using System;
using MathNet.Numerics.Properties;

namespace MathNet.Numerics.LinearAlgebra.Storage
{
    public class DenseColumnMajorMatrixStorage<T> : MatrixStorage<T>
        where T : struct, IEquatable<T>, IFormattable
    {
        // [ruegg] public fields are OK here

        public readonly T[] Data;

        internal DenseColumnMajorMatrixStorage(int rows, int columns)
            : base(rows, columns)
        {
            Data = new T[rows * columns];
        }

        internal DenseColumnMajorMatrixStorage(int rows, int columns, T[] data)
            : base(rows, columns)
        {
            if (data == null)
            {
                throw new ArgumentNullException("data");
            }

            if (data.Length != rows * columns)
            {
                throw new ArgumentOutOfRangeException("data", string.Format(Resources.ArgumentArrayWrongLength, rows * columns));
            }

            Data = data;
        }

        /// <summary>
        /// Retrieves the requested element without range checking.
        /// </summary>
        public override T At(int row, int column)
        {
            return Data[(column * RowCount) + row];
        }

        /// <summary>
        /// Sets the element without range checking.
        /// </summary>
        public override void At(int row, int column, T value)
        {
            Data[(column * RowCount) + row] = value;
        }

        public override void Clear()
        {
            Array.Clear(Data, 0, Data.Length);
        }

        public override void Clear(int rowIndex, int rowCount, int columnIndex, int columnCount)
        {
            if (rowIndex == 0 && columnIndex == 0 && rowCount == RowCount && columnCount == ColumnCount)
            {
                Clear();
                return;
            }

            for (int j = columnIndex; j < columnIndex + columnCount; j++)
            {
                Array.Clear(Data, j*RowCount + rowIndex, rowCount);
            }
        }

        /// <remarks>Parameters assumed to be validated already.</remarks>
        public override void CopyTo(MatrixStorage<T> target, bool skipClearing = false)
        {
            var denseTarget = target as DenseColumnMajorMatrixStorage<T>;
            if (denseTarget != null)
            {
                CopyTo(denseTarget);
                return;
            }

            // FALL BACK

            for (int j = 0, offset = 0; j < ColumnCount; j++, offset += RowCount)
            {
                for (int i = 0; i < RowCount; i++)
                {
                    target.At(i, j, Data[i + offset]);
                }
            }
        }

        void CopyTo(DenseColumnMajorMatrixStorage<T> target)
        {
            if (ReferenceEquals(this, target))
            {
                return;
            }

            if (target == null)
            {
                throw new ArgumentNullException("target");
            }

            if (RowCount != target.RowCount || ColumnCount != target.ColumnCount)
            {
                var message = string.Format(Resources.ArgumentMatrixDimensions2, RowCount + "x" + ColumnCount, target.RowCount + "x" + target.ColumnCount);
                throw new ArgumentException(message, "target");
            }

            //Buffer.BlockCopy(Data, 0, target.Data, 0, Data.Length * System.Runtime.InteropServices.Marshal.SizeOf(typeof(T)));
            Array.Copy(Data, 0, target.Data, 0, Data.Length);
        }

        public override void CopySubMatrixTo(MatrixStorage<T> target,
            int sourceRowIndex, int targetRowIndex, int rowCount,
            int sourceColumnIndex, int targetColumnIndex, int columnCount,
            bool skipClearing = false)
        {
            var denseTarget = target as DenseColumnMajorMatrixStorage<T>;
            if (denseTarget != null)
            {
                CopySubMatrixTo(denseTarget, sourceRowIndex, targetRowIndex, rowCount, sourceColumnIndex, targetColumnIndex, columnCount);
                return;
            }

            // FALL BACK

            base.CopySubMatrixTo(target, sourceRowIndex, targetRowIndex, rowCount, sourceColumnIndex, targetColumnIndex, columnCount, skipClearing);
        }

        void CopySubMatrixTo(DenseColumnMajorMatrixStorage<T> target,
            int sourceRowIndex, int targetRowIndex, int rowCount,
            int sourceColumnIndex, int targetColumnIndex, int columnCount)
        {
            if (target == null)
            {
                throw new ArgumentNullException("target");
            }

            if (ReferenceEquals(this, target))
            {
                throw new NotSupportedException();
            }

            ValidateSubMatrixRange(target,
                sourceRowIndex, targetRowIndex, rowCount,
                sourceColumnIndex, targetColumnIndex, columnCount);

            for (int j = sourceColumnIndex, jj = targetColumnIndex; j < sourceColumnIndex + columnCount; j++, jj++)
            {
                //Buffer.BlockCopy(Data, j*RowCount + sourceRowIndex, target.Data, jj*target.RowCount + targetRowIndex, rowCount * System.Runtime.InteropServices.Marshal.SizeOf(typeof(T)));
                Array.Copy(Data, j*RowCount + sourceRowIndex, target.Data, jj*target.RowCount + targetRowIndex, rowCount);
            }
        }
    }
}