package org.djunits.value.vdouble.vector;
   
   import java.util.Arrays;
   import java.util.List;
   import java.util.SortedMap;
   import java.util.stream.IntStream;
   
   import org.djunits.unit.scale.Scale;
   import org.djunits.value.StorageType;
  import org.djunits.value.ValueException;
  import org.djunits.value.vdouble.scalar.DoubleScalarInterface;
  
  /**
   * Stores the data for a DoubleVector and carries out basic operations.
   * <p>
   * Copyright (c) 2013-2018 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
   * BSD-style license. See <a href="http://opentrafficsim.org/docs/license.html">OpenTrafficSim License</a>.
   * </p>
   * $LastChangedDate: 2015-07-24 02:58:59 +0200 (Fri, 24 Jul 2015) $, @version $Revision: 1147 $, by $Author: averbraeck $,
   * initial version Oct 3, 2015 <br>
   * @author <a href="http://www.tbm.tudelft.nl/averbraeck">Alexander Verbraeck</a>
   * @author <a href="http://www.tudelft.nl/pknoppers">Peter Knoppers</a>
   */
  abstract class DoubleVectorData
  {
      /** the internal storage of the Vector; can be sparse or dense. */
      @SuppressWarnings("checkstyle:visibilitymodifier")
      protected double[] vectorSI;
  
      /** the data type. */
      private final StorageType storageType;
  
      /** threshold to do parallel execution. */
      protected static final int PARALLEL_THRESHOLD = 1000;
  
      /**
       * @param storageType the data type.
       */
      DoubleVectorData(final StorageType storageType)
      {
          super();
          this.storageType = storageType;
      }
  
      /* ============================================================================================ */
      /* ====================================== INSTANTIATION ======================================= */
      /* ============================================================================================ */
  
      /**
       * Instantiate a DoubleVectorData with the right data type.
       * @param values the (SI) values to store
       * @param scale the scale of the unit to use for conversion to SI
       * @param storageType the data type to use
       * @return the DoubleVectorData with the right data type
       * @throws ValueException when values are null, or storageType is null
       */
      public static DoubleVectorData instantiate(final double[] values, final Scale scale, final StorageType storageType)
              throws ValueException
      {
          if (values == null)
          {
              throw new ValueException("DoubleVectorData.instantiate: double[] values is null");
          }
  
          double[] valuesSI = scale.isBaseSIScale() ? values : new double[values.length];
          if (!scale.isBaseSIScale())
          {
              if (values.length > PARALLEL_THRESHOLD)
              {
                  IntStream.range(0, values.length).parallel().forEach(i -> valuesSI[i] = scale.toStandardUnit(values[i]));
              }
              else
              {
                  IntStream.range(0, values.length).forEach(i -> valuesSI[i] = scale.toStandardUnit(values[i]));
              }
          }
  
          switch (storageType)
          {
              case DENSE:
                  return new DoubleVectorDataDense(valuesSI);
  
              case SPARSE:
                  return DoubleVectorDataSparse.instantiate(valuesSI);
  
              default:
                  throw new ValueException("Unknown data type in DoubleVectorData.instantiate: " + storageType);
          }
      }
  
      /**
       * Instantiate a DoubleVectorData with the right data type.
       * @param values the values to store
       * @param scale the scale of the unit to use for conversion to SI
       * @param storageType the data type to use
       * @return the DoubleVectorData with the right data type
       * @throws ValueException when list is null, or storageType is null
       */
      public static DoubleVectorData instantiate(final List<Double> values, final Scale scale, final StorageType storageType)
             throws ValueException
     {
         if (values == null)
         {
             throw new ValueException("DoubleVectorData.instantiate: List<Double> values is null");
         }
 
         double[] valuesSI;
         if (values.size() > PARALLEL_THRESHOLD)
         {
             if (scale.isBaseSIScale())
             {
                 valuesSI = values.parallelStream().mapToDouble(d -> d).toArray();
             }
             else
             {
                 valuesSI = values.parallelStream().mapToDouble(d -> scale.toStandardUnit(d)).toArray();
             }
         }
         else
         {
             if (scale.isBaseSIScale())
             {
                 valuesSI = values.stream().mapToDouble(d -> d).toArray();
             }
             else
             {
                 valuesSI = values.stream().mapToDouble(d -> scale.toStandardUnit(d)).toArray();
             }
         }
 
         switch (storageType)
         {
             case DENSE:
                 return new DoubleVectorDataDense(valuesSI);
 
             case SPARSE:
                 return DoubleVectorDataSparse.instantiate(valuesSI);
 
             default:
                 throw new ValueException("Unknown data type in DoubleVectorData.instantiate: " + storageType);
         }
     }
 
