/*
 * 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.lucene.search;


import java.io.IOException;

import org.apache.lucene.index.DocValues;
import org.apache.lucene.index.IndexSorter;
import org.apache.lucene.index.LeafReader;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.index.NumericDocValues;
import org.apache.lucene.index.SortFieldProvider;
import org.apache.lucene.index.SortedNumericDocValues;
import org.apache.lucene.search.comparators.DoubleComparator;
import org.apache.lucene.search.comparators.FloatComparator;
import org.apache.lucene.search.comparators.IntComparator;
import org.apache.lucene.search.comparators.LongComparator;
import org.apache.lucene.store.DataInput;
import org.apache.lucene.store.DataOutput;
import org.apache.lucene.util.NumericUtils;

SortField for SortedNumericDocValues. 

A SortedNumericDocValues contains multiple values for a field, so sorting with
this technique "selects" a value as the representative sort value for the document.

By default, the minimum value in the list is selected as the sort value, but
this can be customized.
 Like sorting by string, this also supports sorting missing values as first or last, via setMissingValue(Object). 
See Also:
SortedNumericSelector/** 
 * SortField for {@link SortedNumericDocValues}.
 * <p>
 * A SortedNumericDocValues contains multiple values for a field, so sorting with
 * this technique "selects" a value as the representative sort value for the document.
 * <p>
 * By default, the minimum value in the list is selected as the sort value, but
 * this can be customized.
 * <p>
 * Like sorting by string, this also supports sorting missing values as first or last,
 * via {@link #setMissingValue(Object)}.
 * @see SortedNumericSelector
 */
public class SortedNumericSortField extends SortField {
  
  private final SortedNumericSelector.Type selector;
  private final SortField.Type type;
  
  
Creates a sort, by the minimum value in the set 
for the document.
Params:
field – Name of field to sort by.  Must not be null.
type – Type of values/**
   * Creates a sort, by the minimum value in the set 
   * for the document.
   * @param field Name of field to sort by.  Must not be null.
   * @param type Type of values
   */
  public SortedNumericSortField(String field, SortField.Type type) {
    this(field, type, false);
  }
  
  
Creates a sort, possibly in reverse, by the minimum value in the set 
for the document.
Params:
field – Name of field to sort by.  Must not be null.
type – Type of values
reverse – True if natural order should be reversed./**
   * Creates a sort, possibly in reverse, by the minimum value in the set 
   * for the document.
   * @param field Name of field to sort by.  Must not be null.
   * @param type Type of values
   * @param reverse True if natural order should be reversed.
   */
  public SortedNumericSortField(String field, SortField.Type type, boolean reverse) {
    this(field, type, reverse, SortedNumericSelector.Type.MIN);
  }

  
Creates a sort, possibly in reverse, specifying how the sort value from 
the document's set is selected.
Params:
field – Name of field to sort by.  Must not be null.
type – Type of values
reverse – True if natural order should be reversed.
selector – custom selector type for choosing the sort value from the set./**
   * Creates a sort, possibly in reverse, specifying how the sort value from 
   * the document's set is selected.
   * @param field Name of field to sort by.  Must not be null.
   * @param type Type of values
   * @param reverse True if natural order should be reversed.
   * @param selector custom selector type for choosing the sort value from the set.
   */
  public SortedNumericSortField(String field, SortField.Type type, boolean reverse, SortedNumericSelector.Type selector) {
    super(field, SortField.Type.CUSTOM, reverse);
    if (selector == null) {
      throw new NullPointerException();
    }
    if (type == null) {
      throw new NullPointerException();
    }
    this.selector = selector;
    this.type = type;
  }

  
A SortFieldProvider for this sort field /** A SortFieldProvider for this sort field */
  public static final class Provider extends SortFieldProvider {

    
The name this provider is registered under /** The name this provider is registered under */
    public static final String NAME = "SortedNumericSortField";

    
Creates a new Provider /** Creates a new Provider */
    public Provider() {
      super(NAME);
    }

    @Override
    public SortField readSortField(DataInput in) throws IOException {
      SortedNumericSortField sf = new SortedNumericSortField(in.readString(), readType(in), in.readInt() == 1, readSelectorType(in));
      if (in.readInt() == 1) {
        switch (sf.type) {
          case INT:
            sf.setMissingValue(in.readInt());
            break;
          case LONG:
            sf.setMissingValue(in.readLong());
            break;
          case FLOAT:
            sf.setMissingValue(NumericUtils.sortableIntToFloat(in.readInt()));
            break;
          case DOUBLE:
            sf.setMissingValue(NumericUtils.sortableLongToDouble(in.readLong()));
            break;
          default:
            throw new AssertionError();
        }
      }
      return sf;
    }

