/*
    * Copyright (C) 2009 The Guava 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 com.google.common.collect;
  
  import com.google.common.annotations.GwtCompatible;
  
  import java.util.LinkedHashMap;
  import java.util.Map;
  
  import javax.annotation.concurrent.Immutable;
  
  /**
   * A {@code RegularImmutableTable} optimized for sparse data.
   */
  @GwtCompatible
  @Immutable
  final class SparseImmutableTable<R, C, V>
      extends RegularImmutableTable<R, C, V> {
  
    private final ImmutableMap<R, Map<C, V>> rowMap;
    private final ImmutableMap<C, Map<R, V>> columnMap;
    private final int[] iterationOrderRow;
    private final int[] iterationOrderColumn;
  
    SparseImmutableTable(ImmutableList<Cell<R, C, V>> cellList,
        ImmutableSet<R> rowSpace, ImmutableSet<C> columnSpace) {
      Map<R, Integer> rowIndex = Maps.newHashMap();
      Map<R, Map<C, V>> rows = Maps.newLinkedHashMap();
      for (R row : rowSpace) {
        rowIndex.put(row, rows.size());
        rows.put(row, new LinkedHashMap<C, V>());
      }
      Map<C, Map<R, V>> columns = Maps.newLinkedHashMap();
      for (C col : columnSpace) {
        columns.put(col, new LinkedHashMap<R, V>());
      }
      int[] iterationOrderRow = new int[cellList.size()];
      int[] iterationOrderColumn = new int[cellList.size()];
      for (int i = 0; i < cellList.size(); i++) {
        Cell<R, C, V> cell = cellList.get(i);
        R rowKey = cell.getRowKey();
        C columnKey = cell.getColumnKey();
        V value = cell.getValue();
        
        iterationOrderRow[i] = rowIndex.get(rowKey);
        Map<C, V> thisRow = rows.get(rowKey);
        iterationOrderColumn[i] = thisRow.size();
        V oldValue = thisRow.put(columnKey, value);
        if (oldValue != null) {
          throw new IllegalArgumentException("Duplicate value for row=" + rowKey + ", column="
              + columnKey + ": " + value + ", " + oldValue);
        }
        columns.get(columnKey).put(rowKey, value);
      }
      this.iterationOrderRow = iterationOrderRow;
      this.iterationOrderColumn = iterationOrderColumn;
      ImmutableMap.Builder<R, Map<C, V>> rowBuilder = ImmutableMap.builder();
      for (Map.Entry<R, Map<C, V>> row : rows.entrySet()) {
        rowBuilder.put(row.getKey(), ImmutableMap.copyOf(row.getValue()));
      }
      this.rowMap = rowBuilder.build();
      
      ImmutableMap.Builder<C, Map<R, V>> columnBuilder = ImmutableMap.builder();
      for (Map.Entry<C, Map<R, V>> col : columns.entrySet()) {
        columnBuilder.put(col.getKey(), ImmutableMap.copyOf(col.getValue()));
      }
      this.columnMap = columnBuilder.build();
    }
  
    @Override public ImmutableMap<C, Map<R, V>> columnMap() {
      return columnMap;
    }
  
    @Override public ImmutableMap<R, Map<C, V>> rowMap() {
      return rowMap;
    }
  
    @Override
    public int size() {
      return iterationOrderRow.length;
    }
    
    @Override
    Cell<R, C, V> getCell(int index) {
      int rowIndex = iterationOrderRow[index];
      Map.Entry<R, Map<C, V>> rowEntry = rowMap.entrySet().asList().get(rowIndex);
      ImmutableMap<C, V> row = (ImmutableMap<C, V>) rowEntry.getValue();
     int columnIndex = iterationOrderColumn[index];
     Map.Entry<C, V> colEntry = row.entrySet().asList().get(columnIndex);
     return cellOf(rowEntry.getKey(), colEntry.getKey(), colEntry.getValue());
   }
 
   @Override
   V getValue(int index) {
     int rowIndex = iterationOrderRow[index];
     ImmutableMap<C, V> row = (ImmutableMap<C, V>) rowMap.values().asList().get(rowIndex);
     int columnIndex = iterationOrderColumn[index];
     return row.values().asList().get(columnIndex);
   }
 }