     /**
      * Instantiate a DoubleVectorData with the right data type.
      * @param values the values to store
      * @param storageType the data type to use
      * @return the DoubleVectorData with the right data type
      * @throws ValueException when values is null, or storageType is null
      */
     public static DoubleVectorData instantiate(final DoubleScalarInterface[] values, final StorageType storageType)
             throws ValueException
     {
         if (values == null)
         {
             throw new ValueException("DoubleVectorData.instantiate: DoubleScalar[] values is null");
         }
 
         double[] valuesSI;
         if (values.length > PARALLEL_THRESHOLD)
         {
             valuesSI = Arrays.stream(values).parallel().mapToDouble(s -> s.getSI()).toArray();
         }
         else
         {
             valuesSI = Arrays.stream(values).mapToDouble(s -> s.getSI()).toArray();
         }
 
         switch (storageType)
         {
             case DENSE:
                 return new DoubleVectorDataDense(valuesSI);
 
             case SPARSE:
                 return DoubleVectorDataSparse.instantiate(valuesSI);
 
             default:
                 throw new ValueException("Unknown data type in DoubleVectorData.instantiate: " + storageType);
         }
     }
 
     /**
      * Instantiate a DoubleVectorData with the right data type.
      * @param values the DoubleScalar values to store
      * @param storageType the data type to use
      * @return the DoubleVectorData with the right data type
      * @throws ValueException when values is null, or storageType is null
      */
     public static DoubleVectorData instantiateLD(final List<? extends DoubleScalarInterface> values,
             final StorageType storageType) throws ValueException
     {
         if (values == null)
         {
             throw new ValueException("DoubleVectorData.instantiate: values list is null");
         }
 
         double[] valuesSI = values.parallelStream().mapToDouble(s -> s.getSI()).toArray();
 
         switch (storageType)
         {
             case DENSE:
                 return new DoubleVectorDataDense(valuesSI);
 
             case SPARSE:
                 return DoubleVectorDataSparse.instantiate(valuesSI);
 
             default:
                 throw new ValueException("Unknown data type in DoubleVectorData.instantiate: " + storageType);
         }
     }
 
     /**
      * Instantiate a DoubleVectorData with the right data type.
      * @param values the DoubleScalar values to store
      * @param length the length of the vector to pad with 0 after last entry in map
      * @param storageType the data type to use
      * @param <S> the scalar type to use
      * @return the DoubleVectorData with the right data type
      * @throws ValueException when values is null, or storageType is null
      */
     public static <S extends DoubleScalarInterface> DoubleVectorData instantiateMD(final SortedMap<Integer, S> values,
             final int length, final StorageType storageType) throws ValueException
     {
         if (values == null)
         {
             throw new ValueException("DoubleVectorData.instantiate: values map is null");
         }
 
         switch (storageType)
         {
             case DENSE:
             {
                 double[] valuesSI = values.keySet().parallelStream().mapToDouble(index -> values.get(index).getSI()).toArray();
                 return new DoubleVectorDataDense(valuesSI);
             }
 
             case SPARSE:
             {
                 int[] indices = values.keySet().parallelStream().mapToInt(i -> i).toArray();
                 double[] valuesSI = values.values().parallelStream().mapToDouble(s -> s.getSI()).toArray();
                 return new DoubleVectorDataSparse(valuesSI, indices, length);
             }
 
             default:
                 throw new ValueException("Unknown data type in DoubleVectorData.instantiate: " + storageType);
         }
     }
 
     /**
      * Instantiate a DoubleVectorData with the right data type.
      * @param values the DoubleScalar values to store
      * @param length the length of the vector to pad with 0 after last entry in map
      * @param scale the scale of the unit to use for conversion to SI
      * @param storageType the data type to use
      * @return the DoubleVectorData with the right data type
      * @throws ValueException when values is null, or storageType is null
      */
     public static DoubleVectorData instantiate(final SortedMap<Integer, Double> values, final int length, final Scale scale,
             final StorageType storageType) throws ValueException
     {
         if (values == null)
         {
             throw new ValueException("DoubleVectorData.instantiate: values map is null");
         }
 
         switch (storageType)
         {
             case DENSE:
             {
                 double[] valuesSI = values.keySet().parallelStream()
                         .mapToDouble(index -> scale.toStandardUnit(values.get(index))).toArray();
                 return new DoubleVectorDataDense(valuesSI);
             }
 
             case SPARSE:
             {
                 int[] indices = values.keySet().parallelStream().mapToInt(i -> i).toArray();
                 double[] valuesSI = values.values().parallelStream().mapToDouble(d -> scale.toStandardUnit(d)).toArray();
                 return new DoubleVectorDataSparse(valuesSI, indices, length);
             }
 
             default:
                 throw new ValueException("Unknown data type in DoubleVectorData.instantiate: " + storageType);
         }
     }
 
