/*
 * 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
 *
 *   https://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.apache.accumulo.core.data.constraints;

import static java.nio.charset.StandardCharsets.UTF_8;

import java.util.Collections;
import java.util.HashSet;
import java.util.List;

import org.apache.accumulo.access.AccessEvaluator;
import org.apache.accumulo.access.InvalidAccessExpressionException;
import org.apache.accumulo.core.data.ArrayByteSequence;
import org.apache.accumulo.core.data.ColumnUpdate;
import org.apache.accumulo.core.data.Mutation;

/**
 * A constraint that checks the visibility of columns against the actor's authorizations. Violation
 * codes:
 * <ul>
 * <li>1 = failure to parse visibility expression</li>
 * <li>2 = insufficient authorization</li>
 * </ul>
 *
 * <p>
 * This was moved from the org.apache.accumulo.core.constraints package since 2.1.0
 *
 * @since 2.1.0
 */
public class VisibilityConstraint implements Constraint {

  @Override
  public String getViolationDescription(short violationCode) {
    return switch (violationCode) {
      case 1 -> "Malformed column visibility";
      case 2 -> "User does not have authorization on column visibility";
      default -> null;
    };

  }

  @Override
  public List<Short> check(Environment env, Mutation mutation) {
    List<ColumnUpdate> updates = mutation.getUpdates();

    HashSet<String> ok = null;
    if (updates.size() > 1) {
      ok = new HashSet<>();
    }

    AccessEvaluator ve = null;

    for (ColumnUpdate update : updates) {

      byte[] cv = update.getColumnVisibility();
      if (cv.length > 0) {
        String key = null;
        if (ok != null && ok.contains(key = new String(cv, UTF_8))) {
          continue;
        }

        try {

          if (ve == null) {
            var authContainer = env.getAuthorizationsContainer();
            ve = AccessEvaluator.of(auth -> authContainer.contains(new ArrayByteSequence(auth)));
          }

          if (!ve.canAccess(cv)) {
            return Collections.singletonList((short) 2);
          }

        } catch (InvalidAccessExpressionException iaee) {
          return Collections.singletonList((short) 1);
        }

        if (ok != null) {
          ok.add(key);
        }
      }
    }

    return null;
  }
}
