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/*
 * Copyright 2013 serso aka se.solovyev
 *
 * 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.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 * Contact details
 *
 * Email: [email protected]
 * Site:  http://se.solovyev.org
 */

package org.solovyev.android.prefs;

import android.content.SharedPreferences;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;

/**
 * User: serso
 * Date: 12/25/11
 * Time: 12:23 PM
 */

/**
 * Base class for {@link Preference} implementation. Contains preference key and default value
 *
 * @param  type of preference
 */
public abstract class AbstractPreference implements Preference {

    /*
	**********************************************************************
    *
    *                           FIELDS
    *
    **********************************************************************
    */

	@Nonnull
	private final String key;

	private final T defaultValue;

    /*
    **********************************************************************
    *
    *                           CONSTRUCTORS
    *
    **********************************************************************
    */

	protected AbstractPreference(@Nonnull String key, @Nullable T defaultValue) {
		this.key = key;
		this.defaultValue = defaultValue;
	}

    /*
    **********************************************************************
    *
    *                           METHODS
    *
    **********************************************************************
    */

	@Nonnull
	public String getKey() {
		return key;
	}

	public T getDefaultValue() {
		return defaultValue;
	}

	@Override
	public final T getPreference(@Nonnull SharedPreferences preferences) {
		if (isSet(preferences)) {
			return getPersistedValue(preferences);
		} else {
			return this.defaultValue;
		}
	}

	@Override
	public T getPreferenceNoError(@Nonnull SharedPreferences preferences) {
		if (isSet(preferences)) {
			try {
				return getPersistedValue(preferences);
			} catch (RuntimeException e) {
				return this.defaultValue;
			}
		} else {
			return this.defaultValue;
		}
	}

	@Override
	public void putDefault(@Nonnull SharedPreferences preferences) {
		putPreference(preferences, this.defaultValue);
	}

	@Override
	public void putPreference(@Nonnull SharedPreferences preferences, @Nullable T value) {
		if (value != null) {
			final SharedPreferences.Editor editor = preferences.edit();
			putPersistedValue(editor, value);
			editor.commit();
		}
	}

	@Override
	public boolean isSet(@Nonnull SharedPreferences preferences) {
		return preferences.contains(this.key);
	}

	@Override
	public final boolean tryPutDefault(@Nonnull SharedPreferences preferences) {
		final boolean result;

		if (isSet(preferences)) {
			result = false;
		} else {
			putDefault(preferences);
			result = true;
		}

		return result;
	}

	@Override
	public final boolean isSameKey(@Nonnull String key) {
		return this.key.equals(key);
	}

    /*
    **********************************************************************
    *
    *                           ABSTRACT METHODS
    *
    **********************************************************************
    */

	/**
	 * @param preferences preferences container
	 * @return preference value from preferences with key defined by {@link #getKey()} method
	 */
	@Nullable
	protected abstract T getPersistedValue(@Nonnull SharedPreferences preferences);

	/**
	 * Method saved preference to preferences container editor
	 *
	 * @param editor editor in which value must be saved
	 * @param value  value to be saved
	 */
	protected abstract void putPersistedValue(@Nonnull SharedPreferences.Editor editor, @Nonnull T value);

}