     /* ============================================================================================ */
     /* ==================================== UTILITY FUNCTIONS ===================================== */
     /* ============================================================================================ */
 
     /**
      * Return the StorageType (DENSE, SPARSE, etc.) for the stored Vector.
      * @return the StorageType (DENSE, SPARSE, etc.) for the stored Vector
      */
     public final StorageType getStorageType()
     {
         return this.storageType;
     }
 
     /**
      * @return the size of the vector
      */
     public abstract int size();
 
     /**
      * @return whether data type is sparse.
      */
     public boolean isSparse()
     {
         return this.storageType.equals(StorageType.SPARSE);
     }
 
     /**
      * @return the sparse transformation of this data
      */
     public DoubleVectorDataSparse toSparse()
     {
         return isSparse() ? (DoubleVectorDataSparse) this : ((DoubleVectorDataDense) this).toSparse();
     }
 
     /**
      * @return whether data type is dense.
      */
     public boolean isDense()
     {
         return this.storageType.equals(StorageType.DENSE);
     }
 
     /**
      * @return the dense transformation of this data
      */
     public DoubleVectorDataDense toDense()
     {
         return isDense() ? (DoubleVectorDataDense) this : ((DoubleVectorDataSparse) this).toDense();
     }
 
     /**
      * @param index the index to get the value for
      * @return the value at the index
      */
     public abstract double getSI(int index);
 
     /**
      * Sets a value at the index in the vector.
      * @param index the index to set the value for
      * @param valueSI the value at the index
      */
     public abstract void setSI(int index, double valueSI);
 
     /**
      * @return the number of non-zero cells.
      */
     public final int cardinality()
     {
         return (int) Arrays.stream(this.vectorSI).parallel().filter(d -> d != 0.0).count();
     }
 
     /**
      * @return the sum of the values of all cells.
      */
     public final double zSum()
     {
         return Arrays.stream(this.vectorSI).parallel().sum();
     }
 
     /**
      * @return a deep copy of the data.
      */
     public abstract DoubleVectorData copy();
 
     /**
      * @return a safe copy of VectorSI
      */
     public abstract double[] getDenseVectorSI();
 
     /**
      * Check the sizes of this data object and the other data object.
      * @param other the other data object
      * @throws ValueException if vectors have different lengths
      */
     private void checkSizes(final DoubleVectorData other) throws ValueException
     {
         if (this.size() != other.size())
         {
             throw new ValueException("Two data objects used in a DoubleVector operation do not have the same size");
         }
     }
 
     /* ============================================================================================ */
     /* ================================== CALCULATION FUNCTIONS =================================== */
     /* ============================================================================================ */
 
     /**
      * Add two vectors on a cell-by-cell basis. If both vectors are sparse, a sparse vector is returned, otherwise a dense
      * vector is returned.
      * @param right the other data object to add
      * @return the sum of this data object and the other data object
      * @throws ValueException if vectors have different lengths
      */
     public DoubleVectorData plus(final DoubleVectorData right) throws ValueException
     {
         checkSizes(right);
         double[] dv = IntStream.range(0, size()).parallel().mapToDouble(i -> getSI(i) + right.getSI(i)).toArray();
         if (this instanceof DoubleVectorDataSparse && right instanceof DoubleVectorDataSparse)
         {
             return new DoubleVectorDataDense(dv).toSparse();
         }
         return new DoubleVectorDataDense(dv);
     }
 
     /**
      * Add a vector to this vector on a cell-by-cell basis. The type of vector (sparse, dense) stays the same.
      * @param right the other data object to add
      * @throws ValueException if vectors have different lengths
      */
     public abstract void incrementBy(DoubleVectorData right) throws ValueException;
 
     /**
      * Add a number to this vector on a cell-by-cell basis.
      * @param valueSI the value to add
      */
     public void incrementBy(final double valueSI)
     {
         IntStream.range(0, this.vectorSI.length).parallel().forEach(i -> this.vectorSI[i] += valueSI);
     }
 
     /**
      * Subtract two vectors on a cell-by-cell basis. If both vectors are sparse, a sparse vector is returned, otherwise a dense
      * vector is returned.
      * @param right the other data object to subtract
      * @return the sum of this data object and the other data object
      * @throws ValueException if vectors have different lengths
      */
     public DoubleVectorData minus(final DoubleVectorData right) throws ValueException
     {
         checkSizes(right);
         double[] dv = IntStream.range(0, size()).parallel().mapToDouble(i -> getSI(i) - right.getSI(i)).toArray();
         if (this instanceof DoubleVectorDataSparse && right instanceof DoubleVectorDataSparse)
         {
             return new DoubleVectorDataDense(dv).toSparse();
         }
         return new DoubleVectorDataDense(dv);
     }
 
