// <copyright file="DenseVectorStorage.cs" company="Math.NET">
// Math.NET Numerics, part of the Math.NET Project
// http://numerics.mathdotnet.com
// http://github.com/mathnet/mathnet-numerics
// http://mathnetnumerics.codeplex.com
//
// Copyright (c) 2009-2013 Math.NET
//
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using System;
using System.Collections.Generic;
using System.Linq;
using MathNet.Numerics.Properties;
using MathNet.Numerics.Threading;

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

        public readonly T[] Data;

        internal DenseVectorStorage(int length)
            : base(length)
        {
            Data = new T[length];
        }

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

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

            Data = data;
        }

        /// <summary>
        /// True if the vector storage format is dense.
        /// </summary>
        public override bool IsDense
        {
            get { return true; }
        }

        /// <summary>
        /// Retrieves the requested element without range checking.
        /// </summary>
        public override T At(int index)
        {
            return Data[index];
        }

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

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

        public override void Clear(int index, int count)
        {
            Array.Clear(Data, index, count);
        }

        // INITIALIZATION

        public static DenseVectorStorage<T> OfVector(VectorStorage<T> vector)
        {
            var storage = new DenseVectorStorage<T>(vector.Length);
            vector.CopyToUnchecked(storage, skipClearing: true);
            return storage;
        }

        public static DenseVectorStorage<T> OfInit(int length, Func<int, T> init)
        {
            if (length < 1)
            {
                throw new ArgumentOutOfRangeException("length", string.Format(Resources.ArgumentLessThanOne, length));
            }

            var data = new T[length];
            CommonParallel.For(0, data.Length, 4096, (a, b) =>
            {
                for (int i = a; i < b; i++)
                {
                    data[i] = init(i);
                }
            });
            return new DenseVectorStorage<T>(length, data);
        }

        public static DenseVectorStorage<T> OfEnumerable(IEnumerable<T> data)
        {
            if (data == null)
            {
                throw new ArgumentNullException("data");
            }

            var arrayData = data as T[];
            if (arrayData != null)
            {
                var copy = new T[arrayData.Length];
                Array.Copy(arrayData, copy, arrayData.Length);
                return new DenseVectorStorage<T>(copy.Length, copy);
            }

            var array = data.ToArray();
            return new DenseVectorStorage<T>(array.Length, array);
        }

        public static DenseVectorStorage<T> OfIndexedEnumerable(int length, IEnumerable<Tuple<int, T>> data)
        {
            if (data == null)
            {
                throw new ArgumentNullException("data");
            }

            var array = new T[length];
            foreach (var item in data)
            {
                array[item.Item1] = item.Item2;
            }
            return new DenseVectorStorage<T>(array.Length, array);
        }

        // VECTOR COPY

        internal override void CopyToUnchecked(VectorStorage<T> target, bool skipClearing = false)
        {
            var denseTarget = target as DenseVectorStorage<T>;
            if (denseTarget != null)
            {
                if (!ReferenceEquals(this, denseTarget))
                {
                    Array.Copy(Data, 0, denseTarget.Data, 0, Data.Length);
                }
                return;
            }

            // FALL BACK

            for (int i = 0; i < Data.Length; i++)
            {
                target.At(i, Data[i]);
            }
        }

        // ROW COPY

        internal override void CopyToRowUnchecked(MatrixStorage<T> target, int rowIndex, bool skipClearing = false)
        {
            var denseTarget = target as DenseColumnMajorMatrixStorage<T>;
            if (denseTarget != null)
            {
                for (int j = 0; j < Data.Length; j++)
                {
                    denseTarget.Data[j*target.RowCount + rowIndex] = Data[j];
                }
                return;
            }

            // FALL BACK

            for (int j = 0; j < Length; j++)
            {
                target.At(rowIndex, j, Data[j]);
            }
        }

        // COLUMN COPY

        internal override void CopyToColumnUnchecked(MatrixStorage<T> target, int columnIndex, bool skipClearing = false)
        {
            var denseTarget = target as DenseColumnMajorMatrixStorage<T>;
            if (denseTarget != null)
            {
                Array.Copy(Data, 0, denseTarget.Data, columnIndex*denseTarget.RowCount, Data.Length);
                return;
            }

