content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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 com.datastax.oss.driver.internal.core.metadata.schema.queries;
  
  import com.datastax.oss.driver.api.core.config.DefaultDriverOption;
  import edu.umd.cs.findbugs.annotations.NonNull;
  import java.util.ArrayList;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Optional;
  import java.util.Set;
  import java.util.function.Predicate;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  import java.util.regex.PatternSyntaxException;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Filters keyspaces during schema metadata queries.
   *
   * <p>Depending on the circumstances, we do it either on the server side with a WHERE IN clause that
   * will be appended to every query, or on the client side with a predicate that will be applied to
   * every fetched row.
   */
  class RuleBasedKeyspaceFilter implements KeyspaceFilter {
  
    private static final Logger LOG = LoggerFactory.getLogger(RuleBasedKeyspaceFilter.class);
  
    private static final Pattern EXACT_INCLUDE = Pattern.compile("\\w+");
    private static final Pattern EXACT_EXCLUDE = Pattern.compile("!\\s*(\\w+)");
    private static final Pattern REGEX_INCLUDE = Pattern.compile("/(.+)/");
    private static final Pattern REGEX_EXCLUDE = Pattern.compile("!\\s*/(.+)/");
  
    private final String logPrefix;
    private final String whereClause;
    private final Set<String> exactIncludes = new HashSet<>();
    private final Set<String> exactExcludes = new HashSet<>();
    private final List<Predicate<String>> regexIncludes = new ArrayList<>();
    private final List<Predicate<String>> regexExcludes = new ArrayList<>();
  
    private final boolean isDebugEnabled;
    private final Set<String> loggedKeyspaces;
  
    RuleBasedKeyspaceFilter(@NonNull String logPrefix, @NonNull List<String> specs) {
      assert !specs.isEmpty(); // see KeyspaceFilter#newInstance
  
      this.logPrefix = logPrefix;
      for (String spec : specs) {
        spec = spec.trim();
        Matcher matcher;
        if (EXACT_INCLUDE.matcher(spec).matches()) {
          exactIncludes.add(spec);
          if (exactExcludes.remove(spec)) {
            LOG.warn(
                "[{}] '{}' is both included and excluded, ignoring the exclusion", logPrefix, spec);
          }
        } else if ((matcher = EXACT_EXCLUDE.matcher(spec)).matches()) {
          String name = matcher.group(1);
          if (exactIncludes.contains(name)) {
            LOG.warn(
                "[{}] '{}' is both included and excluded, ignoring the exclusion", logPrefix, name);
          } else {
            exactExcludes.add(name);
          }
        } else if ((matcher = REGEX_INCLUDE.matcher(spec)).matches()) {
          compile(matcher.group(1)).map(regexIncludes::add);
        } else if ((matcher = REGEX_EXCLUDE.matcher(spec)).matches()) {
          compile(matcher.group(1)).map(regexExcludes::add);
        } else {
          LOG.warn(
              "[{}] Error while parsing {}: invalid element '{}', skipping",
              logPrefix,
              DefaultDriverOption.METADATA_SCHEMA_REFRESHED_KEYSPACES.getPath(),
              spec);
        }
      }
  
      if (!exactIncludes.isEmpty() && regexIncludes.isEmpty() && regexExcludes.isEmpty()) {
        // We can filter on the server
        whereClause = buildWhereClause(exactIncludes);
        if (!exactExcludes.isEmpty()) {
          // Proceed, but this is probably a mistake
          LOG.warn(
              "[{}] {} only has exact includes and excludes, the excludes are redundant",
              logPrefix,
              DefaultDriverOption.METADATA_SCHEMA_REFRESHED_KEYSPACES.getPath());
        }
        LOG.debug("[{}] Filtering server-side with '{}'", logPrefix, whereClause);
      } else {
        whereClause = "";
        LOG.debug("[{}] No server-side filtering", logPrefix);
      }
  
      isDebugEnabled = LOG.isDebugEnabled();
      loggedKeyspaces = isDebugEnabled ? new HashSet<>() : null;
    }
  
    @NonNull
    @Override
    public String getWhereClause() {
      return whereClause;
    }
  
    @Override
    public boolean includes(@NonNull String keyspace) {
      if (exactIncludes.contains(keyspace)) {
        log(keyspace, true, "it is included by name");
        return true;
      } else if (exactExcludes.contains(keyspace)) {
        log(keyspace, false, "it is excluded by name");
        return false;
      } else if (regexIncludes.isEmpty()) {
        if (regexExcludes.isEmpty()) {
          log(keyspace, false, "it is not included by name");
          return false;
        } else if (matchesAny(keyspace, regexExcludes)) {
          log(keyspace, false, "it matches at least one regex exclude");
          return false;
        } else {
          log(keyspace, true, "it does not match any regex exclude");
          return true;
        }
      } else { // !regexIncludes.isEmpty()
        if (regexExcludes.isEmpty()) {
          if (matchesAny(keyspace, regexIncludes)) {
            log(keyspace, true, "it matches at least one regex include");
            return true;
          } else {
            log(keyspace, false, "it does not match any regex include");
            return false;
          }
        } else {
          if (matchesAny(keyspace, regexIncludes) && !matchesAny(keyspace, regexExcludes)) {
            log(keyspace, true, "it matches at least one regex include, and no regex exclude");
            return true;
          } else {
            log(keyspace, false, "it matches either no regex include, or at least one regex exclude");
            return false;
          }
        }
      }
    }
  
    private void log(@NonNull String keyspace, boolean include, @NonNull String reason) {
      if (isDebugEnabled && loggedKeyspaces.add(keyspace)) {
        LOG.debug(
            "[{}] Filtering {} '{}' because {}", logPrefix, include ? "in" : "out", keyspace, reason);
      }
    }
  
    private boolean matchesAny(String keyspace, List<Predicate<String>> rules) {
      for (Predicate<String> rule : rules) {
        if (rule.test(keyspace)) {
          return true;
        }
      }
      return false;
    }
  
    private Optional<Predicate<String>> compile(String regex) {
      try {
        return Optional.of(Pattern.compile(regex).asPredicate());
      } catch (PatternSyntaxException e) {
        LOG.warn(
            "[{}] Error while parsing {}: syntax error in regex /{}/ ({}), skipping",
            this.logPrefix,
            DefaultDriverOption.METADATA_SCHEMA_REFRESHED_KEYSPACES.getPath(),
            regex,
            e.getMessage());
        return Optional.empty();
      }
    }
  
    private static String buildWhereClause(Set<String> keyspaces) {
      StringBuilder builder = new StringBuilder(" WHERE keyspace_name IN (");
      boolean first = true;
      for (String keyspace : keyspaces) {
        if (first) {
          first = false;
        } else {
          builder.append(",");
        }
        builder.append('\'').append(keyspace).append('\'');
      }
      return builder.append(')').toString();
    }
  }
  