input provided at initialization is valid
	 */
	protected boolean isInitialInputValid(){
		return false;
	}
	
	/**
	 * Returns whether an empty string is a valid input. Typically it is not, because 
	 * the user is required to provide some information e.g. a new type name etc.
	 * 
	 * @return <code>true</code> iff an empty string is valid
	 */
	protected boolean isEmptyInputValid(){
		return false;
	}
	
	/**
	 * Returns the content of the text input field.
	 * 
	 * @return the content of the text input field. Returns <code>null</code> if
	 * not text input field has been created
	 */
	protected String getText() {
		if (fTextField == null)
			return null;
		return fTextField.getText();	
	}
	
	/**
	 * Sets the new text for the text field. Does nothing if the text field has not been created.
	 * @param text the new value
	 */
	protected void setText(String text) {
		if (fTextField == null)
			return;
		fTextField.setText(text);
	}
	
	/**
	 * Returns the text entry field
	 * 
	 * @return the text entry field
	 */
	protected Text getTextField() {
		return fTextField;
	}
	
	/**
	 * Returns the initial value.
	 * 
	 * @return the initial value
	 */
	public String getInitialValue() {
		return fInitialValue;
	}
	
	/**
	 * Performs input validation. Returns a <code>RefactoringStatus</code> which
	 * describes the result of input validation. <code>Null<code> is interpreted
	 * as no error.
	 */
	protected RefactoringStatus validateTextField(String text){
		return null;
	}
	
	protected Text createTextInputField(Composite parent) {
		return createTextInputField(parent, SWT.BORDER);
	}
	
	protected Text createTextInputField(Composite parent, int style) {
		fTextField= new Text(parent, style);
		fTextField.addModifyListener(new ModifyListener() {
			public void modifyText(ModifyEvent e) {
				textModified(getText());
			}
		});
		fTextField.setText(fInitialValue);
		TextFieldNavigationHandler.install(fTextField);
		return fTextField;
	}
	
	/**
	 * Checks the page's state and issues a corresponding error message. The page validation
	 * is computed by calling <code>validatePage</code>.
	 */
	protected void textModified(String text) {	
		if (! isEmptyInputValid() && "".equals(text)){ //$NON-NLS-1$
			setPageComplete(false);
			setErrorMessage(null);
			restoreMessage();
			return;
		}
		if ((! isInitialInputValid()) && fInitialValue.equals(text)){
			setPageComplete(false);
			setErrorMessage(null);
			restoreMessage();
			return;
		}
		
		RefactoringStatus status= validateTextField(text);
		if (status == null)
			status= new RefactoringStatus();
		setPageComplete(status);
	}
	
	/**
	 * Subclasses can override if they want to restore the message differently.
	 * This implementation calls <code>setMessage(null)</code>, which clears the message 
	 * thus exposing the description.
	 */
	protected void restoreMessage(){
		setMessage(null);
	}
	
	/* (non-Javadoc)
	 * Method declared in IDialogPage
	 */
	public void dispose() {
		fTextField= null;	
	}
	
	/* (non-Javadoc)
	 * Method declared in WizardPage
	 */
	public void setVisible(boolean visible) {
		if (visible) {
			textModified(getText());
		}
		super.setVisible(visible);
		if (visible && fTextField != null) {
			fTextField.setFocus();
		}
	}
}