package org.djunits.vecmat.storage;
   
   import java.util.Arrays;
   import java.util.Objects;
   
   import org.djunits.quantity.def.Quantity;
   import org.djunits.unit.UnitInterface;
   import org.djutils.exceptions.Throw;
   
  /**
   * DenseDoubleData implements a dense data grid for N x M matrices or N x 1 or 1 x M vectors with double values.
   * <p>
   * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See
   * for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
   * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
   * @author Alexander Verbraeck
   */
  public class DenseDoubleDataSi implements DataGridSi<DenseDoubleDataSi>
  {
      /** The data stored in row-major format. */
      private final double[] data;
  
      /** The number of rows. */
      private final int rows;
  
      /** the number of columns. */
      private final int cols;
  
      /**
       * Instantiate a data object with one array in row-major format. Note that NO safe copy of the data is stored.
       * @param data the data in row-major format
       * @param rows the number of rows
       * @param cols the number of columns
       * @throws IllegalArgumentException when the size of the data object is not equal to rows*cols, or when the number of rows
       *             or columns is not positive
       */
      public DenseDoubleDataSi(final double[] data, final int rows, final int cols)
      {
          Throw.whenNull(data, "data");
          Throw.when(rows <= 0, IllegalArgumentException.class, "Number of rows <= 0");
          Throw.when(cols <= 0, IllegalArgumentException.class, "Number of columns <= 0");
          Throw.when(data.length != rows * cols, IllegalArgumentException.class,
                  "Data object length != rows * cols, %d != %d * %d", data.length, rows, cols);
          this.data = data;
          this.rows = rows;
          this.cols = cols;
      }
  
      /**
       * Instantiate a data object with a double[rows][cols]. A safe copy of the data is stored.
       * @param data the data in row-major format
       * @throws IllegalArgumentException when the size of the data object is not equal to rows*cols
       */
      @SuppressWarnings("checkstyle:needbraces")
      public DenseDoubleDataSi(final double[][] data)
      {
          Throw.whenNull(data, "data");
          Throw.when(data.length == 0, IllegalArgumentException.class, "Number of rows in the data matrix = 0");
          this.rows = data.length;
          this.cols = data[0].length;
          this.data = new double[this.rows * this.cols];
          for (int r = 0; r < this.rows; r++)
          {
              Throw.when(data[r].length != this.cols, IllegalArgumentException.class,
                      "Number of columns in row %d (%d) is not equal to number of columns in row 0 (%d)", r, data[r].length,
                      this.cols);
              for (int c = 0; c < this.cols; c++)
                  this.data[r * this.cols + c] = data[r][c];
          }
      }
  
      /**
       * Instantiate a data object with a Q[rows][cols]. A safe copy of the data is stored.
       * @param data the data in row-major format
       * @throws IllegalArgumentException when the size of the data object is not equal to rows*cols
       * @param <Q> the quantity type
       * @param <U> the unit type
       */
      @SuppressWarnings("checkstyle:needbraces")
      public <Q extends Quantity<Q, U>, U extends UnitInterface<U, Q>> DenseDoubleDataSi(final Q[][] data)
      {
          Throw.whenNull(data, "data");
          Throw.when(data.length == 0, IllegalArgumentException.class, "Number of rows in the data matrix = 0");
          this.rows = data.length;
          this.cols = data[0].length;
          this.data = new double[this.rows * this.cols];
          for (int r = 0; r < this.rows; r++)
          {
              Throw.when(data[r].length != this.cols, IllegalArgumentException.class,
                      "Number of columns in row %d (%d) is not equal to number of columns in row 0 (%d)", r, data[r].length,
                      this.cols);
              for (int c = 0; c < this.cols; c++)
                  this.data[r * this.cols + c] = data[r][c].si();
          }
      }
  
      @Override
      public int rows()
      {
         return this.rows;
     }
 
     @Override
     public int cols()
     {
         return this.cols;
     }
 
     @Override
     public boolean isDense()
     {
         return true;
     }
 
     @Override
     public boolean isDouble()
     {
         return true;
     }
 
     /**
      * Check whether the row and column are within bounds.
      * @param row the row number
      * @param col the column number
      * @throws IndexOutOfBoundsException when row &gt; rows() or col &gt; cols() or row &lt; 0 or col &lt; 0
      */
     private void checkRowCol(final int row, final int col) throws IndexOutOfBoundsException
     {
         Throw.when(row < 0 || row >= this.rows, IndexOutOfBoundsException.class, "row %d not in range 0..%d", row, this.rows);
         Throw.when(col < 0 || col >= this.cols, IndexOutOfBoundsException.class, "column %d not in range 0..%d", col,
                 this.cols);
     }
 
     @Override
     public double get(final int row, final int col)
     {
         checkRowCol(row, col);
         return this.data[row * this.cols + col];
     }
 
     @Override
     public double[] getDataArray()
     {
         return this.data;
     }
 
     @Override
     public DenseDoubleDataSi copy()
     {
         return new DenseDoubleDataSi(this.data.clone(), rows(), cols());
     }
 
     @SuppressWarnings("checkstyle:needbraces")
     @Override
     public int cardinality()
     {
         int result = 0;
         for (int i = 0; i < this.data.length; i++)
             result += this.data[i] == 0.0 ? 0 : 1;
         return result;
     }
 
     @Override
     public DenseDoubleDataSi instantiateNew(final double[] newData)
     {
         Throw.when(newData.length != rows() * cols(), IllegalArgumentException.class,
                 "Data object length != rows * cols, %d != %d * %d", newData.length, rows(), cols());
         return new DenseDoubleDataSi(newData, rows(), cols());
     }
 
     @Override
     public DenseDoubleDataSi instantiateNew(final double[] newData, final int newRows, final int newCols)
     {
         Throw.when(newData.length != newRows * newCols, IllegalArgumentException.class,
                 "Data object length != rows * cols, %d != %d * %d", newData.length, newRows, newCols);
         return new DenseDoubleDataSi(newData, newRows, newCols);
     }
 
     @Override
     public int hashCode()
     {
         final int prime = 31;
         int result = 1;
         result = prime * result + Arrays.hashCode(this.data);
         result = prime * result + Objects.hash(this.cols, this.rows);
         return result;
     }
 
     @SuppressWarnings("checkstyle:needbraces")
     @Override
     public boolean equals(final Object obj)
     {
         if (this == obj)
             return true;
         if (obj == null)
             return false;
         if (getClass() != obj.getClass())
         {
             if (obj instanceof DataGridSi dg)
                 return this.cols == dg.cols()  && this.rows == dg.rows() && Arrays.equals(this.data, dg.getDataArray());
             return false;
         }
         DenseDoubleDataSi other = (DenseDoubleDataSi) obj;
         return this.cols == other.cols && this.rows == other.rows && Arrays.equals(this.data, other.data);
     }
 
 }