/*
    * Copyright 2021 TiKV Project Authors.
    *
    * 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.tikv.common.key;
  
  import com.google.common.base.Joiner;
  import java.util.ArrayList;
  import java.util.List;
  import org.tikv.common.codec.CodecDataOutput;
  
  public class CompoundKey extends Key {
  
    private final List<Key> keys;
  
    protected CompoundKey(List<Key> keys, byte[] value) {
      super(value);
      this.keys = keys;
    }
  
    public static CompoundKey concat(Key lKey, Key rKey) {
      Builder builder = newBuilder();
      builder.append(lKey).append(rKey);
      return builder.build();
    }
  
    public static Builder newBuilder() {
      return new Builder();
    }
  
    public List<Key> getKeys() {
      return keys;
    }
  
    @Override
    public String toString() {
      return String.format("[%s]", Joiner.on(",").useForNull("Null").join(keys));
    }
  
    public static class Builder {
      private final List<Key> keys = new ArrayList<>();
  
      public Builder append(Key key) {
        if (key instanceof CompoundKey) {
          CompoundKey compKey = (CompoundKey) key;
          for (Key child : compKey.getKeys()) {
            append(child);
          }
        } else {
          keys.add(key);
        }
        return this;
      }
  
      public CompoundKey build() {
        int totalLen = 0;
        for (Key key : keys) {
          totalLen += key.getBytes().length;
        }
        CodecDataOutput cdo = new CodecDataOutput(totalLen);
        for (Key key : keys) {
          cdo.write(key.getBytes());
        }
        return new CompoundKey(keys, cdo.toBytes());
      }
    }
  }