/*******************************************************************************
 * Copyright (c) 2005, 2015 IBM Corporation and others.
 *
 * 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:
 *     IBM Corporation - initial API and implementation
 *     QNX Software System
 *******************************************************************************/
package org.eclipse.cdt.internal.autotools.ui.editors.automake;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.jface.viewers.ILabelProvider;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionListener;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Table;
import org.eclipse.swt.widgets.TableItem;
import org.eclipse.swt.widgets.Text;

/**
 * A selection widget that consists of a list and a text entry field. The list
 * of elements presented are limited to the pattern entered into the text entry
 * field.
 */
public class SelectionList extends Composite {

	// State
	private Object[] fElements;
	protected ILabelProvider fRenderer;
	private boolean fIgnoreCase;

	// Implementation details
	private String[] fRenderedStrings;
	private int[] fFilteredElements;
	private String fRememberedMatchText;

	// SWT widgets
	private Table fList;
	private Text fText;

	/**
	 * Adds a selection change listener to this widget.
	 */
	public void addSelectionListener(SelectionListener listener) {
		fList.addSelectionListener(listener);
	}

	private void createList(int style) {
		fList = new Table(this, style);
		fList.setLayoutData(new GridData(GridData.FILL_BOTH));
		fList.addDisposeListener(e -> fRenderer.dispose());
	}

	private void createText() {
		fText = new Text(this, SWT.BORDER);
		GridData spec = new GridData();
		spec.grabExcessVerticalSpace = false;
		spec.grabExcessHorizontalSpace = true;
		spec.horizontalAlignment = GridData.FILL;
		spec.verticalAlignment = GridData.BEGINNING;
		fText.setLayoutData(spec);
		Listener l = evt -> filter(false);
		fText.addListener(SWT.Modify, l);
	}

	/**
	 * Filters the list of elements according to the pattern entered
	 * into the text entry field.
	 */
	public void filter(boolean forceUpdate) {
		int k = 0;
		String text = fText.getText();
		if (!forceUpdate && text.equals(fRememberedMatchText))
			return;
		fRememberedMatchText = text;
		StringMatcher matcher = new StringMatcher(text + "*", fIgnoreCase, false); //$NON-NLS-1$
		for (int i = 0; i < fElements.length; i++) {
			if (matcher.match(fRenderedStrings[i])) {
				fFilteredElements[k] = i;
				k++;
			}
		}
		fFilteredElements[k] = -1;
		updateListWidget(fFilteredElements, k);
	}

	/**
	 * Returns the currently used filter text.
	 */
	public String getFilter() {
		return fText.getText();
	}

	/**
	 * Returns the selection indices.
	 */
	public int[] getSelectionIndices() {
		return fList.getSelectionIndices();
	}

	/**
	 * Returns a list of selected elements. Note that the type of the elements
	 * returned in the list are the same as the ones passed to the selection list
	 * via <code>setElements</code>. The list doesn't contain the rendered strings.
	 */
	public List<Object> getSelection() {
		if (fList == null || fList.isDisposed() || fList.getSelectionCount() == 0)
			return new ArrayList<>(0);
		int[] listSelection = fList.getSelectionIndices();
		List<Object> selected = new ArrayList<>(listSelection.length);
		for (int i = 0; i < listSelection.length; i++) {
			selected.add(fElements[fFilteredElements[listSelection[i]]]);
		}
		return selected;
	}

	/**
	 * Returns <code>true</code> when the list of elements is empty.
	 */
	public boolean isEmptyList() {
		return fElements == null || fElements.length == 0;
	}

	/**
	 * Creates new instance of the widget.
	 */
	public SelectionList(Composite parent, int style, ILabelProvider renderer, boolean ignoreCase) {
		super(parent, SWT.NONE);
		fRenderer = renderer;
		fIgnoreCase = ignoreCase;
		GridLayout layout = new GridLayout();
		layout.marginHeight = 0;
		layout.marginWidth = 0;
		//XXX: 1G9V58A: ITPUI:WIN2000 - Dialog.convert* methods should be static
		setLayout(layout);
		createText();
		createList(style);
	}

	/**
	 * Removes a selection change listener to this widget.
	 */
	public void removeSelectionListener(SelectionListener listener) {
		fList.removeSelectionListener(listener);
	}

	private String[] renderStrings() {
		String[] strings = new String[fElements.length];
		for (int i = 0; i < strings.length; i++) {
			strings[i] = fRenderer.getText(fElements[i]);
		}
		TwoArrayQuickSort.sort(strings, fElements, fIgnoreCase);
		return strings;
	}

	/**
	 * Select the pattern text.
	 */
	public void selectFilterText() {
		fText.selectAll();
	}

	/**
	 * Sets the list of elements presented in the widget.
	 */
	public void setElements(List<Object> elements, boolean refilter) {
		// We copy the list since we sort it.
		if (elements == null)
			fElements = new Object[0];
		else
			fElements = elements.toArray();
		fFilteredElements = new int[fElements.length + 1];
		fRenderedStrings = renderStrings();
		if (refilter)
			filter(true);
	}

	@Override
	public void setEnabled(boolean enable) {
		super.setEnabled(enable);
		fText.setEnabled(enable);
		fList.setEnabled(enable);
	}

	/**
	 * Sets the filter pattern. Current only prefix filter pattern are supported.
	 */
	public void setFilter(String pattern, boolean refilter) {
		fText.setText(pattern);
		if (refilter)
			filter(true);
	}

	@Override
	public boolean setFocus() {
		return fText.setFocus();
	}

	@Override
	public void setFont(Font font) {
		super.setFont(font);
		fText.setFont(font);
		fList.setFont(font);
	}

	/**
	 * Selects the elements in the list determined by the given
	 * selection indices.
	 */
	protected void setSelection(int[] selection) {
		fList.setSelection(selection);
	}

	private void updateListWidget(int[] indices, int size) {
		if (fList == null || fList.isDisposed())
			return;
		fList.setRedraw(false);
		int itemCount = fList.getItemCount();
		if (size < itemCount) {
			fList.remove(0, itemCount - size - 1);
		}

		TableItem[] items = fList.getItems();
		for (int i = 0; i < size; i++) {
			TableItem ti = null;
			if (i < itemCount) {
				ti = items[i];
			} else {
				ti = new TableItem(fList, i);
			}
			ti.setText(fRenderedStrings[indices[i]]);
			Image img = fRenderer.getImage(fElements[indices[i]]);
			if (img != null)
				ti.setImage(img);
		}
		if (fList.getItemCount() > 0) {
			fList.setSelection(0);
		}

		fList.setRedraw(true);
		Event event = new Event();
		fList.notifyListeners(SWT.Selection, event);
	}
}