    @Override
    public void writeSortField(SortField sf, DataOutput out) throws IOException {
      assert sf instanceof SortedNumericSortField;
      ((SortedNumericSortField)sf).serialize(out);
    }
  }

  private static SortedNumericSelector.Type readSelectorType(DataInput in) throws IOException {
    int selectorType = in.readInt();
    if (selectorType >= SortedNumericSelector.Type.values().length) {
      throw new IllegalArgumentException("Can't deserialize SortedNumericSortField - unknown selector type " + selectorType);
    }
    return SortedNumericSelector.Type.values()[selectorType];
  }

  private void serialize(DataOutput out) throws IOException {
    out.writeString(getField());
    out.writeString(type.toString());
    out.writeInt(reverse ? 1 : 0);
    out.writeInt(selector.ordinal());
    if (missingValue == null) {
      out.writeInt(0);
    }
    else {
      out.writeInt(1);
      // oh for switch expressions...
      switch (type) {
        case INT:
          out.writeInt((int)missingValue);
          break;
        case LONG:
          out.writeLong((long)missingValue);
          break;
        case FLOAT:
          out.writeInt(NumericUtils.floatToSortableInt((float)missingValue));
          break;
        case DOUBLE:
          out.writeLong(NumericUtils.doubleToSortableLong((double)missingValue));
          break;
        default:
          throw new AssertionError();
      }
    }
  }

  
Returns the numeric type in use for this sort /** Returns the numeric type in use for this sort */
  public SortField.Type getNumericType() {
    return type;
  }
  
  
Returns the selector in use for this sort /** Returns the selector in use for this sort */
  public SortedNumericSelector.Type getSelector() {
    return selector;
  }
  
  @Override
  public int hashCode() {
    final int prime = 31;
    int result = super.hashCode();
    result = prime * result + selector.hashCode();
    result = prime * result + type.hashCode();
    return result;
  }

  @Override
  public boolean equals(Object obj) {
    if (this == obj) return true;
    if (!super.equals(obj)) return false;
    if (getClass() != obj.getClass()) return false;
    SortedNumericSortField other = (SortedNumericSortField) obj;
    if (selector != other.selector) return false;
    if (type != other.type) return false;
    return true;
  }

  @Override
  public String toString() {
    StringBuilder buffer = new StringBuilder();
    buffer.append("<sortednumeric" + ": \"").append(getField()).append("\">");
    if (getReverse()) buffer.append('!');
    if (missingValue != null) {
      buffer.append(" missingValue=");
      buffer.append(missingValue);
    }
    buffer.append(" selector=");
    buffer.append(selector);
    buffer.append(" type=");
    buffer.append(type);

    return buffer.toString();
  }
  
  @Override
  public void setMissingValue(Object missingValue) {
    this.missingValue = missingValue;
  }
  
  @Override
  public FieldComparator<?> getComparator(int numHits, int sortPos) {
    switch(type) {
      case INT:
        return new IntComparator(numHits, getField(), (Integer) missingValue, reverse, sortPos) {
          @Override
          public LeafFieldComparator getLeafComparator(LeafReaderContext context) throws IOException {
            return new IntLeafComparator(context) {
              @Override
              protected NumericDocValues getNumericDocValues(LeafReaderContext context, String field) throws IOException {
                return SortedNumericSelector.wrap(DocValues.getSortedNumeric(context.reader(), field), selector, type);
              }
            };
          }
        };
      case FLOAT:
        return new FloatComparator(numHits, getField(), (Float) missingValue, reverse, sortPos) {
          @Override
          public LeafFieldComparator getLeafComparator(LeafReaderContext context) throws IOException {
            return new FloatLeafComparator(context) {
              @Override
              protected NumericDocValues getNumericDocValues(LeafReaderContext context, String field) throws IOException {
                return SortedNumericSelector.wrap(DocValues.getSortedNumeric(context.reader(), field), selector, type);
              }
            };
          }
        };
      case LONG:
        return new LongComparator(numHits, getField(), (Long) missingValue, reverse, sortPos) {
          @Override
          public LeafFieldComparator getLeafComparator(LeafReaderContext context) throws IOException {
            return new LongLeafComparator(context) {
              @Override
              protected NumericDocValues getNumericDocValues(LeafReaderContext context, String field) throws IOException {
                return SortedNumericSelector.wrap(DocValues.getSortedNumeric(context.reader(), field), selector, type);
              }
            };
          }
        };
      case DOUBLE:
        return new DoubleComparator(numHits, getField(), (Double) missingValue, reverse, sortPos) {
          @Override
          public LeafFieldComparator getLeafComparator(LeafReaderContext context) throws IOException {
            return new DoubleLeafComparator(context) {
              @Override
              protected NumericDocValues getNumericDocValues(LeafReaderContext context, String field) throws IOException {
                return SortedNumericSelector.wrap(DocValues.getSortedNumeric(context.reader(), field), selector, type);
              }
            };
          }
        };
      default:
        throw new AssertionError();
    }
  }

  private NumericDocValues getValue(LeafReader reader) throws IOException {
    return SortedNumericSelector.wrap(DocValues.getSortedNumeric(reader, getField()), selector, type);
  }

  @Override
  public IndexSorter getIndexSorter() {
    switch(type) {
      case INT:
        return new IndexSorter.IntSorter(Provider.NAME, (Integer)missingValue, reverse, this::getValue);
      case LONG:
        return new IndexSorter.LongSorter(Provider.NAME, (Long)missingValue, reverse, this::getValue);
      case DOUBLE:
        return new IndexSorter.DoubleSorter(Provider.NAME, (Double)missingValue, reverse, this::getValue);
      case FLOAT:
        return new IndexSorter.FloatSorter(Provider.NAME, (Float)missingValue, reverse, this::getValue);
      default:
        throw new AssertionError();
    }
  }
}