/*
 * The contents of this file are subject to the terms of the Common Development and
 * Distribution License (the License). You may not use this file except in compliance with the
 * License.
 *
 * You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
 * specific language governing permission and limitations under the License.
 *
 * When distributing Covered Software, include this CDDL Header Notice in each file and include
 * the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
 * Header, with the fields enclosed by brackets [] replaced by your own identifying
 * information: "Portions Copyright [year] [name of copyright owner]".
 *
 * Copyright 2008-2009 Sun Microsystems, Inc.
 * Portions Copyright 2012-2016 ForgeRock AS.
 */
package org.opends.server.schema;

import static org.opends.messages.ConfigMessages.*;
import static org.opends.messages.SchemaMessages.*;

import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Set;

import org.forgerock.i18n.LocalizableMessage;
import org.forgerock.i18n.slf4j.LocalizedLogger;
import org.forgerock.opendj.config.server.ConfigChangeResult;
import org.forgerock.opendj.config.server.ConfigException;
import org.forgerock.opendj.ldap.schema.ConflictingSchemaElementException;
import org.forgerock.opendj.ldap.schema.CoreSchema;
import org.forgerock.opendj.ldap.schema.MatchingRule;
import org.forgerock.opendj.ldap.schema.Schema;
import org.forgerock.opendj.ldap.schema.SchemaBuilder;
import org.opends.server.admin.server.ConfigurationChangeListener;
import org.opends.server.admin.std.server.CollationMatchingRuleCfg;
import org.opends.server.api.MatchingRuleFactory;
import org.opends.server.core.DirectoryServer;
import org.opends.server.types.DirectoryException;
import org.opends.server.types.InitializationException;
import org.opends.server.types.Schema.SchemaUpdater;
import org.opends.server.util.CollectionUtils;

/**
 * This class is a factory class for Collation matching rules. It
 * creates different matching rules based on the configuration entries.
 */
public final class CollationMatchingRuleFactory extends
    MatchingRuleFactory<CollationMatchingRuleCfg> implements
    ConfigurationChangeListener<CollationMatchingRuleCfg>
{
  private static final LocalizedLogger logger = LocalizedLogger.getLoggerForThisClass();

  /** Stores the list of available locales on this JVM. */
  private static final Set<Locale> supportedLocales = CollectionUtils.newHashSet(Locale.getAvailableLocales());

  /** Current Configuration. */
  private CollationMatchingRuleCfg currentConfig;
  /** Map of OID and the Matching Rule. */
  private final Map<String, MatchingRule> matchingRules = new HashMap<>();

  /** Creates a new instance of CollationMatchingRuleFactory. */
  public CollationMatchingRuleFactory()
  {
    super();
  }

  @Override
  public final Collection<MatchingRule> getMatchingRules()
  {
    return Collections.unmodifiableCollection(matchingRules.values());
  }

  @Override
  public void initializeMatchingRule(CollationMatchingRuleCfg configuration)
      throws ConfigException, InitializationException
  {
    // The core schema contains all supported collation matching rules so read it for initialization.
    // The server's schemaNG may have different things configured slightly differently
    org.opends.server.types.Schema schema = DirectoryServer.getSchema();
    Schema coreSchema = CoreSchema.getInstance();

    // on startup, the SDK already has existing matching rules
    // remove them all before letting the server set them all up
    // according to what this factory decides must be setup
    final Set<MatchingRule> defaultMatchingRules = getCollationMatchingRules(coreSchema.getMatchingRules());
    unregisterMatchingRules(schema, defaultMatchingRules);
    matchingRules.putAll(collectConfiguredMatchingRules(configuration, coreSchema));

    // Save this configuration.
    currentConfig = configuration;

