using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Xml.Serialization;

namespace TransportGame.Utils
{
    public static class SerializationHelper
    {
        /// <summary>
        /// Converts float matrix to byte array
        /// </summary>
        /// <param name="matrix">Matrix to convert</param>
        /// <remarks>
        /// Bytes are stored as such:
        /// 
        ///     Offset  Size    Content
        ///     ------------------------
        ///     0       4       Width
        ///     4       8       Height
        ///     8       var     32bit floating point values    
        ///     
        /// </remarks>
        /// <returns>Byte array</returns>
        public static byte[] ToByteArray(this float[,] matrix)
        {
            if (matrix == null)
                return null;

            int w = matrix.GetLength(0);
            int h = matrix.GetLength(1);

            List<byte> bytes = new List<byte>();

            bytes.AddRange(BitConverter.GetBytes(w));
            bytes.AddRange(BitConverter.GetBytes(h));

            for (int x = 0; x < w; x++)
                for (int y = 0; y < h; y++)
                    bytes.AddRange(BitConverter.GetBytes(matrix[x, y]));

            return bytes.ToArray();
        }

        /// <summary>
        /// Converts byte array to float matrix
        /// </summary>
        /// <param name="array">Byte array</param>
        /// /// <remarks>
        /// Bytes are expected to be stored as such:
        /// 
        ///     Offset  Size    Content
        ///     ------------------------
        ///     0       4       Width
        ///     4       8       Height
        ///     8       var     32bit floating point values    
        ///     
        /// </remarks>
        /// <returns>Float matrix</returns>
        public static float[,] GetFloatMatrix(this byte[] array)
        {
            if (array == null)
                return null;

            int pos = 0;
            int w = BitConverter.ToInt32(array, pos); pos += sizeof(int);
            int h = BitConverter.ToInt32(array, pos); pos += sizeof(int);

            float[,] grid = new float[w, h];

            for (int x = 0; x < w; x++)
                for (int y = 0; y < h; y++)
                {
                    grid[x, y] = BitConverter.ToSingle(array, pos);
                    pos += sizeof(float);
                }

            return grid;
        }
        
        /// <summary>
        /// Deserializes a file
        /// </summary>
        /// <typeparam name="T">Type to deserialize</typeparam>
        /// <param name="filename">File name</param>
        /// <returns>Deserialized object</returns>
        public static T Deserialize<T>(string filename)
        {
            XmlSerializer serializer = new XmlSerializer(typeof(T));
            var stream = new StreamReader(filename);
            return (T)serializer.Deserialize(stream);
        }
    }
}