ProjectVariablesContentProposalProvider.java

/*
 * Copyright (c) 2017 wetransform GmbH
 * 
 * All rights reserved. This program and the accompanying materials are made
 * available under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the License,
 * or (at your option) any later version.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution. If not, see <http://www.gnu.org/licenses/>.
 * 
 * Contributors:
 *     wetransform GmbH <http://www.wetransform.to>
 */

package eu.esdihumboldt.hale.ui.service.project;

import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;

import org.eclipse.jface.bindings.keys.KeyStroke;
import org.eclipse.jface.bindings.keys.ParseException;
import org.eclipse.jface.fieldassist.IContentProposal;
import org.eclipse.jface.fieldassist.IContentProposalProvider;
import org.eclipse.ui.PlatformUI;

import eu.esdihumboldt.hale.common.core.io.Value;
import eu.esdihumboldt.hale.common.core.io.ValueProperties;
import eu.esdihumboldt.hale.common.core.io.project.ProjectVariables;

/**
 * This class provides content proposals for project variables by loading them
 * via the {@link ProjectService}.<br>
 * <br>
 * <b>Note:</b> After instantiation the result of
 * {@link #getProposals(String, int)} does not change until {@link #reload()} is
 * called.
 * 
 * @author Florian Esser
 */
public class ProjectVariablesContentProposalProvider implements IContentProposalProvider {

	/**
	 * {@link KeyStroke} reprensenting the key combination Ctrl+Space
	 */
	public static KeyStroke CTRL_SPACE = createKeyStroke("Ctrl+Space");

	private final Map<String, Value> variables = new TreeMap<>(String.CASE_INSENSITIVE_ORDER);
	private boolean displayPlaceholderIfEmpty = false;

	/**
	 * Creates the content proposal provider and loads the project variables
	 */
	public ProjectVariablesContentProposalProvider() {
		reload();
	}

	/**
	 * Creates the content proposal provider and loads the project variables
	 * 
	 * @param displayPlaceholderIfEmpty If true and no project variables exist,
	 *            {@link #getProposals(String, int)} will return one
	 *            {@link IContentProposal} hinting on that.
	 */
	public ProjectVariablesContentProposalProvider(boolean displayPlaceholderIfEmpty) {
		this();

		this.displayPlaceholderIfEmpty = displayPlaceholderIfEmpty;
	}

	/**
	 * @see org.eclipse.jface.fieldassist.IContentProposalProvider#getProposals(java.lang.String,
	 *      int)
	 */
	@Override
	public IContentProposal[] getProposals(final String contents, final int position) {
		List<IContentProposal> proposals = new ArrayList<>();
		if (variables != null) {
			if (!variables.isEmpty()) {
				variables.forEach((variable, value) -> proposals
						.add(createContentProposal(contents, position, variable, value)));
			}
			else if (displayPlaceholderIfEmpty) {
				proposals.add(createPlaceholder());
			}
		}

		return proposals.toArray(new IContentProposal[proposals.size()]);

	}

	/**
	 * Refresh the project variables from the {@link ProjectService}
	 */
	public void reload() {
		ProjectService ps = PlatformUI.getWorkbench().getService(ProjectService.class);
		Value value = ps.getConfigurationService()
				.getProperty(ProjectVariables.PROJECT_PROPERTY_VARIABLES);
		ValueProperties properties = value.as(ValueProperties.class);

		variables.clear();
		if (properties != null) {
			variables.putAll(properties);
		}
	}

	/**
	 * Creates a {@link KeyStroke} instance for the given formal key string
	 * representation.
	 * 
	 * @see org.eclipse.jface.bindings.keys.KeyStroke#getInstance(String)
	 * @param key Formal key representation
	 * @return {@link KeyStroke} instance or null if no instance could be
	 *         created for the given key.
	 */
	public static KeyStroke createKeyStroke(String key) {
		try {
			return KeyStroke.getInstance(key);
		} catch (ParseException e) {
			return null;
		}
	}

	private IContentProposal createContentProposal(String contents, int position, String variable,
			Value value) {
		return new IContentProposal() {

			@Override
			public String getLabel() {
				return MessageFormat.format("{0} (project variable)", variable);
			}

			@Override
			public String getDescription() {
				return MessageFormat.format("Variable name: {0}\nDefault value: \"{1}\"", variable,
						value);
			}

			@Override
			public int getCursorPosition() {
				return getContent().length();
			}

			@Override
			public String getContent() {
				StringBuilder content = new StringBuilder();
				if (contents != null && !contents.substring(0, position).endsWith("{")) {
					content.append("{");
				}
				content.append("{project:").append(variable).append("}}");

				return content.toString();
			}
		};
	}

	private IContentProposal createPlaceholder() {
		return new IContentProposal() {

			@Override
			public String getLabel() {
				return "No project variables defined";
			}

			@Override
			public String getDescription() {
				return null;
			}

			@Override
			public int getCursorPosition() {
				return 0;
			}

			@Override
			public String getContent() {
				return "";
			}
		};
	}
}