/*******************************************************************************
 * <copyright>
 *
 * Copyright (c) 2005, 2011 SAP AG.
 * 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:
 *    SAP AG - initial API, implementation and documentation
 *
 * </copyright>
 *
 *******************************************************************************/
package org.eclipse.graphiti.func;

import org.eclipse.graphiti.features.context.IDirectEditingContext;

/**
 * The Interface IProposalSupport.
 * 
 * @noextend This interface is not intended to be extended by clients.
 * @noimplement This interface is not intended to be implemented by clients,
 *              extend {@link AbstractProposalSupport} instead.
 */
public interface IProposalSupport {

	/**
	 * This value will be used if the cell editor is a combo box. This
	 * functionality only applies to TYPE_DROPDOWN.
	 * 
	 * @param context
	 *            the context
	 * @return the possible values for the combo box.
	 */
	IProposal[] getPossibleValues(IDirectEditingContext context);

	/**
	 * This proposals will be used for the completion list of a simple text cell
	 * editor. This functionality only applies to TYPE_TEXT.
	 * 
	 * @param value
	 *            current value
	 * @param caretPosition
	 *            current cursor position
	 * @param context
	 *            the context
	 * @return the proposed values
	 */
	IProposal[] getValueProposals(String value, int caretPosition, IDirectEditingContext context);

	/**
	 * Framework calls this method to let the feature calculate the new value.
	 * 
	 * @param value
	 *            current value
	 * @param caretPosition
	 *            current cursor position
	 * @param choosenValue
	 *            value choosen by user
	 * @param context
	 *            the context
	 * @return the new value
	 */
	String completeValue(String value, int caretPosition, IProposal choosenValue, IDirectEditingContext context);

	/**
	 * This method will be called by clients many times to see if current value
	 * is valid and could be set.
	 * 
	 * @param text
	 *            the value as text
	 * @param proposal
	 *            the value as proposal
	 * @param context
	 *            the context
	 * @return null if value is okay and could be set; any text means value is
	 *         not valid; text is reason for invalidality
	 */
	String checkValueValid(String text, IProposal proposal, IDirectEditingContext context);

	/**
	 * Set the new value. The value comes from the text editing UI component.
	 * 
	 * @param text
	 *            the value
	 * @param proposal
	 *            the selected proposal
	 * @param context
	 *            the context
	 */
	void setValue(String text, IProposal proposal, IDirectEditingContext context);
}