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/*
 * Copyright 2013 Martin Kouba
 *
 * 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.trimou.prettytime.resolver;

import static org.trimou.engine.priority.Priorities.rightAfter;

import java.util.Date;
import java.util.Locale;
import java.util.Set;

import org.ocpsoft.prettytime.PrettyTime;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.trimou.engine.cache.ComputingCache;
import org.trimou.engine.config.ConfigurationKey;
import org.trimou.engine.config.SimpleConfigurationKey;
import org.trimou.engine.convert.Converter;
import org.trimou.engine.convert.ObjectToDateConverter;
import org.trimou.engine.resolver.ArrayIndexResolver;
import org.trimou.engine.resolver.ResolutionContext;
import org.trimou.engine.resolver.Resolver;
import org.trimou.engine.resolver.TransformResolver;
import org.trimou.engine.validation.Validateable;
import org.trimou.prettytime.DefaultPrettyTimeFactory;
import org.trimou.prettytime.PrettyTimeFactory;
import org.trimou.prettytime.PrettyTimeHelper;
import org.trimou.util.Checker;
import org.trimou.util.ImmutableSet;

/**
 * 
 * The PrettyTime resolver. Developers are encouraged to use
 * {@link PrettyTimeHelper} instead of this resolver to avoid the negative
 * performance impact during interpolation.
 * 
 *
 * 
 * Use {@link #MATCH_NAME_KEY} configuration property to customize the name to
 * match.
 * 
 *
 * 
 * If the configuration property with key {@link #ENABLED_KEY} resolves to
 * false, the resolver is marked as invalid.
 * 
 *
 * @author Martin Kouba
 * @see Resolver
 * @see PrettyTimeHelper
 */
public class PrettyTimeResolver extends TransformResolver implements
        Validateable {

    public static final int PRETTY_TIME_RESOLVER_PRIORITY = rightAfter(ArrayIndexResolver.ARRAY_RESOLVER_PRIORITY);

    public static final String COMPUTING_CACHE_CONSUMER_ID = PrettyTimeResolver.class
            .getName();

    public static final ConfigurationKey MATCH_NAME_KEY = new SimpleConfigurationKey(
            PrettyTimeResolver.class.getName() + ".matchName", "prettyTime");

    public static final ConfigurationKey ENABLED_KEY = new SimpleConfigurationKey(
            PrettyTimeResolver.class.getName() + ".enabled", false);

    private static final Logger LOGGER = LoggerFactory
            .getLogger(PrettyTimeResolver.class);

    private final PrettyTimeFactory factory;

    private final Converter converter;

    /**
     * Lazy loading cache of PrettyTime instances
     */
    private ComputingCache prettyTimeCache;

    /**
     *
     */
    public PrettyTimeResolver() {
        this(PRETTY_TIME_RESOLVER_PRIORITY, new DefaultPrettyTimeFactory());
    }

    /**
     *
     * @param priority
     * @param prettyTimeFactory
     */
    public PrettyTimeResolver(int priority, PrettyTimeFactory prettyTimeFactory) {
        this(priority, prettyTimeFactory, new ObjectToDateConverter());
    }

    /**
     *
     * @param priority
     * @param factory
     * @param converter
     */
    public PrettyTimeResolver(int priority, PrettyTimeFactory factory,
            Converter converter) {
        super(priority);
        Checker.checkArgumentsNotNull(factory, converter);
        this.factory = factory;
        this.converter = converter;
    }

    @Override
    public Object transform(Object contextObject, String name,
            ResolutionContext context) {
        Date value = converter.convert(contextObject);
        if (value == null) {
            return null;
        }
        return prettyTimeCache.get(getCurrentLocale()).format(value);
    }

    @Override
    public Set getConfigurationKeys() {
        return ImmutableSet.of(MATCH_NAME_KEY, ENABLED_KEY);
    }

    @Override
    public void init() {
        if (!configuration.getBooleanPropertyValue(ENABLED_KEY)) {
            return;
        }
        super.init();
        setMatchingNames(configuration.getStringPropertyValue(MATCH_NAME_KEY));
        prettyTimeCache = configuration.getComputingCacheFactory().create(
                COMPUTING_CACHE_CONSUMER_ID,
                new ComputingCache.Function() {
                    @Override
                    public PrettyTime compute(Locale key) {
                        return factory.createPrettyTime(key);
                    }
                }, null, 10l, null);
        LOGGER.info("Initialized [matchingName: {}]", matchingName(0));
    }

    @Override
    public boolean isValid() {
        return prettyTimeCache != null;
    }

}