    // Register for change events.
    currentConfig.addCollationChangeListener(this);
  }

  private void unregisterMatchingRules(org.opends.server.types.Schema schema,
      final Collection<MatchingRule> matchingRules) throws ConfigException
  {
    try
    {
      schema.updateSchema(new SchemaUpdater()
      {
        @Override
        public Schema update(SchemaBuilder builder)
        {
          for (final MatchingRule rule : matchingRules)
          {
            builder.removeMatchingRule(rule.getNameOrOID());
          }
          return builder.toSchema();
        }
      });
    }
    catch (DirectoryException e)
    {
      throw new ConfigException(e.getMessageObject(), e);
    }
  }

  private Map<String, MatchingRule> collectConfiguredMatchingRules(CollationMatchingRuleCfg configuration,
      Schema coreSchema)
  {
    final Map<String, MatchingRule> results = new HashMap<>();
    for (String collation : configuration.getCollation())
    {
      CollationMapper mapper = new CollationMapper(collation);

      String nOID = mapper.getNumericOID();
      String languageTag = mapper.getLanguageTag();
      if (nOID == null || languageTag == null)
      {
        logger.error(WARN_ATTR_INVALID_COLLATION_MATCHING_RULE_FORMAT, collation);
        continue;
      }
      Locale locale = getLocale(languageTag);
      if (locale == null)
      {
        // This locale is not supported by JVM.
        logger.error(WARN_ATTR_INVALID_COLLATION_MATCHING_RULE_LOCALE, collation, configuration.dn(), languageTag);
        continue;
      }

      final int[] numericSuffixes = { 1, 2, 3, 4, 5, 6 };
      for (int suffix : numericSuffixes)
      {
        final String oid = nOID + "." + suffix;
        final MatchingRule matchingRule = coreSchema.getMatchingRule(oid);
        results.put(oid, matchingRule);
      }
      // the default (equality) matching rule
      final MatchingRule defaultEqualityMatchingRule = coreSchema.getMatchingRule(nOID);
      results.put(nOID, defaultEqualityMatchingRule);
    }
    return results;
  }

  private Set<MatchingRule> getCollationMatchingRules(Collection<MatchingRule> matchingRules)
  {
    final Set<MatchingRule> results = new HashSet<>();
    for (MatchingRule matchingRule : matchingRules)
    {
      if (matchingRule.getOID().startsWith("1.3.6.1.4.1.42.2.27.9.4."))
      {
        results.add(matchingRule);
      }
    }
    return results;
  }

  @Override
  public void finalizeMatchingRule()
  {
    // De-register the listener.
    currentConfig.removeCollationChangeListener(this);
  }

  @Override
  public ConfigChangeResult applyConfigurationChange(final CollationMatchingRuleCfg configuration)
  {
    // validation has already been performed in isConfigurationChangeAcceptable()
    final ConfigChangeResult ccr = new ConfigChangeResult();

    if (!configuration.isEnabled()
        || currentConfig.isEnabled() != configuration.isEnabled())
    {
      // Don't do anything if:
      // 1. The configuration is disabled.
      // 2. There is a change in the enable status
      // i.e. (disable->enable or enable->disable). In this case, the
      // ConfigManager will have already created the new Factory object.
      return ccr;
    }

    // Since we have come here it means that this Factory is enabled
    // and there is a change in the CollationMatchingRuleFactory's configuration.
    final org.opends.server.types.Schema serverSchema = DirectoryServer.getSchema();
    final Collection<MatchingRule> existingCollationRules = getCollationMatchingRules(serverSchema.getMatchingRules());

    matchingRules.clear();
    final Map<String, MatchingRule> configuredMatchingRules =
        collectConfiguredMatchingRules(configuration, CoreSchema.getInstance());
    matchingRules.putAll(configuredMatchingRules);

