using System;

namespace NumSharp

{

public partial class NDArray

{

/// <summary>

/// Roll array elements along a given axis.

///

/// Elements that roll beyond the last position are re-introduced at the first.

/// </summary>

public NDArray roll(int shift, int axis)

{

if (axis > this.ndim)

throw new IncorrectShapeException();

shift = (axis == 0) ? (-1) * shift : shift;

shift = ((shift % this.shape[axis]) < 0) ? shift + this.shape[axis] : shift;

//TODO! rest of data types and remove usage of .Data, it'll fail if this NDArray's shape is a slice.

switch (dtype.Name)

{

case "Int32":

{

var data = this.Data<int>();

var newData = new int[this.size];

for (int idx = 0; idx < this.size; idx++)

{

int[] indexes = this.Storage.Shape.GetCoordinates(idx);

indexes[axis] = (indexes[axis] + shift) % this.shape[axis];

newData[this.Storage.Shape.GetOffset(indexes)] = data[idx];

}

return new NDArray(newData, this.shape);

}

case "Single":

{

var data = this.Data<float>();

var newData = new float[this.size];

for (int idx = 0; idx < this.size; idx++)

{

int[] indexes = this.Storage.Shape.GetCoordinates(idx);

indexes[axis] = (indexes[axis] + shift) % this.shape[axis];

newData[this.Storage.Shape.GetOffset(indexes)] = data[idx];

}

return new NDArray(newData, this.shape);

}

case "Double":

{

var data = this.Data<double>();

var newData = new double[this.size];

for (int idx = 0; idx < this.size; idx++)

{

int[] indexes = this.Storage.Shape.GetCoordinates(idx);

indexes[axis] = (indexes[axis] + shift) % this.shape[axis];

newData[this.Storage.Shape.GetOffset(indexes)] = data[idx];

}

return new NDArray(newData, this.shape);

}

default:

throw new NotImplementedException($"NDArray.roll {dtype.Name}");

}

}

public NDArray roll(int shift)

{

return null;

//shift = (-1) * shift;

//Array cpy = Arrays.Create(this.dtype, this.size);

//shift = ((shift % this.size) < 0) ? shift + this.size : shift;

////shift = shift % this.size;

//var strg = this.Storage.GetData();

//Array.Copy(strg, shift, cpy, 0, this.size - shift);

//for (int idx = 0; idx < shift; idx++)

// cpy.SetValue(strg.GetValue(idx), this.size - shift + idx);

//var returnValue = new NDArray(this.dtype);

//returnValue.Storage.Allocate(new Shape(this.shape));

//returnValue.Storage.ReplaceData(cpy);

//return returnValue;

}

}

}