package no.uio.ifi.refaktor.handlers;

import java.lang.reflect.InvocationTargetException;

import no.uio.ifi.refaktor.change.changers.RefaktorChanger;

import org.eclipse.core.commands.AbstractHandler;
import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.core.commands.ExecutionException;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.NullProgressMonitor;
import org.eclipse.jface.dialogs.MessageDialog;
import org.eclipse.ui.IWorkbenchWindow;
import org.eclipse.ui.actions.WorkspaceModifyOperation;
import org.eclipse.ui.handlers.HandlerUtil;

public abstract class WorkspaceModificationHandler extends AbstractHandler {
	
	private RefaktorChanger changer;

	public WorkspaceModificationHandler() {
		super();
	}

	protected abstract RefaktorChanger createChanger();
	protected abstract String getTitle();
	protected abstract String getMessage();
	
	@Override
	public Object execute(ExecutionEvent event) throws ExecutionException {
		destroyChanger();
		if (preconditionsAreMet(event) && userConfirms(event)) {
			try {
				modifyWorkspace();
			} catch (InvocationTargetException e) {
				e.printStackTrace();
				makeAndThrowExecutionException(e);
			} catch (InterruptedException e) {
				e.printStackTrace();
				makeAndThrowExecutionException(e);
			}
		}
		return null;
	}

	private void makeAndThrowExecutionException(Throwable e)
			throws ExecutionException {
		throw new ExecutionException(this.getClass().getSimpleName() + " failed",e);
	}

	protected boolean preconditionsAreMet(ExecutionEvent event) throws ExecutionException {
		return true;
	}

	public void modifyWorkspace() throws ExecutionException, InvocationTargetException, InterruptedException {
		WorkspaceModifyOperation op = new WorkspaceModifyOperation() {

			@Override
			protected void execute(IProgressMonitor monitor) throws CoreException, InvocationTargetException, InterruptedException {
				getChanger().execute(monitor);
			}
		};
		op.run(new NullProgressMonitor());
	}

	protected boolean userConfirms(ExecutionEvent event) throws ExecutionException {
		IWorkbenchWindow window = HandlerUtil.getActiveWorkbenchWindowChecked(event);
		return MessageDialog.openQuestion(window.getShell(), getTitle(), getMessage());
	}
	
	protected void destroyChanger() {
		changer = null;
	}

	protected RefaktorChanger getChanger() {
		if (changer == null)
			changer = createChanger();
		return changer;
	}

}