            // FALL BACK

            for (int i = 0; i < Length; i++)
            {
                target.At(i, columnIndex, Data[i]);
            }
        }

        // SUB-VECTOR COPY

        internal override void CopySubVectorToUnchecked(VectorStorage<T> target,
            int sourceIndex, int targetIndex, int count,
            bool skipClearing = false)
        {
            var denseTarget = target as DenseVectorStorage<T>;
            if (denseTarget != null)
            {
                Array.Copy(Data, sourceIndex, denseTarget.Data, targetIndex, count);
                return;
            }

            // FALL BACK

            base.CopySubVectorToUnchecked(target, sourceIndex, targetIndex, count, skipClearing);
        }

        // SUB-ROW COPY

        internal override void CopyToSubRowUnchecked(MatrixStorage<T> target, int rowIndex,
            int sourceColumnIndex, int targetColumnIndex, int columnCount,
            bool skipClearing = false)
        {
            var denseTarget = target as DenseColumnMajorMatrixStorage<T>;
            if (denseTarget != null)
            {
                for (int j = 0; j < Data.Length; j++)
                {
                    denseTarget.Data[(j + targetColumnIndex)*target.RowCount + rowIndex] = Data[j + sourceColumnIndex];
                }
                return;
            }

            // FALL BACK

            for (int j = sourceColumnIndex, jj = targetColumnIndex; j < sourceColumnIndex + columnCount; j++, jj++)
            {
                target.At(rowIndex, jj, Data[j]);
            }
        }

        // SUB-COLUMN COPY

        internal override void CopyToSubColumnUnchecked(MatrixStorage<T> target, int columnIndex,
            int sourceRowIndex, int targetRowIndex, int rowCount,
            bool skipClearing = false)
        {
            var denseTarget = target as DenseColumnMajorMatrixStorage<T>;
            if (denseTarget != null)
            {
                Array.Copy(Data, sourceRowIndex, denseTarget.Data, columnIndex*denseTarget.RowCount + targetRowIndex, rowCount);
                return;
            }

            // FALL BACK

            for (int i = sourceRowIndex, ii = targetRowIndex; i < sourceRowIndex + rowCount; i++, ii++)
            {
                target.At(ii, columnIndex, Data[i]);
            }
        }

        // ENUMERATION

        public override IEnumerable<T> Enumerate()
        {
            return Data;
        }

        public override IEnumerable<Tuple<int, T>> EnumerateIndexed()
        {
            return Data.Select((t, i) => new Tuple<int, T>(i, t));
        }

        public override IEnumerable<T> EnumerateNonZero()
        {
            return Data.Where(x => !Zero.Equals(x));
        }

        public override IEnumerable<Tuple<int, T>> EnumerateNonZeroIndexed()
        {
            for (var i = 0; i < Data.Length; i++)
            {
                if (!Zero.Equals(Data[i]))
                {
                    yield return new Tuple<int, T>(i, Data[i]);
                }
            }
        }

        // FUNCTIONAL COMBINATORS

        internal override void MapToUnchecked<TU>(VectorStorage<TU> target, Func<T, TU> f, bool forceMapZeros = false, bool skipClearing = false)
        {
            var denseTarget = target as DenseVectorStorage<TU>;
            if (denseTarget != null)
            {
                CommonParallel.For(0, Data.Length, 4096, (a, b) =>
                {
                    for (int i = a; i < b; i++)
                    {
                        denseTarget.Data[i] = f(Data[i]);
                    }
                });
                return;
            }

            // FALL BACK

            for (int i = 0; i < Length; i++)
            {
                target.At(i, f(Data[i]));
            }
        }

        internal override void MapIndexedToUnchecked<TU>(VectorStorage<TU> target, Func<int, T, TU> f, bool forceMapZeros = false, bool skipClearing = false)
        {
            var denseTarget = target as DenseVectorStorage<TU>;
            if (denseTarget != null)
            {
                CommonParallel.For(0, Data.Length, 4096, (a, b) =>
                {
                    for (int i = a; i < b; i++)
                    {
                        denseTarget.Data[i] = f(i, Data[i]);
                    }
                });
                return;
            }

            // FALL BACK

            for (int i = 0; i < Length; i++)
            {
                target.At(i, f(i, Data[i]));
            }
        }
    }
}