     /**
      * Subtract a vector from this vector on a cell-by-cell basis. The type of vector (sparse, dense) stays the same.
      * @param right the other data object to subtract
      * @throws ValueException if vectors have different lengths
      */
     public abstract void decrementBy(DoubleVectorData right) throws ValueException;
 
     /**
      * Subtract a number from this vector on a cell-by-cell basis.
      * @param valueSI the value to subtract
      */
     public void decrementBy(final double valueSI)
     {
         IntStream.range(0, this.vectorSI.length).parallel().forEach(i -> this.vectorSI[i] -= valueSI);
     }
 
     /**
      * Multiply two vector on a cell-by-cell basis. If both vectors are dense, a dense vector is returned, otherwise a sparse
      * vector is returned.
      * @param right the other data object to multiply with
      * @return the sum of this data object and the other data object
      * @throws ValueException if vectors have different lengths
      */
     public DoubleVectorData times(final DoubleVectorData right) throws ValueException
     {
         checkSizes(right);
         double[] dv = IntStream.range(0, size()).parallel().mapToDouble(i -> getSI(i) * right.getSI(i)).toArray();
         if (this instanceof DoubleVectorDataDense && right instanceof DoubleVectorDataDense)
         {
             return new DoubleVectorDataDense(dv);
         }
         return new DoubleVectorDataDense(dv).toSparse();
     }
 
     /**
      * Multiply a vector with the values of another vector on a cell-by-cell basis. The type of vector (sparse, dense) stays the
      * same.
      * @param right the other data object to multiply with
      * @throws ValueException if vectors have different lengths
      */
     public abstract void multiplyBy(DoubleVectorData right) throws ValueException;
 
     /**
      * Multiply the values of this vector with a number on a cell-by-cell basis.
      * @param valueSI the value to multiply with
      */
     public void multiplyBy(final double valueSI)
     {
         IntStream.range(0, this.vectorSI.length).parallel().forEach(i -> this.vectorSI[i] *= valueSI);
     }
 
     /**
      * Divide two vectors on a cell-by-cell basis. If both vectors are dense, a dense vector is returned, otherwise a sparse
      * vector is returned.
      * @param right the other data object to divide by
      * @return the sum of this data object and the other data object
      * @throws ValueException if vectors have different lengths
      */
     public DoubleVectorData divide(final DoubleVectorData right) throws ValueException
     {
         checkSizes(right);
         double[] dv = IntStream.range(0, size()).parallel().mapToDouble(i -> getSI(i) / right.getSI(i)).toArray();
         if (this instanceof DoubleVectorDataDense && right instanceof DoubleVectorDataDense)
         {
             return new DoubleVectorDataDense(dv);
         }
         return new DoubleVectorDataDense(dv).toSparse();
     }
 
     /**
      * Divide the values of a vector by the values of another vector on a cell-by-cell basis. The type of vector (sparse, dense)
      * stays the same.
      * @param right the other data object to divide by
      * @throws ValueException if vectors have different lengths
      */
     public abstract void divideBy(DoubleVectorData right) throws ValueException;
 
     /**
      * Divide the values of this vector by a number on a cell-by-cell basis.
      * @param valueSI the value to multiply with
      */
     public void divideBy(final double valueSI)
     {
         IntStream.range(0, this.vectorSI.length).parallel().forEach(i -> this.vectorSI[i] /= valueSI);
     }
 
     /* ============================================================================================ */
     /* =============================== EQUALS, HASHCODE, TOSTRING ================================= */
     /* ============================================================================================ */
 
     /** {@inheritDoc} */
     @Override
     public int hashCode()
     {
         final int prime = 31;
         int result = 1;
         result = prime * result + Arrays.hashCode(this.vectorSI);
         return result;
     }
 
     /** {@inheritDoc} */
     @Override
     @SuppressWarnings("checkstyle:needbraces")
     public boolean equals(final Object obj)
     {
         if (this == obj)
             return true;
         if (obj == null)
             return false;
         if (getClass() != obj.getClass())
             return false;
         DoubleVectorData other = (DoubleVectorData) obj;
         if (!Arrays.equals(this.vectorSI, other.vectorSI))
             return false;
         return true;
     }
 
     /** {@inheritDoc} */
     @Override
     public String toString()
     {
         return "DoubleVectorData [storageType=" + this.storageType + ", vectorSI=" + Arrays.toString(this.vectorSI) + "]";
     }
 }