/*******************************************************************************
 * Copyright (c) 2008 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.equinox.internal.p2.ui.dialogs;

import java.util.ArrayList;
import java.util.List;
import org.eclipse.equinox.internal.provisional.p2.engine.ProvisioningContext;
import org.eclipse.equinox.internal.provisional.p2.metadata.IInstallableUnit;
import org.eclipse.equinox.internal.provisional.p2.ui.ProvUI;
import org.eclipse.equinox.internal.provisional.p2.ui.policy.IQueryProvider;
import org.eclipse.jface.dialogs.Dialog;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.StructuredViewer;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Shell;

/**
 * A StructuredIUGroup is a reusable UI component that displays a
 * structured view of IU's driven by some queries.
 * 
 * @since 3.4
 */
public abstract class StructuredIUGroup {

	private IQueryProvider queryProvider;
	private ProvisioningContext context;
	private FontMetrics fm;
	private StructuredViewer viewer;
	private Composite composite;

	/**
	 * Create a group that represents the available IU's.
	 * 
	 * @param parent the parent composite for the group
	 * @param queryProvider the query provider that defines the queries used
	 * to retrieve elements in the viewer.
	 * @param font The font to use for calculating pixel sizes.  This font is
	 * not managed by the receiver.
	 * @param context the ProvisioningContext describing the context for provisioning.
	 */
	protected StructuredIUGroup(Composite parent, IQueryProvider queryProvider, Font font, ProvisioningContext context) {
		this.queryProvider = queryProvider;
		this.context = context;
		// Set up a fontmetrics for calculations
		GC gc = new GC(parent);
		gc.setFont(font);
		fm = gc.getFontMetrics();
		gc.dispose();
	}

	protected void createGroupComposite(Composite parent) {
		composite = new Composite(parent, SWT.NONE);
		GridData gd = new GridData(SWT.FILL, SWT.FILL, true, true);
		composite.setLayoutData(gd);
		GridLayout layout = new GridLayout();
		layout.marginWidth = 0;
		layout.marginHeight = 0;
		composite.setLayout(layout);

		viewer = createViewer(composite);

		GridData data = new GridData(GridData.FILL_BOTH);
		data.grabExcessHorizontalSpace = true;
		data.grabExcessVerticalSpace = true;
		viewer.getControl().setLayoutData(data);

	}

	protected abstract StructuredViewer createViewer(Composite parent);

	protected Composite getComposite() {
		return composite;
	}

	protected Shell getShell() {
		return composite.getShell();
	}

	protected StructuredViewer getStructuredViewer() {
		return viewer;
	}

	protected IInstallableUnit[] getSelectedIUs() {
		List elements = ((IStructuredSelection) viewer.getSelection()).toList();
		List iusList = new ArrayList(elements.size());

		for (int i = 0; i < elements.size(); i++) {
			IInstallableUnit iu = getIU(elements.get(i));
			if (iu != null)
				iusList.add(iu);
		}
		return (IInstallableUnit[]) iusList.toArray(new IInstallableUnit[iusList.size()]);
	}

	protected IInstallableUnit getIU(Object element) {
		return (IInstallableUnit) ProvUI.getAdapter(element, IInstallableUnit.class);
	}

	protected ProvisioningContext getProvisioningContext() {
		return context;
	}

	protected int convertHorizontalDLUsToPixels(int dlus) {
		return Dialog.convertHorizontalDLUsToPixels(fm, dlus);
	}

	protected IQueryProvider getQueryProvider() {
		return queryProvider;
	}
}