/*
    * 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.hadoop.hbase.codec.prefixtree.encode.column;
  
  import java.io.IOException;
  import java.io.OutputStream;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.codec.prefixtree.PrefixTreeBlockMeta;
  import org.apache.hadoop.hbase.codec.prefixtree.encode.other.ColumnNodeType;
  import org.apache.hadoop.hbase.codec.prefixtree.encode.tokenize.Tokenizer;
  import org.apache.hadoop.hbase.codec.prefixtree.encode.tokenize.TokenizerNode;
  import org.apache.hadoop.hbase.util.CollectionUtils;
  import org.apache.hadoop.hbase.util.vint.UFIntTool;
  
  import com.google.common.collect.Lists;
  
  /**
   * Takes the tokenized family or qualifier data and flattens it into a stream of bytes. The family
   * section is written after the row section, and qualifier section after family section.
   * <p/>
   * The family and qualifier tries, or "column tries", are structured differently than the row trie.
   * The trie cannot be reassembled without external data about the offsets of the leaf nodes, and
   * these external pointers are stored in the nubs and leaves of the row trie. For each cell in a
   * row, the row trie contains a list of offsets into the column sections (along with pointers to
   * timestamps and other per-cell fields). These offsets point to the last column node/token that
   * comprises the column name. To assemble the column name, the trie is traversed in reverse (right
   * to left), with the rightmost tokens pointing to the start of their "parent" node which is the
   * node to the left.
   * <p/>
   * This choice was made to reduce the size of the column trie by storing the minimum amount of
   * offset data. As a result, to find a specific qualifier within a row, you must do a binary search
   * of the column nodes, reassembling each one as you search. Future versions of the PrefixTree might
   * encode the columns in both a forward and reverse trie, which would convert binary searches into
   * more efficient trie searches which would be beneficial for wide rows.
   */
  @InterfaceAudience.Private
  public class ColumnSectionWriter {
  
    public static final int EXPECTED_NUBS_PLUS_LEAVES = 100;
  
    /****************** fields ****************************/
  
    private PrefixTreeBlockMeta blockMeta;
  
    private ColumnNodeType nodeType;
    private Tokenizer tokenizer;
    private int numBytes = 0;
    private ArrayList<TokenizerNode> nonLeaves;
    private ArrayList<TokenizerNode> leaves;
    private ArrayList<TokenizerNode> allNodes;
    private ArrayList<ColumnNodeWriter> columnNodeWriters;
    private List<Integer> outputArrayOffsets;
  
  
    /*********************** construct *********************/
  
    public ColumnSectionWriter() {
      this.nonLeaves = Lists.newArrayList();
      this.leaves = Lists.newArrayList();
      this.outputArrayOffsets = Lists.newArrayList();
    }
  
    public ColumnSectionWriter(PrefixTreeBlockMeta blockMeta, Tokenizer builder,
        ColumnNodeType nodeType) {
      this();// init collections
      reconstruct(blockMeta, builder, nodeType);
    }
  
    public void reconstruct(PrefixTreeBlockMeta blockMeta, Tokenizer builder,
        ColumnNodeType nodeType) {
      this.blockMeta = blockMeta;
      this.tokenizer = builder;
      this.nodeType = nodeType;
    }
  
    public void reset() {
      numBytes = 0;
      nonLeaves.clear();
      leaves.clear();
      outputArrayOffsets.clear();
   }
 
 
   /****************** methods *******************************/
 
   public ColumnSectionWriter compile() {
     if (this.nodeType == ColumnNodeType.FAMILY) {
       // do nothing. max family length fixed at Byte.MAX_VALUE
     } else if (this.nodeType == ColumnNodeType.QUALIFIER) {
       blockMeta.setMaxQualifierLength(tokenizer.getMaxElementLength());
     } else {
       blockMeta.setMaxTagsLength(tokenizer.getMaxElementLength());
     }
     compilerInternals();
     return this;
   }
 
   protected void compilerInternals() {
     tokenizer.setNodeFirstInsertionIndexes();
     tokenizer.appendNodes(nonLeaves, true, false);
 
     tokenizer.appendNodes(leaves, false, true);
 
     allNodes = Lists.newArrayListWithCapacity(nonLeaves.size() + leaves.size());
     allNodes.addAll(nonLeaves);
     allNodes.addAll(leaves);
 
     columnNodeWriters = Lists.newArrayListWithCapacity(CollectionUtils.nullSafeSize(allNodes));
     for (int i = 0; i < allNodes.size(); ++i) {
       TokenizerNode node = allNodes.get(i);
       columnNodeWriters.add(new ColumnNodeWriter(blockMeta, node, this.nodeType));
     }
 
     // leaf widths are known at this point, so add them up
     int totalBytesWithoutOffsets = 0;
     for (int i = allNodes.size() - 1; i >= 0; --i) {
       ColumnNodeWriter columnNodeWriter = columnNodeWriters.get(i);
       // leaves store all but their first token byte
       totalBytesWithoutOffsets += columnNodeWriter.getWidthUsingPlaceholderForOffsetWidth(0);
     }
 
     // figure out how wide our offset FInts are
     int parentOffsetWidth = 0;
     while (true) {
       ++parentOffsetWidth;
       int numBytesFinder = totalBytesWithoutOffsets + parentOffsetWidth * allNodes.size();
       if (numBytesFinder < UFIntTool.maxValueForNumBytes(parentOffsetWidth)) {
         numBytes = numBytesFinder;
         break;
       }// it fits
     }
     if (this.nodeType == ColumnNodeType.FAMILY) {
       blockMeta.setFamilyOffsetWidth(parentOffsetWidth);
     } else if (this.nodeType == ColumnNodeType.QUALIFIER) {
       blockMeta.setQualifierOffsetWidth(parentOffsetWidth);
     } else {
       blockMeta.setTagsOffsetWidth(parentOffsetWidth);
     }
 
     int forwardIndex = 0;
     for (int i = 0; i < allNodes.size(); ++i) {
       TokenizerNode node = allNodes.get(i);
       ColumnNodeWriter columnNodeWriter = columnNodeWriters.get(i);
       int fullNodeWidth = columnNodeWriter
           .getWidthUsingPlaceholderForOffsetWidth(parentOffsetWidth);
       node.setOutputArrayOffset(forwardIndex);
       columnNodeWriter.setTokenBytes(node.getToken());
       if (node.isRoot()) {
         columnNodeWriter.setParentStartPosition(0);
       } else {
         columnNodeWriter.setParentStartPosition(node.getParent().getOutputArrayOffset());
       }
       forwardIndex += fullNodeWidth;
     }
 
     tokenizer.appendOutputArrayOffsets(outputArrayOffsets);
   }
 
   public void writeBytes(OutputStream os) throws IOException {
     for (ColumnNodeWriter columnNodeWriter : columnNodeWriters) {
       columnNodeWriter.writeBytes(os);
     }
   }
 
 
   /************* get/set **************************/
 
   public ArrayList<ColumnNodeWriter> getColumnNodeWriters() {
     return columnNodeWriters;
   }
 
   public int getNumBytes() {
     return numBytes;
   }
 
   public int getOutputArrayOffset(int sortedIndex) {
     return outputArrayOffsets.get(sortedIndex);
   }
 
   public ArrayList<TokenizerNode> getNonLeaves() {
     return nonLeaves;
   }
 
   public ArrayList<TokenizerNode> getLeaves() {
     return leaves;
   }
 
 }