EditorPreferenceReader.java

/*******************************************************************************
 * Copyright (c) 2012-2015 Codenvy, S.A.
 * 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:
 *   Codenvy, S.A. - initial API and implementation
 *******************************************************************************/
package org.eclipse.che.ide.jseditor.client.prefmodel;

import javax.inject.Inject;
import javax.validation.constraints.NotNull;

import org.eclipse.che.ide.api.preferences.PreferencesManager;
import org.eclipse.che.ide.util.loging.Log;
import com.google.gwt.core.client.JavaScriptObject;
import com.google.gwt.json.client.JSONObject;
import com.google.gwt.json.client.JSONParser;
import com.google.gwt.json.client.JSONValue;

/**
 * Utility to read {@link EditorPreferences} from the preferences.
 */
public class EditorPreferenceReader {

    /** The editor preference main property name. */
    private static final String PREFERENCE_PROPERTY = "editor";

    /** the preferences manager instance. */
    private final PreferencesManager preferencesManager;

    @Inject
    public EditorPreferenceReader(final PreferencesManager preferencesManager) {
        this.preferencesManager = preferencesManager;
    }

    /**
     * Retrieves the editor preference object as stored in the preference json string.
     * @return the preference object or null
     */
    private EditorPreferences getPreferencesOrNull() {
        final String prefAsJson = this.preferencesManager.getValue(PREFERENCE_PROPERTY);
        if (prefAsJson == null || prefAsJson.isEmpty()) {
            return null;
        }
        JSONValue propertyObject;
        try {
            final JSONValue parseResult = JSONParser.parseStrict(prefAsJson);
            propertyObject = parseResult.isObject();
        } catch (final RuntimeException e) {
            Log.error(KeymapPrefReader.class, "Error during preference parsing.", e);
            return null;
        }
        if (propertyObject == null) {
            return null;
        }
        JavaScriptObject propertyValue;
        try {
            propertyValue = propertyObject.isObject().getJavaScriptObject();
        } catch (final RuntimeException e) {
            Log.error(KeymapPrefReader.class, "Invalid value for editor preference.", e);
            return null;
        }
        return propertyValue.cast();
    }

    /**
     * Returns the editor preference object.<br>
     * If there is none, return a properly initialized preference object.
     * @return editor preference
     */
    @NotNull
    public EditorPreferences getPreferences() {
        final EditorPreferences resultOrNull = getPreferencesOrNull();
        if (resultOrNull == null) {
            return EditorPreferences.create();
        } else {
            return resultOrNull;
        }
    }

    /**
     * Stores the editor preference object in the preferences.
     * @param newPreferences the pref object to store
     */
    public void setPreferences(final EditorPreferences newPreferences) {
        final JSONObject json = new JSONObject(newPreferences);
        this.preferencesManager.setValue(PREFERENCE_PROPERTY, json.toString());
    }
}