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Common application code (Apache License v2) 2008-2019 Matt Gumbley, DevZendo.org
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/**
 * Copyright (C) 2008-2010 Matt Gumbley, DevZendo.org http://devzendo.org
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.devzendo.commonapp.prefs;

import org.apache.log4j.Logger;

/**
 * A helper class for starting up the Prefs location and factory.
 * @author matt
 *
 */
public abstract class AbstractPrefsStartupHelper {
    private static final Logger LOGGER = Logger
            .getLogger(AbstractPrefsStartupHelper.class);
    private final PrefsFactory mPrefsFactory;
    private final PrefsLocation mPrefsLocation;
    private final PrefsInstantiator mPrefsInstantiator;

    /**
     * Create the prefs startup helper
     * @param prefsLocation the location of the prefs
     * @param prefsFactory the factory where the prefs object will be stored
     * @param prefsInstantiator the instantiator for new Prefs objects
     */
    public AbstractPrefsStartupHelper(
            final PrefsLocation prefsLocation, 
            final PrefsFactory prefsFactory, 
            final PrefsInstantiator prefsInstantiator) {
        mPrefsLocation = prefsLocation;
        mPrefsFactory = prefsFactory;
        mPrefsInstantiator = prefsInstantiator;
    }
    
    /**
     * Initialise the prefs. If this fails, the user wil be notified, and the
     * program will exit. You can't continue without prefs.
     */
    public final void initialisePrefs() {
        LOGGER.debug("Prefs directory is " + mPrefsLocation.getPrefsDir().getAbsolutePath());
        LOGGER.debug("Prefs file is " + mPrefsLocation.getPrefsFile().getAbsolutePath());
        if (!mPrefsLocation.prefsDirectoryExists()) {
            LOGGER.info(String.format("Prefs directory %s does not exist - creating it",
                mPrefsLocation.getPrefsDir().getAbsolutePath()));
            if (!mPrefsLocation.createPrefsDirectory()) {
                LOGGER.warn("Failed to create prefs directory");
                warnUserOfPrefsDirCreationFailure();
                
            } else {
                LOGGER.info("Created prefs directory OK");
            }
        }
        mPrefsFactory.setPrefs(mPrefsInstantiator.instantiatePrefs(mPrefsLocation));
        mPrefsFactory.setPrefsClass(mPrefsInstantiator.getPrefsClass());
        LOGGER.debug("Prefs set in factory");
    }

    /**
     * Warn the user either via GUI or log output of a failure to create the
     * prefs directory.
     */
    protected abstract void warnUserOfPrefsDirCreationFailure();

    /**
     * @return an error message explaining the problem
     */
    protected final String[] createErrorMessage() {
        return new String[] {
                String.format("The '%s' folder cannot be created - the application cannot continue.\n",
                    mPrefsLocation.getPrefsDir().getAbsolutePath()),
            "This folder would be used to remember your options and settings.\n\n",
            "Failure to create this folder may be be due to security permissions, or a full disk.",
        };
    }
}