/*******************************************************************************
 * Copyright (c) 2021 Christian Pontesegger and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     Christian Pontesegger - initial API and implementation
 *******************************************************************************/

package org.eclipse.ease.ui.views.shell.dropins;

import java.time.Duration;

import org.eclipse.ease.IExecutionListener;
import org.eclipse.ease.IReplEngine;
import org.eclipse.ease.IScriptEngine;
import org.eclipse.ease.Script;
import org.eclipse.jface.util.Throttler;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.ui.IWorkbenchPartSite;

public abstract class AbstractDropin implements IShellDropin, IExecutionListener {

	private IReplEngine fEngine;

	private final Throttler fUiUpdater = new Throttler(Display.getDefault(), Duration.ofMillis(500), this::update);

	private boolean fIsActive = false;

	@Override
	public void setScriptEngine(IReplEngine engine) {
		if (fEngine != null)
			fEngine.removeExecutionListener(this);

		fEngine = engine;

		if (fEngine != null)
			fEngine.addExecutionListener(this);
	}

	@Override
	public Composite createPartControl(final IWorkbenchPartSite site, final Composite parent) {
		final Composite composite = createComposite(site, parent);

		fIsActive = true;

		composite.addListener(SWT.Hide, event -> fIsActive = false);
		composite.addListener(SWT.Show, event -> {
			fIsActive = true;
			update();
		});

		return composite;
	}

	@Override
	public void notify(IScriptEngine engine, Script script, int status) {
		switch (status) {
		case IExecutionListener.SCRIPT_END:
			fUiUpdater.throttledExec();
			break;

		case IExecutionListener.ENGINE_END:
			engine.removeExecutionListener(this);
			break;

		default:
			// nothing to do
			break;
		}
	}

	protected void update() {
		if (fIsActive)
			updateUI();
	}

	protected abstract void updateUI();

	protected abstract Composite createComposite(IWorkbenchPartSite site, Composite parent);
}