/*******************************************************************************
 * Copyright (c) 2010-2015 Nokia Siemens Networks Oyj, Finland.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *      Nokia Siemens Networks - initial implementation
 *      Petri Tuononen - Initial implementation
 *******************************************************************************/
package org.eclipse.cdt.managedbuilder.llvm.ui.preferences;

import java.util.regex.Pattern;

import org.eclipse.cdt.managedbuilder.llvm.util.Separators;
import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.dialogs.IDialogConstants;
import org.eclipse.jface.preference.ListEditor;
import org.eclipse.jface.resource.JFaceResources;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.DisposeEvent;
import org.eclipse.swt.events.DisposeListener;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.events.SelectionListener;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.List;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Widget;

/**
 * An abstract list editor that manages a list of input values.
 * The editor displays a list containing the values, buttons for adding and removing
 * values, and Up and Down buttons to adjust the order of elements in the list.
 *
 */
public abstract class LlvmListEditor extends ListEditor {

	/**
	 * The list widget; <code>null</code> if none
	 * (before creation or after disposal).
	 */
	List list;

	/**
	 * The button box containing the Add, Remove, Up, and Down buttons;
	 * <code>null</code> if none (before creation or after disposal).
	 */
	Composite buttonBox;

	/**
	 * The Add button.
	 */
	Button addButton;

	/**
	 * The Remove button.
	 */
	Button removeButton;

	/**
	 * The Up button.
	 */
	Button upButton;

	/**
	 * The Down button.
	 */
	Button downButton;

	/**
	 * The selection listener.
	 */
	private SelectionListener selectionListener;

	/**
	 * Creates a list field editor.
	 *
	 * @param name the name of the preference this field editor works on
	 * @param labelText the label text of the field editor
	 * @param parent the parent of the field editor's control
	 */
	protected LlvmListEditor(String name, String labelText, Composite parent) {
		super(name, labelText, parent);
	}

	@Override
	/**
	 * Combines the given list of items into a single String.
	 * This method is the converse of parseString.
	 */
	protected String createList(String[] items) {
		StringBuilder stringBuilder = new StringBuilder();
		for (String item : items) {
			if (stringBuilder.length() > 0) {
				stringBuilder.append(Separators.getPathSeparator());
			}
			stringBuilder.append(item);
		}
		return stringBuilder.toString();
	}

	@Override
	/** Splits the given String into a list of Strings.
	 * This method is the converse of createList.
	 */
	protected String[] parseString(String stringList) {
		if (stringList != null && stringList.length() > 0) {
			return stringList.split(Pattern.quote(Separators.getPathSeparator()));
		}
		return new String[0];
	}

	/**
	 * Creates the Add, Remove, Up, and Down button in the given button box.
	 *
	 * @param box the box for the buttons
	 */
	private void createButtons(Composite box) {
		this.addButton = createPushButton(box, "ListEditor.add");//$NON-NLS-1$
		this.removeButton = createPushButton(box, "ListEditor.remove");//$NON-NLS-1$
		this.upButton = createPushButton(box, "ListEditor.up");//$NON-NLS-1$
		this.downButton = createPushButton(box, "ListEditor.down");//$NON-NLS-1$
	}

	/**
	 * Helper method to create a push button.
	 *
	 * @param parent the parent control
	 * @param key the resource name used to supply the button's label text
	 * @return Button
	 */
	private Button createPushButton(Composite parent, String key) {
		Button button = new Button(parent, SWT.PUSH);
		button.setText(JFaceResources.getString(key));
		button.setFont(parent.getFont());
		GridData data = new GridData(GridData.FILL_HORIZONTAL);
		int widthHint = convertHorizontalDLUsToPixels(button, IDialogConstants.BUTTON_WIDTH);
		data.widthHint = Math.max(widthHint, button.computeSize(SWT.DEFAULT, SWT.DEFAULT, true).x);
		button.setLayoutData(data);
		button.addSelectionListener(getSelectionListener());
		return button;
	}

	/**
	 * Creates a selection listener.
	 */
	@Override
	public void createSelectionListener() {
		this.selectionListener = new SelectionAdapter() {
			@Override
			public void widgetSelected(SelectionEvent event) {
				Widget widget = event.widget;
				if (widget == LlvmListEditor.this.addButton) {
					addPressed();
				} else if (widget == LlvmListEditor.this.removeButton) {
					removePressed();
				} else if (widget == LlvmListEditor.this.upButton) {
					upPressed();
				} else if (widget == LlvmListEditor.this.downButton) {
					downPressed();
				} else if (widget == LlvmListEditor.this.list) {
					selectionChanged();
				}
			}
		};
	}

