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/*
 * 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 org.apache.parquet.crypto;

import java.nio.charset.StandardCharsets;

import org.apache.parquet.hadoop.metadata.ColumnPath;

public class ColumnEncryptionProperties {

  private final boolean encrypted;
  private final ColumnPath columnPath;
  private final boolean encryptedWithFooterKey;
  private final byte[] keyBytes;
  private final byte[] keyMetaData;

  private ColumnEncryptionProperties(boolean encrypted, ColumnPath columnPath, 
      byte[] keyBytes, byte[] keyMetaData) {

    if (null == columnPath) {
      throw new IllegalArgumentException("Null column path");
    }
    if (!encrypted) {
      if (null != keyBytes) {
        throw new IllegalArgumentException("Setting key on unencrypted column: " + columnPath);
      }
      if (null != keyMetaData) {
        throw new IllegalArgumentException("Setting key metadata on unencrypted column: " + columnPath);
      }
    }
    if ((null != keyBytes) && 
        !(keyBytes.length == 16 || keyBytes.length == 24 || keyBytes.length == 32)) {
      throw new IllegalArgumentException("Wrong key length: " + keyBytes.length + 
          ". Column: " + columnPath);
    }
    encryptedWithFooterKey = (encrypted && (null == keyBytes));
    if (encryptedWithFooterKey && (null != keyMetaData)) {
      throw new IllegalArgumentException("Setting key metadata on column encrypted with footer key:  " +
          columnPath);
    }

    this.encrypted = encrypted;
    this.columnPath = columnPath;
    this.keyBytes = keyBytes;
    this.keyMetaData = keyMetaData;
  }

  /**
   * Convenience builder for regular (not nested) columns.
   * To make sure column name is not misspelled or misplaced, 
   * file writer will verify that column is in file schema.
   *
   * @param name Flat column name
   * @return Builder
   */
  public static Builder builder(String name) {
    return builder(ColumnPath.get(name), true);
  }

  /**
   * Builder for encrypted columns.
   * To make sure column path is not misspelled or misplaced, 
   * file writer will verify this column is in file schema.
   * 
   * @param path Column path
   * @return Builder
   */
  public static Builder builder(ColumnPath path) {
    return builder(path, true);
  }

  static Builder builder(ColumnPath path, boolean encrypt) {
    return new Builder(path, encrypt);
  }

  public static class Builder {
    private final boolean encrypted;
    private final ColumnPath columnPath;

    private byte[] keyBytes;
    private byte[] keyMetaData;

    private Builder(ColumnPath path, boolean encrypted) {
      this.encrypted = encrypted;
      this.columnPath = path;
    }

    /**
     * Set a column-specific key.
     * If key is not set on an encrypted column, the column will
     * be encrypted with the footer key.
     * 
     * @param columnKey Key length must be either 16, 24 or 32 bytes.
     * @return Builder
     */
    public Builder withKey(byte[] columnKey) {
      if (null == columnKey) {
        return this;
      }
      if (null != this.keyBytes) {
        throw new IllegalStateException("Key already set on column: " + columnPath);
      }
      this.keyBytes = new byte[columnKey.length];
      System.arraycopy(columnKey, 0, this.keyBytes, 0, columnKey.length);

      return this;
    }

    /**
     * Set a key retrieval metadata.
     * use either withKeyMetaData or withKeyID, not both.
     * 
     * @param keyMetaData arbitrary byte array with encryption key metadata
     * @return Builder
     */
    public Builder withKeyMetaData(byte[] keyMetaData) {
      if (null == keyMetaData) {
        return this;
      }
      if (null != this.keyMetaData) {
        throw new IllegalStateException("Key metadata already set on column: " + columnPath);
      }
      this.keyMetaData = keyMetaData;

      return this;
    }

    /**
     * Set a key retrieval metadata (converted from String).
     * use either withKeyMetaData or withKeyID, not both.
     * 
     * @param keyId will be converted to metadata (UTF-8 array).
     * @return Builder
     */
    public Builder withKeyID(String keyId) {
      if (null == keyId) {
        return this;
      }
      byte[] metaData = keyId.getBytes(StandardCharsets.UTF_8);

      return withKeyMetaData(metaData);
    }

    public ColumnEncryptionProperties build() {
      return new ColumnEncryptionProperties(encrypted, columnPath, keyBytes, keyMetaData);
    }
  }

  public ColumnPath getPath() {
    return columnPath;
  }

  public boolean isEncrypted() {
    return encrypted;
  }

  public byte[] getKeyBytes() {
    return keyBytes;
  }

  public boolean isEncryptedWithFooterKey() {
    if (!encrypted) return false;
    return encryptedWithFooterKey;
  }

  public byte[] getKeyMetaData() {
    return keyMetaData;
  }
}