    for (Iterator<MatchingRule> it = existingCollationRules.iterator(); it.hasNext();)
    {
      String oid = it.next().getOID();
      if (configuredMatchingRules.remove(oid) != null)
      {
        // no change
        it.remove();
      }
    }
    try
    {
      serverSchema.updateSchema(new SchemaUpdater()
      {
        @Override
        public Schema update(SchemaBuilder builder)
        {
          Collection<MatchingRule> defaultMatchingRules = CoreSchema.getInstance().getMatchingRules();
          for (MatchingRule rule : defaultMatchingRules)
          {
            if (configuredMatchingRules.containsKey(rule.getOID()))
            {
              try
              {
                // added
                builder.buildMatchingRule(rule).addToSchema();
              }
              catch (ConflictingSchemaElementException e)
              {
                ccr.setAdminActionRequired(true);
                ccr.addMessage(WARN_CONFIG_SCHEMA_MR_CONFLICTING_MR.get(configuration.dn(), e.getMessageObject()));
              }
            }
          }
          for (MatchingRule ruleToRemove : existingCollationRules)
          {
            // removed
            builder.removeMatchingRule(ruleToRemove.getOID());
          }
          return builder.toSchema();
        }
      });
    }
    catch (DirectoryException e)
    {
      ccr.setResultCode(e.getResultCode());
      ccr.addMessage(e.getMessageObject());
    }

    currentConfig = configuration;
    return ccr;
  }

  @Override
  public boolean isConfigurationChangeAcceptable(
      CollationMatchingRuleCfg configuration,
      List<LocalizableMessage> unacceptableReasons)
  {
    boolean configAcceptable = true;

    // If the new configuration disables this factory, don't do anything.
    if (!configuration.isEnabled())
    {
      return configAcceptable;
    }

    // If it comes here we don't need to verify MatchingRuleType;
    // it should be okay as its syntax is verified by the admin framework.
    // Iterate over the collations and verify if the format is okay.
    // Also, verify if the locale is allowed by the JVM.
    for (String collation : configuration.getCollation())
    {
      CollationMapper mapper = new CollationMapper(collation);

      String nOID = mapper.getNumericOID();
      String languageTag = mapper.getLanguageTag();
      if (nOID == null || languageTag == null)
      {
        configAcceptable = false;
        unacceptableReasons.add(WARN_ATTR_INVALID_COLLATION_MATCHING_RULE_FORMAT.get(collation));
        continue;
      }

      Locale locale = getLocale(languageTag);
      if (locale == null)
      {
        configAcceptable = false;
        unacceptableReasons.add(WARN_ATTR_INVALID_COLLATION_MATCHING_RULE_LOCALE.get(
                collation, configuration.dn(), languageTag));
        continue;
      }
    }
    return configAcceptable;
  }

  /**
   * Verifies if the locale is supported by the JVM.
   *
   * @param lTag
   *          The language tag specified in the configuration.
   * @return Locale The locale corresponding to the languageTag.
   */
  private Locale getLocale(String lTag)
  {
    // Separates the language and the country from the locale.
    Locale locale;

    int countryIndex = lTag.indexOf("-");
    int variantIndex = lTag.lastIndexOf("-");

    if (countryIndex > 0)
    {
      String lang = lTag.substring(0, countryIndex);
      String country;

      if (variantIndex > countryIndex)
      {
        country = lTag.substring(countryIndex + 1, variantIndex);
        String variant = lTag.substring(variantIndex + 1, lTag.length());
        locale = new Locale(lang, country, variant);
      }
      else
      {
        country = lTag.substring(countryIndex + 1, lTag.length());
        locale = new Locale(lang, country);
      }
    }
    else
    {
      locale = new Locale(lTag);
    }

    if (!supportedLocales.contains(locale))
    {
      // This locale is not supported by this JVM.
      locale = null;
    }
    return locale;
  }

  /** A utility class for extracting the OID and Language Tag from the configuration entry. */
  private final class CollationMapper
  {
    /** OID of the collation rule. */
    private String oid;

    /** Language Tag. */
    private String lTag;

    /**
     * Creates a new instance of CollationMapper.
     *
     * @param collation
     *          The collation text in the LOCALE:OID format.
     */
    private CollationMapper(String collation)
    {
      int index = collation.indexOf(":");
      if (index > 0)
      {
        oid = collation.substring(index + 1, collation.length());
        lTag = collation.substring(0, index);
      }
    }

    /**
     * Returns the OID part of the collation text.
     *
     * @return OID part of the collation text.
     */
    private String getNumericOID()
    {
      return oid;
    }

    /**
     * Returns the language Tag of collation text.
     *
     * @return Language Tag part of the collation text.
     */
    private String getLanguageTag()
    {
      return lTag;
    }
  }
}