	/**
	 * Returns this field editor's button box containing the Add, Remove,
	 * Up, and Down button.
	 *
	 * @param parent the parent control
	 * @return the button box
	 */
	@Override
	public Composite getButtonBoxControl(Composite parent) {
		if (this.buttonBox == null) {
			this.buttonBox = new Composite(parent, SWT.NULL);
			GridLayout layout = new GridLayout();
			layout.marginWidth = 0;
			this.buttonBox.setLayout(layout);
			createButtons(this.buttonBox);
			this.buttonBox.addDisposeListener(new DisposeListener() {
				@Override
				public void widgetDisposed(DisposeEvent event) {
					LlvmListEditor.this.addButton = null;
					LlvmListEditor.this.removeButton = null;
					LlvmListEditor.this.upButton = null;
					LlvmListEditor.this.downButton = null;
					LlvmListEditor.this.buttonBox = null;
				}
			});

		} else {
			checkParent(this.buttonBox, parent);
		}

		selectionChanged();
		return this.buttonBox;
	}

	/**
	 * Returns this field editor's list control.
	 *
	 * @param parent the parent control
	 * @return the list control
	 */
	@Override
	public List getListControl(Composite parent) {
		if (this.list == null) {
			this.list = new List(parent, SWT.BORDER | SWT.MULTI | SWT.V_SCROLL | SWT.H_SCROLL);
			this.list.setFont(parent.getFont());
			this.list.addSelectionListener(getSelectionListener());
			this.list.addDisposeListener(new DisposeListener() {
				@Override
				public void widgetDisposed(DisposeEvent event) {
					LlvmListEditor.this.list = null;
				}
			});
		} else {
			checkParent(this.list, parent);
		}
		return this.list;
	}

	/**
	 * Returns this field editor's selection listener. The listener is created if nessessary.
	 * @return  the selection listener
	 */
	private SelectionListener getSelectionListener() {
		if (this.selectionListener == null) {
			createSelectionListener();
		}
		return this.selectionListener;
	}

	/**
	 * Invoked when the selection in the list has changed.
	 *
	 * <p>
	 * The default implementation of this method utilizes the selection index
	 * and the size of the list to toggle the enablement of the up, down and
	 * remove buttons.
	 * </p>
	 *
	 */
	@Override
	protected void selectionChanged() {
		int index = this.list.getSelectionIndex();
		int size = this.list.getItemCount();

		this.removeButton.setEnabled(index >= 0);
		this.upButton.setEnabled(size > 1 && index > 0);
		this.downButton.setEnabled(size > 1 && index >= 0 && index < size - 1);
	}

	/**
	 * Moves the currently selected item up or down.
	 *
	 * @param up <code>true</code> if the item should move up,
	 *  and <code>false</code> if it should move down
	 */
	private void swap(boolean up) {
		setPresentsDefaultValue(false);
		int index = this.list.getSelectionIndex();
		int target = up ? index - 1 : index + 1;

		if (index >= 0) {
			String[] selection = this.list.getSelection();
			Assert.isTrue(selection.length == 1);
			this.list.remove(index);
			this.list.add(selection[0], target);
			this.list.setSelection(target);
		}
		selectionChanged();
	}

	/**
	 * Returns this field editor's shell.
	 * <p>
	 * This method is internal to the framework; subclasses should not call
	 * this method.
	 * </p>
	 *
	 * @return the shell
	 */
	@Override
	protected Shell getShell() {
		if (this.addButton == null) {
			return null;
		}
		return this.addButton.getShell();
	}

	/**
	 * Notifies that the Add button has been pressed.
	 */
	void addPressed() {
		setPresentsDefaultValue(false);
		String input = getNewInputObject();

		if (input != null) {
			int index = this.list.getSelectionIndex();
			if (index >= 0) {
				this.list.add(input, index + 1);
			} else {
				this.list.add(input, 0);
			}
			selectionChanged();
		}
	}

	/**
	 * Notifies that the Remove button has been pressed.
	 */
	protected abstract void removePressed();

	/**
	 * Notifies that the Up button has been pressed.
	 */
	void upPressed() {
		swap(true);
	}

	/**
	 * Notifies that the Down button has been pressed.
	 */
	void downPressed() {
		swap(false);
	}

}
